construct confidence intervals: Topics by Science.gov

Sample records for construct confidence intervals

Confidence intervals for the population mean tailored to small sample sizes, with applications to survey sampling.

PubMed

Rosenblum, Michael A; Laan, Mark J van der

2009-01-07

The validity of standard confidence intervals constructed in survey sampling is based on the central limit theorem. For small sample sizes, the central limit theorem may give a poor approximation, resulting in confidence intervals that are misleading. We discuss this issue and propose methods for constructing confidence intervals for the population mean tailored to small sample sizes. We present a simple approach for constructing confidence intervals for the population mean based on tail bounds for the sample mean that are correct for all sample sizes. Bernstein's inequality provides one such tail bound. The resulting confidence intervals have guaranteed coverage probability under much weaker assumptions than are required for standard methods. A drawback of this approach, as we show, is that these confidence intervals are often quite wide. In response to this, we present a method for constructing much narrower confidence intervals, which are better suited for practical applications, and that are still more robust than confidence intervals based on standard methods, when dealing with small sample sizes. We show how to extend our approaches to much more general estimation problems than estimating the sample mean. We describe how these methods can be used to obtain more reliable confidence intervals in survey sampling. As a concrete example, we construct confidence intervals using our methods for the number of violent deaths between March 2003 and July 2006 in Iraq, based on data from the study "Mortality after the 2003 invasion of Iraq: A cross sectional cluster sample survey," by Burnham et al. (2006).
Sampling Theory and Confidence Intervals for Effect Sizes: Using ESCI To Illustrate "Bouncing"; Confidence Intervals.

ERIC Educational Resources Information Center

Du, Yunfei

This paper discusses the impact of sampling error on the construction of confidence intervals around effect sizes. Sampling error affects the location and precision of confidence intervals. Meta-analytic resampling demonstrates that confidence intervals can haphazardly bounce around the true population parameter. Special software with graphical…
Confidence intervals from single observations in forest research

Treesearch

Harry T. Valentine; George M. Furnival; Timothy G. Gregoire

1991-01-01

A procedure for constructing confidence intervals and testing hypothese from a single trial or observation is reviewed. The procedure requires a prior, fixed estimate or guess of the outcome of an experiment or sampling. Two examples of applications are described: a confidence interval is constructed for the expected outcome of a systematic sampling of a forested tract...
Constructing Confidence Intervals for Reliability Coefficients Using Central and Noncentral Distributions.

ERIC Educational Resources Information Center

Weber, Deborah A.

Greater understanding and use of confidence intervals is central to changes in statistical practice (G. Cumming and S. Finch, 2001). Reliability coefficients and confidence intervals for reliability coefficients can be computed using a variety of methods. Estimating confidence intervals includes both central and noncentral distribution approaches.…
Confidence intervals for distinguishing ordinal and disordinal interactions in multiple regression.

PubMed

Lee, Sunbok; Lei, Man-Kit; Brody, Gene H

2015-06-01

Distinguishing between ordinal and disordinal interaction in multiple regression is useful in testing many interesting theoretical hypotheses. Because the distinction is made based on the location of a crossover point of 2 simple regression lines, confidence intervals of the crossover point can be used to distinguish ordinal and disordinal interactions. This study examined 2 factors that need to be considered in constructing confidence intervals of the crossover point: (a) the assumption about the sampling distribution of the crossover point, and (b) the possibility of abnormally wide confidence intervals for the crossover point. A Monte Carlo simulation study was conducted to compare 6 different methods for constructing confidence intervals of the crossover point in terms of the coverage rate, the proportion of true values that fall to the left or right of the confidence intervals, and the average width of the confidence intervals. The methods include the reparameterization, delta, Fieller, basic bootstrap, percentile bootstrap, and bias-corrected accelerated bootstrap methods. The results of our Monte Carlo simulation study suggest that statistical inference using confidence intervals to distinguish ordinal and disordinal interaction requires sample sizes more than 500 to be able to provide sufficiently narrow confidence intervals to identify the location of the crossover point. (c) 2015 APA, all rights reserved).
Improved central confidence intervals for the ratio of Poisson means

NASA Astrophysics Data System (ADS)

Cousins, R. D.

The problem of confidence intervals for the ratio of two unknown Poisson means was "solved" decades ago, but a closer examination reveals that the standard solution is far from optimal from the frequentist point of view. We construct a more powerful set of central confidence intervals, each of which is a (typically proper) subinterval of the corresponding standard interval. They also provide upper and lower confidence limits which are more restrictive than the standard limits. The construction follows Neyman's original prescription, though discreteness of the Poisson distribution and the presence of a nuisance parameter (one of the unknown means) lead to slightly conservative intervals. Philosophically, the issue of the appropriateness of the construction method is similar to the issue of conditioning on the margins in 2×2 contingency tables. From a frequentist point of view, the new set maintains (over) coverage of the unknown true value of the ratio of means at each stated confidence level, even though the new intervals are shorter than the old intervals by any measure (except for two cases where they are identical). As an example, when the number 2 is drawn from each Poisson population, the 90% CL central confidence interval on the ratio of means is (0.169, 5.196), rather than (0.108, 9.245). In the cited literature, such confidence intervals have applications in numerous branches of pure and applied science, including agriculture, wildlife studies, manufacturing, medicine, reliability theory, and elementary particle physics.
Empirical likelihood-based confidence intervals for mean medical cost with censored data.

PubMed

Jeyarajah, Jenny; Qin, Gengsheng

2017-11-10

In this paper, we propose empirical likelihood methods based on influence function and jackknife techniques for constructing confidence intervals for mean medical cost with censored data. We conduct a simulation study to compare the coverage probabilities and interval lengths of our proposed confidence intervals with that of the existing normal approximation-based confidence intervals and bootstrap confidence intervals. The proposed methods have better finite-sample performances than existing methods. Finally, we illustrate our proposed methods with a relevant example. Copyright © 2017 John Wiley & Sons, Ltd.
Towards the estimation of effect measures in studies using respondent-driven sampling.

PubMed

Rotondi, Michael A

2014-06-01

Respondent-driven sampling (RDS) is an increasingly common sampling technique to recruit hidden populations. Statistical methods for RDS are not straightforward due to the correlation between individual outcomes and subject weighting; thus, analyses are typically limited to estimation of population proportions. This manuscript applies the method of variance estimates recovery (MOVER) to construct confidence intervals for effect measures such as risk difference (difference of proportions) or relative risk in studies using RDS. To illustrate the approach, MOVER is used to construct confidence intervals for differences in the prevalence of demographic characteristics between an RDS study and convenience study of injection drug users. MOVER is then applied to obtain a confidence interval for the relative risk between education levels and HIV seropositivity and current infection with syphilis, respectively. This approach provides a simple method to construct confidence intervals for effect measures in RDS studies. Since it only relies on a proportion and appropriate confidence limits, it can also be applied to previously published manuscripts.
A comparison of confidence interval methods for the intraclass correlation coefficient in community-based cluster randomization trials with a binary outcome.

PubMed

Braschel, Melissa C; Svec, Ivana; Darlington, Gerarda A; Donner, Allan

2016-04-01

Many investigators rely on previously published point estimates of the intraclass correlation coefficient rather than on their associated confidence intervals to determine the required size of a newly planned cluster randomized trial. Although confidence interval methods for the intraclass correlation coefficient that can be applied to community-based trials have been developed for a continuous outcome variable, fewer methods exist for a binary outcome variable. The aim of this study is to evaluate confidence interval methods for the intraclass correlation coefficient applied to binary outcomes in community intervention trials enrolling a small number of large clusters. Existing methods for confidence interval construction are examined and compared to a new ad hoc approach based on dividing clusters into a large number of smaller sub-clusters and subsequently applying existing methods to the resulting data. Monte Carlo simulation is used to assess the width and coverage of confidence intervals for the intraclass correlation coefficient based on Smith's large sample approximation of the standard error of the one-way analysis of variance estimator, an inverted modified Wald test for the Fleiss-Cuzick estimator, and intervals constructed using a bootstrap-t applied to a variance-stabilizing transformation of the intraclass correlation coefficient estimate. In addition, a new approach is applied in which clusters are randomly divided into a large number of smaller sub-clusters with the same methods applied to these data (with the exception of the bootstrap-t interval, which assumes large cluster sizes). These methods are also applied to a cluster randomized trial on adolescent tobacco use for illustration. When applied to a binary outcome variable in a small number of large clusters, existing confidence interval methods for the intraclass correlation coefficient provide poor coverage. However, confidence intervals constructed using the new approach combined with Smith's method provide nominal or close to nominal coverage when the intraclass correlation coefficient is small (<0.05), as is the case in most community intervention trials. This study concludes that when a binary outcome variable is measured in a small number of large clusters, confidence intervals for the intraclass correlation coefficient may be constructed by dividing existing clusters into sub-clusters (e.g. groups of 5) and using Smith's method. The resulting confidence intervals provide nominal or close to nominal coverage across a wide range of parameters when the intraclass correlation coefficient is small (<0.05). Application of this method should provide investigators with a better understanding of the uncertainty associated with a point estimator of the intraclass correlation coefficient used for determining the sample size needed for a newly designed community-based trial. © The Author(s) 2015.
Intervals for posttest probabilities: a comparison of 5 methods.

PubMed

Mossman, D; Berger, J O

2001-01-01

Several medical articles discuss methods of constructing confidence intervals for single proportions and the likelihood ratio, but scant attention has been given to the systematic study of intervals for the posterior odds, or the positive predictive value, of a test. The authors describe 5 methods of constructing confidence intervals for posttest probabilities when estimates of sensitivity, specificity, and the pretest probability of a disorder are derived from empirical data. They then evaluate each method to determine how well the intervals' coverage properties correspond to their nominal value. When the estimates of pretest probabilities, sensitivity, and specificity are derived from more than 80 subjects and are not close to 0 or 1, all methods generate intervals with appropriate coverage properties. When these conditions are not met, however, the best-performing method is an objective Bayesian approach implemented by a simple simulation using a spreadsheet. Physicians and investigators can generate accurate confidence intervals for posttest probabilities in small-sample situations using the objective Bayesian approach.
Quantitative imaging biomarkers: Effect of sample size and bias on confidence interval coverage.

PubMed

Obuchowski, Nancy A; Bullen, Jennifer

2017-01-01

Introduction Quantitative imaging biomarkers (QIBs) are being increasingly used in medical practice and clinical trials. An essential first step in the adoption of a quantitative imaging biomarker is the characterization of its technical performance, i.e. precision and bias, through one or more performance studies. Then, given the technical performance, a confidence interval for a new patient's true biomarker value can be constructed. Estimating bias and precision can be problematic because rarely are both estimated in the same study, precision studies are usually quite small, and bias cannot be measured when there is no reference standard. Methods A Monte Carlo simulation study was conducted to assess factors affecting nominal coverage of confidence intervals for a new patient's quantitative imaging biomarker measurement and for change in the quantitative imaging biomarker over time. Factors considered include sample size for estimating bias and precision, effect of fixed and non-proportional bias, clustered data, and absence of a reference standard. Results Technical performance studies of a quantitative imaging biomarker should include at least 35 test-retest subjects to estimate precision and 65 cases to estimate bias. Confidence intervals for a new patient's quantitative imaging biomarker measurement constructed under the no-bias assumption provide nominal coverage as long as the fixed bias is <12%. For confidence intervals of the true change over time, linearity must hold and the slope of the regression of the measurements vs. true values should be between 0.95 and 1.05. The regression slope can be assessed adequately as long as fixed multiples of the measurand can be generated. Even small non-proportional bias greatly reduces confidence interval coverage. Multiple lesions in the same subject can be treated as independent when estimating precision. Conclusion Technical performance studies of quantitative imaging biomarkers require moderate sample sizes in order to provide robust estimates of bias and precision for constructing confidence intervals for new patients. Assumptions of linearity and non-proportional bias should be assessed thoroughly.
Confidence intervals for population allele frequencies: the general case of sampling from a finite diploid population of any size.

PubMed

Fung, Tak; Keenan, Kevin

2014-01-01

The estimation of population allele frequencies using sample data forms a central component of studies in population genetics. These estimates can be used to test hypotheses on the evolutionary processes governing changes in genetic variation among populations. However, existing studies frequently do not account for sampling uncertainty in these estimates, thus compromising their utility. Incorporation of this uncertainty has been hindered by the lack of a method for constructing confidence intervals containing the population allele frequencies, for the general case of sampling from a finite diploid population of any size. In this study, we address this important knowledge gap by presenting a rigorous mathematical method to construct such confidence intervals. For a range of scenarios, the method is used to demonstrate that for a particular allele, in order to obtain accurate estimates within 0.05 of the population allele frequency with high probability (> or = 95%), a sample size of > 30 is often required. This analysis is augmented by an application of the method to empirical sample allele frequency data for two populations of the checkerspot butterfly (Melitaea cinxia L.), occupying meadows in Finland. For each population, the method is used to derive > or = 98.3% confidence intervals for the population frequencies of three alleles. These intervals are then used to construct two joint > or = 95% confidence regions, one for the set of three frequencies for each population. These regions are then used to derive a > or = 95%% confidence interval for Jost's D, a measure of genetic differentiation between the two populations. Overall, the results demonstrate the practical utility of the method with respect to informing sampling design and accounting for sampling uncertainty in studies of population genetics, important for scientific hypothesis-testing and also for risk-based natural resource management.
Exact Scheffé-type confidence intervals for output from groundwater flow models: 2. Combined use of hydrogeologic information and calibration data

USGS Publications Warehouse

Cooley, Richard L.

1993-01-01

Calibration data (observed values corresponding to model-computed values of dependent variables) are incorporated into a general method of computing exact Scheffé-type confidence intervals analogous to the confidence intervals developed in part 1 (Cooley, this issue) for a function of parameters derived from a groundwater flow model. Parameter uncertainty is specified by a distribution of parameters conditioned on the calibration data. This distribution was obtained as a posterior distribution by applying Bayes' theorem to the hydrogeologically derived prior distribution of parameters from part 1 and a distribution of differences between the calibration data and corresponding model-computed dependent variables. Tests show that the new confidence intervals can be much smaller than the intervals of part 1 because the prior parameter variance-covariance structure is altered so that combinations of parameters that give poor model fit to the data are unlikely. The confidence intervals of part 1 and the new confidence intervals can be effectively employed in a sequential method of model construction whereby new information is used to reduce confidence interval widths at each stage.
Four Bootstrap Confidence Intervals for the Binomial-Error Model.

ERIC Educational Resources Information Center

Lin, Miao-Hsiang; Hsiung, Chao A.

1992-01-01

Four bootstrap methods are identified for constructing confidence intervals for the binomial-error model. The extent to which similar results are obtained and the theoretical foundation of each method and its relevance and ranges of modeling the true score uncertainty are discussed. (SLD)
Statistical inference for remote sensing-based estimates of net deforestation

Treesearch

Ronald E. McRoberts; Brian F. Walters

2012-01-01

Statistical inference requires expression of an estimate in probabilistic terms, usually in the form of a confidence interval. An approach to constructing confidence intervals for remote sensing-based estimates of net deforestation is illustrated. The approach is based on post-classification methods using two independent forest/non-forest classifications because...
Profile-likelihood Confidence Intervals in Item Response Theory Models.

PubMed

Chalmers, R Philip; Pek, Jolynn; Liu, Yang

2017-01-01

Confidence intervals (CIs) are fundamental inferential devices which quantify the sampling variability of parameter estimates. In item response theory, CIs have been primarily obtained from large-sample Wald-type approaches based on standard error estimates, derived from the observed or expected information matrix, after parameters have been estimated via maximum likelihood. An alternative approach to constructing CIs is to quantify sampling variability directly from the likelihood function with a technique known as profile-likelihood confidence intervals (PL CIs). In this article, we introduce PL CIs for item response theory models, compare PL CIs to classical large-sample Wald-type CIs, and demonstrate important distinctions among these CIs. CIs are then constructed for parameters directly estimated in the specified model and for transformed parameters which are often obtained post-estimation. Monte Carlo simulation results suggest that PL CIs perform consistently better than Wald-type CIs for both non-transformed and transformed parameters.
Confidence intervals and sample size calculations for the standardized mean difference effect size between two normal populations under heteroscedasticity.

PubMed

Shieh, G

2013-12-01

The use of effect sizes and associated confidence intervals in all empirical research has been strongly emphasized by journal publication guidelines. To help advance theory and practice in the social sciences, this article describes an improved procedure for constructing confidence intervals of the standardized mean difference effect size between two independent normal populations with unknown and possibly unequal variances. The presented approach has advantages over the existing formula in both theoretical justification and computational simplicity. In addition, simulation results show that the suggested one- and two-sided confidence intervals are more accurate in achieving the nominal coverage probability. The proposed estimation method provides a feasible alternative to the most commonly used measure of Cohen's d and the corresponding interval procedure when the assumption of homogeneous variances is not tenable. To further improve the potential applicability of the suggested methodology, the sample size procedures for precise interval estimation of the standardized mean difference are also delineated. The desired precision of a confidence interval is assessed with respect to the control of expected width and to the assurance probability of interval width within a designated value. Supplementary computer programs are developed to aid in the usefulness and implementation of the introduced techniques.
Another look at confidence intervals: Proposal for a more relevant and transparent approach

NASA Astrophysics Data System (ADS)

Biller, Steven D.; Oser, Scott M.

2015-02-01

The behaviors of various confidence/credible interval constructions are explored, particularly in the region of low event numbers where methods diverge most. We highlight a number of challenges, such as the treatment of nuisance parameters, and common misconceptions associated with such constructions. An informal survey of the literature suggests that confidence intervals are not always defined in relevant ways and are too often misinterpreted and/or misapplied. This can lead to seemingly paradoxical behaviors and flawed comparisons regarding the relevance of experimental results. We therefore conclude that there is a need for a more pragmatic strategy which recognizes that, while it is critical to objectively convey the information content of the data, there is also a strong desire to derive bounds on model parameter values and a natural instinct to interpret things this way. Accordingly, we attempt to put aside philosophical biases in favor of a practical view to propose a more transparent and self-consistent approach that better addresses these issues.
Confidence Intervals from Realizations of Simulated Nuclear Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Younes, W.; Ratkiewicz, A.; Ressler, J. J.

2017-09-28

Various statistical techniques are discussed that can be used to assign a level of confidence in the prediction of models that depend on input data with known uncertainties and correlations. The particular techniques reviewed in this paper are: 1) random realizations of the input data using Monte-Carlo methods, 2) the construction of confidence intervals to assess the reliability of model predictions, and 3) resampling techniques to impose statistical constraints on the input data based on additional information. These techniques are illustrated with a calculation of the keff value, based on the 235U(n, f) and 239Pu (n, f) cross sections.
Proportion of general factor variance in a hierarchical multiple-component measuring instrument: a note on a confidence interval estimation procedure.

PubMed

Raykov, Tenko; Zinbarg, Richard E

2011-05-01

A confidence interval construction procedure for the proportion of explained variance by a hierarchical, general factor in a multi-component measuring instrument is outlined. The method provides point and interval estimates for the proportion of total scale score variance that is accounted for by the general factor, which could be viewed as common to all components. The approach may also be used for testing composite (one-tailed) or simple hypotheses about this proportion, and is illustrated with a pair of examples. ©2010 The British Psychological Society.

Using Stochastic Approximation Techniques to Efficiently Construct Confidence Intervals for Heritability.

PubMed

Schweiger, Regev; Fisher, Eyal; Rahmani, Elior; Shenhav, Liat; Rosset, Saharon; Halperin, Eran

2018-06-22

Estimation of heritability is an important task in genetics. The use of linear mixed models (LMMs) to determine narrow-sense single-nucleotide polymorphism (SNP)-heritability and related quantities has received much recent attention, due of its ability to account for variants with small effect sizes. Typically, heritability estimation under LMMs uses the restricted maximum likelihood (REML) approach. The common way to report the uncertainty in REML estimation uses standard errors (SEs), which rely on asymptotic properties. However, these assumptions are often violated because of the bounded parameter space, statistical dependencies, and limited sample size, leading to biased estimates and inflated or deflated confidence intervals (CIs). In addition, for larger data sets (e.g., tens of thousands of individuals), the construction of SEs itself may require considerable time, as it requires expensive matrix inversions and multiplications. Here, we present FIESTA (Fast confidence IntErvals using STochastic Approximation), a method for constructing accurate CIs. FIESTA is based on parametric bootstrap sampling, and, therefore, avoids unjustified assumptions on the distribution of the heritability estimator. FIESTA uses stochastic approximation techniques, which accelerate the construction of CIs by several orders of magnitude, compared with previous approaches as well as to the analytical approximation used by SEs. FIESTA builds accurate CIs rapidly, for example, requiring only several seconds for data sets of tens of thousands of individuals, making FIESTA a very fast solution to the problem of building accurate CIs for heritability for all data set sizes.
Diagnostic accuracy of the Amsler grid and the preferential hyperacuity perimetry in the screening of patients with age-related macular degeneration: systematic review and meta-analysis.

PubMed

Faes, L; Bodmer, N S; Bachmann, L M; Thiel, M A; Schmid, M K

2014-07-01

To clarify the screening potential of the Amsler grid and preferential hyperacuity perimetry (PHP) in detecting or ruling out wet age-related macular degeneration (AMD). Medline, Scopus and Web of Science (by citation of reference) were searched. Checking of reference lists of review articles and of included articles complemented electronic searches. Papers were selected, assessed, and extracted in duplicate. Systematic review and meta-analysis. Twelve included studies enrolled 903 patients and allowed constructing 27 two-by-two tables. Twelve tables reported on the Amsler grid and its modifications, twelve tables reported on the PHP, one table assessed the MCPT and two tables assessed the M-charts. All but two studies had a case-control design. The pooled sensitivity of studies assessing the Amsler grid was 0.78 (95% confidence intervals; 0.64-0.87), and the pooled specificity was 0.97 (95% confidence intervals; 0.91-0.99). The corresponding positive and negative likelihood ratios were 23.1 (95% confidence intervals; 8.4-64.0) and 0.23 (95% confidence intervals; 0.14-0.39), respectively. The pooled sensitivity of studies assessing the PHP was 0.85 (95% confidence intervals; 0.80-0.89), and specificity was 0.87 (95% confidence intervals; 0.82-0.91). The corresponding positive and negative likelihood ratios were 6.7 (95% confidence intervals; 4.6-9.8) and 0.17 (95% confidence intervals; 0.13-0.23). No pooling was possible for MCPT and M-charts. Results from small preliminary studies show promising test performance characteristics both for the Amsler grid and PHP to rule out wet AMD in the screening setting. To what extent these findings can be transferred to a real clinic practice still needs to be established.
Confidence limit calculation for antidotal potency ratio derived from lethal dose 50

PubMed Central

Manage, Ananda; Petrikovics, Ilona

2013-01-01

AIM: To describe confidence interval calculation for antidotal potency ratios using bootstrap method. METHODS: We can easily adapt the nonparametric bootstrap method which was invented by Efron to construct confidence intervals in such situations like this. The bootstrap method is a resampling method in which the bootstrap samples are obtained by resampling from the original sample. RESULTS: The described confidence interval calculation using bootstrap method does not require the sampling distribution antidotal potency ratio. This can serve as a substantial help for toxicologists, who are directed to employ the Dixon up-and-down method with the application of lower number of animals to determine lethal dose 50 values for characterizing the investigated toxic molecules and eventually for characterizing the antidotal protections by the test antidotal systems. CONCLUSION: The described method can serve as a useful tool in various other applications. Simplicity of the method makes it easier to do the calculation using most of the programming software packages. PMID:25237618
Nonparametric spirometry reference values for Hispanic Americans.

PubMed

Glenn, Nancy L; Brown, Vanessa M

2011-02-01

Recent literature sites ethnic origin as a major factor in developing pulmonary function reference values. Extensive studies established reference values for European and African Americans, but not for Hispanic Americans. The Third National Health and Nutrition Examination Survey defines Hispanic as individuals of Spanish speaking cultures. While no group was excluded from the target population, sample size requirements only allowed inclusion of individuals who identified themselves as Mexican Americans. This research constructs nonparametric reference value confidence intervals for Hispanic American pulmonary function. The method is applicable to all ethnicities. We use empirical likelihood confidence intervals to establish normal ranges for reference values. Its major advantage: it is model free, but shares asymptotic properties of model based methods. Statistical comparisons indicate that empirical likelihood interval lengths are comparable to normal theory intervals. Power and efficiency studies agree with previously published theoretical results.
Confidence in Altman-Bland plots: a critical review of the method of differences.

PubMed

Ludbrook, John

2010-02-01

1. Altman and Bland argue that the virtue of plotting differences against averages in method-comparison studies is that 95% confidence limits for the differences can be constructed. These allow authors and readers to judge whether one method of measurement could be substituted for another. 2. The technique is often misused. So I have set out, by statistical argument and worked examples, to advise pharmacologists and physiologists how best to construct these limits. 3. First, construct a scattergram of differences on averages, then calculate the line of best fit for the linear regression of differences on averages. If the slope of the regression is shown to differ from zero, there is proportional bias. 4. If there is no proportional bias and if the scatter of differences is uniform (homoscedasticity), construct 'classical' 95% confidence limits. 5. If there is proportional bias yet homoscedasticity, construct hyperbolic 95% confidence limits (prediction interval) around the line of best fit. 6. If there is proportional bias and the scatter of values for differences increases progressively as the average values increase (heteroscedasticity), log-transform the raw values from the two methods and replot differences against averages. If this eliminates proportional bias and heteroscedasticity, construct 'classical' 95% confidence limits. Otherwise, construct horizontal V-shaped 95% confidence limits around the line of best fit of differences on averages or around the weighted least products line of best fit to the original data. 7. In designing a method-comparison study, consult a qualified biostatistician, obey the rules of randomization and make replicate observations.
Methods for calculating confidence and credible intervals for the residual between-study variance in random effects meta-regression models

PubMed Central

2014-01-01

Background Meta-regression is becoming increasingly used to model study level covariate effects. However this type of statistical analysis presents many difficulties and challenges. Here two methods for calculating confidence intervals for the magnitude of the residual between-study variance in random effects meta-regression models are developed. A further suggestion for calculating credible intervals using informative prior distributions for the residual between-study variance is presented. Methods Two recently proposed and, under the assumptions of the random effects model, exact methods for constructing confidence intervals for the between-study variance in random effects meta-analyses are extended to the meta-regression setting. The use of Generalised Cochran heterogeneity statistics is extended to the meta-regression setting and a Newton-Raphson procedure is developed to implement the Q profile method for meta-analysis and meta-regression. WinBUGS is used to implement informative priors for the residual between-study variance in the context of Bayesian meta-regressions. Results Results are obtained for two contrasting examples, where the first example involves a binary covariate and the second involves a continuous covariate. Intervals for the residual between-study variance are wide for both examples. Conclusions Statistical methods, and R computer software, are available to compute exact confidence intervals for the residual between-study variance under the random effects model for meta-regression. These frequentist methods are almost as easily implemented as their established counterparts for meta-analysis. Bayesian meta-regressions are also easily performed by analysts who are comfortable using WinBUGS. Estimates of the residual between-study variance in random effects meta-regressions should be routinely reported and accompanied by some measure of their uncertainty. Confidence and/or credible intervals are well-suited to this purpose. PMID:25196829
Robust Coefficients Alpha and Omega and Confidence Intervals With Outlying Observations and Missing Data: Methods and Software.

PubMed

Zhang, Zhiyong; Yuan, Ke-Hai

2016-06-01

Cronbach's coefficient alpha is a widely used reliability measure in social, behavioral, and education sciences. It is reported in nearly every study that involves measuring a construct through multiple items. With non-tau-equivalent items, McDonald's omega has been used as a popular alternative to alpha in the literature. Traditional estimation methods for alpha and omega often implicitly assume that data are complete and normally distributed. This study proposes robust procedures to estimate both alpha and omega as well as corresponding standard errors and confidence intervals from samples that may contain potential outlying observations and missing values. The influence of outlying observations and missing data on the estimates of alpha and omega is investigated through two simulation studies. Results show that the newly developed robust method yields substantially improved alpha and omega estimates as well as better coverage rates of confidence intervals than the conventional nonrobust method. An R package coefficientalpha is developed and demonstrated to obtain robust estimates of alpha and omega.
Robust Coefficients Alpha and Omega and Confidence Intervals With Outlying Observations and Missing Data

PubMed Central

Zhang, Zhiyong; Yuan, Ke-Hai

2015-01-01

Cronbach’s coefficient alpha is a widely used reliability measure in social, behavioral, and education sciences. It is reported in nearly every study that involves measuring a construct through multiple items. With non-tau-equivalent items, McDonald’s omega has been used as a popular alternative to alpha in the literature. Traditional estimation methods for alpha and omega often implicitly assume that data are complete and normally distributed. This study proposes robust procedures to estimate both alpha and omega as well as corresponding standard errors and confidence intervals from samples that may contain potential outlying observations and missing values. The influence of outlying observations and missing data on the estimates of alpha and omega is investigated through two simulation studies. Results show that the newly developed robust method yields substantially improved alpha and omega estimates as well as better coverage rates of confidence intervals than the conventional nonrobust method. An R package coefficientalpha is developed and demonstrated to obtain robust estimates of alpha and omega. PMID:29795870
Joint distribution approaches to simultaneously quantifying benefit and risk.

PubMed

Shaffer, Michele L; Watterberg, Kristi L

2006-10-12

The benefit-risk ratio has been proposed to measure the tradeoff between benefits and risks of two therapies for a single binary measure of efficacy and a single adverse event. The ratio is calculated from the difference in risk and difference in benefit between therapies. Small sample sizes or expected differences in benefit or risk can lead to no solution or problematic solutions for confidence intervals. Alternatively, using the joint distribution of benefit and risk, confidence regions for the differences in risk and benefit can be constructed in the benefit-risk plane. The information in the joint distribution can be summarized by choosing regions of interest in this plane. Using Bayesian methodology provides a very flexible framework for summarizing information in the joint distribution. Data from a National Institute of Child Health & Human Development trial of hydrocortisone illustrate the construction of confidence regions and regions of interest in the benefit-risk plane, where benefit is survival without supplemental oxygen at 36 weeks postmenstrual age, and risk is gastrointestinal perforation. For the subgroup of infants exposed to chorioamnionitis the confidence interval based on the benefit-risk ratio is wide (Benefit-risk ratio: 1.52; 90% confidence interval: 0.23 to 5.25). Choosing regions of appreciable risk and acceptable risk in the benefit-risk plane confirms the uncertainty seen in the wide confidence interval for the benefit-risk ratio--there is a greater than 50% chance of falling into the region of acceptable risk--while visually allowing the uncertainty in risk and benefit to be shown separately. Applying Bayesian methodology, an incremental net health benefit analysis shows there is a 72% chance of having a positive incremental net benefit if hydrocortisone is used in place of placebo if one is willing to incur at most one gastrointestinal perforation for each additional infant that survives without supplemental oxygen. If the benefit-risk ratio is presented, the joint distribution of benefit and risk also should be shown. These regions avoid the ambiguity associated with collapsing benefit and risk to a single dimension. Bayesian methods allow even greater flexibility in simultaneously quantifying benefit and risk.
Precision Interval Estimation of the Response Surface by Means of an Integrated Algorithm of Neural Network and Linear Regression

NASA Technical Reports Server (NTRS)

Lo, Ching F.

1999-01-01

The integration of Radial Basis Function Networks and Back Propagation Neural Networks with the Multiple Linear Regression has been accomplished to map nonlinear response surfaces over a wide range of independent variables in the process of the Modem Design of Experiments. The integrated method is capable to estimate the precision intervals including confidence and predicted intervals. The power of the innovative method has been demonstrated by applying to a set of wind tunnel test data in construction of response surface and estimation of precision interval.
Confidence intervals for single-case effect size measures based on randomization test inversion.

PubMed

Michiels, Bart; Heyvaert, Mieke; Meulders, Ann; Onghena, Patrick

2017-02-01

In the current paper, we present a method to construct nonparametric confidence intervals (CIs) for single-case effect size measures in the context of various single-case designs. We use the relationship between a two-sided statistical hypothesis test at significance level α and a 100 (1 - α) % two-sided CI to construct CIs for any effect size measure θ that contain all point null hypothesis θ values that cannot be rejected by the hypothesis test at significance level α. This method of hypothesis test inversion (HTI) can be employed using a randomization test as the statistical hypothesis test in order to construct a nonparametric CI for θ. We will refer to this procedure as randomization test inversion (RTI). We illustrate RTI in a situation in which θ is the unstandardized and the standardized difference in means between two treatments in a completely randomized single-case design. Additionally, we demonstrate how RTI can be extended to other types of single-case designs. Finally, we discuss a few challenges for RTI as well as possibilities when using the method with other effect size measures, such as rank-based nonoverlap indices. Supplementary to this paper, we provide easy-to-use R code, which allows the user to construct nonparametric CIs according to the proposed method.
The risk of lung cancer after cessation of asbestos exposure in construction workers using pleural malignant mesothelioma as a marker of exposure.

PubMed

Järvholm, Bengt; Aström, Evelina

2014-12-01

To study the risk of lung cancer in heavily asbestos-exposed workers after the exposure to asbestos has ended. Lung cancer was studied in a cohort of 189,896 Swedish construction workers through a linkage with the Swedish Cancer Registry. Asbestos exposure was estimated by the incidence of malignant mesothelioma in the occupational group. There were in total 2835 cases of lung cancer. Workers with heavy exposure to asbestos had an increased risk of lung cancer (relative risks = 1.74; 95% confidence interval, 1.25 to 2.41) before exposure ended and a similar risk to those with low exposure 20 years after the exposure had ceased (relative risks = 0.94; 95% confidence interval, 0.77 to 1.15). Workers with heavy exposure to asbestos have a similar risk of lung cancer as persons with low or no exposure 20 years after the exposure has ended.
High definition versus standard definition white light endoscopy for detecting dysplasia in patients with Barrett's esophagus.

PubMed

Sami, S S; Subramanian, V; Butt, W M; Bejkar, G; Coleman, J; Mannath, J; Ragunath, K

2015-01-01

High-definition endoscopy systems provide superior image resolution. The aim of this study was to assess the utility of high definition compared with standard definition endoscopy system for detecting dysplastic lesions in patients with Barrett's esophagus. A retrospective cohort study of patients with non-dysplastic Barrett's esophagus undergoing routine surveillance was performed. Data were retrieved from the central hospital electronic database. Procedures performed for non-surveillance indications, Barrett's esophagus Prague C0M1 classification with no specialized intestinal metaplasia on histology, patients diagnosed with any dysplasia or cancer on index endoscopy, and procedures using advanced imaging techniques were excluded. Logistic regression models were constructed to estimate adjusted odds ratios and 95% confidence intervals comparing outcomes with standard definition and high-definition systems. The high definition was superior to standard definition system in targeted detection of all dysplastic lesions (odds ratio 3.27, 95% confidence interval 1.27-8.40) as well as overall dysplasia detected on both random and target biopsies (odds ratio 2.36, 95% confidence interval 1.50-3.72). More non-dysplastic lesions were detected with the high-definition system (odds ratio 1.16, 95% confidence interval 1.01-1.33). There was no difference between high definition and standard definition endoscopy in the overall (random and target) high-grade dysplasia or cancers detected (odds ratio 0.93, 95% confidence interval 0.83-1.04). Trainee endoscopists, number of biopsies taken, and male sex were all significantly associated with a higher yield for dysplastic lesions. The use of the high-definition endoscopy system is associated with better targeted detection of any dysplasia during routine Barrett's esophagus surveillance. However, high-definition endoscopy cannot replace random biopsies at present time. © 2014 International Society for Diseases of the Esophagus.
Persistent opioid use following Cesarean delivery: patterns and predictors among opioid naïve women

PubMed Central

Bateman, Brian T.; Franklin, Jessica M.; Bykov, Katsiaryna; Avorn, Jerry; Shrank, William H.; Brennan, Troyen A.; Landon, Joan E.; Rathmell, James P.; Huybrechts, Krista F.; Fischer, Michael A.; Choudhry, Niteesh K.

2016-01-01

Background The incidence of opioid-related death in women has increased five-fold over the past decade. For many women, their initial opioid exposure will occur in the setting of routine medical care. Approximately 1 in 3 deliveries in the U.S. is by Cesarean and opioids are commonly prescribed for post-surgical pain management. Objective The objective of this study was to determine the risk that opioid naïve women prescribed opioids after Cesarean delivery will subsequently become consistent prescription opioid users in the year following delivery, and to identify predictors for this behavior. Study Design We identified women in a database of commercial insurance beneficiaries who underwent Cesarean delivery and who were opioid-naïve in the year prior to delivery. To identify persistent users of opioids, we used trajectory models, which group together patients with similar patterns of medication filling during follow-up, based on patterns of opioid dispensing in the year following Cesarean delivery. We then constructed a multivariable logistic regression model to identify independent risk factors for membership in the persistent user group. Results 285 of 80,127 (0.36%, 95% confidence interval 0.32 to 0.40), opioid-naïve women became persistent opioid users (identified using trajectory models based on monthly patterns of opioid dispensing) following Cesarean delivery. Demographics and baseline comorbidity predicted such use with moderate discrimination (c statistic = 0.73). Significant predictors included a history of cocaine abuse (risk 7.41%; adjusted odds ratio 6.11, 95% confidence interval 1.03 to 36.31) and other illicit substance abuse (2.36%; adjusted odds ratio 2.78, 95% confidence interval 1.12 to 6.91), tobacco use (1.45%; adjusted odds ratio 3.04, 95% confidence interval 2.03 to 4.55), back pain (0.69%; adjusted odds ratio 1.74, 95% confidence interval 1.33 to 2.29), migraines (0.91%; adjusted odds ratio 2.14, 95% confidence interval 1.58 to 2.90), antidepressant use (1.34%; adjusted odds ratio 3.19, 95% confidence interval 2.41 to 4.23) and benzodiazepine use (1.99%; adjusted odds ratio 3.72, 95% confidence interval 2.64 to 5.26) in the year prior to Cesarean delivery. Conclusions A very small proportion of opioid-naïve women (approximately 1 in 300) become persistent prescription opioid users following Cesarean delivery. Pre-existing psychiatric comorbidity, certain pain conditions, and substance use/abuse conditions identifiable at the time of initial opioid prescribing were predictors of persistent use. PMID:26996986
Confidence intervals for the first crossing point of two hazard functions.

PubMed

Cheng, Ming-Yen; Qiu, Peihua; Tan, Xianming; Tu, Dongsheng

2009-12-01

The phenomenon of crossing hazard rates is common in clinical trials with time to event endpoints. Many methods have been proposed for testing equality of hazard functions against a crossing hazards alternative. However, there has been relatively few approaches available in the literature for point or interval estimation of the crossing time point. The problem of constructing confidence intervals for the first crossing time point of two hazard functions is considered in this paper. After reviewing a recent procedure based on Cox proportional hazard modeling with Box-Cox transformation of the time to event, a nonparametric procedure using the kernel smoothing estimate of the hazard ratio is proposed. The proposed procedure and the one based on Cox proportional hazard modeling with Box-Cox transformation of the time to event are both evaluated by Monte-Carlo simulations and applied to two clinical trial datasets.
Quantile regression models of animal habitat relationships

USGS Publications Warehouse

Cade, Brian S.

2003-01-01

Typically, all factors that limit an organism are not measured and included in statistical models used to investigate relationships with their environment. If important unmeasured variables interact multiplicatively with the measured variables, the statistical models often will have heterogeneous response distributions with unequal variances. Quantile regression is an approach for estimating the conditional quantiles of a response variable distribution in the linear model, providing a more complete view of possible causal relationships between variables in ecological processes. Chapter 1 introduces quantile regression and discusses the ordering characteristics, interval nature, sampling variation, weighting, and interpretation of estimates for homogeneous and heterogeneous regression models. Chapter 2 evaluates performance of quantile rankscore tests used for hypothesis testing and constructing confidence intervals for linear quantile regression estimates (0 ≤ τ ≤ 1). A permutation F test maintained better Type I errors than the Chi-square T test for models with smaller n, greater number of parameters p, and more extreme quantiles τ. Both versions of the test required weighting to maintain correct Type I errors when there was heterogeneity under the alternative model. An example application related trout densities to stream channel width:depth. Chapter 3 evaluates a drop in dispersion, F-ratio like permutation test for hypothesis testing and constructing confidence intervals for linear quantile regression estimates (0 ≤ τ ≤ 1). Chapter 4 simulates from a large (N = 10,000) finite population representing grid areas on a landscape to demonstrate various forms of hidden bias that might occur when the effect of a measured habitat variable on some animal was confounded with the effect of another unmeasured variable (spatially and not spatially structured). Depending on whether interactions of the measured habitat and unmeasured variable were negative (interference interactions) or positive (facilitation interactions), either upper (τ > 0.5) or lower (τ < 0.5) quantile regression parameters were less biased than mean rate parameters. Sampling (n = 20 - 300) simulations demonstrated that confidence intervals constructed by inverting rankscore tests provided valid coverage of these biased parameters. Quantile regression was used to estimate effects of physical habitat resources on a bivalve mussel (Macomona liliana) in a New Zealand harbor by modeling the spatial trend surface as a cubic polynomial of location coordinates.
Reliable results from stochastic simulation models

Treesearch

Donald L., Jr. Gochenour; Leonard R. Johnson

1973-01-01

Development of a computer simulation model is usually done without fully considering how long the model should run (e.g. computer time) before the results are reliable. However construction of confidence intervals (CI) about critical output parameters from the simulation model makes it possible to determine the point where model results are reliable. If the results are...
Confidence intervals for differences between volumes under receiver operating characteristic surfaces (VUS) and generalized Youden indices (GYIs).

PubMed

Yin, Jingjing; Nakas, Christos T; Tian, Lili; Reiser, Benjamin

2018-03-01

This article explores both existing and new methods for the construction of confidence intervals for differences of indices of diagnostic accuracy of competing pairs of biomarkers in three-class classification problems and fills the methodological gaps for both parametric and non-parametric approaches in the receiver operating characteristic surface framework. The most widely used such indices are the volume under the receiver operating characteristic surface and the generalized Youden index. We describe implementation of all methods and offer insight regarding the appropriateness of their use through a large simulation study with different distributional and sample size scenarios. Methods are illustrated using data from the Alzheimer's Disease Neuroimaging Initiative study, where assessment of cognitive function naturally results in a three-class classification setting.
On Some Confidence Intervals for Estimating the Mean of a Skewed Population

ERIC Educational Resources Information Center

Shi, W.; Kibria, B. M. Golam

2007-01-01

A number of methods are available in the literature to measure confidence intervals. Here, confidence intervals for estimating the population mean of a skewed distribution are considered. This note proposes two alternative confidence intervals, namely, Median t and Mad t, which are simple adjustments to the Student's t confidence interval. In…
Statistical considerations in the development of injury risk functions.

PubMed

McMurry, Timothy L; Poplin, Gerald S

2015-01-01

We address 4 frequently misunderstood and important statistical ideas in the construction of injury risk functions. These include the similarities of survival analysis and logistic regression, the correct scale on which to construct pointwise confidence intervals for injury risk, the ability to discern which form of injury risk function is optimal, and the handling of repeated tests on the same subject. The statistical models are explored through simulation and examination of the underlying mathematics. We provide recommendations for the statistically valid construction and correct interpretation of single-predictor injury risk functions. This article aims to provide useful and understandable statistical guidance to improve the practice in constructing injury risk functions.

Treatment selection in a randomized clinical trial via covariate-specific treatment effect curves.

PubMed

Ma, Yunbei; Zhou, Xiao-Hua

2017-02-01

For time-to-event data in a randomized clinical trial, we proposed two new methods for selecting an optimal treatment for a patient based on the covariate-specific treatment effect curve, which is used to represent the clinical utility of a predictive biomarker. To select an optimal treatment for a patient with a specific biomarker value, we proposed pointwise confidence intervals for each covariate-specific treatment effect curve and the difference between covariate-specific treatment effect curves of two treatments. Furthermore, to select an optimal treatment for a future biomarker-defined subpopulation of patients, we proposed confidence bands for each covariate-specific treatment effect curve and the difference between each pair of covariate-specific treatment effect curve over a fixed interval of biomarker values. We constructed the confidence bands based on a resampling technique. We also conducted simulation studies to evaluate finite-sample properties of the proposed estimation methods. Finally, we illustrated the application of the proposed method in a real-world data set.
Nondepressive Psychosocial Factors and CKD Outcomes in Black Americans.

PubMed

Lunyera, Joseph; Davenport, Clemontina A; Bhavsar, Nrupen A; Sims, Mario; Scialla, Julia; Pendergast, Jane; Hall, Rasheeda; Tyson, Crystal C; Russell, Jennifer St Clair; Wang, Wei; Correa, Adolfo; Boulware, L Ebony; Diamantidis, Clarissa J

2018-02-07

Established risk factors for CKD do not fully account for risk of CKD in black Americans. We studied the association of nondepressive psychosocial factors with risk of CKD in the Jackson Heart Study. We used principal component analysis to identify underlying constructs from 12 psychosocial baseline variables (perceived daily, lifetime, and burden of lifetime discrimination; stress; anger in; anger out; hostility; pessimism; John Henryism; spirituality; perceived social status; and social support). Using multivariable models adjusted for demographics and comorbidity, we examined the association of psychosocial variables with baseline CKD prevalence, eGFR decline, and incident CKD during follow-up. Of 3390 (64%) Jackson Heart Study participants with the required data, 656 (19%) had prevalent CKD. Those with CKD (versus no CKD) had lower perceived daily (mean [SD] score =7.6 [8.5] versus 9.7 [9.0]) and lifetime discrimination (2.5 [2.0] versus 3.1 [2.2]), lower perceived stress (4.2 [4.0] versus 5.2 [4.4]), higher hostility (12.1 [5.2] versus 11.5 [4.8]), higher John Henryism (30.0 [4.8] versus 29.7 [4.4]), and higher pessimism (2.3 [2.2] versus 2.0 [2.1]; all P <0.05). Principal component analysis identified three factors from the 12 psychosocial variables: factor 1, life stressors (perceived discrimination, stress); factor 2, moods (anger, hostility); and, factor 3, coping strategies (John Henryism, spirituality, social status, social support). After adjustments, factor 1 (life stressors) was negatively associated with prevalent CKD at baseline among women only: odds ratio, 0.76 (95% confidence interval, 0.65 to 0.89). After a median follow-up of 8 years, identified psychosocial factors were not significantly associated with eGFR decline (life stressors: β =0.08; 95% confidence interval, -0.02 to 0.17; moods: β =0.03; 95% confidence interval, -0.06 to 0.13; coping: β =-0.02; 95% confidence interval, -0.12 to 0.08) or incident CKD (life stressors: odds ratio, 1.07; 95% confidence interval, 0.88 to 1.29; moods: odds ratio, 1.02; 95% confidence interval, 0.84 to 1.24; coping: odds ratio, 0.91; 95% confidence interval, 0.75 to 1.11). Greater life stressors were associated with lower prevalence of CKD at baseline in the Jackson Heart Study. However, psychosocial factors were not associated with risk of CKD over a median follow-up of 8 years. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_01_03_CJASNPodcast_18_2_L.mp3. Copyright © 2018 by the American Society of Nephrology.
Test Statistics and Confidence Intervals to Establish Noninferiority between Treatments with Ordinal Categorical Data.

PubMed

Zhang, Fanghong; Miyaoka, Etsuo; Huang, Fuping; Tanaka, Yutaka

2015-01-01

The problem for establishing noninferiority is discussed between a new treatment and a standard (control) treatment with ordinal categorical data. A measure of treatment effect is used and a method of specifying noninferiority margin for the measure is provided. Two Z-type test statistics are proposed where the estimation of variance is constructed under the shifted null hypothesis using U-statistics. Furthermore, the confidence interval and the sample size formula are given based on the proposed test statistics. The proposed procedure is applied to a dataset from a clinical trial. A simulation study is conducted to compare the performance of the proposed test statistics with that of the existing ones, and the results show that the proposed test statistics are better in terms of the deviation from nominal level and the power.
Cross-cultural adaptation and measurement properties of the Brazilian Portuguese Version of the Victorian Institute of Sport Assessment-Patella (VISA-P) scale.

PubMed

Wageck, Bruna Borges; de Noronha, Marcos; Lopes, Alexandre Dias; da Cunha, Ronaldo Alves; Takahashi, Ricardo Hisayoshi; Costa, Leonardo Oliveira Pena

2013-03-01

Clinical measurement. To translate, adapt, and test the measurement properties of the Brazilian Portuguese version of the Victorian Institute of Sport Assessment-Patella (VISA-P) questionnaire. It is important to objectively measure symptoms and functional limitations related to patellar tendinopathy using outcome measures that have been validated in the language of the target population. Cross-cultural adaptations are also useful to enhance the understanding of the measurement properties of an assessment tool, regardless of the target language. The VISA-P questionnaire was translated into Brazilian Portuguese, culturally adapted, and titled VISA-P Brazil. It was then administered on 2 occasions with a 24- to 48-hour interval between them, and a third time after a month of physical therapy treatment. The following measurement properties were analyzed: internal consistency, test-retest reliability, agreement, construct validity, floor and ceiling effects, and responsiveness. The VISA-P Brazil had high internal consistency (Cronbach α = .76; if item deleted, Cronbach α = .69-.78), excellent reliability and agreement (intraclass correlation coefficient = 0.91; 95% confidence interval: 0.85, 0.95; standard error of measurement, 5.2 points; minimal detectable change at the 90% confidence level, 12.2 points), and good construct validity (Pearson r = 0.60 compared to Lysholm). No ceiling and floor effects were detected for the VISA-P Brazil, and the responsiveness, based on 32 patients receiving physical therapy intervention for 1 month, demonstrated a large effect size of 0.97 (95% confidence interval: 0.68, 1.25). The VISA-P Brazil is a reproducible and responsive tool and can be used in clinical practice and research to assess the severity of pain and disability of patients with patellar tendinopathy.
Reducing the width of confidence intervals for the difference between two population means by inverting adaptive tests.

PubMed

O'Gorman, Thomas W

2018-05-01

In the last decade, it has been shown that an adaptive testing method could be used, along with the Robbins-Monro search procedure, to obtain confidence intervals that are often narrower than traditional confidence intervals. However, these confidence interval limits require a great deal of computation and some familiarity with stochastic search methods. We propose a method for estimating the limits of confidence intervals that uses only a few tests of significance. We compare these limits to those obtained by a lengthy Robbins-Monro stochastic search and find that the proposed method is nearly as accurate as the Robbins-Monro search. Adaptive confidence intervals that are produced by the proposed method are often narrower than traditional confidence intervals when the distributions are long-tailed, skewed, or bimodal. Moreover, the proposed method of estimating confidence interval limits is easy to understand, because it is based solely on the p-values from a few tests of significance.
Accurate estimation of normal incidence absorption coefficients with confidence intervals using a scanning laser Doppler vibrometer

NASA Astrophysics Data System (ADS)

Vuye, Cedric; Vanlanduit, Steve; Guillaume, Patrick

2009-06-01

When using optical measurements of the sound fields inside a glass tube, near the material under test, to estimate the reflection and absorption coefficients, not only these acoustical parameters but also confidence intervals can be determined. The sound fields are visualized using a scanning laser Doppler vibrometer (SLDV). In this paper the influence of different test signals on the quality of the results, obtained with this technique, is examined. The amount of data gathered during one measurement scan makes a thorough statistical analysis possible leading to the knowledge of confidence intervals. The use of a multi-sine, constructed on the resonance frequencies of the test tube, shows to be a very good alternative for the traditional periodic chirp. This signal offers the ability to obtain data for multiple frequencies in one measurement, without the danger of a low signal-to-noise ratio. The variability analysis in this paper clearly shows the advantages of the proposed multi-sine compared to the periodic chirp. The measurement procedure and the statistical analysis are validated by measuring the reflection ratio at a closed end and comparing the results with the theoretical value. Results of the testing of two building materials (an acoustic ceiling tile and linoleum) are presented and compared to supplier data.
Receiver Operating Characteristic Analysis for Classification Based on Various Prior Probabilities of Groups with an Application to Breath Analysis

NASA Astrophysics Data System (ADS)

Cimermanová, K.

2009-01-01

In this paper we illustrate the influence of prior probabilities of diseases on diagnostic reasoning. For various prior probabilities of classified groups characterized by volatile organic compounds of breath profile, smokers and non-smokers, we constructed the ROC curve and the Youden index with related asymptotic pointwise confidence intervals.
Robust Coefficients Alpha and Omega and Confidence Intervals with Outlying Observations and Missing Data Methods and Software

ERIC Educational Resources Information Center

Zhang, Zhiyong; Yuan, Ke-Hai

2016-01-01

Cronbach's coefficient alpha is a widely used reliability measure in social, behavioral, and education sciences. It is reported in nearly every study that involves measuring a construct through multiple items. With non-tau-equivalent items, McDonald's omega has been used as a popular alternative to alpha in the literature. Traditional estimation…
Robust Coefficients Alpha and Omega and Confidence Intervals with Outlying Observations and Missing Data: Methods and Software

ERIC Educational Resources Information Center

Zhang, Zhiyong; Yuan, Ke-Hai

2016-01-01

Cronbach's coefficient alpha is a widely used reliability measure in social, behavioral, and education sciences. It is reported in nearly every study that involves measuring a construct through multiple items. With non-tau-equivalent items, McDonald's omega has been used as a popular alternative to alpha in the literature. Traditional estimation…
Quantitative survival impact of composite treatment delays in head and neck cancer.

PubMed

Ho, Allen S; Kim, Sungjin; Tighiouart, Mourad; Mita, Alain; Scher, Kevin S; Epstein, Joel B; Laury, Anna; Prasad, Ravi; Ali, Nabilah; Patio, Chrysanta; St-Clair, Jon Mallen; Zumsteg, Zachary S

2018-05-09

Multidisciplinary management of head and neck cancer (HNC) must reconcile increasingly sophisticated subspecialty care with timeliness of care. Prior studies examined the individual effects of delays in diagnosis-to-treatment interval, postoperative interval, and radiation interval but did not consider them collectively. The objective of the current study was to investigate the combined impact of these interwoven intervals on patients with HNC. Patients with HNC who underwent curative-intent surgery with radiation were identified in the National Cancer Database between 2004 and 2013. Multivariable models were constructed using restricted cubic splines to determine nonlinear relations with overall survival. Overall, 15,064 patients were evaluated. After adjustment for covariates, only prolonged postoperative interval (P < .001) and radiation interval (P < .001) independently predicted for worse outcomes, whereas the association of diagnosis-to-treatment interval with survival disappeared. By using multivariable restricted cubic spline functions, increasing postoperative interval did not affect mortality until 40 days after surgery, and each day of delay beyond this increased the risk of mortality until 70 days after surgery (hazard ratio, 1.14; 95% confidence interval, 1.01-1.28; P = .029). For radiation interval, mortality escalated continuously with each additional day of delay, plateauing at 55 days (hazard ratio, 1.25; 95% confidence interval, 1.11-1.41; P < .001). Delays beyond these change points were not associated with further survival decrements. Increasing delays in postoperative and radiation intervals are associated independently with an escalating risk of mortality that plateaus beyond certain thresholds. Delays in initiating therapy, conversely, are eclipsed in importance when appraised in conjunction with the entire treatment course. Such findings may redirect focus to streamlining those intervals that are most sensitive to delays when considering survival burden. Cancer 2018. © 2018 American Cancer Society. © 2018 American Cancer Society.
Can 3-dimensional power Doppler indices improve the prenatal diagnosis of a potentially morbidly adherent placenta in patients with placenta previa?

PubMed

Haidar, Ziad A; Papanna, Ramesha; Sibai, Baha M; Tatevian, Nina; Viteri, Oscar A; Vowels, Patricia C; Blackwell, Sean C; Moise, Kenneth J

2017-08-01

Traditionally, 2-dimensional ultrasound parameters have been used for the diagnosis of a suspected morbidly adherent placenta previa. More objective techniques have not been well studied yet. The objective of the study was to determine the ability of prenatal 3-dimensional power Doppler analysis of flow and vascular indices to predict the morbidly adherent placenta objectively. A prospective cohort study was performed in women between 28 and 32 gestational weeks with known placenta previa. Patients underwent a two-dimensional gray-scale ultrasound that determined management decisions. 3-Dimensional power Doppler volumes were obtained during the same examination and vascular, flow, and vascular flow indices were calculated after manual tracing of the viewed placenta in the sweep; data were blinded to obstetricians. Morbidly adherent placenta was confirmed by histology. Severe morbidly adherent placenta was defined as increta/percreta on histology, blood loss >2000 mL, and >2 units of PRBC transfused. Sensitivities, specificities, predictive values, and likelihood ratios were calculated. Student t and χ 2 tests, logistic regression, receiver-operating characteristic curves, and intra- and interrater agreements using Kappa statistics were performed. The following results were found: (1) 50 women were studied: 23 had morbidly adherent placenta, of which 12 (52.2%) were severe morbidly adherent placenta; (2) 2-dimensional parameters diagnosed morbidly adherent placenta with a sensitivity of 82.6% (95% confidence interval, 60.4-94.2), a specificity of 88.9% (95% confidence interval, 69.7-97.1), a positive predictive value of 86.3% (95% confidence interval, 64.0-96.4), a negative predictive value of 85.7% (95% confidence interval, 66.4-95.3), a positive likelihood ratio of 7.4 (95% confidence interval, 2.5-21.9), and a negative likelihood ratio of 0.2 (95% confidence interval, 0.08-0.48); (3) mean values of the vascular index (32.8 ± 7.4) and the vascular flow index (14.2 ± 3.8) were higher in morbidly adherent placenta (P < .001); (4) area under the receiver-operating characteristic curve for the vascular and vascular flow indices were 0.99 and 0.97, respectively; (5) the vascular index ≥21 predicted morbidly adherent placenta with a sensitivity and a specificity of 95% (95% confidence interval, 88.2-96.9) and 91%, respectively (95% confidence interval, 87.5-92.4), 92% positive predictive value (95% confidence interval, 85.5-94.3), 90% negative predictive value (95% confidence interval, 79.9-95.3), positive likelihood ratio of 10.55 (95% confidence interval, 7.06-12.75), and negative likelihood ratio of 0.05 (95% confidence interval, 0.03-0.13); and (6) for the severe morbidly adherent placenta, 2-dimensional ultrasound had a sensitivity of 33.3% (95% confidence interval, 11.3-64.6), a specificity of 81.8% (95% confidence interval, 47.8-96.8), a positive predictive value of 66.7% (95% confidence interval, 24.1-94.1), a negative predictive value of 52.9% (95% confidence interval, 28.5-76.1), a positive likelihood ratio of 1.83 (95% confidence interval, 0.41-8.11), and a negative likelihood ratio of 0.81 (95% confidence interval, 0.52-1.26). A vascular index ≥31 predicted the diagnosis of a severe morbidly adherent placenta with a 100% sensitivity (95% confidence interval, 72-100), a 90% specificity (95% confidence interval, 81.7-93.8), an 88% positive predictive value (95% confidence interval, 55.0-91.3), a 100% negative predictive value (95% confidence interval, 90.9-100), a positive likelihood ratio of 10.0 (95% confidence interval, 3.93-16.13), and a negative likelihood ratio of 0 (95% confidence interval, 0-0.34). Intrarater and interrater agreements were 94% (P < .001) and 93% (P < .001), respectively. The vascular index accurately predicts the morbidly adherent placenta in patients with placenta previa. In addition, 3-dimensional power Doppler vascular and vascular flow indices were more predictive of severe cases of morbidly adherent placenta compared with 2-dimensional ultrasound. This objective technique may limit the variations in diagnosing morbidly adherent placenta because of the subjectivity of 2-dimensional ultrasound interpretations. Copyright © 2017 Elsevier Inc. All rights reserved.
Reliability and validity of the de Morton Mobility Index in individuals with sub-acute stroke.

PubMed

Braun, Tobias; Marks, Detlef; Thiel, Christian; Grüneberg, Christian

2018-02-04

To establish the validity and reliability of the de Morton Mobility Index (DEMMI) in patients with sub-acute stroke. This cross-sectional study was performed in a neurological rehabilitation hospital. We assessed unidimensionality, construct validity, internal consistency reliability, inter-rater reliability, minimal detectable change and possible floor and ceiling effects of the DEMMI in adult patients with sub-acute stroke. The study included a total sample of 121 patients with sub-acute stroke. We analysed validity (n = 109) and reliability (n = 51) in two sub-samples. Rasch analysis indicated unidimensionality with an overall fit to the model (chi-square = 12.37, p = 0.577). All hypotheses on construct validity were confirmed. Internal consistency reliability (Cronbach's alpha = 0.94) and inter-rater reliability (intraclass correlation coefficient = 0.95; 95% confidence interval: 0.92-0.97) were excellent. The minimal detectable change with 90% confidence was 13 points. No floor or ceiling effects were evident. These results indicate unidimensionality, sufficient internal consistency reliability, inter-rater reliability, and construct validity of the DEMMI in patients with a sub-acute stroke. Advantages of the DEMMI in clinical application are the short administration time, no need for special equipment and interval level data. The de Morton Mobility Index, therefore, may be a useful performance-based bedside test to measure mobility in individuals with a sub-acute stroke across the whole mobility spectrum. Implications for Rehabilitation The de Morton Mobility Index (DEMMI) is an unidimensional measurement instrument of mobility in individuals with sub-acute stroke. The DEMMI has excellent internal consistency and inter-rater reliability, and sufficient construct validity. The minimal detectable change of the DEMMI with 90% confidence in stroke rehabilitation is 13 points. The lack of any floor or ceiling effects on hospital admission indicates applicability across the whole mobility spectrum of patients with sub-acute stroke.
Association of Modality with Mortality among Canadian Aboriginals

PubMed Central

Hemmelgarn, Brenda; Rigatto, Claudio; Komenda, Paul; Yeates, Karen; Promislow, Steven; Mojica, Julie; Tangri, Navdeep

2012-01-01

Summary Background and objectives Previous studies have shown that Aboriginals and Caucasians experience similar outcome on dialysis in Canada. Using the Canadian Organ Replacement Registry, this study examined whether dialysis modality (peritoneal or hemodialysis) impacted mortality in Aboriginal patients. Design, setting, participants, & measurements This study identified 31,576 adult patients (hemodialysis: Aboriginal=1839, Caucasian=21,430; peritoneal dialysis: Aboriginal=554, Caucasian=6769) who initiated dialysis between January of 2000 and December of 2009. Aboriginal status was identified by self-report. Dialysis modality was determined 90 days after dialysis initiation. Multivariate Cox proportional hazards and competing risk models were constructed to determine the association between race and mortality by dialysis modality. Results During the study period, 939 (51.1%) Aboriginals and 12,798 (53.3%) Caucasians initiating hemodialysis died, whereas 166 (30.0%) and 2037 (30.1%), respectively, initiating peritoneal dialysis died. Compared with Caucasians, Aboriginals on hemodialysis had a comparable risk of mortality (adjusted hazards ratio=1.04, 95% confidence interval=0.96–1.11, P=0.37). However, on peritoneal dialysis, Aboriginals experienced a higher risk of mortality (adjusted hazards ratio=1.36, 95% confidence interval=1.13–1.62, P=0.001) and technique failure (adjusted hazards ratio=1.29, 95% confidence interval=1.03–1.60, P=0.03) than Caucasians. The risk of technique failure varied by patient age, with younger Aboriginals (<50 years old) more likely to develop technique failure than Caucasians (adjusted hazards ratio=1.76, 95% confidence interval=1.23–2.52, P=0.002). Conclusions Aboriginals on peritoneal dialysis experience higher mortality and technique failure relative to Caucasians. Reasons for this race disparity in peritoneal dialysis outcomes are unclear. PMID:22997343
Heritability of and mortality prediction with a longevity phenotype: the healthy aging index.

PubMed

Sanders, Jason L; Minster, Ryan L; Barmada, M Michael; Matteini, Amy M; Boudreau, Robert M; Christensen, Kaare; Mayeux, Richard; Borecki, Ingrid B; Zhang, Qunyuan; Perls, Thomas; Newman, Anne B

2014-04-01

Longevity-associated genes may modulate risk for age-related diseases and survival. The Healthy Aging Index (HAI) may be a subphenotype of longevity, which can be constructed in many studies for genetic analysis. We investigated the HAI's association with survival in the Cardiovascular Health Study and heritability in the Long Life Family Study. The HAI includes systolic blood pressure, pulmonary vital capacity, creatinine, fasting glucose, and Modified Mini-Mental Status Examination score, each scored 0, 1, or 2 using approximate tertiles and summed from 0 (healthy) to 10 (unhealthy). In Cardiovascular Health Study, the association with mortality and accuracy predicting death were determined with Cox proportional hazards analysis and c-statistics, respectively. In Long Life Family Study, heritability was determined with a variance component-based family analysis using a polygenic model. Cardiovascular Health Study participants with unhealthier index scores (7-10) had 2.62-fold (95% confidence interval: 2.22, 3.10) greater mortality than participants with healthier scores (0-2). The HAI alone predicted death moderately well (c-statistic = 0.643, 95% confidence interval: 0.626, 0.661, p < .0001) and slightly worse than age alone (c-statistic = 0.700, 95% confidence interval: 0.684, 0.717, p < .0001; p < .0001 for comparison of c-statistics). Prediction increased significantly with adjustment for demographics, health behaviors, and clinical comorbidities (c-statistic = 0.780, 95% confidence interval: 0.765, 0.794, p < .0001). In Long Life Family Study, the heritability of the HAI was 0.295 (p < .0001) overall, 0.387 (p < .0001) in probands, and 0.238 (p = .0004) in offspring. The HAI should be investigated further as a candidate phenotype for uncovering longevity-associated genes in humans.
Heritability of and Mortality Prediction With a Longevity Phenotype: The Healthy Aging Index

PubMed Central

2014-01-01

Background. Longevity-associated genes may modulate risk for age-related diseases and survival. The Healthy Aging Index (HAI) may be a subphenotype of longevity, which can be constructed in many studies for genetic analysis. We investigated the HAI’s association with survival in the Cardiovascular Health Study and heritability in the Long Life Family Study. Methods. The HAI includes systolic blood pressure, pulmonary vital capacity, creatinine, fasting glucose, and Modified Mini-Mental Status Examination score, each scored 0, 1, or 2 using approximate tertiles and summed from 0 (healthy) to 10 (unhealthy). In Cardiovascular Health Study, the association with mortality and accuracy predicting death were determined with Cox proportional hazards analysis and c-statistics, respectively. In Long Life Family Study, heritability was determined with a variance component–based family analysis using a polygenic model. Results. Cardiovascular Health Study participants with unhealthier index scores (7–10) had 2.62-fold (95% confidence interval: 2.22, 3.10) greater mortality than participants with healthier scores (0–2). The HAI alone predicted death moderately well (c-statistic = 0.643, 95% confidence interval: 0.626, 0.661, p < .0001) and slightly worse than age alone (c-statistic = 0.700, 95% confidence interval: 0.684, 0.717, p < .0001; p < .0001 for comparison of c-statistics). Prediction increased significantly with adjustment for demographics, health behaviors, and clinical comorbidities (c-statistic = 0.780, 95% confidence interval: 0.765, 0.794, p < .0001). In Long Life Family Study, the heritability of the HAI was 0.295 (p < .0001) overall, 0.387 (p < .0001) in probands, and 0.238 (p = .0004) in offspring. Conclusion. The HAI should be investigated further as a candidate phenotype for uncovering longevity-associated genes in humans. PMID:23913930
Development and validation of the Myasthenia Gravis Impairment Index.

PubMed

Barnett, Carolina; Bril, Vera; Kapral, Moira; Kulkarni, Abhaya; Davis, Aileen M

2016-08-30

We aimed to develop a measure of myasthenia gravis impairment using a previously developed framework and to evaluate reliability and validity, specifically face, content, and construct validity. The first draft of the Myasthenia Gravis Impairment Index (MGII) included examination items from available measures enriched with newly developed, patient-reported items, modified after patient input. International neuromuscular specialists evaluated face and content validity via an e-mail survey. Test-retest reliability was assessed in stable patients at a 3-week interval and interrater reliability was evaluated in the same day. Construct validity was assessed through correlations between the MGII and other measures and by comparing scores in different patient groups. The first draft was assessed by 18 patients, and 72 specialists answered the survey. The second draft had 7 examination and 22 patient-reported items. Field testing included 200 patients, with 54 patients completing the reliability studies. Test-retest reliability of the total score was good (intraclass correlation coefficient 0.92; 95% confidence interval 0.79-0.94), as was interrater reliability of the examination component (intraclass correlation coefficient 0.81; 95% confidence interval 0.79-0.94). The MGII correlated well with comparison measures, with higher correlations with the MG-activities of daily living (r = 0.91) and MG-specific quality of life 15-item scale (r = 0.78). When assessing different patient groups, the scores followed expected patterns. The MGII was developed using a patient-centered framework of myasthenia-related impairments and incorporating patient input throughout the development process. It is reliable in an outpatient setting and has demonstrated construct validity. Responsiveness studies are under way. © 2016 American Academy of Neurology.
Development and validation of the Myasthenia Gravis Impairment Index

PubMed Central

Bril, Vera; Kapral, Moira; Kulkarni, Abhaya; Davis, Aileen M.

2016-01-01

Objective: We aimed to develop a measure of myasthenia gravis impairment using a previously developed framework and to evaluate reliability and validity, specifically face, content, and construct validity. Methods: The first draft of the Myasthenia Gravis Impairment Index (MGII) included examination items from available measures enriched with newly developed, patient-reported items, modified after patient input. International neuromuscular specialists evaluated face and content validity via an e-mail survey. Test–retest reliability was assessed in stable patients at a 3-week interval and interrater reliability was evaluated in the same day. Construct validity was assessed through correlations between the MGII and other measures and by comparing scores in different patient groups. Results: The first draft was assessed by 18 patients, and 72 specialists answered the survey. The second draft had 7 examination and 22 patient-reported items. Field testing included 200 patients, with 54 patients completing the reliability studies. Test–retest reliability of the total score was good (intraclass correlation coefficient 0.92; 95% confidence interval 0.79–0.94), as was interrater reliability of the examination component (intraclass correlation coefficient 0.81; 95% confidence interval 0.79–0.94). The MGII correlated well with comparison measures, with higher correlations with the MG–activities of daily living (r = 0.91) and MG-specific quality of life 15-item scale (r = 0.78). When assessing different patient groups, the scores followed expected patterns. Conclusions: The MGII was developed using a patient-centered framework of myasthenia-related impairments and incorporating patient input throughout the development process. It is reliable in an outpatient setting and has demonstrated construct validity. Responsiveness studies are under way. PMID:27402891
Occupation and the prevalence of respiratory health symptoms and conditions: the Atherosclerosis Risk in Communities Study.

PubMed

Mirabelli, Maria C; London, Stephanie J; Charles, Luenda E; Pompeii, Lisa A; Wagenknecht, Lynne E

2012-02-01

To examine associations between occupation and respiratory health in a large, population-based cohort of adults in the United States. Data from 15,273 participants, aged 45 to 64 years, in the Atherosclerosis Risk in Communities study were used to examine associations of current or most recent job held with the prevalence of self-reported chronic cough, chronic bronchitis, wheezing, asthma, and measures of lung function collected by spirometry. Eleven percent of participants reported wheezing and 9% were classified as having airway obstruction. Compared with individuals in managerial and administrative jobs, increased prevalences of respiratory outcomes were observed among participants in selected occupations, including construction and extractive trades (wheezing, prevalence ratio = 1.92, 95% confidence interval = 1.35, 2.73; airway obstruction, prevalence ratio = 1.31, 95% confidence interval = 1.05, 1.65). Specific occupations are associated with adverse respiratory health.
Estimation of treatment effect in a subpopulation: An empirical Bayes approach.

PubMed

Shen, Changyu; Li, Xiaochun; Jeong, Jaesik

2016-01-01

It is well recognized that the benefit of a medical intervention may not be distributed evenly in the target population due to patient heterogeneity, and conclusions based on conventional randomized clinical trials may not apply to every person. Given the increasing cost of randomized trials and difficulties in recruiting patients, there is a strong need to develop analytical approaches to estimate treatment effect in subpopulations. In particular, due to limited sample size for subpopulations and the need for multiple comparisons, standard analysis tends to yield wide confidence intervals of the treatment effect that are often noninformative. We propose an empirical Bayes approach to combine both information embedded in a target subpopulation and information from other subjects to construct confidence intervals of the treatment effect. The method is appealing in its simplicity and tangibility in characterizing the uncertainty about the true treatment effect. Simulation studies and a real data analysis are presented.
New estimates of elasticity of demand for healthcare in rural China.

PubMed

Zhou, Zhongliang; Su, Yanfang; Gao, Jianmin; Xu, Ling; Zhang, Yaoguang

2011-12-01

Only limited empirical studies reported own-price elasticity of demand for health care in rural China. Neither research on income elasticity of demand for health care nor cross-price elasticity of demand for inpatient versus outpatient services in rural China has been reported. However, elasticity of demand is informative to evaluate current policy and to guide further policy making. Our study contributes to the literature by estimating three elasticities (i.e., own-price elasticity, cross-price elasticity, and income elasticity of demand for health care based on nationwide-representative data. We aim to answer three empirical questions with regard to health expenditure in rural China: (1) Which service is more sensitive to price change, outpatient or inpatient service? (2) Is outpatient service a substitute or complement to inpatient service? and (3) Does demand for inpatient services grow faster than demand for outpatient services with income growth? Based on data from a National Health Services Survey, a Probit regression model with probability of outpatient visit and probability of inpatient visit as dependent variables and a zero-truncated negative binomial regression model with outpatient visits as dependent variable were constructed to isolate the effects of price and income on demand for health care. Both pooled and separated regressions for 2003 and 2008 were conducted with tests of robustness. Own-price elasticities of demand for first outpatient visit, outpatient visits among users and first inpatient visit are -0.519 [95% confidence interval (-0.703, -0.336)], -0.547 [95% confidence interval (-0.747, -0.347)] and -0.372 [95% confidence interval (-0.517, -0.226)], respectively. Cross-price elasticities of demand for first outpatient visit, outpatient visits among users and first inpatient visit are 0.073 [95% confidence interval (-0.176, 0.322)], 0.308 [95% confidence interval (0.087, 0.528)], and 0.059 [95% confidence interval (-0.085, 0.204)], respectively. Income elasticities of demand for first outpatient visit, outpatient visits among users and first inpatient visit are 0.098 [95% confidence interval (0.018, 0.178)], 0.136 [95% confidence interval (0.028, 0.245)] and 0.521 [95% confidence interval (0.438, 0.605)], respectively. The aforementioned results are in 2008, which hold similar pattern as results in 2003 as well as results from pooled data of two periods. First, no significant difference is detected between sensitivity of outpatient services and sensitivity of inpatient services, responding to own-price change. Second, inpatient services are substitutes to outpatient services. Third, the growth of inpatient services is faster than the growth in outpatient services in response to income growth. The major findings from this paper suggest refining insurance policy in rural China. First, from a cost-effectiveness perspective, changing outpatient price is at least as effective as changing inpatient price to adjust demand of health care. Second, the current national guideline of healthcare reform to increase the reimbursement rate for inpatient services will crowd out outpatient services; however, we have no evidence about the change in demand for inpatient service if insurance covers outpatient services. Third, a referral system and gate-keeping system should be established to guide rural patients to utilize outpatient service. Copyright Â© 2011 Elsevier Ireland Ltd. All rights reserved.

Analysis of Test-Retest Reliability, Construct Validity, and Internal Consistency of the Brazilian Version of the Pelvic Girdle Questionnaire.

PubMed

Simões, Luan; Teixeira-Salmela, Luci Fuscaldi; Magalhães, Lívia; Stuge, Britt; Laurentino, Glória; Wanderley, Elaine; Barros, Raphaela; Lemos, Andrea

2018-04-24

The purpose of this study was to evaluate test-retest reliability, construct validity, and internal consistency of the Brazilian version of the Pelvic Girdle Questionnaire (PGQ-Brazil). Analysis of the measurement properties was carried out in 4 steps. Step 1 was the pilot study, on which basis 4 hypotheses were formulated. These hypotheses were tested during the next step (construct validity, step 2) by completion of the questionnaire by the 2 groups (in pain [n = 105] and not in pain [n = 52]). For implementation of the PGQ-Brazil in the group with pain, we calculated the internal consistency (step 3) and, 7 days later, test-retest reliability (step 4) by re-application of the instrument in this group. First, the PGQ-Brazil was able to discriminate between these groups (construct validity). Second, test-retest reliability (intraclass correlation coefficients for Activities subscale [0.97 with 95% confidence interval of 0.95-0.98] and Symptoms subscale [0.98 with 95% confidence interval of 0.97-0.98] and κ coefficient between 0.50 and 0.89 for the items) was found to be good; the Bland-Altman test indicated satisfactory agreement. The Rasch analysis indicated good internal consistency, and the instrument's ability to divide the participants into at least 3 levels of skills was confirmed. In contrast, a ceiling effect was observed, as 24% of pregnant women exhibited skills superior to what the PGQ-Brazil could evaluate. The PGQ-Brazil had good internal consistency, test-retest reliability, and construct validity in assessment of limitations in activities and symptoms of pregnant women with pelvic girdle pain. Copyright © 2018. Published by Elsevier Inc.
Introduction to Sample Size Choice for Confidence Intervals Based on "t" Statistics

ERIC Educational Resources Information Center

Liu, Xiaofeng Steven; Loudermilk, Brandon; Simpson, Thomas

2014-01-01

Sample size can be chosen to achieve a specified width in a confidence interval. The probability of obtaining a narrow width given that the confidence interval includes the population parameter is defined as the power of the confidence interval, a concept unfamiliar to many practitioners. This article shows how to utilize the Statistical Analysis…
An Introduction to Confidence Intervals for Both Statistical Estimates and Effect Sizes.

ERIC Educational Resources Information Center

Capraro, Mary Margaret

This paper summarizes methods of estimating confidence intervals, including classical intervals and intervals for effect sizes. The recent American Psychological Association (APA) Task Force on Statistical Inference report suggested that confidence intervals should always be reported, and the fifth edition of the APA "Publication Manual"…
Evaluation of confidence intervals for a steady-state leaky aquifer model

USGS Publications Warehouse

Christensen, S.; Cooley, R.L.

1999-01-01

The fact that dependent variables of groundwater models are generally nonlinear functions of model parameters is shown to be a potentially significant factor in calculating accurate confidence intervals for both model parameters and functions of the parameters, such as the values of dependent variables calculated by the model. The Lagrangian method of Vecchia and Cooley [Vecchia, A.V. and Cooley, R.L., Water Resources Research, 1987, 23(7), 1237-1250] was used to calculate nonlinear Scheffe-type confidence intervals for the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence intervals are compared to corresponding linear intervals. As suggested by the significant nonlinearity of the regression model, linear confidence intervals are often not accurate. The commonly made assumption that widths of linear confidence intervals always underestimate the actual (nonlinear) widths was not correct. Results show that nonlinear effects can cause the nonlinear intervals to be asymmetric and either larger or smaller than the linear approximations. Prior information on transmissivities helps reduce the size of the confidence intervals, with the most notable effects occurring for the parameters on which there is prior information and for head values in parameter zones for which there is prior information on the parameters.The fact that dependent variables of groundwater models are generally nonlinear functions of model parameters is shown to be a potentially significant factor in calculating accurate confidence intervals for both model parameters and functions of the parameters, such as the values of dependent variables calculated by the model. The Lagrangian method of Vecchia and Cooley was used to calculate nonlinear Scheffe-type confidence intervals for the parameters and the simulated heads of a steady-state groundwater flow model covering 450 km2 of a leaky aquifer. The nonlinear confidence intervals are compared to corresponding linear intervals. As suggested by the significant nonlinearity of the regression model, linear confidence intervals are often not accurate. The commonly made assumption that widths of linear confidence intervals always underestimate the actual (nonlinear) widths was not correct. Results show that nonlinear effects can cause the nonlinear intervals to be asymmetric and either larger or smaller than the linear approximations. Prior information on transmissivities helps reduce the size of the confidence intervals, with the most notable effects occurring for the parameters on which there is prior information and for head values in parameter zones for which there is prior information on the parameters.
Sample size planning for composite reliability coefficients: accuracy in parameter estimation via narrow confidence intervals.

PubMed

Terry, Leann; Kelley, Ken

2012-11-01

Composite measures play an important role in psychology and related disciplines. Composite measures almost always have error. Correspondingly, it is important to understand the reliability of the scores from any particular composite measure. However, the point estimates of the reliability of composite measures are fallible and thus all such point estimates should be accompanied by a confidence interval. When confidence intervals are wide, there is much uncertainty in the population value of the reliability coefficient. Given the importance of reporting confidence intervals for estimates of reliability, coupled with the undesirability of wide confidence intervals, we develop methods that allow researchers to plan sample size in order to obtain narrow confidence intervals for population reliability coefficients. We first discuss composite reliability coefficients and then provide a discussion on confidence interval formation for the corresponding population value. Using the accuracy in parameter estimation approach, we develop two methods to obtain accurate estimates of reliability by planning sample size. The first method provides a way to plan sample size so that the expected confidence interval width for the population reliability coefficient is sufficiently narrow. The second method ensures that the confidence interval width will be sufficiently narrow with some desired degree of assurance (e.g., 99% assurance that the 95% confidence interval for the population reliability coefficient will be less than W units wide). The effectiveness of our methods was verified with Monte Carlo simulation studies. We demonstrate how to easily implement the methods with easy-to-use and freely available software. ©2011 The British Psychological Society.
An Alternative to Cohen's Standardized Mean Difference Effect Size: A Robust Parameter and Confidence Interval in the Two Independent Groups Case

ERIC Educational Resources Information Center

Algina, James; Keselman, H. J.; Penfield, Randall D.

2005-01-01

The authors argue that a robust version of Cohen's effect size constructed by replacing population means with 20% trimmed means and the population standard deviation with the square root of a 20% Winsorized variance is a better measure of population separation than is Cohen's effect size. The authors investigated coverage probability for…
A new model for cork weight estimation in Northern Portugal with methodology for construction of confidence intervals

Treesearch

Teresa J.F. Fonseca; Bernard R. Parresol

2001-01-01

Cork, a unique biological material, is a highly valued non-timber forest product. Portugal is the leading producer of cork with 52 percent of the world production. Tree cork weight models have been developed for Southern Portugal, but there are no representative published models for Northern Portugal. Because cork trees may have a different form between Northern and...
Confidence intervals for the between-study variance in random-effects meta-analysis using generalised heterogeneity statistics: should we use unequal tails?

PubMed

Jackson, Dan; Bowden, Jack

2016-09-07

Confidence intervals for the between study variance are useful in random-effects meta-analyses because they quantify the uncertainty in the corresponding point estimates. Methods for calculating these confidence intervals have been developed that are based on inverting hypothesis tests using generalised heterogeneity statistics. Whilst, under the random effects model, these new methods furnish confidence intervals with the correct coverage, the resulting intervals are usually very wide, making them uninformative. We discuss a simple strategy for obtaining 95 % confidence intervals for the between-study variance with a markedly reduced width, whilst retaining the nominal coverage probability. Specifically, we consider the possibility of using methods based on generalised heterogeneity statistics with unequal tail probabilities, where the tail probability used to compute the upper bound is greater than 2.5 %. This idea is assessed using four real examples and a variety of simulation studies. Supporting analytical results are also obtained. Our results provide evidence that using unequal tail probabilities can result in shorter 95 % confidence intervals for the between-study variance. We also show some further results for a real example that illustrates how shorter confidence intervals for the between-study variance can be useful when performing sensitivity analyses for the average effect, which is usually the parameter of primary interest. We conclude that using unequal tail probabilities when computing 95 % confidence intervals for the between-study variance, when using methods based on generalised heterogeneity statistics, can result in shorter confidence intervals. We suggest that those who find the case for using unequal tail probabilities convincing should use the '1-4 % split', where greater tail probability is allocated to the upper confidence bound. The 'width-optimal' interval that we present deserves further investigation.
Improved confidence intervals when the sample is counted an integer times longer than the blank.

PubMed

Potter, William Edward; Strzelczyk, Jadwiga Jodi

2011-05-01

Past computer solutions for confidence intervals in paired counting are extended to the case where the ratio of the sample count time to the blank count time is taken to be an integer, IRR. Previously, confidence intervals have been named Neyman-Pearson confidence intervals; more correctly they should have been named Neyman confidence intervals or simply confidence intervals. The technique utilized mimics a technique used by Pearson and Hartley to tabulate confidence intervals for the expected value of the discrete Poisson and Binomial distributions. The blank count and the contribution of the sample to the gross count are assumed to be Poisson distributed. The expected value of the blank count, in the sample count time, is assumed known. The net count, OC, is taken to be the gross count minus the product of IRR with the blank count. The probability density function (PDF) for the net count can be determined in a straightforward manner.
Graphing within-subjects confidence intervals using SPSS and S-Plus.

PubMed

Wright, Daniel B

2007-02-01

Within-subjects confidence intervals are often appropriate to report and to display. Loftus and Masson (1994) have reported methods to calculate these, and their use is becoming common. In the present article, procedures for calculating within-subjects confidence intervals in SPSS and S-Plus are presented (an R version is on the accompanying Web site). The procedure in S-Plus allows the user to report the bias corrected and adjusted bootstrap confidence intervals as well as the standard confidence intervals based on traditional methods. The presented code can be easily altered to fit the individual user's needs.
Myocardial perfusion magnetic resonance imaging using sliding-window conjugate-gradient highly constrained back-projection reconstruction for detection of coronary artery disease.

PubMed

Ma, Heng; Yang, Jun; Liu, Jing; Ge, Lan; An, Jing; Tang, Qing; Li, Han; Zhang, Yu; Chen, David; Wang, Yong; Liu, Jiabin; Liang, Zhigang; Lin, Kai; Jin, Lixin; Bi, Xiaoming; Li, Kuncheng; Li, Debiao

2012-04-15

Myocardial perfusion magnetic resonance imaging (MRI) with sliding-window conjugate-gradient highly constrained back-projection reconstruction (SW-CG-HYPR) allows whole left ventricular coverage, improved temporal and spatial resolution and signal/noise ratio, and reduced cardiac motion-related image artifacts. The accuracy of this technique for detecting coronary artery disease (CAD) has not been determined in a large number of patients. We prospectively evaluated the diagnostic performance of myocardial perfusion MRI with SW-CG-HYPR in patients with suspected CAD. A total of 50 consecutive patients who were scheduled for coronary angiography with suspected CAD underwent myocardial perfusion MRI with SW-CG-HYPR at 3.0 T. The perfusion defects were interpreted qualitatively by 2 blinded observers and were correlated with x-ray angiographic stenoses ≥50%. The prevalence of CAD was 56%. In the per-patient analysis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SW-CG-HYPR was 96% (95% confidence interval 82% to 100%), 82% (95% confidence interval 60% to 95%), 87% (95% confidence interval 70% to 96%), 95% (95% confidence interval 74% to100%), and 90% (95% confidence interval 82% to 98%), respectively. In the per-vessel analysis, the corresponding values were 98% (95% confidence interval 91% to 100%), 89% (95% confidence interval 80% to 94%), 86% (95% confidence interval 76% to 93%), 99% (95% confidence interval 93% to 100%), and 93% (95% confidence interval 89% to 97%), respectively. In conclusion, myocardial perfusion MRI using SW-CG-HYPR allows whole left ventricular coverage and high resolution and has high diagnostic accuracy in patients with suspected CAD. Copyright © 2012 Elsevier Inc. All rights reserved.
Alternative methods to evaluate trial level surrogacy.

PubMed

Abrahantes, Josè Cortiñas; Shkedy, Ziv; Molenberghs, Geert

2008-01-01

The evaluation and validation of surrogate endpoints have been extensively studied in the last decade. Prentice [1] and Freedman, Graubard and Schatzkin [2] laid the foundations for the evaluation of surrogate endpoints in randomized clinical trials. Later, Buyse et al. [5] proposed a meta-analytic methodology, producing different methods for different settings, which was further studied by Alonso and Molenberghs [9], in their unifying approach based on information theory. In this article, we focus our attention on the trial-level surrogacy and propose alternative procedures to evaluate such surrogacy measure, which do not pre-specify the type of association. A promising correction based on cross-validation is investigated. As well as the construction of confidence intervals for this measure. In order to avoid making assumption about the type of relationship between the treatment effects and its distribution, a collection of alternative methods, based on regression trees, bagging, random forests, and support vector machines, combined with bootstrap-based confidence interval and, should one wish, in conjunction with a cross-validation based correction, will be proposed and applied. We apply the various strategies to data from three clinical studies: in opthalmology, in advanced colorectal cancer, and in schizophrenia. The results obtained for the three case studies are compared; they indicate that using random forest or bagging models produces larger estimated values for the surrogacy measure, which are in general stabler and the confidence interval narrower than linear regression and support vector regression. For the advanced colorectal cancer studies, we even found the trial-level surrogacy is considerably different from what has been reported. In general the alternative methods are more computationally demanding, and specially the calculation of the confidence intervals, require more computational time that the delta-method counterpart. First, more flexible modeling techniques can be used, allowing for other type of association. Second, when no cross-validation-based correction is applied, overly optimistic trial-level surrogacy estimates will be found, thus cross-validation is highly recommendable. Third, the use of the delta method to calculate confidence intervals is not recommendable since it makes assumptions valid only in very large samples. It may also produce range-violating limits. We therefore recommend alternatives: bootstrap methods in general. Also, the information-theoretic approach produces comparable results with the bagging and random forest approaches, when cross-validation correction is applied. It is also important to observe that, even for the case in which the linear model might be a good option too, bagging methods perform well too, and their confidence intervals were more narrow.
Explorations in Statistics: Confidence Intervals

ERIC Educational Resources Information Center

Curran-Everett, Douglas

2009-01-01

Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This third installment of "Explorations in Statistics" investigates confidence intervals. A confidence interval is a range that we expect, with some level of confidence, to include the true value of a population parameter…
Life-Space Assessment questionnaire: Novel measurement properties for Brazilian community-dwelling older adults.

PubMed

Simões, Maria do Socorro Mp; Garcia, Isabel Ff; Costa, Lucíola da Cm; Lunardi, Adriana C

2018-05-01

The Life-Space Assessment (LSA) assesses mobility from the spaces that older adults go, and how often and how independent they move. Despite its increased use, LSA measurement properties remain unclear. The aim of the present study was to analyze the content validity, reliability, construct validity and interpretability of the LSA for Brazilian community-dwelling older adults. In this clinimetric study we analyzed the measurement properties (content validity, reliability, construct validity and interpretability) of the LSA administered to 80 Brazilian community-dwelling older adults. Reliability was analyzed by Cronbach's alpha (internal consistency), intraclass correlation coefficients and 95% confidence interval (reproducibility), and standard error of measurement (measurement error). Construct validity was analyzed by Pearson's correlations between the LSA and accelerometry (time in inactivity and moderate-to-vigorous activities), and interpretability was analyzed by determination of the minimal detectable change, and floor and ceiling effects. The LSA met the criteria for content validity. The Cronbach's alpha was 0.92, intraclass correlation coefficient was 0.97 (95% confidence interval 0.95-0.98) and standard error of measurement was 4.12. The LSA showed convergence with accelerometry (negative correlation with time in inactivity and positive correlation with time in moderate to vigorous activities), the minimal detectable change was 0.36 and we observed no floor or ceiling effects. The LSA showed adequate reliability, validity and interpretability for life-space mobility assessment of Brazilian community-dwelling older adults. Geriatr Gerontol Int 2018; 18: 783-789. © 2018 Japan Geriatrics Society.
Short-Term Estimates of Growth Using Curriculum-Based Measurement of Oral Reading Fluency: Estimating Standard Error of the Slope to Construct Confidence Intervals

ERIC Educational Resources Information Center

Christ, Theodore J.

2006-01-01

Curriculum-based measurement of oral reading fluency (CBM-R) is an established procedure used to index the level and trend of student growth. A substantial literature base exists regarding best practices in the administration and interpretation of CBM-R; however, research has yet to adequately address the potential influence of measurement error.…
Using an R Shiny to Enhance the Learning Experience of Confidence Intervals

ERIC Educational Resources Information Center

Williams, Immanuel James; Williams, Kelley Kim

2018-01-01

Many students find understanding confidence intervals difficult, especially because of the amalgamation of concepts such as confidence levels, standard error, point estimates and sample sizes. An R Shiny application was created to assist the learning process of confidence intervals using graphics and data from the US National Basketball…
Obtaining appropriate interval estimates for age when multiple indicators are used: evaluation of an ad-hoc procedure.

PubMed

Fieuws, Steffen; Willems, Guy; Larsen-Tangmose, Sara; Lynnerup, Niels; Boldsen, Jesper; Thevissen, Patrick

2016-03-01

When an estimate of age is needed, typically multiple indicators are present as found in skeletal or dental information. There exists a vast literature on approaches to estimate age from such multivariate data. Application of Bayes' rule has been proposed to overcome drawbacks of classical regression models but becomes less trivial as soon as the number of indicators increases. Each of the age indicators can lead to a different point estimate ("the most plausible value for age") and a prediction interval ("the range of possible values"). The major challenge in the combination of multiple indicators is not the calculation of a combined point estimate for age but the construction of an appropriate prediction interval. Ignoring the correlation between the age indicators results in intervals being too small. Boldsen et al. (2002) presented an ad-hoc procedure to construct an approximate confidence interval without the need to model the multivariate correlation structure between the indicators. The aim of the present paper is to bring under attention this pragmatic approach and to evaluate its performance in a practical setting. This is all the more needed since recent publications ignore the need for interval estimation. To illustrate and evaluate the method, Köhler et al. (1995) third molar scores are used to estimate the age in a dataset of 3200 male subjects in the juvenile age range.
Alternative Confidence Interval Methods Used in the Diagnostic Accuracy Studies

PubMed Central

Gülhan, Orekıcı Temel

2016-01-01

Background/Aim. It is necessary to decide whether the newly improved methods are better than the standard or reference test or not. To decide whether the new diagnostics test is better than the gold standard test/imperfect standard test, the differences of estimated sensitivity/specificity are calculated with the help of information obtained from samples. However, to generalize this value to the population, it should be given with the confidence intervals. The aim of this study is to evaluate the confidence interval methods developed for the differences between the two dependent sensitivity/specificity values on a clinical application. Materials and Methods. In this study, confidence interval methods like Asymptotic Intervals, Conditional Intervals, Unconditional Interval, Score Intervals, and Nonparametric Methods Based on Relative Effects Intervals are used. Besides, as clinical application, data used in diagnostics study by Dickel et al. (2010) has been taken as a sample. Results. The results belonging to the alternative confidence interval methods for Nickel Sulfate, Potassium Dichromate, and Lanolin Alcohol are given as a table. Conclusion. While preferring the confidence interval methods, the researchers have to consider whether the case to be compared is single ratio or dependent binary ratio differences, the correlation coefficient between the rates in two dependent ratios and the sample sizes. PMID:27478491
Alternative Confidence Interval Methods Used in the Diagnostic Accuracy Studies.

PubMed

Erdoğan, Semra; Gülhan, Orekıcı Temel

2016-01-01

Background/Aim. It is necessary to decide whether the newly improved methods are better than the standard or reference test or not. To decide whether the new diagnostics test is better than the gold standard test/imperfect standard test, the differences of estimated sensitivity/specificity are calculated with the help of information obtained from samples. However, to generalize this value to the population, it should be given with the confidence intervals. The aim of this study is to evaluate the confidence interval methods developed for the differences between the two dependent sensitivity/specificity values on a clinical application. Materials and Methods. In this study, confidence interval methods like Asymptotic Intervals, Conditional Intervals, Unconditional Interval, Score Intervals, and Nonparametric Methods Based on Relative Effects Intervals are used. Besides, as clinical application, data used in diagnostics study by Dickel et al. (2010) has been taken as a sample. Results. The results belonging to the alternative confidence interval methods for Nickel Sulfate, Potassium Dichromate, and Lanolin Alcohol are given as a table. Conclusion. While preferring the confidence interval methods, the researchers have to consider whether the case to be compared is single ratio or dependent binary ratio differences, the correlation coefficient between the rates in two dependent ratios and the sample sizes.
Modified Confidence Intervals for the Mean of an Autoregressive Process.

DTIC Science & Technology

1985-08-01

Validity of the method 45 3.6 Theorem 47 4 Derivation of corrections 48 Introduction 48 The zero order pivot 50 4.1 Algorithm 50 CONTENTS The first...of standard confidence intervals. There are several standard methods of setting confidence intervals in simulations, including the regener- ative... method , batch means, and time series methods . We-will focus-s on improved confidence intervals for the mean of an autoregressive process, and as such our

Publication Bias in Meta-Analysis: Confidence Intervals for Rosenthal's Fail-Safe Number.

PubMed

Fragkos, Konstantinos C; Tsagris, Michail; Frangos, Christos C

2014-01-01

The purpose of the present paper is to assess the efficacy of confidence intervals for Rosenthal's fail-safe number. Although Rosenthal's estimator is highly used by researchers, its statistical properties are largely unexplored. First of all, we developed statistical theory which allowed us to produce confidence intervals for Rosenthal's fail-safe number. This was produced by discerning whether the number of studies analysed in a meta-analysis is fixed or random. Each case produces different variance estimators. For a given number of studies and a given distribution, we provided five variance estimators. Confidence intervals are examined with a normal approximation and a nonparametric bootstrap. The accuracy of the different confidence interval estimates was then tested by methods of simulation under different distributional assumptions. The half normal distribution variance estimator has the best probability coverage. Finally, we provide a table of lower confidence intervals for Rosenthal's estimator.
Publication Bias in Meta-Analysis: Confidence Intervals for Rosenthal's Fail-Safe Number

PubMed Central

Fragkos, Konstantinos C.; Tsagris, Michail; Frangos, Christos C.

2014-01-01

The purpose of the present paper is to assess the efficacy of confidence intervals for Rosenthal's fail-safe number. Although Rosenthal's estimator is highly used by researchers, its statistical properties are largely unexplored. First of all, we developed statistical theory which allowed us to produce confidence intervals for Rosenthal's fail-safe number. This was produced by discerning whether the number of studies analysed in a meta-analysis is fixed or random. Each case produces different variance estimators. For a given number of studies and a given distribution, we provided five variance estimators. Confidence intervals are examined with a normal approximation and a nonparametric bootstrap. The accuracy of the different confidence interval estimates was then tested by methods of simulation under different distributional assumptions. The half normal distribution variance estimator has the best probability coverage. Finally, we provide a table of lower confidence intervals for Rosenthal's estimator. PMID:27437470
Abstract: Inference and Interval Estimation for Indirect Effects With Latent Variable Models.

PubMed

Falk, Carl F; Biesanz, Jeremy C

2011-11-30

Models specifying indirect effects (or mediation) and structural equation modeling are both popular in the social sciences. Yet relatively little research has compared methods that test for indirect effects among latent variables and provided precise estimates of the effectiveness of different methods. This simulation study provides an extensive comparison of methods for constructing confidence intervals and for making inferences about indirect effects with latent variables. We compared the percentile (PC) bootstrap, bias-corrected (BC) bootstrap, bias-corrected accelerated (BC a ) bootstrap, likelihood-based confidence intervals (Neale & Miller, 1997), partial posterior predictive (Biesanz, Falk, and Savalei, 2010), and joint significance tests based on Wald tests or likelihood ratio tests. All models included three reflective latent variables representing the independent, dependent, and mediating variables. The design included the following fully crossed conditions: (a) sample size: 100, 200, and 500; (b) number of indicators per latent variable: 3 versus 5; (c) reliability per set of indicators: .7 versus .9; (d) and 16 different path combinations for the indirect effect (α = 0, .14, .39, or .59; and β = 0, .14, .39, or .59). Simulations were performed using a WestGrid cluster of 1680 3.06GHz Intel Xeon processors running R and OpenMx. Results based on 1,000 replications per cell and 2,000 resamples per bootstrap method indicated that the BC and BC a bootstrap methods have inflated Type I error rates. Likelihood-based confidence intervals and the PC bootstrap emerged as methods that adequately control Type I error and have good coverage rates.
Interval estimation and optimal design for the within-subject coefficient of variation for continuous and binary variables

PubMed Central

Shoukri, Mohamed M; Elkum, Nasser; Walter, Stephen D

2006-01-01

Background In this paper we propose the use of the within-subject coefficient of variation as an index of a measurement's reliability. For continuous variables and based on its maximum likelihood estimation we derive a variance-stabilizing transformation and discuss confidence interval construction within the framework of a one-way random effects model. We investigate sample size requirements for the within-subject coefficient of variation for continuous and binary variables. Methods We investigate the validity of the approximate normal confidence interval by Monte Carlo simulations. In designing a reliability study, a crucial issue is the balance between the number of subjects to be recruited and the number of repeated measurements per subject. We discuss efficiency of estimation and cost considerations for the optimal allocation of the sample resources. The approach is illustrated by an example on Magnetic Resonance Imaging (MRI). We also discuss the issue of sample size estimation for dichotomous responses with two examples. Results For the continuous variable we found that the variance stabilizing transformation improves the asymptotic coverage probabilities on the within-subject coefficient of variation for the continuous variable. The maximum like estimation and sample size estimation based on pre-specified width of confidence interval are novel contribution to the literature for the binary variable. Conclusion Using the sample size formulas, we hope to help clinical epidemiologists and practicing statisticians to efficiently design reliability studies using the within-subject coefficient of variation, whether the variable of interest is continuous or binary. PMID:16686943
Trends and racial and ethnic disparities in the prevalence of pregestational type 1 and type 2 diabetes in Northern California: 1996-2014.

PubMed

Peng, Tiffany Y; Ehrlich, Samantha F; Crites, Yvonne; Kitzmiller, John L; Kuzniewicz, Michael W; Hedderson, Monique M; Ferrara, Assiamira

2017-02-01

Despite concern for adverse perinatal outcomes in women with diabetes mellitus before pregnancy, recent data on the prevalence of pregestational type 1 and type 2 diabetes mellitus in the United States are lacking. The purpose of this study was to estimate changes in the prevalence of overall pregestational diabetes mellitus (all types) and pregestational type 1 and type 2 diabetes mellitus and to estimate whether changes varied by race-ethnicity from 1996-2014. We conducted a cohort study among 655,428 pregnancies at a Northern California integrated health delivery system from 1996-2014. Logistic regression analyses provided estimates of prevalence and trends. The age-adjusted prevalence (per 100 deliveries) of overall pregestational diabetes mellitus increased from 1996-1999 to 2012-2014 (from 0.58 [95% confidence interval, 0.54-0.63] to 1.06 [95% confidence interval, 1.00-1.12]; P trend <.0001). Significant increases occurred in all racial-ethnic groups; the largest relative increase was among Hispanic women (121.8% [95% confidence interval, 84.4-166.7]); the smallest relative increase was among non-Hispanic white women (49.6% [95% confidence interval, 27.5-75.4]). The age-adjusted prevalence of pregestational type 1 and type 2 diabetes mellitus increased from 0.14 (95% confidence interval, 0.12-0.16) to 0.23 (95% confidence interval, 0.21-0.27; P trend <.0001) and from 0.42 (95% confidence interval, 0.38-0.46) to 0.78 (95% confidence interval, 0.73-0.83; P trend <.0001), respectively. The greatest relative increase in the prevalence of type 1 diabetes mellitus was in non-Hispanic white women (118.4% [95% confidence interval, 70.0-180.5]), who had the lowest increases in the prevalence of type 2 diabetes mellitus (13.6% [95% confidence interval, -8.0 to 40.1]). The greatest relative increase in the prevalence of type 2 diabetes mellitus was in Hispanic women (125.2% [95% confidence interval, 84.8-174.4]), followed by African American women (102.0% [95% confidence interval, 38.3-194.3]) and Asian women (93.3% [95% confidence interval, 48.9-150.9]). The prevalence of overall pregestational diabetes mellitus and pregestational type 1 and type 2 diabetes mellitus increased from 1996-1999 to 2012-2014 and racial-ethnic disparities were observed, possibly because of differing prevalence of maternal obesity. Targeted prevention efforts, preconception care, and disease management strategies are needed to reduce the burden of diabetes mellitus and its sequelae. Copyright © 2016 Elsevier Inc. All rights reserved.
More accurate, calibrated bootstrap confidence intervals for correlating two autocorrelated climate time series

NASA Astrophysics Data System (ADS)

Olafsdottir, Kristin B.; Mudelsee, Manfred

2013-04-01

Estimation of the Pearson's correlation coefficient between two time series to evaluate the influences of one time depended variable on another is one of the most often used statistical method in climate sciences. Various methods are used to estimate confidence interval to support the correlation point estimate. Many of them make strong mathematical assumptions regarding distributional shape and serial correlation, which are rarely met. More robust statistical methods are needed to increase the accuracy of the confidence intervals. Bootstrap confidence intervals are estimated in the Fortran 90 program PearsonT (Mudelsee, 2003), where the main intention was to get an accurate confidence interval for correlation coefficient between two time series by taking the serial dependence of the process that generated the data into account. However, Monte Carlo experiments show that the coverage accuracy for smaller data sizes can be improved. Here we adapt the PearsonT program into a new version called PearsonT3, by calibrating the confidence interval to increase the coverage accuracy. Calibration is a bootstrap resampling technique, which basically performs a second bootstrap loop or resamples from the bootstrap resamples. It offers, like the non-calibrated bootstrap confidence intervals, robustness against the data distribution. Pairwise moving block bootstrap is used to preserve the serial correlation of both time series. The calibration is applied to standard error based bootstrap Student's t confidence intervals. The performances of the calibrated confidence intervals are examined with Monte Carlo simulations, and compared with the performances of confidence intervals without calibration, that is, PearsonT. The coverage accuracy is evidently better for the calibrated confidence intervals where the coverage error is acceptably small (i.e., within a few percentage points) already for data sizes as small as 20. One form of climate time series is output from numerical models which simulate the climate system. The method is applied to model data from the high resolution ocean model, INALT01 where the relationship between the Agulhas Leakage and the North Brazil Current is evaluated. Preliminary results show significant correlation between the two variables when there is 10 year lag between them, which is more or less the time that takes the Agulhas Leakage water to reach the North Brazil Current. Mudelsee, M., 2003. Estimating Pearson's correlation coefficient with bootstrap confidence interval from serially dependent time series. Mathematical Geology 35, 651-665.
The P Value Problem in Otolaryngology: Shifting to Effect Sizes and Confidence Intervals.

PubMed

Vila, Peter M; Townsend, Melanie Elizabeth; Bhatt, Neel K; Kao, W Katherine; Sinha, Parul; Neely, J Gail

2017-06-01

There is a lack of reporting effect sizes and confidence intervals in the current biomedical literature. The objective of this article is to present a discussion of the recent paradigm shift encouraging the use of reporting effect sizes and confidence intervals. Although P values help to inform us about whether an effect exists due to chance, effect sizes inform us about the magnitude of the effect (clinical significance), and confidence intervals inform us about the range of plausible estimates for the general population mean (precision). Reporting effect sizes and confidence intervals is a necessary addition to the biomedical literature, and these concepts are reviewed in this article.
The Effects of Optimism and Gratitude on Physical Activity, Biomarkers, and Readmissions Following an Acute Coronary Syndrome: The Gratitude Research in Acute Coronary Events (GRACE) Study

PubMed Central

Huffman, Jeff C.; Beale, Eleanor E.; Celano, Christopher M.; Beach, Scott R.; Belcher, Arianna M.; Moore, Shannon V.; Suarez, Laura; Motiwala, Shweta R.; Gandhi, Parul U.; Gaggin, Hanna; Januzzi, James L.

2015-01-01

Background Positive psychological constructs, such as optimism, are associated with beneficial health outcomes. However, no study has separately examined the effects of multiple positive psychological constructs on behavioral, biological, and clinical outcomes after an acute coronary syndrome (ACS). Accordingly, we aimed to investigate associations of baseline optimism and gratitude with subsequent physical activity, prognostic biomarkers, and cardiac rehospitalizations in post-ACS patients. Methods and Results Participants were enrolled during admission for ACS and underwent assessments at baseline (2 weeks post-ACS) and follow-up (6 months later). Associations between baseline positive psychological constructs and subsequent physical activity/biomarkers were analyzed using multivariable linear regression. Associations between baseline positive constructs and 6-month rehospitalizations were assessed via multivariable Cox regression. Overall, 164 participants enrolled and completed the baseline 2-week assessments. Baseline optimism was significantly associated with greater physical activity at 6 months (n=153; β=102.5; 95% confidence interval [13.6-191.5]; p=.024), controlling for baseline activity and sociodemographic, medical, and negative psychological covariates. Baseline optimism was also associated with lower rates of cardiac readmissions at 6 months (N=164), controlling for age, gender, and medical comorbidity (hazard ratio=.92; 95% confidence interval [.86-.98]; p=.006). There were no significant relationships between optimism and biomarkers. Gratitude was minimally associated with post-ACS outcomes. Conclusions Post-ACS optimism, but not gratitude, was prospectively and independently associated with superior physical activity and fewer cardiac readmissions. Whether interventions that target optimism can successfully increase optimism or improve cardiovascular outcomes in post-ACS patients is not yet known, but can be tested in future studies. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01709669. PMID:26646818
Effects of Optimism and Gratitude on Physical Activity, Biomarkers, and Readmissions After an Acute Coronary Syndrome: The Gratitude Research in Acute Coronary Events Study.

PubMed

Huffman, Jeff C; Beale, Eleanor E; Celano, Christopher M; Beach, Scott R; Belcher, Arianna M; Moore, Shannon V; Suarez, Laura; Motiwala, Shweta R; Gandhi, Parul U; Gaggin, Hanna K; Januzzi, James L

2016-01-01

Positive psychological constructs, such as optimism, are associated with beneficial health outcomes. However, no study has separately examined the effects of multiple positive psychological constructs on behavioral, biological, and clinical outcomes after an acute coronary syndrome (ACS). Accordingly, we aimed to investigate associations of baseline optimism and gratitude with subsequent physical activity, prognostic biomarkers, and cardiac rehospitalizations in post-ACS patients. Participants were enrolled during admission for ACS and underwent assessments at baseline (2 weeks post-ACS) and follow-up (6 months later). Associations between baseline positive psychological constructs and subsequent physical activity/biomarkers were analyzed using multivariable linear regression. Associations between baseline positive constructs and 6-month rehospitalizations were assessed via multivariable Cox regression. Overall, 164 participants enrolled and completed the baseline 2-week assessments. Baseline optimism was significantly associated with greater physical activity at 6 months (n=153; β=102.5; 95% confidence interval, 13.6-191.5; P=0.024), controlling for baseline activity and sociodemographic, medical, and negative psychological covariates. Baseline optimism was also associated with lower rates of cardiac readmissions at 6 months (n=164), controlling for age, sex, and medical comorbidity (hazard ratio, 0.92; 95% confidence interval, [0.86-0.98]; P=0.006). There were no significant relationships between optimism and biomarkers. Gratitude was minimally associated with post-ACS outcomes. Post-ACS optimism, but not gratitude, was prospectively and independently associated with superior physical activity and fewer cardiac readmissions. Whether interventions that target optimism can successfully increase optimism or improve cardiovascular outcomes in post-ACS patients is not yet known, but can be tested in future studies. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01709669. © 2015 American Heart Association, Inc.
Confidence Intervals for Error Rates Observed in Coded Communications Systems

NASA Astrophysics Data System (ADS)

Hamkins, J.

2015-05-01

We present methods to compute confidence intervals for the codeword error rate (CWER) and bit error rate (BER) of a coded communications link. We review several methods to compute exact and approximate confidence intervals for the CWER, and specifically consider the situation in which the true CWER is so low that only a handful, if any, codeword errors are able to be simulated. In doing so, we answer the question of how long an error-free simulation must be run in order to certify that a given CWER requirement is met with a given level of confidence, and discuss the bias introduced by aborting a simulation after observing the first codeword error. Next, we turn to the lesser studied problem of determining confidence intervals for the BER of coded systems. Since bit errors in systems that use coding or higher-order modulation do not occur independently, blind application of a method that assumes independence leads to inappropriately narrow confidence intervals. We present a new method to compute the confidence interval properly, using the first and second sample moments of the number of bit errors per codeword. This is the first method we know of to compute a confidence interval for the BER of a coded or higher-order modulation system.
Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism.

PubMed

Hounslow, Mark W

2016-08-30

Long intervals of single geomagnetic polarity (superchrons) reflect geodynamo processes, driven by core-mantle boundary interactions; however, it is not clear what initiates the start and end of superchrons, other than superchrons probably reflect lower heat flow across the core-mantle boundary compared with adjacent intervals. Here geomagnetic polarity timescales, with confidence intervals, are constructed before and following the reverse polarity Kiaman (Carboniferous-Permian) and Moyero (Ordovician) superchrons, providing a window into the geodynamo processes. Similar to the Cretaceous, asymmetry in reversal rates is seen in the Palaeozoic superchrons, but the higher reversal rates imply higher heatflow thresholds for entering the superchron state. Similar to the Cretaceous superchron, unusually long-duration chrons characterize the ∼10 Myr interval adjacent to the superchrons, indicating a transitional reversing state to the superchrons. This may relate to a weak pattern in the clustering of chron durations superimposed on the dominant random arrangement of chron durations.
Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism

PubMed Central

Hounslow, Mark W.

2016-01-01

Long intervals of single geomagnetic polarity (superchrons) reflect geodynamo processes, driven by core–mantle boundary interactions; however, it is not clear what initiates the start and end of superchrons, other than superchrons probably reflect lower heat flow across the core–mantle boundary compared with adjacent intervals. Here geomagnetic polarity timescales, with confidence intervals, are constructed before and following the reverse polarity Kiaman (Carboniferous–Permian) and Moyero (Ordovician) superchrons, providing a window into the geodynamo processes. Similar to the Cretaceous, asymmetry in reversal rates is seen in the Palaeozoic superchrons, but the higher reversal rates imply higher heatflow thresholds for entering the superchron state. Similar to the Cretaceous superchron, unusually long-duration chrons characterize the ∼10 Myr interval adjacent to the superchrons, indicating a transitional reversing state to the superchrons. This may relate to a weak pattern in the clustering of chron durations superimposed on the dominant random arrangement of chron durations. PMID:27572303
Modifications to the Patient Rule-Induction Method that utilize non-additive combinations of genetic and environmental effects to define partitions that predict ischemic heart disease.

PubMed

Dyson, Greg; Frikke-Schmidt, Ruth; Nordestgaard, Børge G; Tybjaerg-Hansen, Anne; Sing, Charles F

2009-05-01

This article extends the Patient Rule-Induction Method (PRIM) for modeling cumulative incidence of disease developed by Dyson et al. (Genet Epidemiol 31:515-527) to include the simultaneous consideration of non-additive combinations of predictor variables, a significance test of each combination, an adjustment for multiple testing and a confidence interval for the estimate of the cumulative incidence of disease in each partition. We employ the partitioning algorithm component of the Combinatorial Partitioning Method to construct combinations of predictors, permutation testing to assess the significance of each combination, theoretical arguments for incorporating a multiple testing adjustment and bootstrap resampling to produce the confidence intervals. An illustration of this revised PRIM utilizing a sample of 2,258 European male participants from the Copenhagen City Heart Study is presented that assesses the utility of genetic variants in predicting the presence of ischemic heart disease beyond the established risk factors.
Modifications to the Patient Rule-Induction Method that utilize non-additive combinations of genetic and environmental effects to define partitions that predict ischemic heart disease

PubMed Central

Dyson, Greg; Frikke-Schmidt, Ruth; Nordestgaard, Børge G.; Tybjærg-Hansen, Anne; Sing, Charles F.

2009-01-01

This paper extends the Patient Rule-Induction Method (PRIM) for modeling cumulative incidence of disease developed by Dyson et al. (2007) to include the simultaneous consideration of non-additive combinations of predictor variables, a significance test of each combination, an adjustment for multiple testing and a confidence interval for the estimate of the cumulative incidence of disease in each partition. We employ the partitioning algorithm component of the Combinatorial Partitioning Method (CPM) to construct combinations of predictors, permutation testing to assess the significance of each combination, theoretical arguments for incorporating a multiple testing adjustment and bootstrap resampling to produce the confidence intervals. An illustration of this revised PRIM utilizing a sample of 2258 European male participants from the Copenhagen City Heart Study is presented that assesses the utility of genetic variants in predicting the presence of ischemic heart disease beyond the established risk factors. PMID:19025787
Estimating age at a specified length from the von Bertalanffy growth function

USGS Publications Warehouse

Ogle, Derek H.; Isermann, Daniel A.

2017-01-01

Estimating the time required (i.e., age) for fish in a population to reach a specific length (e.g., legal harvest length) is useful for understanding population dynamics and simulating the potential effects of length-based harvest regulations. The age at which a population reaches a specific mean length is typically estimated by fitting a von Bertalanffy growth function to length-at-age data and then rearranging the best-fit equation to solve for age at the specified length. This process precludes the use of standard frequentist methods to compute confidence intervals and compare estimates of age at the specified length among populations. We provide a parameterization of the von Bertalanffy growth function that has age at a specified length as a parameter. With this parameterization, age at a specified length is directly estimated, and standard methods can be used to construct confidence intervals and make among-group comparisons for this parameter. We demonstrate use of the new parameterization with two data sets.
Musculoskeletal disorders among Thai women in construction-related work.

PubMed

Hanklang, Suda; Kaewboonchoo, Orawan; Silpasuwan, Pimpan; Mungarndee, Suriyaphun S

2014-03-01

A cross-sectional study was conducted to determine the prevalence of musculoskeletal disorder symptoms and its risk factors among women rebar workers. A simple random sampling method was used and data were collected by face-to-face interview and ergonomic assessment from February to March 2011. A total of 272 women rebar workers with at least 6 months' job experience participated in this study. The findings revealed that 57.7% of workers reported musculoskeletal disorder symptoms with low back and shoulders as the most common body parts affected (46.0%). Multiple logistic regression analysis indicated 2 variables that are significantly associated with musculoskeletal disorders: prolonged working hours (adjusted odds ratio = 7.63; 95% confidence interval = 2.06-28.31) and awkward posture (adjusted odds ratio = 43.79; 95% confidence interval = 17.09-112.20). The high prevalence of musculoskeletal disorders among women rebar workers suggests that an appropriate ergonomic workstation design and ergonomic training for women rebar workers are necessary.
Vaginal antimycotics and the risk for spontaneous abortions.

PubMed

Daniel, Sharon; Rotem, Reut; Koren, Gideon; Lunenfeld, Eitan; Levy, Amalia

2018-06-01

Spontaneous abortions are the most common complication of pregnancy. Clotrimazole and miconazole are widely used vaginal-antimycotic agents used for the treatment of vulvovaginal candidiasis. A previous study has suggested an increased risk of miscarriage associated with these azoles, which may lead health professionals to refrain from their use even if clinically indicated. The aim of the current study was to assess the risk for spontaneous abortions following first trimester exposure to vaginal antimycotics. A historical cohort study was conducted including all clinically apparent pregnancies that began from January 2003 through December 2009 and admitted for birth or spontaneous abortion at Soroka Medical Center, Clalit Health Services, Beer-Sheva, Israel. A computerized database of medication dispensation was linked with 2 computerized databases containing information on births and spontaneous abortions. Time-varying Cox regression models were constructed adjusting for mother's age, diabetes mellitus, hypothyroidism, obesity, hypercoagulable or inflammatory conditions, recurrent miscarriages, intrauterine contraceptive device, ethnicity, tobacco use, and the year of admission. A total of 65,457 pregnancies were included in the study: 58,949 (90.1%) ended with birth and 6508 (9.9%) with a spontaneous abortion. Overall, 3246 (5%) pregnancies were exposed to vaginal antimycotic medications until the 20th gestational week: 2712 (4.2%) were exposed to clotrimazole and 633 (1%) to miconazole. Exposure to vaginal antimycotics was not associated with spontaneous abortions as a group (crude hazard ratio, 1.11; 95% confidence interval, 0.96-1.29; adjusted hazard ratio, 1.11; 95% confidence interval, 0.96-1.29) and specifically for clotrimazole (adjusted hazard ratio, 1.05; 95% confidence interval, 0.89-1.25) and miconazole (adjusted hazard ratio, 1.34; 95% confidence interval, 0.99-1.80). Furthermore, no association was found between categories of dosage of vaginal antimycotics and spontaneous abortions. Exposure to vaginal antimycotics was not associated with spontaneous abortions. Copyright © 2018 Elsevier Inc. All rights reserved.
Sample variance in weak lensing: How many simulations are required?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petri, Andrea; May, Morgan; Haiman, Zoltan

Constraining cosmology using weak gravitational lensing consists of comparing a measured feature vector of dimension N b with its simulated counterpart. An accurate estimate of the N b × N b feature covariance matrix C is essential to obtain accurate parameter confidence intervals. When C is measured from a set of simulations, an important question is how large this set should be. To answer this question, we construct different ensembles of N r realizations of the shear field, using a common randomization procedure that recycles the outputs from a smaller number N s ≤ N r of independent ray-tracing N-bodymore » simulations. We study parameter confidence intervals as a function of (N s, N r) in the range 1 ≤ N s ≤ 200 and 1 ≤ N r ≲ 105. Previous work [S. Dodelson and M. D. Schneider, Phys. Rev. D 88, 063537 (2013)] has shown that Gaussian noise in the feature vectors (from which the covariance is estimated) lead, at quadratic order, to an O(1/N r) degradation of the parameter confidence intervals. Using a variety of lensing features measured in our simulations, including shear-shear power spectra and peak counts, we show that cubic and quartic covariance fluctuations lead to additional O(1/N 2 r) error degradation that is not negligible when N r is only a factor of few larger than N b. We study the large N r limit, and find that a single, 240 Mpc/h sized 512 3-particle N-body simulation (N s = 1) can be repeatedly recycled to produce as many as N r = few × 10 4 shear maps whose power spectra and high-significance peak counts can be treated as statistically independent. Lastly, a small number of simulations (N s = 1 or 2) is sufficient to forecast parameter confidence intervals at percent accuracy.« less
Sample variance in weak lensing: How many simulations are required?

DOE PAGES

Petri, Andrea; May, Morgan; Haiman, Zoltan

2016-03-24

Constraining cosmology using weak gravitational lensing consists of comparing a measured feature vector of dimension N b with its simulated counterpart. An accurate estimate of the N b × N b feature covariance matrix C is essential to obtain accurate parameter confidence intervals. When C is measured from a set of simulations, an important question is how large this set should be. To answer this question, we construct different ensembles of N r realizations of the shear field, using a common randomization procedure that recycles the outputs from a smaller number N s ≤ N r of independent ray-tracing N-bodymore » simulations. We study parameter confidence intervals as a function of (N s, N r) in the range 1 ≤ N s ≤ 200 and 1 ≤ N r ≲ 105. Previous work [S. Dodelson and M. D. Schneider, Phys. Rev. D 88, 063537 (2013)] has shown that Gaussian noise in the feature vectors (from which the covariance is estimated) lead, at quadratic order, to an O(1/N r) degradation of the parameter confidence intervals. Using a variety of lensing features measured in our simulations, including shear-shear power spectra and peak counts, we show that cubic and quartic covariance fluctuations lead to additional O(1/N 2 r) error degradation that is not negligible when N r is only a factor of few larger than N b. We study the large N r limit, and find that a single, 240 Mpc/h sized 512 3-particle N-body simulation (N s = 1) can be repeatedly recycled to produce as many as N r = few × 10 4 shear maps whose power spectra and high-significance peak counts can be treated as statistically independent. Lastly, a small number of simulations (N s = 1 or 2) is sufficient to forecast parameter confidence intervals at percent accuracy.« less
Comparative bioavailability of two oral formulations of ketorolac tromethamine: Dolac and Exodol.

PubMed

Flores-Murrieta, F J; Granados-Soto, V; Castañeda-Hernández, G; Herrera, J E; Hong, E

1994-03-01

The bioavailability of ketorolac after administration of two oral formulations containing 10 mg of ketorolac tromethamine, Exodol and Dolac, to 12 healthy Mexican volunteers was compared. Subjects received both formulations according to a randomized crossover design and blood samples were drawn at selected times during 24 h. Ketorolac plasma concentrations were determined by HPLC and individual plasma-concentration-against-time curves were constructed. Maximal plasma concentration and AUC0-24 values were compared by analysis of variance followed by Westlake's confidence interval test. 90% confidence limits ranged from 80 to 125% for Cmax and from 85 to 118% for AUC0-24. It is concluded that the two assayed formulations are bioequivalent.

Method of self-consistent evaluation of absolute emission probabilities of particles and gamma rays

NASA Astrophysics Data System (ADS)

Badikov, Sergei; Chechev, Valery

2017-09-01

In assumption of well installed decay scheme the method provides a) exact balance relationships, b) lower (compared to the traditional techniques) uncertainties of recommended absolute emission probabilities of particles and gamma rays, c) evaluation of correlations between the recommended emission probabilities (for the same and different decay modes). Application of the method for the decay data evaluation for even curium isotopes led to paradoxical results. The multidimensional confidence regions for the probabilities of the most intensive alpha transitions constructed on the basis of present and the ENDF/B-VII.1, JEFF-3.1, DDEP evaluations are inconsistent whereas the confidence intervals for the evaluated probabilities of single transitions agree with each other.
Beyond Description in Interpersonal Construct Validation: Methodological Advances in the Circumplex Structural Summary Approach.

PubMed

Zimmermann, Johannes; Wright, Aidan G C

2017-01-01

The interpersonal circumplex is a well-established structural model that organizes interpersonal functioning within the two-dimensional space marked by dominance and affiliation. The structural summary method (SSM) was developed to evaluate the interpersonal nature of other constructs and measures outside the interpersonal circumplex. To date, this method has been primarily descriptive, providing no way to draw inferences when comparing SSM parameters across constructs or groups. We describe a newly developed resampling-based method for deriving confidence intervals, which allows for SSM parameter comparisons. In a series of five studies, we evaluated the accuracy of the approach across a wide range of possible sample sizes and parameter values, and demonstrated its utility for posing theoretical questions on the interpersonal nature of relevant constructs (e.g., personality disorders) using real-world data. As a result, the SSM is strengthened for its intended purpose of construct evaluation and theory building. © The Author(s) 2015.
Minimax confidence intervals in geomagnetism

NASA Technical Reports Server (NTRS)

Stark, Philip B.

1992-01-01

The present paper uses theory of Donoho (1989) to find lower bounds on the lengths of optimally short fixed-length confidence intervals (minimax confidence intervals) for Gauss coefficients of the field of degree 1-12 using the heat flow constraint. The bounds on optimal minimax intervals are about 40 percent shorter than Backus' intervals: no procedure for producing fixed-length confidence intervals, linear or nonlinear, can give intervals shorter than about 60 percent the length of Backus' in this problem. While both methods rigorously account for the fact that core field models are infinite-dimensional, the application of the techniques to the geomagnetic problem involves approximations and counterfactual assumptions about the data errors, and so these results are likely to be extremely optimistic estimates of the actual uncertainty in Gauss coefficients.
Using Screencast Videos to Enhance Undergraduate Students' Statistical Reasoning about Confidence Intervals

ERIC Educational Resources Information Center

Strazzeri, Kenneth Charles

2013-01-01

The purposes of this study were to investigate (a) undergraduate students' reasoning about the concepts of confidence intervals (b) undergraduate students' interactions with "well-designed" screencast videos on sampling distributions and confidence intervals, and (c) how screencast videos improve undergraduate students' reasoning ability…
Construction of a high-density genetic map by specific locus amplified fragment sequencing (SLAF-seq) and its application to Quantitative Trait Loci (QTL) analysis for boll weight in upland cotton (Gossypium hirsutum.).

PubMed

Zhang, Zhen; Shang, Haihong; Shi, Yuzhen; Huang, Long; Li, Junwen; Ge, Qun; Gong, Juwu; Liu, Aiying; Chen, Tingting; Wang, Dan; Wang, Yanling; Palanga, Koffi Kibalou; Muhammad, Jamshed; Li, Weijie; Lu, Quanwei; Deng, Xiaoying; Tan, Yunna; Song, Weiwu; Cai, Juan; Li, Pengtao; Rashid, Harun or; Gong, Wankui; Yuan, Youlu

2016-04-11

Upland Cotton (Gossypium hirsutum) is one of the most important worldwide crops it provides natural high-quality fiber for the industrial production and everyday use. Next-generation sequencing is a powerful method to identify single nucleotide polymorphism markers on a large scale for the construction of a high-density genetic map for quantitative trait loci mapping. In this research, a recombinant inbred lines population developed from two upland cotton cultivars 0-153 and sGK9708 was used to construct a high-density genetic map through the specific locus amplified fragment sequencing method. The high-density genetic map harbored 5521 single nucleotide polymorphism markers which covered a total distance of 3259.37 cM with an average marker interval of 0.78 cM without gaps larger than 10 cM. In total 18 quantitative trait loci of boll weight were identified as stable quantitative trait loci and were detected in at least three out of 11 environments and explained 4.15-16.70 % of the observed phenotypic variation. In total, 344 candidate genes were identified within the confidence intervals of these stable quantitative trait loci based on the cotton genome sequence. These genes were categorized based on their function through gene ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis and eukaryotic orthologous groups analysis. This research reported the first high-density genetic map for Upland Cotton (Gossypium hirsutum) with a recombinant inbred line population using single nucleotide polymorphism markers developed by specific locus amplified fragment sequencing. We also identified quantitative trait loci of boll weight across 11 environments and identified candidate genes within the quantitative trait loci confidence intervals. The results of this research would provide useful information for the next-step work including fine mapping, gene functional analysis, pyramiding breeding of functional genes as well as marker-assisted selection.
CALCULATION OF NONLINEAR CONFIDENCE AND PREDICTION INTERVALS FOR GROUND-WATER FLOW MODELS.

USGS Publications Warehouse

Cooley, Richard L.; Vecchia, Aldo V.

1987-01-01

A method is derived to efficiently compute nonlinear confidence and prediction intervals on any function of parameters derived as output from a mathematical model of a physical system. The method is applied to the problem of obtaining confidence and prediction intervals for manually-calibrated ground-water flow models. To obtain confidence and prediction intervals resulting from uncertainties in parameters, the calibrated model and information on extreme ranges and ordering of the model parameters within one or more independent groups are required. If random errors in the dependent variable are present in addition to uncertainties in parameters, then calculation of prediction intervals also requires information on the extreme range of error expected. A simple Monte Carlo method is used to compute the quantiles necessary to establish probability levels for the confidence and prediction intervals. Application of the method to a hypothetical example showed that inclusion of random errors in the dependent variable in addition to uncertainties in parameters can considerably widen the prediction intervals.
Bootstrapping Confidence Intervals for Robust Measures of Association.

ERIC Educational Resources Information Center

King, Jason E.

A Monte Carlo simulation study was conducted to determine the bootstrap correction formula yielding the most accurate confidence intervals for robust measures of association. Confidence intervals were generated via the percentile, adjusted, BC, and BC(a) bootstrap procedures and applied to the Winsorized, percentage bend, and Pearson correlation…
Interpretation of Confidence Interval Facing the Conflict

ERIC Educational Resources Information Center

Andrade, Luisa; Fernández, Felipe

2016-01-01

As literature has reported, it is usual that university students in statistics courses, and even statistics teachers, interpret the confidence level associated with a confidence interval as the probability that the parameter value will be between the lower and upper interval limits. To confront this misconception, class activities have been…
Evaluating Independent Proportions for Statistical Difference, Equivalence, Indeterminacy, and Trivial Difference Using Inferential Confidence Intervals

ERIC Educational Resources Information Center

Tryon, Warren W.; Lewis, Charles

2009-01-01

Tryon presented a graphic inferential confidence interval (ICI) approach to analyzing two independent and dependent means for statistical difference, equivalence, replication, indeterminacy, and trivial difference. Tryon and Lewis corrected the reduction factor used to adjust descriptive confidence intervals (DCIs) to create ICIs and introduced…
Generalized Bootstrap Method for Assessment of Uncertainty in Semivariogram Inference

USGS Publications Warehouse

Olea, R.A.; Pardo-Iguzquiza, E.

2011-01-01

The semivariogram and its related function, the covariance, play a central role in classical geostatistics for modeling the average continuity of spatially correlated attributes. Whereas all methods are formulated in terms of the true semivariogram, in practice what can be used are estimated semivariograms and models based on samples. A generalized form of the bootstrap method to properly model spatially correlated data is used to advance knowledge about the reliability of empirical semivariograms and semivariogram models based on a single sample. Among several methods available to generate spatially correlated resamples, we selected a method based on the LU decomposition and used several examples to illustrate the approach. The first one is a synthetic, isotropic, exhaustive sample following a normal distribution, the second example is also a synthetic but following a non-Gaussian random field, and a third empirical sample consists of actual raingauge measurements. Results show wider confidence intervals than those found previously by others with inadequate application of the bootstrap. Also, even for the Gaussian example, distributions for estimated semivariogram values and model parameters are positively skewed. In this sense, bootstrap percentile confidence intervals, which are not centered around the empirical semivariogram and do not require distributional assumptions for its construction, provide an achieved coverage similar to the nominal coverage. The latter cannot be achieved by symmetrical confidence intervals based on the standard error, regardless if the standard error is estimated from a parametric equation or from bootstrap. ?? 2010 International Association for Mathematical Geosciences.
Four applications of permutation methods to testing a single-mediator model.

PubMed

Taylor, Aaron B; MacKinnon, David P

2012-09-01

Four applications of permutation tests to the single-mediator model are described and evaluated in this study. Permutation tests work by rearranging data in many possible ways in order to estimate the sampling distribution for the test statistic. The four applications to mediation evaluated here are the permutation test of ab, the permutation joint significance test, and the noniterative and iterative permutation confidence intervals for ab. A Monte Carlo simulation study was used to compare these four tests with the four best available tests for mediation found in previous research: the joint significance test, the distribution of the product test, and the percentile and bias-corrected bootstrap tests. We compared the different methods on Type I error, power, and confidence interval coverage. The noniterative permutation confidence interval for ab was the best performer among the new methods. It successfully controlled Type I error, had power nearly as good as the most powerful existing methods, and had better coverage than any existing method. The iterative permutation confidence interval for ab had lower power than do some existing methods, but it performed better than any other method in terms of coverage. The permutation confidence interval methods are recommended when estimating a confidence interval is a primary concern. SPSS and SAS macros that estimate these confidence intervals are provided.
Race, Ethnicity, Language, Social Class, and Health Communication Inequalities: A Nationally-Representative Cross-Sectional Study

PubMed Central

Viswanath, Kasisomayajula; Ackerson, Leland K.

2011-01-01

Background While mass media communications can be an important source of health information, there are substantial social disparities in health knowledge that may be related to media use. The purpose of this study is to investigate how the use of cancer-related health communications is patterned by race, ethnicity, language, and social class. Methodology/Principal Findings In a nationally-representative cross-sectional telephone survey, 5,187 U.S. adults provided information about demographic characteristics, cancer information seeking, and attention to and trust in health information from television, radio, newspaper, magazines, and the Internet. Cancer information seeking was lowest among Spanish-speaking Hispanics (odds ratio: 0.42; 95% confidence interval: 0.28–0.63) compared to non-Hispanic whites. Spanish-speaking Hispanics were more likely than non-Hispanic whites to pay attention to (odds ratio: 3.10; 95% confidence interval: 2.07–4.66) and trust (odds ratio: 2.61; 95% confidence interval: 1.53–4.47) health messages from the radio. Non-Hispanic blacks were more likely than non-Hispanic whites to pay attention to (odds ratio: 2.39; 95% confidence interval: 1.88–3.04) and trust (odds ratio: 2.16; 95% confidence interval: 1.61–2.90) health messages on television. Those who were college graduates tended to pay more attention to health information from newspapers (odds ratio: 1.98; 95% confidence interval: 1.42–2.75), magazines (odds ratio: 1.86; 95% confidence interval: 1.32–2.60), and the Internet (odds ratio: 4.74; 95% confidence interval: 2.70–8.31) and had less trust in cancer-related health information from television (odds ratio: 0.44; 95% confidence interval: 0.32–0.62) and radio (odds ratio: 0.54; 95% confidence interval: 0.34–0.86) compared to those who were not high school graduates. Conclusions/Significance Health media use is patterned by race, ethnicity, language and social class. Providing greater access to and enhancing the quality of health media by taking into account factors associated with social determinants may contribute to addressing social disparities in health. PMID:21267450
Preconceptional and prenatal supplementary folic acid and multivitamin intake and autism spectrum disorders.

PubMed

Virk, Jasveer; Liew, Zeyan; Olsen, Jørn; Nohr, Ellen A; Catov, Janet M; Ritz, Beate

2016-08-01

To evaluate whether early folic acid supplementation during pregnancy prevents diagnosis of autism spectrum disorders in offspring. Information on autism spectrum disorder diagnosis was obtained from the National Hospital Register and the Central Psychiatric Register. We estimated risk ratios for autism spectrum disorders for children whose mothers took folate or multivitamin supplements from 4 weeks prior from the last menstrual period through to 8 weeks after the last menstrual period (-4 to 8 weeks) by three 4-week periods. We did not find an association between early folate or multivitamin intake for autism spectrum disorder (folic acid-adjusted risk ratio: 1.06, 95% confidence interval: 0.82-1.36; multivitamin-adjusted risk ratio: 1.00, 95% confidence interval: 0.82-1.22), autistic disorder (folic acid-adjusted risk ratio: 1.18, 95% confidence interval: 0.76-1.84; multivitamin-adjusted risk ratio: 1.22, 95% confidence interval: 0.87-1.69), Asperger's syndrome (folic acid-adjusted risk ratio: 0.85, 95% confidence interval: 0.46-1.53; multivitamin-adjusted risk ratio: 0.95, 95% confidence interval: 0.62-1.46), or pervasive developmental disorder-not otherwise specified (folic acid-adjusted risk ratio: 1.07, 95% confidence interval: 0.75-1.54; multivitamin: adjusted risk ratio: 0.87, 95% confidence interval: 0.65-1.17) compared with women reporting no supplement use in the same period. We did not find any evidence to corroborate previous reports of a reduced risk for autism spectrum disorders in offspring of women using folic acid supplements in early pregnancy. © The Author(s) 2015.
Applying Bootstrap Resampling to Compute Confidence Intervals for Various Statistics with R

ERIC Educational Resources Information Center

Dogan, C. Deha

2017-01-01

Background: Most of the studies in academic journals use p values to represent statistical significance. However, this is not a good indicator of practical significance. Although confidence intervals provide information about the precision of point estimation, they are, unfortunately, rarely used. The infrequent use of confidence intervals might…
Reporting Confidence Intervals and Effect Sizes: Collecting the Evidence

ERIC Educational Resources Information Center

Zientek, Linda Reichwein; Ozel, Z. Ebrar Yetkiner; Ozel, Serkan; Allen, Jeff

2012-01-01

Confidence intervals (CIs) and effect sizes are essential to encourage meta-analytic thinking and to accumulate research findings. CIs provide a range of plausible values for population parameters with a degree of confidence that the parameter is in that particular interval. CIs also give information about how precise the estimates are. Comparison…
Confidence Intervals for Effect Sizes: Applying Bootstrap Resampling

ERIC Educational Resources Information Center

Banjanovic, Erin S.; Osborne, Jason W.

2016-01-01

Confidence intervals for effect sizes (CIES) provide readers with an estimate of the strength of a reported statistic as well as the relative precision of the point estimate. These statistics offer more information and context than null hypothesis statistic testing. Although confidence intervals have been recommended by scholars for many years,…
Bootstrap Confidence Intervals for Ordinary Least Squares Factor Loadings and Correlations in Exploratory Factor Analysis

ERIC Educational Resources Information Center

Zhang, Guangjian; Preacher, Kristopher J.; Luo, Shanhong

2010-01-01

This article is concerned with using the bootstrap to assign confidence intervals for rotated factor loadings and factor correlations in ordinary least squares exploratory factor analysis. Coverage performances of "SE"-based intervals, percentile intervals, bias-corrected percentile intervals, bias-corrected accelerated percentile…
Accuracy in parameter estimation for targeted effects in structural equation modeling: sample size planning for narrow confidence intervals.

PubMed

Lai, Keke; Kelley, Ken

2011-06-01

In addition to evaluating a structural equation model (SEM) as a whole, often the model parameters are of interest and confidence intervals for those parameters are formed. Given a model with a good overall fit, it is entirely possible for the targeted effects of interest to have very wide confidence intervals, thus giving little information about the magnitude of the population targeted effects. With the goal of obtaining sufficiently narrow confidence intervals for the model parameters of interest, sample size planning methods for SEM are developed from the accuracy in parameter estimation approach. One method plans for the sample size so that the expected confidence interval width is sufficiently narrow. An extended procedure ensures that the obtained confidence interval will be no wider than desired, with some specified degree of assurance. A Monte Carlo simulation study was conducted that verified the effectiveness of the procedures in realistic situations. The methods developed have been implemented in the MBESS package in R so that they can be easily applied by researchers. © 2011 American Psychological Association
Commentary on Holmes et al. (2007): resolving the debate on when extinction risk is predictable.

PubMed

Ellner, Stephen P; Holmes, Elizabeth E

2008-08-01

We reconcile the findings of Holmes et al. (Ecology Letters, 10, 2007, 1182) that 95% confidence intervals for quasi-extinction risk were narrow for many vertebrates of conservation concern, with previous theory predicting wide confidence intervals. We extend previous theory, concerning the precision of quasi-extinction estimates as a function of population dynamic parameters, prediction intervals and quasi-extinction thresholds, and provide an approximation that specifies the prediction interval and threshold combinations where quasi-extinction estimates are precise (vs. imprecise). This allows PVA practitioners to define the prediction interval and threshold regions of safety (low risk with high confidence), danger (high risk with high confidence), and uncertainty.
Maternal and neonatal outcomes of antenatal anemia in a Scottish population: a retrospective cohort study.

PubMed

Rukuni, Ruramayi; Bhattacharya, Sohinee; Murphy, Michael F; Roberts, David; Stanworth, Simon J; Knight, Marian

2016-05-01

Antenatal anemia is a major public health problem in the UK, yet there is limited high quality evidence for associated poor clinical outcomes. The objectives of this study were to estimate the incidence and clinical outcomes of antenatal anemia in a Scottish population. A retrospective cohort study of 80 422 singleton pregnancies was conducted using data from the Aberdeen Maternal and Neonatal Databank between 1995 and 2012. Antenatal anemia was defined as haemoglobin ≤ 10 g/dl during pregnancy. Incidence was calculated with 95% confidence intervals and compared over time using a chi-squared test for trend. Multivariable logistic regression was used to adjust for confounding variables. Results are presented as adjusted odds ratios with 95% confidence interval. The overall incidence of antenatal anemia was 9.3 cases/100 singleton pregnancies (95% confidence interval 9.1-9.5), decreasing from 16.9/100 to 4.1/100 singleton pregnancies between 1995 and 2012 (p < 0.001). Maternal anemia was associated with antepartum hemorrhage (adjusted odds ratio 1.26, 95% confidence interval 1.17-1.36), postpartum infection (adjusted odds ratio 1.89, 95% confidence interval 1.39-2.57), transfusion (adjusted odds ratio 1.87, 95% confidence interval 1.65-2.13) and stillbirth (adjusted odds ratio 1.42, 95% confidence interval 1.04-1.94), reduced odds of postpartum hemorrhage (adjusted odds ratio 0.92, 95% confidence interval 0.86-0.98) and low birthweight (adjusted odds ratio 0.77, 95% confidence interval 0.69-0.86). No other outcomes were statistically significant. This study shows the incidence of antenatal anemia is decreasing steadily within this Scottish population. However, given that anemia is a readily correctable risk factor for major causes of morbidity and mortality in the UK, further work is required to investigate appropriate preventive measures. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.

Opioid analgesia in mechanically ventilated children: results from the multicenter Measuring Opioid Tolerance Induced by Fentanyl study.

PubMed

Anand, Kanwaljeet J S; Clark, Amy E; Willson, Douglas F; Berger, John; Meert, Kathleen L; Zimmerman, Jerry J; Harrison, Rick; Carcillo, Joseph A; Newth, Christopher J L; Bisping, Stephanie; Holubkov, Richard; Dean, J Michael; Nicholson, Carol E

2013-01-01

To examine the clinical factors associated with increased opioid dose among mechanically ventilated children in the pediatric intensive care unit. Prospective, observational study with 100% accrual of eligible patients. Seven pediatric intensive care units from tertiary-care children's hospitals in the Collaborative Pediatric Critical Care Research Network. Four hundred nineteen children treated with morphine or fentanyl infusions. None. Data on opioid use, concomitant therapy, demographic and explanatory variables were collected. Significant variability occurred in clinical practices, with up to 100-fold differences in baseline opioid doses, average daily or total doses, or peak infusion rates. Opioid exposure for 7 or 14 days required doubling of the daily opioid dose in 16% patients (95% confidence interval 12%-19%) and 20% patients (95% confidence interval 16%-24%), respectively. Among patients receiving opioids for longer than 3 days (n = 225), this occurred in 28% (95% confidence interval 22%-33%) and 35% (95% confidence interval 29%-41%) by 7 or 14 days, respectively. Doubling of the opioid dose was more likely to occur following opioid infusions for 7 days or longer (odds ratio 7.9, 95% confidence interval 4.3-14.3; p < 0.001) or co-therapy with midazolam (odds ratio 5.6, 95% confidence interval 2.4-12.9; p < 0.001), and it was less likely to occur if morphine was used as the primary opioid (vs. fentanyl) (odds ratio 0.48, 95% confidence interval 0.25-0.92; p = 0.03), for patients receiving higher initial doses (odds ratio 0.96, 95% confidence interval 0.95-0.98; p < 0.001), or if patients had prior pediatric intensive care unit admissions (odds ratio 0.37, 95% confidence interval 0.15-0.89; p = 0.03). Mechanically ventilated children require increasing opioid doses, often associated with prolonged opioid exposure or the need for additional sedation. Efforts to reduce prolonged opioid exposure and clinical practice variation may prevent the complications of opioid therapy.
Exploring separable components of institutional confidence.

PubMed

Hamm, Joseph A; PytlikZillig, Lisa M; Tomkins, Alan J; Herian, Mitchel N; Bornstein, Brian H; Neeley, Elizabeth M

2011-01-01

Despite its contemporary and theoretical importance in numerous social scientific disciplines, institutional confidence research is limited by a lack of consensus regarding the distinctions and relationships among related constructs (e.g., trust, confidence, legitimacy, distrust, etc.). This study examined four confidence-related constructs that have been used in studies of trust/confidence in the courts: dispositional trust, trust in institutions, obligation to obey the law, and cynicism. First, the separability of the four constructs was examined by exploratory factor analyses. Relationships among the constructs were also assessed. Next, multiple regression analyses were used to explore each construct's independent contribution to confidence in the courts. Finally, a second study replicated the first study and also examined the stability of the institutional confidence constructs over time. Results supported the hypothesized separability of, and correlations among, the four confidence-related constructs. The extent to which the constructs independently explained the observed variance in confidence in the courts differed as a function of the specific operationalization of confidence in the courts and the individual predictor measures. Implications for measuring institutional confidence and future research directions are discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Confidence Intervals for the Mean: To Bootstrap or Not to Bootstrap

ERIC Educational Resources Information Center

Calzada, Maria E.; Gardner, Holly

2011-01-01

The results of a simulation conducted by a research team involving undergraduate and high school students indicate that when data is symmetric the student's "t" confidence interval for a mean is superior to the studied non-parametric bootstrap confidence intervals. When data is skewed and for sample sizes n greater than or equal to 10,…
Confidence Intervals Make a Difference: Effects of Showing Confidence Intervals on Inferential Reasoning

ERIC Educational Resources Information Center

Hoekstra, Rink; Johnson, Addie; Kiers, Henk A. L.

2012-01-01

The use of confidence intervals (CIs) as an addition or as an alternative to null hypothesis significance testing (NHST) has been promoted as a means to make researchers more aware of the uncertainty that is inherent in statistical inference. Little is known, however, about whether presenting results via CIs affects how readers judge the…
Using Asymptotic Results to Obtain a Confidence Interval for the Population Median

ERIC Educational Resources Information Center

Jamshidian, M.; Khatoonabadi, M.

2007-01-01

Almost all introductory and intermediate level statistics textbooks include the topic of confidence interval for the population mean. Almost all these texts introduce the median as a robust measure of central tendency. Only a few of these books, however, cover inference on the population median and in particular confidence interval for the median.…
ScoreRel CI: An Excel Program for Computing Confidence Intervals for Commonly Used Score Reliability Coefficients

ERIC Educational Resources Information Center

Barnette, J. Jackson

2005-01-01

An Excel program developed to assist researchers in the determination and presentation of confidence intervals around commonly used score reliability coefficients is described. The software includes programs to determine confidence intervals for Cronbachs alpha, Pearson r-based coefficients such as those used in test-retest and alternate forms…
Depressive symptoms in nonresident african american fathers and involvement with their sons.

PubMed

Davis, R Neal; Caldwell, Cleopatra Howard; Clark, Sarah J; Davis, Matthew M

2009-12-01

Our objective was to determine whether paternal depressive symptoms were associated with less father involvement among African American fathers not living with their children (ie, nonresident fathers). We analyzed survey data for 345 fathers enrolled in a program for nonresident African American fathers and their preteen sons. Father involvement included measures of contact, closeness, monitoring, communication, and conflict. We used bivariate analyses and multivariate logistic regression analysis to examine associations between father involvement and depressive symptoms. Thirty-six percent of fathers reported moderate depressive symptoms, and 11% reported severe depressive symptoms. In bivariate analyses, depressive symptoms were associated with less contact, less closeness, low monitoring, and increased conflict. In multivariate analyses controlling for basic demographic features, fathers with moderate depressive symptoms were more likely to have less contact (adjusted odds ratio: 1.7 [95% confidence interval: 1.1-2.8]), less closeness (adjusted odds ratio: 2.1 [95% confidence interval: 1.3-3.5]), low monitoring (adjusted odds ratio: 2.7 [95% confidence interval: 1.4-5.2]), and high conflict (adjusted odds ratio: 2.1 [95% confidence interval: 1.2-3.6]). Fathers with severe depressive symptoms also were more likely to have less contact (adjusted odds ratio: 3.1 [95% confidence interval: 1.4-7.2]), less closeness (adjusted odds ratio: 2.6 [95% confidence interval: 1.2-5.7]), low monitoring (adjusted odds ratio: 2.8 [95% confidence interval: 1.1-7.1]), and high conflict (adjusted odds ratio: 2.6 [95% confidence interval: 1.1-5.9]). Paternal depressive symptoms may be an important, but modifiable, barrier for nonresident African American fathers willing to be more involved with their children.
Ethnic variations in morbidity and mortality from lower respiratory tract infections: a retrospective cohort study.

PubMed

Simpson, Colin R; Steiner, Markus Fc; Cezard, Genevieve; Bansal, Narinder; Fischbacher, Colin; Douglas, Anne; Bhopal, Raj; Sheikh, Aziz

2015-10-01

There is evidence of substantial ethnic variations in asthma morbidity and the risk of hospitalisation, but the picture in relation to lower respiratory tract infections is unclear. We carried out an observational study to identify ethnic group differences for lower respiratory tract infections. A retrospective, cohort study. Scotland. 4.65 million people on whom information was available from the 2001 census, followed from May 2001 to April 2010. Hospitalisations and deaths (any time following first hospitalisation) from lower respiratory tract infections, adjusted risk ratios and hazard ratios by ethnicity and sex were calculated. We multiplied ratios and confidence intervals by 100, so the reference Scottish White population's risk ratio and hazard ratio was 100. Among men, adjusted risk ratios for lower respiratory tract infection hospitalisation were lower in Other White British (80, 95% confidence interval 73-86) and Chinese (69, 95% confidence interval 56-84) populations and higher in Pakistani groups (152, 95% confidence interval 136-169). In women, results were mostly similar to those in men (e.g. Chinese 68, 95% confidence interval 56-82), although higher adjusted risk ratios were found among women of the Other South Asians group (145, 95% confidence interval 120-175). Survival (adjusted hazard ratio) following lower respiratory tract infection for Pakistani men (54, 95% confidence interval 39-74) and women (31, 95% confidence interval 18-53) was better than the reference population. Substantial differences in the rates of lower respiratory tract infections amongst different ethnic groups in Scotland were found. Pakistani men and women had particularly high rates of lower respiratory tract infection hospitalisation. The reasons behind the high rates of lower respiratory tract infection in the Pakistani community are now required. © The Royal Society of Medicine.
Risk factors of childhood asthma in children attending Lyari General Hospital.

PubMed

Kamran, Amber; Hanif, Shahina; Murtaza, Ghulam

2015-06-01

To determine the factors associated with asthma in children. The case-control study was conducted in the paediatrics clinic of Lyari General Hospital, Karachi, from May to October 2010. Children 1-15 years of age attending the clinic represented the cases, while the control group had children who were closely related (sibling or cousin) to the cases but did not have the symptoms of disease at the time. Data was collected through a proforma and analysed using SPSS 10. Of the total 346 subjects, 173(50%) each comprised the two groups. According to univariable analysis the risk factors were presence of at least one smoker (odds ratio: 3.6; 95% confidence interval: 2.3-5.8), resident of kacha house (odds ratio: 16.2; 95% confidence interval: 3.8-69.5),living in room without windows (odds ratio: 9.3; 95% confidence interval: 2.1-40.9) and living in houses without adequate sunlight (odds ratio: 1.6; 95% confidence interval: 1.2-2.4).Using multivariable modelling, family history of asthma (odds ratio: 5.9; 95% confidence interval: 3.1-11.6), presence of at least one smoker at home (odds ratio: 4.1; 95% confidence interval: 2.3-7.2), people living in a room without a window (odds ratio: 5.5; 95% confidence interval: 1.15-26.3) and people living in an area without adequate sunlight (odds ratio: 2.2; 95% confidence interval: 1.13-4.31) were found to be independent risk factors of asthma in children adjusting for age, gender and history of weaning. Family history of asthma, children living with at least one smoker at home, room without windows and people living in an area without sunlight were major risk factors of childhood asthma.
A comparison of confidence interval methods for the concordance correlation coefficient and intraclass correlation coefficient with small number of raters.

PubMed

Feng, Dai; Svetnik, Vladimir; Coimbra, Alexandre; Baumgartner, Richard

2014-01-01

The intraclass correlation coefficient (ICC) with fixed raters or, equivalently, the concordance correlation coefficient (CCC) for continuous outcomes is a widely accepted aggregate index of agreement in settings with small number of raters. Quantifying the precision of the CCC by constructing its confidence interval (CI) is important in early drug development applications, in particular in qualification of biomarker platforms. In recent years, there have been several new methods proposed for construction of CIs for the CCC, but their comprehensive comparison has not been attempted. The methods consisted of the delta method and jackknifing with and without Fisher's Z-transformation, respectively, and Bayesian methods with vague priors. In this study, we carried out a simulation study, with data simulated from multivariate normal as well as heavier tailed distribution (t-distribution with 5 degrees of freedom), to compare the state-of-the-art methods for assigning CI to the CCC. When the data are normally distributed, the jackknifing with Fisher's Z-transformation (JZ) tended to provide superior coverage and the difference between it and the closest competitor, the Bayesian method with the Jeffreys prior was in general minimal. For the nonnormal data, the jackknife methods, especially the JZ method, provided the coverage probabilities closest to the nominal in contrast to the others which yielded overly liberal coverage. Approaches based upon the delta method and Bayesian method with conjugate prior generally provided slightly narrower intervals and larger lower bounds than others, though this was offset by their poor coverage. Finally, we illustrated the utility of the CIs for the CCC in an example of a wake after sleep onset (WASO) biomarker, which is frequently used in clinical sleep studies of drugs for treatment of insomnia.
Standardized likelihood ratio test for comparing several log-normal means and confidence interval for the common mean.

PubMed

Krishnamoorthy, K; Oral, Evrim

2017-12-01

Standardized likelihood ratio test (SLRT) for testing the equality of means of several log-normal distributions is proposed. The properties of the SLRT and an available modified likelihood ratio test (MLRT) and a generalized variable (GV) test are evaluated by Monte Carlo simulation and compared. Evaluation studies indicate that the SLRT is accurate even for small samples, whereas the MLRT could be quite liberal for some parameter values, and the GV test is in general conservative and less powerful than the SLRT. Furthermore, a closed-form approximate confidence interval for the common mean of several log-normal distributions is developed using the method of variance estimate recovery, and compared with the generalized confidence interval with respect to coverage probabilities and precision. Simulation studies indicate that the proposed confidence interval is accurate and better than the generalized confidence interval in terms of coverage probabilities. The methods are illustrated using two examples.
Calculation of Confidence Intervals for the Maximum Magnitude of Earthquakes in Different Seismotectonic Zones of Iran

NASA Astrophysics Data System (ADS)

Salamat, Mona; Zare, Mehdi; Holschneider, Matthias; Zöller, Gert

2017-03-01

The problem of estimating the maximum possible earthquake magnitude m_max has attracted growing attention in recent years. Due to sparse data, the role of uncertainties becomes crucial. In this work, we determine the uncertainties related to the maximum magnitude in terms of confidence intervals. Using an earthquake catalog of Iran, m_max is estimated for different predefined levels of confidence in six seismotectonic zones. Assuming the doubly truncated Gutenberg-Richter distribution as a statistical model for earthquake magnitudes, confidence intervals for the maximum possible magnitude of earthquakes are calculated in each zone. While the lower limit of the confidence interval is the magnitude of the maximum observed event,the upper limit is calculated from the catalog and the statistical model. For this aim, we use the original catalog which no declustering methods applied on as well as a declustered version of the catalog. Based on the study by Holschneider et al. (Bull Seismol Soc Am 101(4):1649-1659, 2011), the confidence interval for m_max is frequently unbounded, especially if high levels of confidence are required. In this case, no information is gained from the data. Therefore, we elaborate for which settings finite confidence levels are obtained. In this work, Iran is divided into six seismotectonic zones, namely Alborz, Azerbaijan, Zagros, Makran, Kopet Dagh, Central Iran. Although calculations of the confidence interval in Central Iran and Zagros seismotectonic zones are relatively acceptable for meaningful levels of confidence, results in Kopet Dagh, Alborz, Azerbaijan and Makran are not that much promising. The results indicate that estimating m_max from an earthquake catalog for reasonable levels of confidence alone is almost impossible.
Effects of safety and health training on work-related injury among construction laborers.

PubMed

Dong, Xiuwen; Entzel, Pamela; Men, Yurong; Chowdhury, Risana; Schneider, Scott

2004-12-01

This study was designed to evaluate the effects of safety and health training on work-related injury in the construction industry. Union health insurance records, union training records, and workers compensation data for 1993 and 1994 were analyzed for more than 8000 construction laborers in Washington State. After controlling for demographic factors, laborers who received safety and health training during the study period were 12% (95% confidence interval [CI] = 0.75-1.02) less likely than nontrained laborers to file for workers compensation. Among workers 16 to 24 years old, training was associated with a 42% (95% CI = 0.35-0.95) reduction in claims. These findings provide evidence of the effectiveness of safety and health training in preventing occupational injuries among construction laborers, particularly among younger workers. However, the results cover only a limited time and the long-term effects remain unclear.
Risk factors for low birth weight according to the multiple logistic regression model. A retrospective cohort study in José María Morelos municipality, Quintana Roo, Mexico.

PubMed

Franco Monsreal, José; Tun Cobos, Miriam Del Ruby; Hernández Gómez, José Ricardo; Serralta Peraza, Lidia Esther Del Socorro

2018-01-17

Low birth weight has been an enigma for science over time. There have been many researches on its causes and its effects. Low birth weight is an indicator that predicts the probability of a child surviving. In fact, there is an exponential relationship between weight deficit, gestational age, and perinatal mortality. Multiple logistic regression is one of the most expressive and versatile statistical instruments available for the analysis of data in both clinical and epidemiology settings, as well as in public health. To assess in a multivariate fashion the importance of 17 independent variables in low birth weight (dependent variable) of children born in the Mayan municipality of José María Morelos, Quintana Roo, Mexico. Analytical observational epidemiological cohort study with retrospective temporality. Births that met the inclusion criteria occurred in the "Hospital Integral Jose Maria Morelos" of the Ministry of Health corresponding to the Maya municipality of Jose Maria Morelos during the period from August 1, 2014 to July 31, 2015. The total number of newborns recorded was 1,147; 84 of which (7.32%) had low birth weight. To estimate the independent association between the explanatory variables (potential risk factors) and the response variable, a multiple logistic regression analysis was performed using the IBM SPSS Statistics 22 software. In ascending numerical order values of odds ratio > 1 indicated the positive contribution of explanatory variables or possible risk factors: "unmarried" marital status (1.076, 95% confidence interval: 0.550 to 2.104); age at menarche ≤ 12 years (1.08, 95% confidence interval: 0.64 to 1.84); history of abortion(s) (1.14, 95% confidence interval: 0.44 to 2.93); maternal weight < 50 kg (1.51, 95% confidence interval: 0.83 to 2.76); number of prenatal consultations ≤ 5 (1.86, 95% confidence interval: 0.94 to 3.66); maternal age ≥ 36 years (3.5, 95% confidence interval: 0.40 to 30.47); maternal age ≤ 19 years (3.59, 95% confidence interval: 0.43 to 29.87); number of deliveries = 1 (3.86, 95% confidence interval: 0.33 to 44.85); personal pathological history (4.78, 95% confidence interval: 2.16 to 10.59); pathological obstetric history (5.01, 95% confidence interval: 1.66 to 15.18); maternal height < 150 cm (5.16, 95% confidence interval: 3.08 to 8.65); number of births ≥ 5 (5.99, 95% confidence interval: 0.51 to 69.99); and smoking (15.63, 95% confidence interval: 1.07 to 227.97). Four of the independent variables (personal pathological history, obstetric pathological history, maternal stature <150 centimeters and smoking) showed a significant positive contribution, thus they can be considered as clear risk factors for low birth weight. The use of the logistic regression model in the Mayan municipality of José María Morelos, will allow estimating the probability of low birth weight for each pregnant woman in the future, which will be useful for the health authorities of the region.
Reliability of confidence intervals calculated by bootstrap and classical methods using the FIA 1-ha plot design

Treesearch

H. T. Schreuder; M. S. Williams

2000-01-01

In simulation sampling from forest populations using sample sizes of 20, 40, and 60 plots respectively, confidence intervals based on the bootstrap (accelerated, percentile, and t-distribution based) were calculated and compared with those based on the classical t confidence intervals for mapped populations and subdomains within those populations. A 68.1 ha mapped...
Confidence Intervals for Proportion Estimates in Complex Samples. Research Report. ETS RR-06-21

ERIC Educational Resources Information Center

Oranje, Andreas

2006-01-01

Confidence intervals are an important tool to indicate uncertainty of estimates and to give an idea of probable values of an estimate if a different sample from the population was drawn or a different sample of measures was used. Standard symmetric confidence intervals for proportion estimates based on a normal approximation can yield bounds…
A Comparison of Methods for Estimating Confidence Intervals for Omega-Squared Effect Size

ERIC Educational Resources Information Center

Finch, W. Holmes; French, Brian F.

2012-01-01

Effect size use has been increasing in the past decade in many research areas. Confidence intervals associated with effect sizes are encouraged to be reported. Prior work has investigated the performance of confidence interval estimation with Cohen's d. This study extends this line of work to the analysis of variance case with more than two…
Patient, surgeon, and hospital disparities associated with benign hysterectomy approach and perioperative complications.

PubMed

Mehta, Ambar; Xu, Tim; Hutfless, Susan; Makary, Martin A; Sinno, Abdulrahman K; Tanner, Edward J; Stone, Rebecca L; Wang, Karen; Fader, Amanda N

2017-05-01

Hysterectomy is among the most common major surgical procedures performed in women. Approximately 450,000 hysterectomy procedures are performed each year in the United States for benign indications. However, little is known regarding contemporary US hysterectomy trends for women with benign disease with respect to operative technique and perioperative complications, and the association between these 2 factors with patient, surgeon, and hospital characteristics. We sought to describe contemporary hysterectomy trends and explore associations between patient, surgeon, and hospital characteristics with surgical approach and perioperative complications. Hysterectomies performed for benign indications by general gynecologists from July 2012 through September 2014 were analyzed in the all-payer Maryland Health Services Cost Review Commission database. We excluded hysterectomies performed by gynecologic oncologists, reproductive endocrinologists, and female pelvic medicine and reconstructive surgeons. We included both open hysterectomies and those performed by minimally invasive surgery, which included vaginal hysterectomies. Perioperative complications were defined using the Agency for Healthcare Research and Quality patient safety indicators. Surgeon hysterectomy volume during the 2-year study period was analyzed (0-5 cases annually = very low, 6-10 = low, 11-20 = medium, and ≥21 = high). We utilized logistic regression and negative binomial regression to identify patient, surgeon, and hospital characteristics associated with minimally invasive surgery utilization and perioperative complications, respectively. A total of 5660 hospitalizations were identified during the study period. Most patients (61.5%) had an open hysterectomy; 38.5% underwent a minimally invasive surgery procedure (25.1% robotic, 46.6% laparoscopic, 28.3% vaginal). Most surgeons (68.2%) were very low- or low-volume surgeons. Factors associated with a lower likelihood of undergoing minimally invasive surgery included older patient age (reference 45-64 years; 20-44 years: adjusted odds ratio, 1.16; 95% confidence interval, 1.05-1.28), black race (reference white; adjusted odds ratio, 0.70; 95% confidence interval, 0.63-0.78), Hispanic ethnicity (adjusted odds ratio, 0.62; 95% confidence interval, 0.48-0.80), smaller hospital (reference large; small: adjusted odds ratio, 0.26; 95% confidence interval, 0.15-0.45; medium: adjusted odds ratio, 0.87; 95% confidence interval, 0.79-0.96), medium hospital hysterectomy volume (reference ≥200 hysterectomies; 100-200: adjusted odds ratio, 0.78; 95% confidence interval, 0.71-0.87), and medium vs high surgeon volume (reference high; medium: adjusted odds ratio, 0.87; 95% confidence interval, 0.78-0.97). Complications occurred in 25.8% of open and 8.2% of minimally invasive hysterectomies (P < .0001). Minimally invasive hysterectomy (adjusted odds ratio, 0.22; 95% confidence interval, 0.17-0.27) and large hysterectomy volume hospitals (reference ≥200 hysterectomies; 1-100: adjusted odds ratio, 2.26; 95% confidence interval, 1.60-3.20; 101-200: adjusted odds ratio, 1.63; 95% confidence interval, 1.23-2.16) were associated with fewer complications, while patient payer, including Medicare (reference private; adjusted odds ratio, 1.86; 95% confidence interval, 1.33-2.61), Medicaid (adjusted odds ratio, 1.63; 95% confidence interval, 1.30-2.04), and self-pay status (adjusted odds ratio, 2.41; 95% confidence interval, 1.40-4.12), and very-low and low surgeon hysterectomy volume (reference ≥21 cases; 1-5 cases: adjusted odds ratio, 1.73; 95% confidence interval, 1.22-2.47; 6-10 cases: adjusted odds ratio, 1.60; 95% confidence interval, 1.11-2.23) were associated with perioperative complications. Use of minimally invasive hysterectomy for benign indications remains variable, with most patients undergoing open, more morbid procedures. Older and black patients and smaller hospitals are associated with open hysterectomy. Patient race and payer status, hysterectomy approach, and surgeon volume were associated with perioperative complications. Hysterectomies performed for benign indications by high-volume surgeons or by minimally invasive techniques may represent an opportunity to reduce preventable harm. Copyright © 2017 Elsevier Inc. All rights reserved.
Variability of child access prevention laws and pediatric firearm injuries.

PubMed

Hamilton, Emma C; Miller, Charles C; Cox, Charles S; Lally, Kevin P; Austin, Mary T

2018-04-01

State-level child access prevention (CAP) laws impose criminal liability on adults who negligently allow children access to firearms. The CAP laws can be further divided into strong CAP laws which impose criminal liability for negligently stored firearms and weak CAP laws that prohibit adults from intentionally, knowingly, and/or recklessly providing firearms to a minor. We hypothesized that strong CAP laws would be associated with a greater reduction in pediatric firearm injuries than weak CAP laws. We constructed a cross-sectional national study using the Healthcare Cost and Utilization Project-Kids Inpatient Database from 2006 and 2009 using weighted counts of firearm-related admissions among children younger than 18 years. Poisson regression was used to estimate the association of CAP laws with pediatric firearm injuries. After adjusting for race, sex, age, and socioeconomic income quartile, strong CAP laws were associated with a significant reduction in all (incidence rate ratio, 0.70; 95% confidence interval, 0.52-0.93), self-inflicted (incidence rate ratio, 0.46; 95% confidence interval, 0.26-0.79), and unintentional (incidence rate ratio, 0.56; 95% confidence interval, 0.43-0.74) pediatric firearm injuries. Weak CAP laws, which only impose liability for reckless endangerment, were associated with an increased risk of all pediatric firearm injuries. The association of CAP laws on hospitalizations for pediatric firearm injuries differed greatly depending on whether a state had adopted a strong CAP law or a weak CAP law. Implementation of strong CAP laws by each state, which require safe storage of firearms, has the potential to significantly reduce pediatric firearm injuries. Prognostic and epidemiology study, level III.
Cardiac rehabilitation attendance and outcomes in coronary artery disease patients.

PubMed

Martin, Billie-Jean; Hauer, Trina; Arena, Ross; Austford, Leslie D; Galbraith, P Diane; Lewin, Adriane M; Knudtson, Merril L; Ghali, William A; Stone, James A; Aggarwal, Sandeep G

2012-08-07

Cardiac rehabilitation (CR) is an efficacious yet underused treatment for patients with coronary artery disease. The objective of this study was to determine the association between CR completion and mortality and resource use. We conducted a prospective cohort study of 5886 subjects (20.8% female; mean age, 60.6 years) who had undergone angiography and were referred for CR in Calgary, AB, Canada, between 1996 and 2009. Outcomes of interest included freedom from emergency room visits, hospitalization, and survival in CR completers versus noncompleters, adjusted for clinical covariates, treatment strategy, and coronary anatomy. Hazard ratios for events for CR completers versus noncompleters were also constructed. A propensity model was used to match completers to noncompleters on baseline characteristics, and each outcome was compared between propensity-matched groups. Of the subjects referred for CR, 2900 (49.3%) completed the program, and an additional 554 subjects started but did not complete CR. CR completion was associated with a lower risk of death, with an adjusted hazard ratio of 0.59 (95% confidence interval, 0.49-0.70). CR completion was also associated with a decreased risk of all-cause hospitalization (adjusted hazard ratio, 0.77; 95% confidence interval, 0.71-0.84) and cardiac hospitalization (adjusted hazard ratio, 0.68; 95% confidence interval, 0.55-0.83) but not with emergency room visits. Propensity-matched analysis demonstrated a persistent association between CR completion and reduced mortality. Among those coronary artery disease patients referred, CR completion is associated with improved survival and decreased hospitalization. There is a need to explore reasons for nonattendance and to test interventions to improve attendance after referral.

Methods for estimating confidence intervals in interrupted time series analyses of health interventions.

PubMed

Zhang, Fang; Wagner, Anita K; Soumerai, Stephen B; Ross-Degnan, Dennis

2009-02-01

Interrupted time series (ITS) is a strong quasi-experimental research design, which is increasingly applied to estimate the effects of health services and policy interventions. We describe and illustrate two methods for estimating confidence intervals (CIs) around absolute and relative changes in outcomes calculated from segmented regression parameter estimates. We used multivariate delta and bootstrapping methods (BMs) to construct CIs around relative changes in level and trend, and around absolute changes in outcome based on segmented linear regression analyses of time series data corrected for autocorrelated errors. Using previously published time series data, we estimated CIs around the effect of prescription alerts for interacting medications with warfarin on the rate of prescriptions per 10,000 warfarin users per month. Both the multivariate delta method (MDM) and the BM produced similar results. BM is preferred for calculating CIs of relative changes in outcomes of time series studies, because it does not require large sample sizes when parameter estimates are obtained correctly from the model. Caution is needed when sample size is small.
Inactivation of the Haemophilus ducreyi luxS gene affects the virulence of this pathogen in human subjects.

PubMed

Labandeira-Rey, Maria; Janowicz, Diane M; Blick, Robert J; Fortney, Kate R; Zwickl, Beth; Katz, Barry P; Spinola, Stanley M; Hansen, Eric J

2009-08-01

Haemophilus ducreyi 35000HP contains a homologue of the luxS gene, which encodes an enzyme that synthesizes autoinducer 2 (AI-2) in other gram-negative bacteria. H. ducreyi 35000HP produced AI-2 that functioned in a Vibrio harveyi-based reporter system. A H. ducreyi luxS mutant was constructed by insertional inactivation of the luxS gene and lost the ability to produce AI-2. Provision of the H. ducreyi luxS gene in trans partially restored AI-2 production by the mutant. The luxS mutant was compared with its parent for virulence in the human challenge model of experimental chancroid. The pustule-formation rate in 5 volunteers was 93.3% (95% confidence interval, 81.7%-99.9%) at 15 parent sites and 60.0% (95% confidence interval, 48.3%-71.7%) at 15 mutant sites (1-tailed P < .001). Thus, the luxS mutant was partially attenuated for virulence. This is the first report of AI-2 production contributing to the pathogenesis of a genital ulcer disease.
A comparison of confidence/credible interval methods for the area under the ROC curve for continuous diagnostic tests with small sample size.

PubMed

Feng, Dai; Cortese, Giuliana; Baumgartner, Richard

2017-12-01

The receiver operating characteristic (ROC) curve is frequently used as a measure of accuracy of continuous markers in diagnostic tests. The area under the ROC curve (AUC) is arguably the most widely used summary index for the ROC curve. Although the small sample size scenario is common in medical tests, a comprehensive study of small sample size properties of various methods for the construction of the confidence/credible interval (CI) for the AUC has been by and large missing in the literature. In this paper, we describe and compare 29 non-parametric and parametric methods for the construction of the CI for the AUC when the number of available observations is small. The methods considered include not only those that have been widely adopted, but also those that have been less frequently mentioned or, to our knowledge, never applied to the AUC context. To compare different methods, we carried out a simulation study with data generated from binormal models with equal and unequal variances and from exponential models with various parameters and with equal and unequal small sample sizes. We found that the larger the true AUC value and the smaller the sample size, the larger the discrepancy among the results of different approaches. When the model is correctly specified, the parametric approaches tend to outperform the non-parametric ones. Moreover, in the non-parametric domain, we found that a method based on the Mann-Whitney statistic is in general superior to the others. We further elucidate potential issues and provide possible solutions to along with general guidance on the CI construction for the AUC when the sample size is small. Finally, we illustrate the utility of different methods through real life examples.
Opioid Analgesics and Adverse Outcomes among Hemodialysis Patients.

PubMed

Ishida, Julie H; McCulloch, Charles E; Steinman, Michael A; Grimes, Barbara A; Johansen, Kirsten L

2018-05-07

Patients on hemodialysis frequently experience pain and may be particularly vulnerable to opioid-related complications. However, data evaluating the risks of opioid use in patients on hemodialysis are limited. Using the US Renal Data System, we conducted a cohort study evaluating the association between opioid use (modeled as a time-varying exposure and expressed in standardized oral morphine equivalents) and time to first emergency room visit or hospitalization for altered mental status, fall, and fracture among 140,899 Medicare-covered adults receiving hemodialysis in 2011. We evaluated risk according to average daily total opioid dose (>60 mg, ≤60 mg, and per 60-mg dose increment) and specific agents (per 60-mg dose increment). The median age was 61 years old, 52% were men, and 50% were white. Sixty-four percent received opioids, and 17% had an episode of altered mental status (15,658 events), fall (7646 events), or fracture (4151 events) in 2011. Opioid use was associated with risk for all outcomes in a dose-dependent manner: altered mental status (lower dose: hazard ratio, 1.28; 95% confidence interval, 1.23 to 1.34; higher dose: hazard ratio, 1.67; 95% confidence interval, 1.56 to 1.78; hazard ratio, 1.29 per 60 mg; 95% confidence interval, 1.26 to 1.33), fall (lower dose: hazard ratio, 1.28; 95% confidence interval, 1.21 to 1.36; higher dose: hazard ratio, 1.45; 95% confidence interval, 1.31 to 1.61; hazard ratio, 1.04 per 60 mg; 95% confidence interval, 1.03 to 1.05), and fracture (lower dose: hazard ratio, 1.44; 95% confidence interval, 1.33 to 1.56; higher dose: hazard ratio, 1.65; 95% confidence interval, 1.44 to 1.89; hazard ratio, 1.04 per 60 mg; 95% confidence interval, 1.04 to 1.05). All agents were associated with a significantly higher hazard of altered mental status, and several agents were associated with a significantly higher hazard of fall and fracture. Opioids were associated with adverse outcomes in patients on hemodialysis, and this risk was present even at lower dosing and for agents that guidelines have recommended for use. Copyright © 2018 by the American Society of Nephrology.
Pregnancy outcome in joint hypermobility syndrome and Ehlers-Danlos syndrome.

PubMed

Sundelin, Heléne E K; Stephansson, Olof; Johansson, Kari; Ludvigsson, Jonas F

2017-01-01

An increased risk of preterm birth in women with joint hypermobility syndrome or Ehlers-Danlos syndrome is suspected. In this nationwide cohort study from 1997 through 2011, women with either joint hypermobility syndrome or Ehlers-Danlos syndrome or both disorders were identified through the Swedish Patient Register, and linked to the Medical Birth Register. Thereby, 314 singleton births to women with joint hypermobility syndrome/Ehlers-Danlos syndrome before delivery were identified. These births were compared with 1 247 864 singleton births to women without a diagnosis of joint hypermobility syndrome/Ehlers-Danlos syndrome. We used logistic regression, adjusted for maternal age, smoking, parity, and year of birth, to calculate adjusted odds ratios for adverse pregnancy outcomes. Maternal joint hypermobility syndrome/Ehlers-Danlos syndrome was not associated with any of our outcomes: preterm birth (adjusted odds ratio = 0.6, 95% confidence interval 0.3-1.2), preterm premature rupture of membranes (adjusted odds ratio = 0.8; 95% confidence interval 0.3-2.2), cesarean section (adjusted odds ratio = 0.9, 95% confidence interval 0.7-1.2), stillbirth (adjusted odds ratio = 1.1, 95% confidence interval 0.2-7.9), low Apgar score (adjusted odds ratio = 1.6, 95% confidence interval 0.7-3.6), small for gestational age (adjusted odds ratio = 0.9, 95% confidence interval 0.4-1.8) or large for gestational age (adjusted odds ratio = 1.2, 95% confidence interval 0.6-2.1). Examining only women with Ehlers-Danlos syndrome (n = 62), we found a higher risk of induction of labor (adjusted odds ratio = 2.6; 95% confidence interval 1.4-4.6) and amniotomy (adjusted odds ratio = 3.8; 95% confidence interval 2.0-7.1). No excess risks for adverse pregnancy outcome were seen in joint hypermobility syndrome. Women with joint hypermobility syndrome/Ehlers-Danlos syndrome do not seem to be at increased risk of adverse pregnancy outcome. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.
Comprehension of confidence intervals - development and piloting of patient information materials for people with multiple sclerosis: qualitative study and pilot randomised controlled trial.

PubMed

Rahn, Anne C; Backhus, Imke; Fuest, Franz; Riemann-Lorenz, Karin; Köpke, Sascha; van de Roemer, Adrianus; Mühlhauser, Ingrid; Heesen, Christoph

2016-09-20

Presentation of confidence intervals alongside information about treatment effects can support informed treatment choices in people with multiple sclerosis. We aimed to develop and pilot-test different written patient information materials explaining confidence intervals in people with relapsing-remitting multiple sclerosis. Further, a questionnaire on comprehension of confidence intervals was developed and piloted. We developed different patient information versions aiming to explain confidence intervals. We used an illustrative example to test three different approaches: (1) short version, (2) "average weight" version and (3) "worm prophylaxis" version. Interviews were conducted using think-aloud and teach-back approaches to test feasibility and analysed using qualitative content analysis. To assess comprehension of confidence intervals, a six-item multiple choice questionnaire was developed and tested in a pilot randomised controlled trial using the online survey software UNIPARK. Here, the average weight version (intervention group) was tested against a standard patient information version on confidence intervals (control group). People with multiple sclerosis were invited to take part using existing mailing-lists of people with multiple sclerosis in Germany and were randomised using the UNIPARK algorithm. Participants were blinded towards group allocation. Primary endpoint was comprehension of confidence intervals, assessed with the six-item multiple choice questionnaire with six points representing perfect knowledge. Feasibility of the patient information versions was tested with 16 people with multiple sclerosis. For the pilot randomised controlled trial, 64 people with multiple sclerosis were randomised (intervention group: n = 36; control group: n = 28). More questions were answered correctly in the intervention group compared to the control group (mean 4.8 vs 3.8, mean difference 1.1 (95 % CI 0.42-1.69), p = 0.002). The questionnaire's internal consistency was moderate (Cronbach's alpha = 0.56). The pilot-phase shows promising results concerning acceptability and feasibility. Pilot randomised controlled trial results indicate that the patient information is well understood and that knowledge gain on confidence intervals can be assessed with a set of six questions. German Clinical Trials Register: DRKS00008561 . Registered 8th of June 2015.
Ethnic Differences in Incidence and Outcomes of Childhood Nephrotic Syndrome.

PubMed

Banh, Tonny H M; Hussain-Shamsy, Neesha; Patel, Viral; Vasilevska-Ristovska, Jovanka; Borges, Karlota; Sibbald, Cathryn; Lipszyc, Deborah; Brooke, Josefina; Geary, Denis; Langlois, Valerie; Reddon, Michele; Pearl, Rachel; Levin, Leo; Piekut, Monica; Licht, Christoph P B; Radhakrishnan, Seetha; Aitken-Menezes, Kimberly; Harvey, Elizabeth; Hebert, Diane; Piscione, Tino D; Parekh, Rulan S

2016-10-07

Ethnic differences in outcomes among children with nephrotic syndrome are unknown. We conducted a longitudinal study at a single regional pediatric center comparing ethnic differences in incidence from 2001 to 2011 census data and longitudinal outcomes, including relapse rates, time to first relapse, frequently relapsing disease, and use of cyclophosphamide. Among 711 children, 24% were European, 33% were South Asian, 10% were East/Southeast Asian, and 33% were of other origins. Over 10 years, the overall incidence increased from 1.99/100,000 to 4.71/100,000 among children ages 1-18 years old. In 2011, South Asians had a higher incidence rate ratio of 6.61 (95% confidence interval, 3.16 to 15.1) compared with Europeans. East/Southeast Asians had a similar incidence rate ratio (0.76; 95% confidence interval, 0.13 to 2.94) to Europeans. We determined outcomes in 455 children from the three largest ethnic groups with steroid-sensitive disease over a median of 4 years. South Asian and East/Southeast Asian children had significantly lower odds of frequently relapsing disease at 12 months (South Asian: adjusted odds ratio; 0.55; 95% confidence interval, 0.39 to 0.77; East/Southeast Asian: adjusted odds ratio; 0.42; 95% confidence interval, 0.34 to 0.51), fewer subsequent relapses (South Asian: adjusted odds ratio; 0.64; 95% confidence interval, 0.50 to 0.81; East/Southeast Asian: adjusted odds ratio; 0.47; 95% confidence interval, 0.24 to 0.91), lower risk of a first relapse (South Asian: adjusted hazard ratio, 0.74; 95% confidence interval, 0.67 to 0.83; East/Southeast Asian: adjusted hazard ratio, 0.65; 95% CI, 0.63 to 0.68), and lower use of cyclophosphamide (South Asian: adjusted hazard ratio, 0.82; 95% confidence interval, 0.53 to 1.28; East/Southeast Asian: adjusted hazard ratio, 0.54; 95% confidence interval, 0.41 to 0.71) compared with European children. Despite the higher incidence among South Asians, South and East/Southeast Asian children have significantly less complicated clinical outcomes compared with Europeans. Copyright © 2016 by the American Society of Nephrology.
Mutual information identifies spurious Hurst phenomena in resting state EEG and fMRI data

NASA Astrophysics Data System (ADS)

von Wegner, Frederic; Laufs, Helmut; Tagliazucchi, Enzo

2018-02-01

Long-range memory in time series is often quantified by the Hurst exponent H , a measure of the signal's variance across several time scales. We analyze neurophysiological time series from electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) resting state experiments with two standard Hurst exponent estimators and with the time-lagged mutual information function applied to discretized versions of the signals. A confidence interval for the mutual information function is obtained from surrogate Markov processes with equilibrium distribution and transition matrix identical to the underlying signal. For EEG signals, we construct an additional mutual information confidence interval from a short-range correlated, tenth-order autoregressive model. We reproduce the previously described Hurst phenomenon (H >0.5 ) in the analytical amplitude of alpha frequency band oscillations, in EEG microstate sequences, and in fMRI signals, but we show that the Hurst phenomenon occurs without long-range memory in the information-theoretical sense. We find that the mutual information function of neurophysiological data behaves differently from fractional Gaussian noise (fGn), for which the Hurst phenomenon is a sufficient condition to prove long-range memory. Two other well-characterized, short-range correlated stochastic processes (Ornstein-Uhlenbeck, Cox-Ingersoll-Ross) also yield H >0.5 , whereas their mutual information functions lie within the Markovian confidence intervals, similar to neural signals. In these processes, which do not have long-range memory by construction, a spurious Hurst phenomenon occurs due to slow relaxation times and heteroscedasticity (time-varying conditional variance). In summary, we find that mutual information correctly distinguishes long-range from short-range dependence in the theoretical and experimental cases discussed. Our results also suggest that the stationary fGn process is not sufficient to describe neural data, which seem to belong to a more general class of stochastic processes, in which multiscale variance effects produce Hurst phenomena without long-range dependence. In our experimental data, the Hurst phenomenon and long-range memory appear as different system properties that should be estimated and interpreted independently.
Confidence intervals for correlations when data are not normal.

PubMed

Bishara, Anthony J; Hittner, James B

2017-02-01

With nonnormal data, the typical confidence interval of the correlation (Fisher z') may be inaccurate. The literature has been unclear as to which of several alternative methods should be used instead, and how extreme a violation of normality is needed to justify an alternative. Through Monte Carlo simulation, 11 confidence interval methods were compared, including Fisher z', two Spearman rank-order methods, the Box-Cox transformation, rank-based inverse normal (RIN) transformation, and various bootstrap methods. Nonnormality often distorted the Fisher z' confidence interval-for example, leading to a 95 % confidence interval that had actual coverage as low as 68 %. Increasing the sample size sometimes worsened this problem. Inaccurate Fisher z' intervals could be predicted by a sample kurtosis of at least 2, an absolute sample skewness of at least 1, or significant violations of normality hypothesis tests. Only the Spearman rank-order and RIN transformation methods were universally robust to nonnormality. Among the bootstrap methods, an observed imposed bootstrap came closest to accurate coverage, though it often resulted in an overly long interval. The results suggest that sample nonnormality can justify avoidance of the Fisher z' interval in favor of a more robust alternative. R code for the relevant methods is provided in supplementary materials.
Inverse modeling with RZWQM2 to predict water quality

USGS Publications Warehouse

Nolan, Bernard T.; Malone, Robert W.; Ma, Liwang; Green, Christopher T.; Fienen, Michael N.; Jaynes, Dan B.

2011-01-01

This chapter presents guidelines for autocalibration of the Root Zone Water Quality Model (RZWQM2) by inverse modeling using PEST parameter estimation software (Doherty, 2010). Two sites with diverse climate and management were considered for simulation of N losses by leaching and in drain flow: an almond [Prunus dulcis (Mill.) D.A. Webb] orchard in the San Joaquin Valley, California and the Walnut Creek watershed in central Iowa, which is predominantly in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Inverse modeling provides an objective statistical basis for calibration that involves simultaneous adjustment of model parameters and yields parameter confidence intervals and sensitivities. We describe operation of PEST in both parameter estimation and predictive analysis modes. The goal of parameter estimation is to identify a unique set of parameters that minimize a weighted least squares objective function, and the goal of predictive analysis is to construct a nonlinear confidence interval for a prediction of interest by finding a set of parameters that maximizes or minimizes the prediction while maintaining the model in a calibrated state. We also describe PEST utilities (PAR2PAR, TSPROC) for maintaining ordered relations among model parameters (e.g., soil root growth factor) and for post-processing of RZWQM2 outputs representing different cropping practices at the Iowa site. Inverse modeling provided reasonable fits to observed water and N fluxes and directly benefitted the modeling through: (i) simultaneous adjustment of multiple parameters versus one-at-a-time adjustment in manual approaches; (ii) clear indication by convergence criteria of when calibration is complete; (iii) straightforward detection of nonunique and insensitive parameters, which can affect the stability of PEST and RZWQM2; and (iv) generation of confidence intervals for uncertainty analysis of parameters and model predictions. Composite scaled sensitivities, which reflect the total information provided by the observations for a parameter, indicated that most of the RZWQM2 parameters at the California study site (CA) and Iowa study site (IA) could be reliably estimated by regression. Correlations obtained in the CA case indicated that all model parameters could be uniquely estimated by inverse modeling. Although water content at field capacity was highly correlated with bulk density (−0.94), the correlation is less than the threshold for nonuniqueness (0.95, absolute value basis). Additionally, we used truncated singular value decomposition (SVD) at CA to mitigate potential problems with highly correlated and insensitive parameters. Singular value decomposition estimates linear combinations (eigenvectors) of the original process-model parameters. Parameter confidence intervals (CIs) at CA indicated that parameters were reliably estimated with the possible exception of an organic pool transfer coefficient (R45), which had a comparatively wide CI. However, the 95% confidence interval for R45 (0.03–0.35) is mostly within the range of values reported for this parameter. Predictive analysis at CA generated confidence intervals that were compared with independently measured annual water flux (groundwater recharge) and median nitrate concentration in a collocated monitoring well as part of model evaluation. Both the observed recharge (42.3 cm yr−1) and nitrate concentration (24.3 mg L−1) were within their respective 90% confidence intervals, indicating that overall model error was within acceptable limits.
Facebook and Twitter vaccine sentiment in response to measles outbreaks.

PubMed

Deiner, Michael S; Fathy, Cherie; Kim, Jessica; Niemeyer, Katherine; Ramirez, David; Ackley, Sarah F; Liu, Fengchen; Lietman, Thomas M; Porco, Travis C

2017-11-01

Social media posts regarding measles vaccination were classified as pro-vaccination, expressing vaccine hesitancy, uncertain, or irrelevant. Spearman correlations with Centers for Disease Control and Prevention-reported measles cases and differenced smoothed cumulative case counts over this period were reported (using time series bootstrap confidence intervals). A total of 58,078 Facebook posts and 82,993 tweets were identified from 4 January 2009 to 27 August 2016. Pro-vaccination posts were correlated with the US weekly reported cases (Facebook: Spearman correlation 0.22 (95% confidence interval: 0.09 to 0.34), Twitter: 0.21 (95% confidence interval: 0.06 to 0.34)). Vaccine-hesitant posts, however, were uncorrelated with measles cases in the United States (Facebook: 0.01 (95% confidence interval: -0.13 to 0.14), Twitter: 0.0011 (95% confidence interval: -0.12 to 0.12)). These findings may result from more consistent social media engagement by individuals expressing vaccine hesitancy, contrasted with media- or event-driven episodic interest on the part of individuals favoring current policy.
Exact Scheffé-type confidence intervals for output from groundwater flow models: 1. Use of hydrogeologic information

USGS Publications Warehouse

Cooley, Richard L.

1993-01-01

A new method is developed to efficiently compute exact Scheffé-type confidence intervals for output (or other function of parameters) g(β) derived from a groundwater flow model. The method is general in that parameter uncertainty can be specified by any statistical distribution having a log probability density function (log pdf) that can be expanded in a Taylor series. However, for this study parameter uncertainty is specified by a statistical multivariate beta distribution that incorporates hydrogeologic information in the form of the investigator's best estimates of parameters and a grouping of random variables representing possible parameter values so that each group is defined by maximum and minimum bounds and an ordering according to increasing value. The new method forms the confidence intervals from maximum and minimum limits of g(β) on a contour of a linear combination of (1) the quadratic form for the parameters used by Cooley and Vecchia (1987) and (2) the log pdf for the multivariate beta distribution. Three example problems are used to compare characteristics of the confidence intervals for hydraulic head obtained using different weights for the linear combination. Different weights generally produced similar confidence intervals, whereas the method of Cooley and Vecchia (1987) often produced much larger confidence intervals.
A confidence interval analysis of sampling effort, sequencing depth, and taxonomic resolution of fungal community ecology in the era of high-throughput sequencing.

PubMed

Oono, Ryoko

2017-01-01

High-throughput sequencing technology has helped microbial community ecologists explore ecological and evolutionary patterns at unprecedented scales. The benefits of a large sample size still typically outweigh that of greater sequencing depths per sample for accurate estimations of ecological inferences. However, excluding or not sequencing rare taxa may mislead the answers to the questions 'how and why are communities different?' This study evaluates the confidence intervals of ecological inferences from high-throughput sequencing data of foliar fungal endophytes as case studies through a range of sampling efforts, sequencing depths, and taxonomic resolutions to understand how technical and analytical practices may affect our interpretations. Increasing sampling size reliably decreased confidence intervals across multiple community comparisons. However, the effects of sequencing depths on confidence intervals depended on how rare taxa influenced the dissimilarity estimates among communities and did not significantly decrease confidence intervals for all community comparisons. A comparison of simulated communities under random drift suggests that sequencing depths are important in estimating dissimilarities between microbial communities under neutral selective processes. Confidence interval analyses reveal important biases as well as biological trends in microbial community studies that otherwise may be ignored when communities are only compared for statistically significant differences.
The Applicability of Confidence Intervals of Quantiles for the Generalized Logistic Distribution

NASA Astrophysics Data System (ADS)

Shin, H.; Heo, J.; Kim, T.; Jung, Y.

2007-12-01

The generalized logistic (GL) distribution has been widely used for frequency analysis. However, there is a little study related to the confidence intervals that indicate the prediction accuracy of distribution for the GL distribution. In this paper, the estimation of the confidence intervals of quantiles for the GL distribution is presented based on the method of moments (MOM), maximum likelihood (ML), and probability weighted moments (PWM) and the asymptotic variances of each quantile estimator are derived as functions of the sample sizes, return periods, and parameters. Monte Carlo simulation experiments are also performed to verify the applicability of the derived confidence intervals of quantile. As the results, the relative bias (RBIAS) and relative root mean square error (RRMSE) of the confidence intervals generally increase as return period increases and reverse as sample size increases. And PWM for estimating the confidence intervals performs better than the other methods in terms of RRMSE when the data is almost symmetric while ML shows the smallest RBIAS and RRMSE when the data is more skewed and sample size is moderately large. The GL model was applied to fit the distribution of annual maximum rainfall data. The results show that there are little differences in the estimated quantiles between ML and PWM while distinct differences in MOM.
A confidence interval analysis of sampling effort, sequencing depth, and taxonomic resolution of fungal community ecology in the era of high-throughput sequencing

PubMed Central

2017-01-01

High-throughput sequencing technology has helped microbial community ecologists explore ecological and evolutionary patterns at unprecedented scales. The benefits of a large sample size still typically outweigh that of greater sequencing depths per sample for accurate estimations of ecological inferences. However, excluding or not sequencing rare taxa may mislead the answers to the questions ‘how and why are communities different?’ This study evaluates the confidence intervals of ecological inferences from high-throughput sequencing data of foliar fungal endophytes as case studies through a range of sampling efforts, sequencing depths, and taxonomic resolutions to understand how technical and analytical practices may affect our interpretations. Increasing sampling size reliably decreased confidence intervals across multiple community comparisons. However, the effects of sequencing depths on confidence intervals depended on how rare taxa influenced the dissimilarity estimates among communities and did not significantly decrease confidence intervals for all community comparisons. A comparison of simulated communities under random drift suggests that sequencing depths are important in estimating dissimilarities between microbial communities under neutral selective processes. Confidence interval analyses reveal important biases as well as biological trends in microbial community studies that otherwise may be ignored when communities are only compared for statistically significant differences. PMID:29253889
Primary repair of penetrating colon injuries: a systematic review.

PubMed

Singer, Marc A; Nelson, Richard L

2002-12-01

Primary repair of penetrating colon injuries is an appealing management option; however, uncertainty about its safety persists. This study was conducted to compare the morbidity and mortality of primary repair with fecal diversion in the management of penetrating colon injuries by use of a meta-analysis of randomized, prospective trials. We searched for prospective, randomized trials in MEDLINE (1966 to November 2001), the Cochrane Library, and EMBase using the terms colon, penetrating, injury, colostomy, prospective, and randomized. Studies were included if they were randomized, controlled trials that compared the outcomes of primary repair with fecal diversion in the management of penetrating colon injuries. Five studies were included. Reviewers performed data extraction independently. Outcomes evaluated from each trial included mortality, total complications, infectious complications, intra-abdominal infections, wound complications, penetrating abdominal trauma index, and length of stay. Peto odds ratios for combined effect were calculated with a 95 percent confidence interval for each outcome. Heterogeneity was also assessed for each outcome. The penetrating abdominal trauma index of included subjects did not differ significantly between studies. Mortality was not significantly different between groups (odds ratio, 1.70; 95 percent confidence interval, 0.51-5.66). However, total complications (odds ratio, 0.28; 95 percent confidence interval, 0.18-0.42), total infectious complications (odds ratio, 0.41; 95 percent confidence interval, 0.27-0.63), abdominal infections including dehiscence (odds ratio, 0.59; 95 percent confidence interval, 0.38-0.94), abdominal infections excluding dehiscence (odds ratio, 0.52; 95 percent confidence interval, 0.31-0.86), wound complications including dehiscence (odds ratio, 0.55; 95 percent confidence interval, 0.34-0.89), and wound complications excluding dehiscence (odds ratio, 0.43; 95 percent confidence interval, 0.25-0.76) all significantly favored primary repair. Meta-analysis of currently published randomized, controlled trials favors primary repair over fecal diversion for penetrating colon injuries.
Bullying and mental health and suicidal behaviour among 14- to 15-year-olds in a representative sample of Australian children.

PubMed

Ford, Rebecca; King, Tania; Priest, Naomi; Kavanagh, Anne

2017-09-01

To provide the first Australian population-based estimates of the association between bullying and adverse mental health outcomes and suicidality among Australian adolescents. Analysis of data from 3537 adolescents, aged 14-15 years from Wave 6 of the K-cohort of Longitudinal Study of Australian Children was conducted. We used Poisson and linear regression to estimate associations between bullying type (none, relational-verbal, physical, both types) and role (no role, victim, bully, victim and bully), and mental health (measured by the Strengths and Difficulties Questionnaire, symptoms of anxiety and depression) and suicidality. Adolescents involved in bullying had significantly increased Strengths and Difficulties Questionnaire, depression and anxiety scores in all bullying roles and types. In terms of self-harm and suicidality, bully-victims had the highest risk of self-harm (prevalence rate ratio 4.7, 95% confidence interval [3.26, 6.83]), suicidal ideation (prevalence rate ratio 4.3, 95% confidence interval [2.83, 6.49]), suicidal plan (prevalence rate ratio 4.1, 95% confidence interval [2.54, 6.58]) and attempts (prevalence rate ratio 2.7, 95% confidence interval [1.39, 5.13]), followed by victims then bullies. The experience of both relational-verbal and physical bullying was associated with the highest risk of self-harm (prevalence rate ratio 4.6, 95% confidence interval [3.15, 6.60]), suicidal ideation or plans (prevalence rate ratio 4.6, 95% confidence interval [3.05, 6.95]; and 4.8, 95% confidence interval [3.01, 7.64], respectively) or suicide attempts (prevalence rate ratio 3.5, 95% confidence interval [1.90, 6.30]). This study presents the first national, population-based estimates of the associations between bullying by peers and mental health outcomes in Australian adolescents. The markedly increased risk of poor mental health outcomes, self-harm and suicidal ideation and behaviours among adolescents who experienced bullying highlights the importance of addressing bullying in school settings.
Ethnic variations in morbidity and mortality from lower respiratory tract infections: a retrospective cohort study

PubMed Central

Steiner, Markus FC; Cezard, Genevieve; Bansal, Narinder; Fischbacher, Colin; Douglas, Anne; Bhopal, Raj; Sheikh, Aziz

2015-01-01

Objective There is evidence of substantial ethnic variations in asthma morbidity and the risk of hospitalisation, but the picture in relation to lower respiratory tract infections is unclear. We carried out an observational study to identify ethnic group differences for lower respiratory tract infections. Design A retrospective, cohort study. Setting Scotland. Participants 4.65 million people on whom information was available from the 2001 census, followed from May 2001 to April 2010. Main outcome measures Hospitalisations and deaths (any time following first hospitalisation) from lower respiratory tract infections, adjusted risk ratios and hazard ratios by ethnicity and sex were calculated. We multiplied ratios and confidence intervals by 100, so the reference Scottish White population’s risk ratio and hazard ratio was 100. Results Among men, adjusted risk ratios for lower respiratory tract infection hospitalisation were lower in Other White British (80, 95% confidence interval 73–86) and Chinese (69, 95% confidence interval 56–84) populations and higher in Pakistani groups (152, 95% confidence interval 136–169). In women, results were mostly similar to those in men (e.g. Chinese 68, 95% confidence interval 56–82), although higher adjusted risk ratios were found among women of the Other South Asians group (145, 95% confidence interval 120–175). Survival (adjusted hazard ratio) following lower respiratory tract infection for Pakistani men (54, 95% confidence interval 39–74) and women (31, 95% confidence interval 18–53) was better than the reference population. Conclusions Substantial differences in the rates of lower respiratory tract infections amongst different ethnic groups in Scotland were found. Pakistani men and women had particularly high rates of lower respiratory tract infection hospitalisation. The reasons behind the high rates of lower respiratory tract infection in the Pakistani community are now required. PMID:26152675
Simulation workshops with first year midwifery students.

PubMed

Catling, Christine; Hogan, Rosemarie; Fox, Deborah; Cummins, Allison; Kelly, Michelle; Sheehan, Athena

2016-03-01

Simulated teaching methods enable a safe learning environment that are structured, constructive and reflective. We prepared a 2-day simulation project to help prepare students for their first clinical practice. A quasi-experimental pre-test - post-test design was conducted. Qualitative data from the open-ended survey questions were analysed using content analysis. Confidence intervals and p-values were calculated to demonstrate the changes in participants' levels of understanding/ability or confidence in clinical midwifery skills included in the simulation. 71 midwifery students participated. Students rated their understanding, confidence, and abilities as higher after the simulation workshop, and higher still after their clinical experience. There were five main themes arising from the qualitative data: having a learning experience, building confidence, identifying learning needs, developing communication skills and putting skills into practise. First year midwifery students felt well prepared for the clinical workplace following the simulation workshops. Self-rated understanding, confidence and abilities in clinical midwifery skills were significantly higher following consolidation during clinical placement. Longitudinal studies on the relationship between simulation activities and student's overall clinical experience, their intentions to remain in midwifery, and facility feedback, would be desirable. Copyright © 2015 Elsevier Ltd. All rights reserved.
The prognostic value of the QT interval and QT interval dispersion in all-cause and cardiac mortality and morbidity in a population of Danish citizens.

PubMed

Elming, H; Holm, E; Jun, L; Torp-Pedersen, C; Køber, L; Kircshoff, M; Malik, M; Camm, J

1998-09-01

To evaluate the prognostic value of the QT interval and QT interval dispersion in total and in cardiovascular mortality, as well as in cardiac morbidity, in a general population. The QT interval was measured in all leads from a standard 12-lead ECG in a random sample of 1658 women and 1797 men aged 30-60 years. QT interval dispersion was calculated from the maximal difference between QT intervals in any two leads. All cause mortality over 13 years, and cardiovascular mortality as well as cardiac morbidity over 11 years, were the main outcome parameters. Subjects with a prolonged QT interval (430 ms or more) or prolonged QT interval dispersion (80 ms or more) were at higher risk of cardiovascular death and cardiac morbidity than subjects whose QT interval was less than 360 ms, or whose QT interval dispersion was less than 30 ms. Cardiovascular death relative risk ratios, adjusted for age, gender, myocardial infarct, angina pectoris, diabetes mellitus, arterial hypertension, smoking habits, serum cholesterol level, and heart rate were 2.9 for the QT interval (95% confidence interval 1.1-7.8) and 4.4 for QT interval dispersion (95% confidence interval 1.0-19-1). Fatal and non-fatal cardiac morbidity relative risk ratios were similar, at 2.7 (95% confidence interval 1.4-5.5) for the QT interval and 2.2 (95% confidence interval 1.1-4.0) for QT interval dispersion. Prolongation of the QT interval and QT interval dispersion independently affected the prognosis of cardiovascular mortality and cardiac fatal and non-fatal morbidity in a general population over 11 years.

Using Confidence Intervals and Recurrence Intervals to Determine Precipitation Delivery Mechanisms Responsible for Mass Wasting Events.

NASA Astrophysics Data System (ADS)

Ulizio, T. P.; Bilbrey, C.; Stoyanoff, N.; Dixon, J. L.

2015-12-01

Mass wasting events are geologic hazards that impact human life and property across a variety of landscapes. These movements can be triggered by tectonic activity, anomalous precipitation events, or both; acting to decrease the factor of safety ratio on a hillslope to the point of failure. There exists an active hazard landscape in the West Boulder River drainage of Park Co., MT in which the mechanisms of slope failure are unknown. It is known that region has not seen significant tectonic activity within the last decade, leaving anomalous precipitation events as the likely trigger for slope failures in the landscape. Precipitation can be delivered to a landscape via rainfall or snow; it was the aim of this study to determine the precipitation delivery mechanism most likely responsible for movements in the West Boulder drainage following the Jungle Wildfire of 2006. Data was compiled from four SNOTEL sites in the surrounding area, spanning 33 years, focusing on, but not limited to; maximum snow water equivalent (SWE) values in a water year, median SWE values on the date which maximum SWE was recorded in a water year, the total precipitation accumulated in a water year, etc. Means were computed and 99% confidence intervals were constructed around these means. Recurrence intervals and exceedance probabilities were computed for maximum SWE values and total precipitation accumulated in a water year to determine water years with anomalous precipitation. It was determined that the water year 2010-2011 received an anomalously high amount of SWE, and snow melt in the spring of this water year likely triggered recent mass waste movements. This data is further supported by Google Earth imagery, showing movements between 2009 and 2011. Return intervals for the maximum SWE value in 2010-11 for the Placer Basin SNOTEL site was 34 years, while return intervals for the Box Canyon and Monument Peak SNOTEL sites were 17.5 and 17 years respectively. Max SWE values lie outside the upper bound of the 99% confidence interval at all SNOTEL sites while precipitation accumulated in the form of rain is within the expected average, indicating an anomalously snow year and average amounts of rainfall during the same water year. This information can be used to better predict circumstances leading to slope failures in northern latitude alpine landscapes.
Corrected confidence bands for functional data using principal components.

PubMed

Goldsmith, J; Greven, S; Crainiceanu, C

2013-03-01

Functional principal components (FPC) analysis is widely used to decompose and express functional observations. Curve estimates implicitly condition on basis functions and other quantities derived from FPC decompositions; however these objects are unknown in practice. In this article, we propose a method for obtaining correct curve estimates by accounting for uncertainty in FPC decompositions. Additionally, pointwise and simultaneous confidence intervals that account for both model- and decomposition-based variability are constructed. Standard mixed model representations of functional expansions are used to construct curve estimates and variances conditional on a specific decomposition. Iterated expectation and variance formulas combine model-based conditional estimates across the distribution of decompositions. A bootstrap procedure is implemented to understand the uncertainty in principal component decomposition quantities. Our method compares favorably to competing approaches in simulation studies that include both densely and sparsely observed functions. We apply our method to sparse observations of CD4 cell counts and to dense white-matter tract profiles. Code for the analyses and simulations is publicly available, and our method is implemented in the R package refund on CRAN. Copyright © 2013, The International Biometric Society.
Corrected Confidence Bands for Functional Data Using Principal Components

PubMed Central

Goldsmith, J.; Greven, S.; Crainiceanu, C.

2014-01-01

Functional principal components (FPC) analysis is widely used to decompose and express functional observations. Curve estimates implicitly condition on basis functions and other quantities derived from FPC decompositions; however these objects are unknown in practice. In this article, we propose a method for obtaining correct curve estimates by accounting for uncertainty in FPC decompositions. Additionally, pointwise and simultaneous confidence intervals that account for both model- and decomposition-based variability are constructed. Standard mixed model representations of functional expansions are used to construct curve estimates and variances conditional on a specific decomposition. Iterated expectation and variance formulas combine model-based conditional estimates across the distribution of decompositions. A bootstrap procedure is implemented to understand the uncertainty in principal component decomposition quantities. Our method compares favorably to competing approaches in simulation studies that include both densely and sparsely observed functions. We apply our method to sparse observations of CD4 cell counts and to dense white-matter tract profiles. Code for the analyses and simulations is publicly available, and our method is implemented in the R package refund on CRAN. PMID:23003003
Intakes of magnesium, potassium, and calcium and the risk of stroke among men.

PubMed

Adebamowo, Sally N; Spiegelman, Donna; Flint, Alan J; Willett, Walter C; Rexrode, Kathryn M

2015-10-01

Intakes of magnesium, potassium, and calcium have been inversely associated with the incidence of hypertension, a known risk factor for stroke. However, only a few studies have examined intakes of these cations in relation to risk of stroke. The aim of this study was to investigate whether high intake of magnesium, potassium, and calcium is associated with reduced stroke risk among men. We prospectively examined the associations between intakes of magnesium, potassium, and calcium from diet and supplements, and the risk of incident stroke among 42 669 men in the Health Professionals Follow-up Study, aged 40 to 75 years and free of diagnosed cardiovascular disease and cancer at baseline in 1986. We calculated the hazard ratio of total, ischemic, and haemorrhagic strokes by quintiles of each cation intake, and of a combined dietary score of all three cations, using multivariate Cox proportional hazard models. During 24 years of follow-up, 1547 total stroke events were documented. In multivariate analyses, the relative risks and 95% confidence intervals of total stroke for men in the highest vs. lowest quintile were 0·87 (95% confidence interval, 0·74-1·02; P, trend = 0·04) for dietary magnesium, 0·89 (95% confidence interval, 0·76-1·05; P, trend = 0·10) for dietary potassium, and 0·89 (95% confidence interval, 0·75-1·04; P, trend = 0·25) for dietary calcium intake. The relative risk of total stroke for men in the highest vs. lowest quintile was 0·74 (95% confidence interval, 0·59-0·93; P, trend = 0·003) for supplemental magnesium, 0·66 (95% confidence interval, 0·50-0·86; P, trend = 0·002) for supplemental potassium, and 1·01 (95% confidence interval, 0·84-1·20; P, trend = 0·83) for supplemental calcium intake. For total intake (dietary and supplemental), the relative risk of total stroke for men in the highest vs. lowest quintile was 0·83 (95% confidence interval, 0·70-0·99; P, trend = 0·04) for magnesium, 0·88 (95% confidence interval, 0·75-4; P, trend = 6) for potassium, and 3 (95% confidence interval, 79-09; P, trend = 84) for calcium. Men in the highest quintile for a combined dietary score of all three cations had a multivariate relative risk of 0·79 (95% confidence interval, 0·67-0·92; P, trend = 0·008) for total stroke, compared with those in the lowest. A diet rich in magnesium, potassium, and calcium may contribute to reduced risk of stroke among men. Because of significant collinearity, the independent contribution of each cation is difficult to define. © 2015 World Stroke Organization.
Neuraxial analgesia to increase the success rate of external cephalic version: a systematic review and meta-analysis of randomized controlled trials.

PubMed

Magro-Malosso, Elena Rita; Saccone, Gabriele; Di Tommaso, Mariarosaria; Mele, Michele; Berghella, Vincenzo

2016-09-01

External cephalic version is a medical procedure in which the fetus is externally manipulated to assume the cephalic presentation. The use of neuraxial analgesia for facilitating the version has been evaluated in several randomized clinical trials, but its potential effects are still controversial. The objective of the study was to evaluate the effectiveness of neuraxial analgesia as an intervention to increase the success rate of external cephalic version. Searches were performed in electronic databases with the use of a combination of text words related to external cephalic version and neuraxial analgesia from the inception of each database to January 2016. We included all randomized clinical trials of women, with a gestational age ≥36 weeks and breech or transverse fetal presentation, undergoing external cephalic version who were randomized to neuraxial analgesia, including spinal, epidural, or combined spinal-epidural techniques (ie, intervention group) or to a control group (either intravenous analgesia or no treatment). The primary outcome was the successful external cephalic version. The summary measures were reported as relative risk or as mean differences with a 95% confidence interval. Nine randomized clinical trials (934 women) were included in this review. Women who received neuraxial analgesia had a significantly higher incidence of successful external cephalic version (58.4% vs 43.1%; relative risk, 1.44, 95% confidence interval, 1.27-1.64), cephalic presentation in labor (55.1% vs 40.2%; relative risk, 1.37, 95% confidence interval, 1.08-1.73), and vaginal delivery (54.0% vs 44.6%; relative risk, 1.21, 95% confidence interval, 1.04-1.41) compared with those who did not. Women who were randomized to the intervention group also had a significantly lower incidence of cesarean delivery (46.0% vs 55.3%; relative risk, 0.83, 95% confidence interval, 0.71-0.97), maternal discomfort (1.2% vs 9.3%; relative risk, 0.12, 95% confidence interval, 0.02-0.99), and lower pain, assessed by the visual analog scale pain score (mean difference, -4.52 points, 95% confidence interval, -5.35 to 3.69) compared with the control group. The incidences of emergency cesarean delivery (1.6% vs 2.5%; relative risk, 0.63, 95% confidence interval, 0.24-1.70), transient bradycardia (11.8% vs 8.3%; relative risk, 1.42, 95% confidence interval, 0.72-2.80), nonreassuring fetal testing, excluding transient bradycardia, after external cephalic version (6.9% vs 7.4%; relative risk, 0.93, 95% confidence interval, 0.53-1.64), and abruption placentae (0.4% vs 0.4%; relative risk, 1.01, 95% confidence interval, 0.06-16.1) were similar. Administration of neuraxial analgesia significantly increases the success rate of external cephalic version among women with malpresentation at term or late preterm, which then significantly increases the incidence of vaginal delivery. Copyright © 2016 Elsevier Inc. All rights reserved.
Add-On Antihypertensive Medications to Angiotensin-Aldosterone System Blockers in Diabetes: A Comparative Effectiveness Study.

PubMed

Schroeder, Emily B; Chonchol, Michel; Shetterly, Susan M; Powers, J David; Adams, John L; Schmittdiel, Julie A; Nichols, Gregory A; O'Connor, Patrick J; Steiner, John F

2018-05-07

In individuals with diabetes, the comparative effectiveness of add-on antihypertensive medications added to an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker on the risk of significant kidney events is unknown. We used an observational, multicenter cohort of 21,897 individuals with diabetes to compare individuals who added β -blockers, dihydropyridine calcium channel blockers, loop diuretics, or thiazide diuretics to angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. We examined the hazard of significant kidney events, cardiovascular events, and death using Cox proportional hazard models with propensity score weighting. The composite significant kidney event end point was defined as the first occurrence of a ≥30% decline in eGFR to an eGFR<60 ml/min per 1.73 m 2 , initiation of dialysis, or kidney transplant. The composite cardiovascular event end point was defined as the first occurrence of hospitalization for acute myocardial infarction, acute coronary syndrome, stroke, or congestive heart failure; coronary artery bypass grafting; or percutaneous coronary intervention, and it was only examined in those free of cardiovascular disease at baseline. Over a maximum of 5 years, there were 4707 significant kidney events, 1498 deaths, and 818 cardiovascular events. Compared with thiazide diuretics, hazard ratios for significant kidney events for β -blockers, calcium channel blockers, and loop diuretics were 0.81 (95% confidence interval, 0.74 to 0.89), 0.67 (95% confidence interval, 0.58 to 0.78), and 1.19 (95% confidence interval, 1.00 to 1.41), respectively. Compared with thiazide diuretics, hazard ratios of mortality for β -blockers, calcium channel blockers, and loop diuretics were 1.19 (95% confidence interval, 0.97 to 1.44), 0.73 (95% confidence interval, 0.52 to 1.03), and 1.67 (95% confidence interval, 1.31 to 2.13), respectively. Compared with thiazide diuretics, hazard ratios of cardiovascular events for β -blockers, calcium channel blockers, and loop diuretics compared with thiazide diuretics were 1.65 (95% confidence interval, 1.39 to 1.96), 1.05 (95% confidence interval, 0.80 to 1.39), and 1.55 (95% confidence interval, 1.05 to 2.27), respectively. Compared with thiazide diuretics, calcium channel blockers were associated with a lower risk of significant kidney events and a similar risk of cardiovascular events. Copyright © 2018 by the American Society of Nephrology.
Maternal steroid therapy for fetuses with second-degree immune-mediated congenital atrioventricular block: a systematic review and meta-analysis.

PubMed

Ciardulli, Andrea; D'Antonio, Francesco; Magro-Malosso, Elena R; Manzoli, Lamberto; Anisman, Paul; Saccone, Gabriele; Berghella, Vincenzo

2018-03-07

To explore the effect of maternal fluorinated steroid therapy on fetuses affected by second-degree immune-mediated congenital atrioventricular block. Studies reporting the outcome of fetuses with second-degree immune-mediated congenital atrioventricular block diagnosed on prenatal ultrasound and treated with fluorinated steroids compared with those not treated were included. The primary outcome was the overall progression of congenital atrioventricular block to either continuous or intermittent third-degree congenital atrioventricular block at birth. Meta-analyses of proportions using random effect model and meta-analyses using individual data random-effect logistic regression were used. Five studies (71 fetuses) were included. The progression rate to congenital atrioventricular block at birth in fetuses treated with steroids was 52% (95% confidence interval 23-79) and in fetuses not receiving steroid therapy 73% (95% confidence interval 39-94). The overall rate of regression to either first-degree, intermittent first-/second-degree or sinus rhythm in fetuses treated with steroids was 25% (95% confidence interval 12-41) compared with 23% (95% confidence interval 8-44) in those not treated. Stable (constant) second-degree congenital atrioventricular block at birth was present in 11% (95% confidence interval 2-27) of cases in the treated group and in none of the newborns in the untreated group, whereas complete regression to sinus rhythm occurred in 21% (95% confidence interval 6-42) of fetuses receiving steroids vs. 9% (95% confidence interval 0-41) of those untreated. There is still limited evidence as to the benefit of administered fluorinated steroids in terms of affecting outcome of fetuses with second-degree immune-mediated congenital atrioventricular block. © 2018 Nordic Federation of Societies of Obstetrics and Gynecology.
Active management of the third stage of labor with and without controlled cord traction: a systematic review and meta-analysis of randomized controlled trials.

PubMed

Du, Yongming; Ye, Man; Zheng, Feiyun

2014-07-01

To determine the specific effect of controlled cord traction in the third stage of labor in the prevention of postpartum hemorrhage. We searched PubMed, Scopus and Web of Science (inception to 30 October 2013). Randomized controlled trials comparing controlled cord traction with hands-off management in the third stage of labor were included. Five randomized controlled trials involving a total of 30 532 participants were eligible. No significant difference was found between controlled cord traction and hands-off management groups with respect to the incidence of severe postpartum hemorrhage (relative risk 0.91, 95% confidence interval 0.77-1.08), need for blood transfusion (relative risk 0.96, 95% confidence interval 0.69-1.33) or therapeutic uterotonics (relative risk 0.94, 95% confidence interval 0.88-1.01). However, controlled cord traction reduced the incidence of postpartum hemorrhage in general (relative risk 0.93, 95% confidence interval 0.87-0.99; number-needed-to-treat 111, 95% confidence interval 61-666), as well manual removal of the placenta (relative risk 0.70, 95% confidence interval 0.58-0.84) and duration of the third stage of labor (mean difference -3.20, 95% confidence interval -3.21 to -3.19). Controlled cord traction appears to reduce the risk of any postpartum hemorrhage in a general sense, as well as manual removal of the placenta and the duration of the third stage of labor. However, the reduction in the occurrence of severe postpartum hemorrhage, need for additional uterotonics and blood transfusion is not statistically significant. © 2014 Nordic Federation of Societies of Obstetrics and Gynecology.
Loss of DPC4/SMAD4 expression in primary gastrointestinal neuroendocrine tumors is associated with cancer-related death after resection.

PubMed

Roland, Christina L; Starker, Lee F; Kang, Y; Chatterjee, Deyali; Estrella, Jeannelyn; Rashid, Asif; Katz, Matthew H; Aloia, Thomas A; Lee, Jeffrey E; Dasari, Arvind; Yao, James C; Fleming, Jason B

2017-03-01

Gastrointestinal neuroendocrine tumors have frequent loss of DPC4/SMAD4 expression, a known tumor suppressor. The impact of SMAD4 loss on gastrointestinal neuroendocrine tumors aggressiveness or cancer-related patient outcomes is not defined. We examined the expression of SMAD4 in resected gastrointestinal neuroendocrine tumors and its impact on oncologic outcomes. Patients who underwent complete curative operative resection of gastrointestinal neuroendocrine tumors were identified retrospectively (n = 38). Immunohistochemical staining for SMAD4 expression was scored by a blinded pathologist and correlated with clinicopathologic features and oncologic outcomes. Twenty-nine percent of the gastrointestinal neuroendocrine tumors were SMAD4-negative and 71% SMAD4-positive. Median overall survival was 155 months (95% confidence interval, 102-208 months). Loss of SMAD4 was associated with both decreased median disease-free survival (28 months; 95% confidence interval, 16-40) months compared with 223 months (95% confidence interval, 3-443 months) for SMAD4-positive patients (P = .03) and decreased median disease-specific survival (SMAD4: 137 [95% confidence interval, 81-194] months versus SMAD4-positive: 204 [95% confidence interval, 143-264] months; P = .04). This translated into a decrease in median overall survival (SMAD4-negative: 125 (95% confidence interval, 51-214) months versus SMAD4-positive: 185 (95% confidence interval, 138-232) months; P = .02). Consistent with the known biology of the DPC4/SMAD4 gene, an absence of its protein expression in primary gastrointestinal neuroendocrine tumors was negatively associated with outcomes after curative operative resection. Copyright © 2016 Elsevier Inc. All rights reserved.
Calculation of the confidence intervals for transformation parameters in the registration of medical images

PubMed Central

Bansal, Ravi; Staib, Lawrence H.; Laine, Andrew F.; Xu, Dongrong; Liu, Jun; Posecion, Lainie F.; Peterson, Bradley S.

2010-01-01

Images from different individuals typically cannot be registered precisely because anatomical features within the images differ across the people imaged and because the current methods for image registration have inherent technological limitations that interfere with perfect registration. Quantifying the inevitable error in image registration is therefore of crucial importance in assessing the effects that image misregistration may have on subsequent analyses in an imaging study. We have developed a mathematical framework for quantifying errors in registration by computing the confidence intervals of the estimated parameters (3 translations, 3 rotations, and 1 global scale) for the similarity transformation. The presence of noise in images and the variability in anatomy across individuals ensures that estimated registration parameters are always random variables. We assume a functional relation among intensities across voxels in the images, and we use the theory of nonlinear, least-squares estimation to show that the parameters are multivariate Gaussian distributed. We then use the covariance matrix of this distribution to compute the confidence intervals of the transformation parameters. These confidence intervals provide a quantitative assessment of the registration error across the images. Because transformation parameters are nonlinearly related to the coordinates of landmark points in the brain, we subsequently show that the coordinates of those landmark points are also multivariate Gaussian distributed. Using these distributions, we then compute the confidence intervals of the coordinates for landmark points in the image. Each of these confidence intervals in turn provides a quantitative assessment of the registration error at a particular landmark point. Because our method is computationally intensive, however, its current implementation is limited to assessing the error of the parameters in the similarity transformation across images. We assessed the performance of our method in computing the error in estimated similarity parameters by applying that method to real world dataset. Our results showed that the size of the confidence intervals computed using our method decreased – i.e. our confidence in the registration of images from different individuals increased – for increasing amounts of blur in the images. Moreover, the size of the confidence intervals increased for increasing amounts of noise, misregistration, and differing anatomy. Thus, our method precisely quantified confidence in the registration of images that contain varying amounts of misregistration and varying anatomy across individuals. PMID:19138877
Reliability of the identification of the systemic inflammatory response syndrome in critically ill infants and children.

PubMed

Juskewitch, Justin E; Prasad, Swati; Salas, Carlos F Santillan; Huskins, W Charles

2012-01-01

To assess interobserver reliability of the identification of episodes of the systemic inflammatory response syndrome in critically ill hospitalized infants and children. Retrospective, cross-sectional study of the application of the 2005 consensus definition of systemic inflammatory response syndrome in infants and children by two independent, trained reviewers using information in the electronic medical record. Eighteen-bed pediatric multidisciplinary medical/surgical pediatric intensive care unit. A randomly selected sample of children admitted consecutively to the pediatric intensive care unit between May 1 and September 30, 2009. None. Sixty infants and children were selected from a total of 343 admitted patients. Their median age was 3.9 yrs (interquartile range, 1.5-12.7), 57% were female, and 68% were Caucasian. Nineteen (32%) children were identified by both reviewers as having an episode of systemic inflammatory response syndrome (88% agreement, 95% confidence interval 78-94; κ = 0.75, 95% confidence interval 0.59-0.92). Among these 19 children, agreement between the reviewers for individual systemic inflammatory response syndrome criteria was: temperature (84%, 95% confidence interval 60-97); white blood cell count (89%, 95% confidence interval 67-99); respiratory rate (84%, 95% confidence interval 60-97); and heart rate (68%, 95% confidence interval 33-87). Episodes of systemic inflammatory response syndrome in critically ill infants and children can be identified reproducibly using the consensus definition.
What was different about exposures reported by male Australian Gulf War veterans for the 1991 Persian Gulf War, compared with exposures reported for other deployments?

PubMed

Glass, Deborah C; Sim, Malcolm R; Kelsall, Helen L; Ikin, Jill F; McKenzie, Dean; Forbes, Andrew; Ittak, Peter

2006-07-01

This study identified chemical and environmental exposures specifically associated with the 1991 Persian Gulf War. Exposures were self-reported in a postal questionnaire, in the period of 2000-2002, by 1,424 Australian male Persian Gulf War veterans in relation to their 1991 Persian Gulf War deployment and by 625 Persian Gulf War veterans and 514 members of a military comparison group in relation to other active deployments. Six of 28 investigated exposures were experienced more frequently during the Persian Gulf War than during other deployments; these were exposure to smoke (odds ratio [OR], 4.4; 95% confidence interval, 3.0-6.6), exposure to dust (OR, 3.7; 95% confidence interval, 2.6-5.3), exposure to chemical warfare agents (OR, 3.9; 95% confidence interval, 2.1-7.9), use of respiratory protective equipment (OR, 13.6; 95% confidence interval, 7.6-26.8), use of nuclear, chemical, and biological protective suits (OR, 8.9; 95% confidence interval, 5.4-15.4), and entering/inspecting enemy equipment (OR, 3.1; 95% confidence interval, 2.1-4.8). Other chemical and environmental exposures were not specific to the Persian Gulf War deployment but were also reported in relation to other deployments. The number of exposures reported was related to service type and number of deployments but not to age or rank.
Statin therapy in lower limb peripheral arterial disease: Systematic review and meta-analysis.

PubMed

Antoniou, George A; Fisher, Robert K; Georgiadis, George S; Antoniou, Stavros A; Torella, Francesco

2014-11-01

To investigate and analyse the existing evidence supporting statin therapy in patients with lower limb atherosclerotic arterial disease. A systematic search of electronic information sources was undertaken to identify studies comparing cardiovascular outcomes in patients with lower limb peripheral arterial disease treated with a statin and those not receiving a statin. Estimates were combined applying fixed- or random-effects models. Twelve observational cohort studies and two randomised trials reporting 19,368 patients were selected. Statin therapy was associated with reduced all-cause mortality (odds ratio 0.60, 95% confidence interval 0.46-0.78) and incidence of stroke (odds ratio 0.77, 95% confidence interval 0.67-0.89). A trend towards improved cardiovascular mortality (odds ratio 0.62, 95% confidence interval 0.35-1.11), myocardial infarction (odds ratio 0.62, 95% confidence interval 0.38-1.01), and the composite of death/myocardial infarction/stroke (odds ratio 0.91, 95% confidence interval 0.81-1.03), was identified. Meta-analyses of studies performing adjustments showed decreased all-cause mortality in statin users (hazard ratio 0.77, 95% confidence interval 0.68-0.86). Evidence supporting statins' protective role in patients with lower limb peripheral arterial disease is insufficient. Statin therapy seems to be effective in reducing all-cause mortality and the incidence cerebrovascular events in patients diagnosed with peripheral arterial disease. Copyright © 2014 Elsevier Inc. All rights reserved.
Estimation and confidence intervals for empirical mixing distributions

USGS Publications Warehouse

Link, W.A.; Sauer, J.R.

1995-01-01

Questions regarding collections of parameter estimates can frequently be expressed in terms of an empirical mixing distribution (EMD). This report discusses empirical Bayes estimation of an EMD, with emphasis on the construction of interval estimates. Estimation of the EMD is accomplished by substitution of estimates of prior parameters in the posterior mean of the EMD. This procedure is examined in a parametric model (the normal-normal mixture) and in a semi-parametric model. In both cases, the empirical Bayes bootstrap of Laird and Louis (1987, Journal of the American Statistical Association 82, 739-757) is used to assess the variability of the estimated EMD arising from the estimation of prior parameters. The proposed methods are applied to a meta-analysis of population trend estimates for groups of birds.
Experimental congruence of interval scale production from paired comparisons and ranking for image evaluation

NASA Astrophysics Data System (ADS)

Handley, John C.; Babcock, Jason S.; Pelz, Jeff B.

2003-12-01

Image evaluation tasks are often conducted using paired comparisons or ranking. To elicit interval scales, both methods rely on Thurstone's Law of Comparative Judgment in which objects closer in psychological space are more often confused in preference comparisons by a putative discriminal random process. It is often debated whether paired comparisons and ranking yield the same interval scales. An experiment was conducted to assess scale production using paired comparisons and ranking. For this experiment a Pioneer Plasma Display and Apple Cinema Display were used for stimulus presentation. Observers performed rank order and paired comparisons tasks on both displays. For each of five scenes, six images were created by manipulating attributes such as lightness, chroma, and hue using six different settings. The intention was to simulate the variability from a set of digital cameras or scanners. Nineteen subjects, (5 females, 14 males) ranging from 19-51 years of age participated in this experiment. Using a paired comparison model and a ranking model, scales were estimated for each display and image combination yielding ten scale pairs, ostensibly measuring the same psychological scale. The Bradley-Terry model was used for the paired comparisons data and the Bradley-Terry-Mallows model was used for the ranking data. Each model was fit using maximum likelihood estimation and assessed using likelihood ratio tests. Approximate 95% confidence intervals were also constructed using likelihood ratios. Model fits for paired comparisons were satisfactory for all scales except those from two image/display pairs; the ranking model fit uniformly well on all data sets. Arguing from overlapping confidence intervals, we conclude that paired comparisons and ranking produce no conflicting decisions regarding ultimate ordering of treatment preferences, but paired comparisons yield greater precision at the expense of lack-of-fit.
On the appropriateness of applying chi-square distribution based confidence intervals to spectral estimates of helicopter flyover data

NASA Technical Reports Server (NTRS)

Rutledge, Charles K.

1988-01-01

The validity of applying chi-square based confidence intervals to far-field acoustic flyover spectral estimates was investigated. Simulated data, using a Kendall series and experimental acoustic data from the NASA/McDonnell Douglas 500E acoustics test, were analyzed. Statistical significance tests to determine the equality of distributions of the simulated and experimental data relative to theoretical chi-square distributions were performed. Bias and uncertainty errors associated with the spectral estimates were easily identified from the data sets. A model relating the uncertainty and bias errors to the estimates resulted, which aided in determining the appropriateness of the chi-square distribution based confidence intervals. Such confidence intervals were appropriate for nontonally associated frequencies of the experimental data but were inappropriate for tonally associated estimate distributions. The appropriateness at the tonally associated frequencies was indicated by the presence of bias error and noncomformity of the distributions to the theoretical chi-square distribution. A technique for determining appropriate confidence intervals at the tonally associated frequencies was suggested.
A short note on jackknifing the concordance correlation coefficient.

PubMed

Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir

2014-02-10

Lin's concordance correlation coefficient (CCC) is a very popular scaled index of agreement used in applied statistics. To obtain a confidence interval (CI) for the estimate of CCC, jackknifing was proposed and shown to perform well in simulation as well as in applications. However, a theoretical proof of the validity of the jackknife CI for the CCC has not been presented yet. In this note, we establish a sufficient condition for using the jackknife method to construct the CI for the CCC. Copyright © 2013 John Wiley & Sons, Ltd.
Woodstoves, formaldehyde, and respiratory disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tuthill, R.W.

1984-12-01

Telephone interviews were completed in Western Massachusetts in April 1983 for 399 households (91.5 percent) in a random sample of households with elementary school children. Woodstoves were used in 64.7 percent of the homes, but such use was not associated with acute respiratory illness. However, formaldehyde exposure was significantly related, with a risk ratio of 2.4 (95 percent confidence interval 1.7-3.4). New construction/remodeling and new upholstered furniture had additive effects. Neither woodstove use nor formaldehyde exposure were significantly associated with asthma, chronic bronchitis, or allergies.
Gaussian process regression for tool wear prediction

NASA Astrophysics Data System (ADS)

Kong, Dongdong; Chen, Yongjie; Li, Ning

2018-05-01

To realize and accelerate the pace of intelligent manufacturing, this paper presents a novel tool wear assessment technique based on the integrated radial basis function based kernel principal component analysis (KPCA_IRBF) and Gaussian process regression (GPR) for real-timely and accurately monitoring the in-process tool wear parameters (flank wear width). The KPCA_IRBF is a kind of new nonlinear dimension-increment technique and firstly proposed for feature fusion. The tool wear predictive value and the corresponding confidence interval are both provided by utilizing the GPR model. Besides, GPR performs better than artificial neural networks (ANN) and support vector machines (SVM) in prediction accuracy since the Gaussian noises can be modeled quantitatively in the GPR model. However, the existence of noises will affect the stability of the confidence interval seriously. In this work, the proposed KPCA_IRBF technique helps to remove the noises and weaken its negative effects so as to make the confidence interval compressed greatly and more smoothed, which is conducive for monitoring the tool wear accurately. Moreover, the selection of kernel parameter in KPCA_IRBF can be easily carried out in a much larger selectable region in comparison with the conventional KPCA_RBF technique, which helps to improve the efficiency of model construction. Ten sets of cutting tests are conducted to validate the effectiveness of the presented tool wear assessment technique. The experimental results show that the in-process flank wear width of tool inserts can be monitored accurately by utilizing the presented tool wear assessment technique which is robust under a variety of cutting conditions. This study lays the foundation for tool wear monitoring in real industrial settings.
A nationwide population-based retrospective cohort study of the risk of uterine, ovarian and breast cancer in women with polycystic ovary syndrome.

PubMed

Shen, Cheng-Che; Yang, Albert C; Hung, Jeng-Hsiu; Hu, Li-Yu; Tsai, Shih-Jen

2015-01-01

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. We used a nationwide population-based retrospective cohort study to explore the relationship between PCOS and the subsequent development of gynecological cancers including uterine, breast, or ovarian cancer. We identified subjects who were diagnosed with PCOS between January 1, 2000, and December 31, 2004, in the Taiwan National Health Insurance (NHI) Research Database. A comparison cohort was constructed for patients without known PCOS who were also matched according to age. All PCOS and control patients were observed until diagnosed with breast cancer, ovarian cancer, or uterine cancer or until death, withdrawal from the NHI system, or December 31, 2009. The PCOS cohort consisted of 3,566 patients, and the comparison cohort consisted of 14,264 matched control patients without PCOS. The adjusted hazard ratio (HR) of uterine cancer and breast cancer in subjects with PCOS were higher (HR: 8.42 [95% confidence interval: 1.62-43.89] and HR: 1.99 [95% confidence interval: 1.05-3.77], respectively) than that of the controls during the follow-up. With the Monte Carlo method, only the mean adjusted HR of 1,000 comparisons for developing uterine cancer during the follow-up period was greater for the PCOS group than for the control groups (HR: 4.71, 95% confidence interval: 1.57-14.11). PCOS might increase the risk of subsequent newly diagnosed uterine cancer. It is critical that further large-scale, well-designed studies be conducted to confirm the association between PCOS and gynecological cancer risk. ©AlphaMed Press.

Prognostic utility of novel biomarkers of cardiovascular stress: the Framingham Heart Study.

PubMed

Wang, Thomas J; Wollert, Kai C; Larson, Martin G; Coglianese, Erin; McCabe, Elizabeth L; Cheng, Susan; Ho, Jennifer E; Fradley, Michael G; Ghorbani, Anahita; Xanthakis, Vanessa; Kempf, Tibor; Benjamin, Emelia J; Levy, Daniel; Vasan, Ramachandran S; Januzzi, James L

2012-09-25

Biomarkers for predicting cardiovascular events in community-based populations have not consistently added information to standard risk factors. A limitation of many previously studied biomarkers is their lack of cardiovascular specificity. To determine the prognostic value of 3 novel biomarkers induced by cardiovascular stress, we measured soluble ST2, growth differentiation factor-15, and high-sensitivity troponin I in 3428 participants (mean age, 59 years; 53% women) in the Framingham Heart Study. We performed multivariable-adjusted proportional hazards models to assess the individual and combined ability of the biomarkers to predict adverse outcomes. We also constructed a "multimarker" score composed of the 3 biomarkers in addition to B-type natriuretic peptide and high-sensitivity C-reactive protein. During a mean follow-up of 11.3 years, there were 488 deaths, 336 major cardiovascular events, 162 heart failure events, and 142 coronary events. In multivariable-adjusted models, the 3 new biomarkers were associated with each end point (P<0.001) except coronary events. Individuals with multimarker scores in the highest quartile had a 3-fold risk of death (adjusted hazard ratio, 3.2; 95% confidence interval, 2.2-4.7; P<0.001), 6-fold risk of heart failure (6.2; 95% confidence interval, 2.6-14.8; P<0.001), and 2-fold risk of cardiovascular events (1.9; 95% confidence interval, 1.3-2.7; P=0.001). Addition of the multimarker score to clinical variables led to significant increases in the c statistic (P=0.005 or lower) and net reclassification improvement (P=0.001 or lower). Multiple biomarkers of cardiovascular stress are detectable in ambulatory individuals and add prognostic value to standard risk factors for predicting death, overall cardiovascular events, and heart failure.
Economic Analysis of Anatomic Plating Versus Tubular Plating for the Treatment of Fibula Fractures.

PubMed

Chang, Gerard; Bhat, Suneel B; Raikin, Steven M; Kane, Justin M; Kay, Andrew; Ahmad, Jamal; Pedowitz, David I; Krieg, James

2018-03-01

Ankle fractures are among the most common injuries requiring operative management. Implant choices include one-third tubular plates and anatomically precontoured plates. Although cadaveric studies have not revealed biomechanical differences between various plate constructs, there are substantial cost differences. This study sought to characterize the economic implications of implant choice. A retrospective review was undertaken of 201 consecutive patients with operatively treated OTA type 44B and 44C ankles. A Nationwide Inpatient Sample query was performed to estimate the incidence of ankle fractures requiring fibular plating, and a Monte Carlo simulation was conducted with the estimated at-risk US population for associated plate-specific costs. The authors estimated an annual incidence of operatively treated ankle fractures in the United States of 59,029. The average cost was $90.86 (95% confidence interval, $90.84-$90.87) for a one-third tubular plate vs $746.97 (95% confidence interval, $746.55-$747.39) for an anatomic plate. Across the United States, use of only one-third tubular plating over anatomic plating would result in statistically significant savings of $38,729,517 (95% confidence interval, $38,704,773-$38,754,261; P<.0001). General use of one-third tubular plating instead of anatomic plating whenever possible for fibula fractures could result in cost savings of up to nearly $40 million annually in the United States. Unless clinically justifiable on a per-case basis, or until the advent of studies showing substantial clinical benefit, there currently is no reason for the increased expense from widespread use of anatomic plating for fractures amenable to one-third tubular plating. [Orthopedics. 2018; 41(2):e252-e256.]. Copyright 2018, SLACK Incorporated.
Probabilistic properties of the Curve Number

NASA Astrophysics Data System (ADS)

Rutkowska, Agnieszka; Banasik, Kazimierz; Kohnova, Silvia; Karabova, Beata

2013-04-01

The determination of the Curve Number (CN) is fundamental for the hydrological rainfall-runoff SCS-CN method which assesses the runoff volume in small catchments. The CN depends on geomorphologic and physiographic properties of the catchment and traditionally it is assumed to be constant for each catchment. Many practitioners and researchers observe, however, that the parameter is characterized by a variability. This sometimes causes inconsistency in the river discharge prediction using the SCS-CN model. Hence probabilistic and statistical methods are advisable to investigate the CN as a random variable and to complement and improve the deterministic model. The results that will be presented contain determination of the probabilistic properties of the CNs for various Slovakian and Polish catchments using statistical methods. The detailed study concerns the description of empirical distributions (characteristics, QQ-plots and coefficients of goodness of fit, histograms), testing of the statistical hypotheses about some theoretical distributions (Kolmogorov-Smirnow, Anderson-Darling, Cramer-von Mises, χ2, Shapiro-Wilk), construction of confidence intervals and comparisons among catchments. The relationship between confidence intervals and the ARC soil classification will also be performed. The comparison between the border values of the confidence intervals and the ARC I and ARC III conditions is crucial for further modeling. The study of the response of the catchment to the stormy rainfall depth when the variability of the CN arises is also of special interest. ACKNOWLEDGMENTS The investigation described in the contribution has been initiated by first Author research visit to Technical University of Bratislava in 2012 within a STSM of the COST Action ES0901. Data used here have been provided by research project no. N N305 396238 founded by PL-Ministry of Science and Higher Education. The support provided by the organizations is gratefully acknowledged.
Ticagrelor Versus Aspirin in Acute Embolic Stroke of Undetermined Source.

PubMed

Amarenco, Pierre; Albers, Gregory W; Denison, Hans; Easton, J Donald; Evans, Scott R; Held, Peter; Hill, Michael D; Jonasson, Jenny; Kasner, Scott E; Ladenvall, Per; Minematsu, Kazuo; Molina, Carlos A; Wang, Yongjun; Wong, K S Lawrence; Johnston, S Claiborne

2017-09-01

Ticagrelor is an effective antiplatelet therapy among patients with atherosclerotic disease and, therefore, could be more effective than aspirin in preventing recurrent stroke and cardiovascular events among patients with embolic stroke of unknown source (ESUS), which includes patients with ipsilateral stenosis <50% and aortic arch atherosclerosis. We randomized 13 199 patients with a noncardioembolic, nonsevere ischemic stroke or high-risk transient ischemic attack to ticagrelor (180 mg loading dose on day 1 followed by 90 mg twice daily for days 2-90) or aspirin (300 mg on day 1 followed by 100 mg daily for days 2-90) within 24 hours of symptom onset. In all patients, investigators informed on the presence of ipsilateral stenosis ≥50%, small deep infarct <15 mm, and on cardiac source of embolism detected after enrollment or rare causes, which allowed to construct an ESUS category in all other patients with documented brain infarction. The primary end point was the time to the occurrence of stroke, myocardial infarction, or death within 90 days. ESUS was identified in 4329 (32.8%) patients. There was no treatment-by-ESUS category interaction ( P =0.83). Hazard ratio in ESUS patients was 0.87 (95% confidence interval, 0.68-1.10; P =0.24). However, hazard ratio was 0.51 (95% confidence interval, 0.29-0.90; P =0.02) in ESUS patients with ipsilateral stenosis <50% or aortic arch atherosclerosis (n=961) and 0.98 (95% confidence interval, 0.76-1.27; P =0.89) in the remaining ESUS patients (n=3368; P for heterogeneity =0.04). In this post hoc, exploratory analysis, we found no treatment-by-ESUS category interaction. ESUS subgroups have heterogeneous response to treatment (Funded by AstraZeneca). URL: http://www.clinicaltrials.gov. Unique identifier: NCT01994720. © 2017 American Heart Association, Inc.
A comparison of statistical methods for evaluating matching performance of a biometric identification device: a preliminary report

NASA Astrophysics Data System (ADS)

Schuckers, Michael E.; Hawley, Anne; Livingstone, Katie; Mramba, Nona

2004-08-01

Confidence intervals are an important way to assess and estimate a parameter. In the case of biometric identification devices, several approaches to confidence intervals for an error rate have been proposed. Here we evaluate six of these methods. To complete this evaluation, we simulate data from a wide variety of parameter values. This data are simulated via a correlated binary distribution. We then determine how well these methods do at what they say they do: capturing the parameter inside the confidence interval. In addition, the average widths of the various confidence intervals are recorded for each set of parameters. The complete results of this simulation are presented graphically for easy comparison. We conclude by making a recommendation regarding which method performs best.
Prevalence of Injury in Occupation and Industry: Role of Obesity in the National Health Interview Survey 2004 to 2013.

PubMed

Gu, Ja K; Charles, Luenda E; Fekedulegn, Desta; Ma, Claudia C; Andrew, Michael E; Burchfiel, Cecil M

2016-04-01

The aim of this study was to estimate prevalence of injury by occupation and industry and obesity's role. Self-reported injuries were collected annually for US workers during 2004 to 2013. Prevalence ratios (PRs) and 95% confidence intervals (CIs) were obtained from fitted logistic regression models. Overall weighted injury prevalence during the previous three months was 77 per 10,000 workers. Age-adjusted injury prevalence was greatest for Construction and Extraction workers (169.7/10,000) followed by Production (160.6) among occupations, while workers in the Construction industry sector (147.9) had the highest injury prevalence followed by the Agriculture/Forestry/Fishing/Mining/Utilities sector (122.1). Overweight and obese workers were 26% to 45% more likely to experience injuries than normal-weight workers. The prevalence of injury, highest for Construction workers, gradually increased as body mass index levels increased in most occupational and industry groups.
Analysis of ethnic disparities in workers' compensation claims using data linkage.

PubMed

Friedman, Lee S; Ruestow, Peter; Forst, Linda

2012-10-01

The overall goal of this research project was to assess ethnic disparities in monetary compensation among construction workers injured on the job through the linkage of medical records and workers' compensation data. Probabilistic linkage of medical records with workers' compensation claim data. In the final multivariable robust regression model, compensation was $5824 higher (P = 0.030; 95% confidence interval: 551 to 11,097) for white non-Hispanic workers than for other ethnic groups when controlling for injury severity, affected body region, type of injury, average weekly wage, weeks of temporary total disability, percent permanent partial disability, death, or attorney use. The analysis indicates that white non-Hispanic construction workers are awarded higher monetary settlements despite the observation that for specific injuries the mean temporary total disability and permanent partial disability were equivalent to or lower than those in Hispanic and black construction workers.
Expression of Proteins Involved in Epithelial-Mesenchymal Transition as Predictors of Metastasis and Survival in Breast Cancer Patients

DTIC Science & Technology

2013-11-01

Ptrend 0.78 0.62 0.75 Unconditional logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals (CI) for risk of node...Ptrend 0.71 0.67 Unconditional logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals (CI) for risk of high-grade tumors... logistic regression was used to estimate odds ratios (OR) and 95 % confidence intervals (CI) for the associations between each of the seven SNPs and
Psychometric properties of the Activities-specific Balance Confidence Scale among individuals with a lower-limb amputation.

PubMed

Miller, William C; Deathe, A Barry; Speechley, Mark

2003-05-01

To evaluate the internal consistency, test-retest reliability, and construct validity of the Activities-specific Balance Confidence (ABC) Scale among people who have a lower-limb amputation. Retest design. A university-affiliated outpatient amputee clinic in Ontario. Two samples of individuals who have unilateral transtibial and transfemoral amputation. Sample 1 (n=54) was a consecutive and sample 2 (n=329) a convenience sample of all members of the clinic population. Not applicable. Repeated application of the ABC Scale, a 16-item questionnaire that assesses confidence in performing various mobility-related tasks. Correlation to test hypothesized relationships between the ABC Scale and the 2-minute walk (2MWT) and the timed up-and-go (TUG) tests; and assessment of the ability of the ABC Scale to discriminate among groups based on amputation cause, amputation level, mobility device use, automatic stepping ability, wearing time, stair climbing ability, and walking distance. Test-retest reliability (intraclass correlation coefficient) of the ABC Scale was .91 (95% confidence interval [CI], .84-.95) with individual item test-retest coefficients ranging from .53 to .87. Internal consistency, measured by Cronbach alpha, was .95. Hypothesized associations with the 2MWT and TUG test were observed with correlations of .72 (95% CI, .56-.84) and -.70 (95% CI, -.82 to -.53), respectively. The ABC Scale discriminated between all groups except those based on amputation level. Balance confidence, as measured by the ABC Scale, is a construct that provides unique information potentially useful to clinicians who provide amputee rehabilitation. The ABC Scale is reliable, with strong support for validity. Study of the scale's responsiveness is recommended.
Closed-form confidence intervals for functions of the normal mean and standard deviation.

PubMed

Donner, Allan; Zou, G Y

2012-08-01

Confidence interval methods for a normal mean and standard deviation are well known and simple to apply. However, the same cannot be said for important functions of these parameters. These functions include the normal distribution percentiles, the Bland-Altman limits of agreement, the coefficient of variation and Cohen's effect size. We present a simple approach to this problem by using variance estimates recovered from confidence limits computed for the mean and standard deviation separately. All resulting confidence intervals have closed forms. Simulation results demonstrate that this approach performs very well for limits of agreement, coefficients of variation and their differences.
Assessing equity of healthcare utilization in rural China: results from nationally representative surveys from 1993 to 2008

PubMed Central

2013-01-01

Background The phenomenon of inequitable healthcare utilization in rural China interests policymakers and researchers; however, the inequity has not been actually measured to present the magnitude and trend using nationally representative data. Methods Based on the National Health Service Survey (NHSS) in 1993, 1998, 2003, and 2008, the Probit model with the probability of outpatient visit and the probability of inpatient visit as the dependent variables is applied to estimate need-predicted healthcare utilization. Furthermore, need-standardized healthcare utilization is assessed through indirect standardization method. Concentration index is measured to reflect income-related inequity of healthcare utilization. Results The concentration index of need-standardized outpatient utilization is 0.0486[95% confidence interval (0.0399, 0.0574)], 0.0310[95% confidence interval (0.0229, 0.0390)], 0.0167[95% confidence interval (0.0069, 0.0264)] and −0.0108[95% confidence interval (−0.0213, -0.0004)] in 1993, 1998, 2003 and 2008, respectively. For inpatient service, the concentration index is 0.0529[95% confidence interval (0.0349, 0.0709)], 0.1543[95% confidence interval (0.1356, 0.1730)], 0.2325[95% confidence interval (0.2132, 0.2518)] and 0.1313[95% confidence interval (0.1174, 0.1451)] in 1993, 1998, 2003 and 2008, respectively. Conclusions Utilization of both outpatient and inpatient services was pro-rich in rural China with the exception of outpatient service in 2008. With the same needs for healthcare, rich rural residents utilized more healthcare service than poor rural residents. Compared to utilization of outpatient service, utilization of inpatient service was more inequitable. Inequity of utilization of outpatient service reduced gradually from 1993 to 2008; meanwhile, inequity of inpatient service utilization increased dramatically from 1993 to 2003 and decreased significantly from 2003 to 2008. Recent attempts in China to increase coverage of insurance and primary healthcare could be a contributing factor to counteract the inequity of outpatient utilization, but better benefit packages and delivery strategies still need to be tested and scaled up to reduce future inequity in inpatient utilization in rural China. PMID:23688260
Exposure to power frequency electric fields and the risk of childhood cancer in the UK

PubMed Central

Skinner, J; Mee, T J; Blackwell, R P; Maslanyj, M P; Simpson, J; Allen, S G; Day, N E

2002-01-01

The United Kingdom Childhood Cancer Study, a population-based case–control study covering the whole of Great Britain, incorporated a pilot study measuring electric fields. Measurements were made in the homes of 473 children who were diagnosed with a malignant neoplasm between 1992 and 1996 and who were aged 0–14 at diagnosis, together with 453 controls matched on age, sex and geographical location. Exposure assessments comprised resultant spot measurements in the child's bedroom and the family living-room. Temporal stability of bedroom fields was investigated through continuous logging of the 48-h vertical component at the child's bedside supported by repeat spot measurements. The principal exposure metric used was the mean of the pillow and bed centre measurements. For the 273 cases and 276 controls with fully validated measures, comparing those with a measured electric field exposure ⩾20 V m−1 to those in a reference category of exposure <10 V m−1, odds ratios of 1.31 (95% confidence interval 0.68–2.54) for acute lymphoblastic leukaemia, 1.32 (95% confidence interval 0.73–2.39) for total leukaemia, 2.12 (95% confidence interval 0.78–5.78) for central nervous system cancers and 1.26 (95% confidence interval 0.77–2.07) for all malignancies were obtained. When considering the 426 cases and 419 controls with no invalid measures, the corresponding odds ratios were 0.86 (95% confidence interval 0.49–1.51) for acute lymphoblastic leukaemia, 0.93 (95% confidence interval 0.56–1.54) for total leukaemia, 1.43 (95% confidence interval 0.68–3.02) for central nervous system cancers and 0.90 (95% confidence interval 0.59–1.35) for all malignancies. With exposure modelled as a continuous variable, odds ratios for an increase in the principal metric of 10 V m−1 were close to unity for all disease categories, never differing significantly from one. British Journal of Cancer (2002) 87, 1257–1266. doi:10.1038/sj.bjc.6600602 www.bjcancer.com © 2002 Cancer Research UK PMID:12439715
A risk score for predicting coronary artery disease in women with angina pectoris and abnormal stress test finding.

PubMed

Lo, Monica Y; Bonthala, Nirupama; Holper, Elizabeth M; Banks, Kamakki; Murphy, Sabina A; McGuire, Darren K; de Lemos, James A; Khera, Amit

2013-03-15

Women with angina pectoris and abnormal stress test findings commonly have no epicardial coronary artery disease (CAD) at catheterization. The aim of the present study was to develop a risk score to predict obstructive CAD in such patients. Data were analyzed from 337 consecutive women with angina pectoris and abnormal stress test findings who underwent cardiac catheterization at our center from 2003 to 2007. Forward selection multivariate logistic regression analysis was used to identify the independent predictors of CAD, defined by ≥50% diameter stenosis in ≥1 epicardial coronary artery. The independent predictors included age ≥55 years (odds ratio 2.3, 95% confidence interval 1.3 to 4.0), body mass index <30 kg/m(2) (odds ratio 1.9, 95% confidence interval 1.1 to 3.1), smoking (odds ratio 2.6, 95% confidence interval 1.4 to 4.8), low high-density lipoprotein cholesterol (odds ratio 2.9, 95% confidence interval 1.5 to 5.5), family history of premature CAD (odds ratio 2.4, 95% confidence interval 1.0 to 5.7), lateral abnormality on stress imaging (odds ratio 2.8, 95% confidence interval 1.5 to 5.5), and exercise capacity <5 metabolic equivalents (odds ratio 2.4, 95% confidence interval 1.1 to 5.6). Assigning each variable 1 point summed to constitute a risk score, a graded association between the score and prevalent CAD (ptrend <0.001). The risk score demonstrated good discrimination with a cross-validated c-statistic of 0.745 (95% confidence interval 0.70 to 0.79), and an optimized cutpoint of a score of ≤2 included 62% of the subjects and had a negative predictive value of 80%. In conclusion, a simple clinical risk score of 7 characteristics can help differentiate those more or less likely to have CAD among women with angina pectoris and abnormal stress test findings. This tool, if validated, could help to guide testing strategies in women with angina pectoris. Copyright © 2013 Elsevier Inc. All rights reserved.
Confidence Intervals for True Scores Using the Skew-Normal Distribution

ERIC Educational Resources Information Center

Garcia-Perez, Miguel A.

2010-01-01

A recent comparative analysis of alternative interval estimation approaches and procedures has shown that confidence intervals (CIs) for true raw scores determined with the Score method--which uses the normal approximation to the binomial distribution--have actual coverage probabilities that are closest to their nominal level. It has also recently…
The Role of Short-Term Memory Capacity and Task Experience for Overconfidence in Judgment under Uncertainty

ERIC Educational Resources Information Center

Hansson, Patrik; Juslin, Peter; Winman, Anders

2008-01-01

Research with general knowledge items demonstrates extreme overconfidence when people estimate confidence intervals for unknown quantities, but close to zero overconfidence when the same intervals are assessed by probability judgment. In 3 experiments, the authors investigated if the overconfidence specific to confidence intervals derives from…
Confidence Intervals for Weighted Composite Scores under the Compound Binomial Error Model

ERIC Educational Resources Information Center

Kim, Kyung Yong; Lee, Won-Chan

2018-01-01

Reporting confidence intervals with test scores helps test users make important decisions about examinees by providing information about the precision of test scores. Although a variety of estimation procedures based on the binomial error model are available for computing intervals for test scores, these procedures assume that items are randomly…
Performance analysis of complex repairable industrial systems using PSO and fuzzy confidence interval based methodology.

PubMed

Garg, Harish

2013-03-01

The main objective of the present paper is to propose a methodology for analyzing the behavior of the complex repairable industrial systems. In real-life situations, it is difficult to find the most optimal design policies for MTBF (mean time between failures), MTTR (mean time to repair) and related costs by utilizing available resources and uncertain data. For this, the availability-cost optimization model has been constructed for determining the optimal design parameters for improving the system design efficiency. The uncertainties in the data related to each component of the system are estimated with the help of fuzzy and statistical methodology in the form of the triangular fuzzy numbers. Using these data, the various reliability parameters, which affects the system performance, are obtained in the form of the fuzzy membership function by the proposed confidence interval based fuzzy Lambda-Tau (CIBFLT) methodology. The computed results by CIBFLT are compared with the existing fuzzy Lambda-Tau methodology. Sensitivity analysis on the system MTBF has also been addressed. The methodology has been illustrated through a case study of washing unit, the main part of the paper industry. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.
Utility of functioning in predicting costs of care for patients with mood and anxiety disorders: a prospective cohort study

PubMed Central

Cieza, Alarcos; Baldwin, David S.

2017-01-01

Development of payment systems for mental health services has been hindered by limited evidence for the utility of diagnosis or symptoms in predicting costs of care. We investigated the utility of functioning information in predicting costs for patients with mood and anxiety disorders. This was a prospective cohort study involving 102 adult patients attending a tertiary referral specialist clinic for mood and anxiety disorders. The main outcome was total costs, calculated by applying unit costs to healthcare use data. After adjusting for covariates, a significant total costs association was yielded for functioning (eβ=1.02; 95% confidence interval: 1.01–1.03), but not depressive symptom severity or anxiety symptom severity. When we accounted for the correlations between the main independent variables by constructing an abridged functioning metric, a significant total costs association was again yielded for functioning (eβ=1.04; 95% confidence interval: 1.01–1.09), but not symptom severity. The utility of functioning in predicting costs for patients with mood and anxiety disorders was supported. Functioning information could be useful within mental health payment systems. PMID:28383309
Quantile-based bias correction and uncertainty quantification of extreme event attribution statements

DOE PAGES

Jeon, Soyoung; Paciorek, Christopher J.; Wehner, Michael F.

2016-02-16

Extreme event attribution characterizes how anthropogenic climate change may have influenced the probability and magnitude of selected individual extreme weather and climate events. Attribution statements often involve quantification of the fraction of attributable risk (FAR) or the risk ratio (RR) and associated confidence intervals. Many such analyses use climate model output to characterize extreme event behavior with and without anthropogenic influence. However, such climate models may have biases in their representation of extreme events. To account for discrepancies in the probabilities of extreme events between observational datasets and model datasets, we demonstrate an appropriate rescaling of the model output basedmore » on the quantiles of the datasets to estimate an adjusted risk ratio. Our methodology accounts for various components of uncertainty in estimation of the risk ratio. In particular, we present an approach to construct a one-sided confidence interval on the lower bound of the risk ratio when the estimated risk ratio is infinity. We demonstrate the methodology using the summer 2011 central US heatwave and output from the Community Earth System Model. In this example, we find that the lower bound of the risk ratio is relatively insensitive to the magnitude and probability of the actual event.« less
Standard errors and confidence intervals for variable importance in random forest regression, classification, and survival.

PubMed

Ishwaran, Hemant; Lu, Min

2018-06-04

Random forests are a popular nonparametric tree ensemble procedure with broad applications to data analysis. While its widespread popularity stems from its prediction performance, an equally important feature is that it provides a fully nonparametric measure of variable importance (VIMP). A current limitation of VIMP, however, is that no systematic method exists for estimating its variance. As a solution, we propose a subsampling approach that can be used to estimate the variance of VIMP and for constructing confidence intervals. The method is general enough that it can be applied to many useful settings, including regression, classification, and survival problems. Using extensive simulations, we demonstrate the effectiveness of the subsampling estimator and in particular find that the delete-d jackknife variance estimator, a close cousin, is especially effective under low subsampling rates due to its bias correction properties. These 2 estimators are highly competitive when compared with the .164 bootstrap estimator, a modified bootstrap procedure designed to deal with ties in out-of-sample data. Most importantly, subsampling is computationally fast, thus making it especially attractive for big data settings. Copyright © 2018 John Wiley & Sons, Ltd.

TARGETED SEQUENTIAL DESIGN FOR TARGETED LEARNING INFERENCE OF THE OPTIMAL TREATMENT RULE AND ITS MEAN REWARD.

PubMed

Chambaz, Antoine; Zheng, Wenjing; van der Laan, Mark J

2017-01-01

This article studies the targeted sequential inference of an optimal treatment rule (TR) and its mean reward in the non-exceptional case, i.e. , assuming that there is no stratum of the baseline covariates where treatment is neither beneficial nor harmful, and under a companion margin assumption. Our pivotal estimator, whose definition hinges on the targeted minimum loss estimation (TMLE) principle, actually infers the mean reward under the current estimate of the optimal TR. This data-adaptive statistical parameter is worthy of interest on its own. Our main result is a central limit theorem which enables the construction of confidence intervals on both mean rewards under the current estimate of the optimal TR and under the optimal TR itself. The asymptotic variance of the estimator takes the form of the variance of an efficient influence curve at a limiting distribution, allowing to discuss the efficiency of inference. As a by product, we also derive confidence intervals on two cumulated pseudo-regrets, a key notion in the study of bandits problems. A simulation study illustrates the procedure. One of the corner-stones of the theoretical study is a new maximal inequality for martingales with respect to the uniform entropy integral.
Generalized anxiety disorder prevalence and comorbidity with depression in coronary heart disease: a meta-analysis.

PubMed

Tully, Phillip J; Cosh, Suzanne M

2013-12-01

Generalized anxiety disorder prevalence and comorbidity with depression in coronary heart disease patients remain unquantified. Systematic searching of Medline, Embase, SCOPUS and PsycINFO databases revealed 1025 unique citations. Aggregate generalized anxiety disorder prevalence (12 studies, N = 3485) was 10.94 per cent (95% confidence interval: 7.8-13.99) and 13.52 per cent (95% confidence interval: 8.39-18.66) employing Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria (random effects). Lifetime generalized anxiety disorder prevalence was 25.80 per cent (95% confidence interval: 20.84-30.77). In seven studies, modest correlation was evident between generalized anxiety disorder and depression, Fisher's Z = .30 (95% confidence interval: .19-.42), suggesting that each psychiatric disorder is best conceptualized as contributing unique variance to coronary heart disease prognosis.
Autonomous motivation mediates the relation between goals for physical activity and physical activity behavior in adolescents.

PubMed

Duncan, Michael J; Eyre, Emma Lj; Bryant, Elizabeth; Seghers, Jan; Galbraith, Niall; Nevill, Alan M

2017-04-01

Overall, 544 children (mean age ± standard deviation = 14.2 ± .94 years) completed self-report measures of physical activity goal content, behavioral regulations, and physical activity behavior. Body mass index was determined from height and mass. The indirect effect of intrinsic goal content on physical activity was statistically significant via autonomous ( b = 162.27; 95% confidence interval [89.73, 244.70]), but not controlled motivation ( b = 5.30; 95% confidence interval [-39.05, 45.16]). The indirect effect of extrinsic goal content on physical activity was statistically significant via autonomous ( b = 106.25; 95% confidence interval [63.74, 159.13]) but not controlled motivation ( b = 17.28; 95% confidence interval [-31.76, 70.21]). Weight status did not alter these findings.
Confidence intervals for a difference between lognormal means in cluster randomization trials.

PubMed

Poirier, Julia; Zou, G Y; Koval, John

2017-04-01

Cluster randomization trials, in which intact social units are randomized to different interventions, have become popular in the last 25 years. Outcomes from these trials in many cases are positively skewed, following approximately lognormal distributions. When inference is focused on the difference between treatment arm arithmetic means, existent confidence interval procedures either make restricting assumptions or are complex to implement. We approach this problem by assuming log-transformed outcomes from each treatment arm follow a one-way random effects model. The treatment arm means are functions of multiple parameters for which separate confidence intervals are readily available, suggesting that the method of variance estimates recovery may be applied to obtain closed-form confidence intervals. A simulation study showed that this simple approach performs well in small sample sizes in terms of empirical coverage, relatively balanced tail errors, and interval widths as compared to existing methods. The methods are illustrated using data arising from a cluster randomization trial investigating a critical pathway for the treatment of community acquired pneumonia.
Development and Validation of a Mobile Device-based External Ventricular Drain Simulator.

PubMed

Morone, Peter J; Bekelis, Kimon; Root, Brandon K; Singer, Robert J

2017-10-01

Multiple external ventricular drain (EVD) simulators have been created, yet their cost, bulky size, and nonreusable components limit their accessibility to residency programs. To create and validate an animated EVD simulator that is accessible on a mobile device. We developed a mobile-based EVD simulator that is compatible with iOS (Apple Inc., Cupertino, California) and Android-based devices (Google, Mountain View, California) and can be downloaded from the Apple App and Google Play Store. Our simulator consists of a learn mode, which teaches users the procedure, and a test mode, which assesses users' procedural knowledge. Twenty-eight participants, who were divided into expert and novice categories, completed the simulator in test mode and answered a postmodule survey. This was graded using a 5-point Likert scale, with 5 representing the highest score. Using the survey results, we assessed the module's face and content validity, whereas construct validity was evaluated by comparing the expert and novice test scores. Participants rated individual survey questions pertaining to face and content validity a median score of 4 out of 5. When comparing test scores, generated by the participants completing the test mode, the experts scored higher than the novices (mean, 71.5; 95% confidence interval, 69.2 to 73.8 vs mean, 48; 95% confidence interval, 44.2 to 51.6; P < .001). We created a mobile-based EVD simulator that is inexpensive, reusable, and accessible. Our results demonstrate that this simulator is face, content, and construct valid. Copyright © 2017 by the Congress of Neurological Surgeons
The Distribution of the Product Explains Normal Theory Mediation Confidence Interval Estimation.

PubMed

Kisbu-Sakarya, Yasemin; MacKinnon, David P; Miočević, Milica

2014-05-01

The distribution of the product has several useful applications. One of these applications is its use to form confidence intervals for the indirect effect as the product of 2 regression coefficients. The purpose of this article is to investigate how the moments of the distribution of the product explain normal theory mediation confidence interval coverage and imbalance. Values of the critical ratio for each random variable are used to demonstrate how the moments of the distribution of the product change across values of the critical ratio observed in research studies. Results of the simulation study showed that as skewness in absolute value increases, coverage decreases. And as skewness in absolute value and kurtosis increases, imbalance increases. The difference between testing the significance of the indirect effect using the normal theory versus the asymmetric distribution of the product is further illustrated with a real data example. This article is the first study to show the direct link between the distribution of the product and indirect effect confidence intervals and clarifies the results of previous simulation studies by showing why normal theory confidence intervals for indirect effects are often less accurate than those obtained from the asymmetric distribution of the product or from resampling methods.
Statistical inference for the within-device precision of quantitative measurements in assay validation.

PubMed

Liu, Jen-Pei; Lu, Li-Tien; Liao, C T

2009-09-01

Intermediate precision is one of the most important characteristics for evaluation of precision in assay validation. The current methods for evaluation of within-device precision recommended by the Clinical Laboratory Standard Institute (CLSI) guideline EP5-A2 are based on the point estimator. On the other hand, in addition to point estimators, confidence intervals can provide a range for the within-device precision with a probability statement. Therefore, we suggest a confidence interval approach for assessment of the within-device precision. Furthermore, under the two-stage nested random-effects model recommended by the approved CLSI guideline EP5-A2, in addition to the current Satterthwaite's approximation and the modified large sample (MLS) methods, we apply the technique of generalized pivotal quantities (GPQ) to derive the confidence interval for the within-device precision. The data from the approved CLSI guideline EP5-A2 illustrate the applications of the confidence interval approach and comparison of results between the three methods. Results of a simulation study on the coverage probability and expected length of the three methods are reported. The proposed method of the GPQ-based confidence intervals is also extended to consider the between-laboratories variation for precision assessment.
Prolonged corrected QT interval is predictive of future stroke events even in subjects without ECG-diagnosed left ventricular hypertrophy.

PubMed

Ishikawa, Joji; Ishikawa, Shizukiyo; Kario, Kazuomi

2015-03-01

We attempted to evaluate whether subjects who exhibit prolonged corrected QT (QTc) interval (≥440 ms in men and ≥460 ms in women) on ECG, with and without ECG-diagnosed left ventricular hypertrophy (ECG-LVH; Cornell product, ≥244 mV×ms), are at increased risk of stroke. Among the 10 643 subjects, there were a total of 375 stroke events during the follow-up period (128.7±28.1 months; 114 142 person-years). The subjects with prolonged QTc interval (hazard ratio, 2.13; 95% confidence interval, 1.22-3.73) had an increased risk of stroke even after adjustment for ECG-LVH (hazard ratio, 1.71; 95% confidence interval, 1.22-2.40). When we stratified the subjects into those with neither a prolonged QTc interval nor ECG-LVH, those with a prolonged QTc interval but without ECG-LVH, and those with ECG-LVH, multivariate-adjusted Cox proportional hazards analysis demonstrated that the subjects with prolonged QTc intervals but not ECG-LVH (1.2% of all subjects; incidence, 10.7%; hazard ratio, 2.70, 95% confidence interval, 1.48-4.94) and those with ECG-LVH (incidence, 7.9%; hazard ratio, 1.83; 95% confidence interval, 1.31-2.57) had an increased risk of stroke events, compared with those with neither a prolonged QTc interval nor ECG-LVH. In conclusion, prolonged QTc interval was associated with stroke risk even among patients without ECG-LVH in the general population. © 2014 American Heart Association, Inc.
Rank score and permutation testing alternatives for regression quantile estimates

USGS Publications Warehouse

Cade, B.S.; Richards, J.D.; Mielke, P.W.

2006-01-01

Performance of quantile rank score tests used for hypothesis testing and constructing confidence intervals for linear quantile regression estimates (0 ≤ τ ≤ 1) were evaluated by simulation for models with p = 2 and 6 predictors, moderate collinearity among predictors, homogeneous and hetero-geneous errors, small to moderate samples (n = 20–300), and central to upper quantiles (0.50–0.99). Test statistics evaluated were the conventional quantile rank score T statistic distributed as χ2 random variable with q degrees of freedom (where q parameters are constrained by H 0:) and an F statistic with its sampling distribution approximated by permutation. The permutation F-test maintained better Type I errors than the T-test for homogeneous error models with smaller n and more extreme quantiles τ. An F distributional approximation of the F statistic provided some improvements in Type I errors over the T-test for models with > 2 parameters, smaller n, and more extreme quantiles but not as much improvement as the permutation approximation. Both rank score tests required weighting to maintain correct Type I errors when heterogeneity under the alternative model increased to 5 standard deviations across the domain of X. A double permutation procedure was developed to provide valid Type I errors for the permutation F-test when null models were forced through the origin. Power was similar for conditions where both T- and F-tests maintained correct Type I errors but the F-test provided some power at smaller n and extreme quantiles when the T-test had no power because of excessively conservative Type I errors. When the double permutation scheme was required for the permutation F-test to maintain valid Type I errors, power was less than for the T-test with decreasing sample size and increasing quantiles. Confidence intervals on parameters and tolerance intervals for future predictions were constructed based on test inversion for an example application relating trout densities to stream channel width:depth.
A growth reference for mid upper arm circumference for age among school age children and adolescents, and validation for mortality: growth curve construction and longitudinal cohort study

PubMed Central

Mramba, Lazarus; Ngari, Moses; Mwangome, Martha; Muchai, Lilian; Bauni, Evasius; Walker, A Sarah; Gibb, Diana M; Fegan, Gregory

2017-01-01

Objectives To construct growth curves for mid-upper-arm circumference (MUAC)-for-age z score for 5-19 year olds that accord with the World Health Organization growth standards, and to evaluate their discriminatory performance for subsequent mortality. Design Growth curve construction and longitudinal cohort study. Setting United States and international growth data, and cohorts in Kenya, Uganda, and Zimbabwe. Participants The Health Examination Survey (HES)/National Health and Nutrition Examination Survey (NHANES) US population datasets (age 5-25 years), which were used to construct the 2007 WHO growth reference for body mass index in this age group, were merged with an imputed dataset matching the distribution of the WHO 2006 growth standards age 2-6 years. Validation data were from 685 HIV infected children aged 5-17 years participating in the Antiretroviral Research for Watoto (ARROW) trial in Uganda and Zimbabwe; and 1741 children aged 5-13 years discharged from a rural Kenyan hospital (3.8% HIV infected). Both cohorts were followed-up for survival during one year. Main outcome measures Concordance with WHO 2006 growth standards at age 60 months and survival during one year according to MUAC-for-age and body mass index-for-age z scores. Results The new growth curves transitioned smoothly with WHO growth standards at age 5 years. MUAC-for-age z scores of −2 to −3 and less than−3, compared with −2 or more, was associated with hazard ratios for death within one year of 3.63 (95% confidence interval 0.90 to 14.7; P=0.07) and 11.1 (3.40 to 36.0; P<0.001), respectively, among ARROW trial participants; and 2.22 (1.01 to 4.9; P=0.04) and 5.15 (2.49 to 10.7; P<0.001), respectively, among Kenyan children after discharge from hospital. The AUCs for MUAC-for-age and body mass index-for-age z scores for discriminating subsequent mortality were 0.81 (95% confidence interval 0.70 to 0.92) and 0.75 (0.63 to 0.86) in the ARROW trial (absolute difference 0.06, 95% confidence interval −0.032 to 0.16; P=0.2) and 0.73 (0.65 to 0.80) and 0.58 (0.49 to 0.67), respectively, in Kenya (absolute difference in AUC 0.15, 0.07 to 0.23; P=0.0002). Conclusions The MUAC-for-age z score is at least as effective as the body mass index-for-age z score for assessing mortality risks associated with undernutrition among African school aged children and adolescents. MUAC can provide simplified screening and diagnosis within nutrition and HIV programmes, and in research. PMID:28774873
Reliability of the AMA Guides to the Evaluation of Permanent Impairment.

PubMed

Forst, Linda; Friedman, Lee; Chukwu, Abraham

2010-12-01

AMA's Guides to the Evaluation of Permanent Impairment is used to rate loss of function and determine compensation and ability to work after injury or illness; however, there are few studies that evaluate reliability or construct validity. To evaluate the reliability of the fifth and sixth editions for back injury; to determine best methods for further study. Intra-class correlation coefficients within and between raters were relatively high. There was wider variability for individual cases. Impairment ratings were lower and correlated less well for the sixth edition, though confidence intervals overlapped. The sixth edition may not be an improvement over the fifth. A research agenda should include investigations of reliability and construct validity for different body sites and organ systems along the entire rating scale and among different categories of raters.
Asymptotic Normality of the Maximum Pseudolikelihood Estimator for Fully Visible Boltzmann Machines.

PubMed

Nguyen, Hien D; Wood, Ian A

2016-04-01

Boltzmann machines (BMs) are a class of binary neural networks for which there have been numerous proposed methods of estimation. Recently, it has been shown that in the fully visible case of the BM, the method of maximum pseudolikelihood estimation (MPLE) results in parameter estimates, which are consistent in the probabilistic sense. In this brief, we investigate the properties of MPLE for the fully visible BMs further, and prove that MPLE also yields an asymptotically normal parameter estimator. These results can be used to construct confidence intervals and to test statistical hypotheses. These constructions provide a closed-form alternative to the current methods that require Monte Carlo simulation or resampling. We support our theoretical results by showing that the estimator behaves as expected in simulation studies.
Calculating Confidence Intervals for Regional Economic Impacts of Recreastion by Bootstrapping Visitor Expenditures

Treesearch

Donald B.K. English

2000-01-01

In this paper I use bootstrap procedures to develop confidence intervals for estimates of total industrial output generated per thousand tourist visits. Mean expenditures from replicated visitor expenditure data included weights to correct for response bias. Impacts were estimated with IMPLAN. Ninety percent interval endpoints were 6 to 16 percent above or below the...
Does blood transfusion affect intermediate survival after coronary artery bypass surgery?

PubMed

Mikkola, R; Heikkinen, J; Lahtinen, J; Paone, R; Juvonen, T; Biancari, F

2013-01-01

The aim of this study was to investigate the impact of transfusion of blood products on intermediate outcome after coronary artery bypass surgery. Complete data on perioperative blood transfusion in patients undergoing coronary artery bypass surgery were available from 2001 patients who were operated at our institution. Transfusion of any blood product (relative risk = 1.678, 95% confidence interval = 1.087-2.590) was an independent predictor of all-cause mortality. The additive effect of each blood product on all-cause mortality (relative risk = 1.401, 95% confidence interval = 1.203-1.630) and cardiac mortality (relative risk = 1.553, 95% confidence interval = 1.273-1.895) was evident when the sum of each blood product was included in the regression models. However, when single blood products were included in the regression model, transfusion of fresh frozen plasma/Octaplas® was the only blood product associated with increased risk of all-cause mortality (relative risk = 1.692, 95% confidence interval = 1.222-2.344) and cardiac mortality (relative risk = 2.125, 95% confidence interval = 1.414-3.194). The effect of blood product transfusion was particularly evident during the first three postoperative months. Since follow-up was truncated at 3 months, transfusion of any blood product was a significant predictor of all-cause mortality (relative risk = 2.998, 95% confidence interval = 1.053-0.537). Analysis of patients who survived or had at least 3 months of potential follow-up showed that transfusion of any blood product was not associated with a significantly increased risk of intermediate all-cause mortality (relative risk = 1.430, 95% confidence interval = 0.880-2.323). Transfusion of any blood product is associated with a significant risk of all-cause and cardiac mortality after coronary artery bypass surgery. Such a risk seems to be limited to the early postoperative period and diminishes later on. Among blood products, perioperative use of fresh frozen plasma or Octaplas seems to be the main determinant of mortality.
Rapid Contour-based Segmentation for 18F-FDG PET Imaging of Lung Tumors by Using ITK-SNAP: Comparison to Expert-based Segmentation.

PubMed

Besson, Florent L; Henry, Théophraste; Meyer, Céline; Chevance, Virgile; Roblot, Victoire; Blanchet, Elise; Arnould, Victor; Grimon, Gilles; Chekroun, Malika; Mabille, Laurence; Parent, Florence; Seferian, Andrei; Bulifon, Sophie; Montani, David; Humbert, Marc; Chaumet-Riffaud, Philippe; Lebon, Vincent; Durand, Emmanuel

2018-04-03

Purpose To assess the performance of the ITK-SNAP software for fluorodeoxyglucose (FDG) positron emission tomography (PET) segmentation of complex-shaped lung tumors compared with an optimized, expert-based manual reference standard. Materials and Methods Seventy-six FDG PET images of thoracic lesions were retrospectively segmented by using ITK-SNAP software. Each tumor was manually segmented by six raters to generate an optimized reference standard by using the simultaneous truth and performance level estimate algorithm. Four raters segmented 76 FDG PET images of lung tumors twice by using ITK-SNAP active contour algorithm. Accuracy of ITK-SNAP procedure was assessed by using Dice coefficient and Hausdorff metric. Interrater and intrarater reliability were estimated by using intraclass correlation coefficients of output volumes. Finally, the ITK-SNAP procedure was compared with currently recommended PET tumor delineation methods on the basis of thresholding at 41% volume of interest (VOI; VOI 41 ) and 50% VOI (VOI 50 ) of the tumor's maximal metabolism intensity. Results Accuracy estimates for the ITK-SNAP procedure indicated a Dice coefficient of 0.83 (95% confidence interval: 0.77, 0.89) and a Hausdorff distance of 12.6 mm (95% confidence interval: 9.82, 15.32). Interrater reliability was an intraclass correlation coefficient of 0.94 (95% confidence interval: 0.91, 0.96). The intrarater reliabilities were intraclass correlation coefficients above 0.97. Finally, VOI 41 and VOI 50 accuracy metrics were as follows: Dice coefficient, 0.48 (95% confidence interval: 0.44, 0.51) and 0.34 (95% confidence interval: 0.30, 0.38), respectively, and Hausdorff distance, 25.6 mm (95% confidence interval: 21.7, 31.4) and 31.3 mm (95% confidence interval: 26.8, 38.4), respectively. Conclusion ITK-SNAP is accurate and reliable for active-contour-based segmentation of heterogeneous thoracic PET tumors. ITK-SNAP surpassed the recommended PET methods compared with ground truth manual segmentation. © RSNA, 2018.
Amnioinfusion for meconium-stained liquor in labour.

PubMed

Hofmeyr, G J

2000-01-01

Amnioinfusion aims to prevent or relieve umbilical cord compression during labour by infusing a solution into the uterine cavity. It is also thought to dilute meconium when present in the amniotic fluid and so reduce the risk of meconium aspiration. However it may be that the mechanism of effect is that it corrects oligohydramnios (reduced amniotic fluid), for which thick meconium staining is a marker. The objective of this review was to assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome. The Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register were searched. Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid. Eligibility and trial quality were assessed by one reviewer. Ten studies, most involving small numbers of participants, were included. Under standard perinatal surveillance, amnioinfusion was associated with a reduction in the following: heavy meconium staining of the liquor (relative risk 0.03, 95% confidence interval 0.01 to 0.15); variable fetal heart rate deceleration (relative risk 0.47, 95% confidence interval 0.24 to 0. 90); and a trend to reduced caesarean section overall (relative risk 0.83, 95% confidence interval 0.69 to 1.00). No perinatal deaths were reported. Under limited perinatal surveillance, amnioinfusion was associated with a reduction in the following: meconium aspiration syndrome (relative risk 0.24, 95% confidence interval 0. 12 to 0.48); neonatal hypoxic ischaemic encephalopathy (relative risk 0.07, 95% confidence interval 0.01 to 0.56) and neonatal ventilation or intensive care unit admission (relative risk 0.56, 95% confidence interval 0.39 to 0.79); there was a trend towards reduced perinatal mortality (relative risk 0.34, 95% confidence interval 0.11 to 1.06). Amnioinfusion is associated with improvements in perinatal outcome, particularly in settings where facilities for perinatal surveillance are limited. The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.
Amnioinfusion for meconium-stained liquor in labour.

PubMed

Hofmeyr, G J

2002-01-01

Amnioinfusion aims to prevent or relieve umbilical cord compression during labour by infusing a solution into the uterine cavity. It is also thought to dilute meconium when present in the amniotic fluid and so reduce the risk of meconium aspiration. However, it may be that the mechanism of effect is that it corrects oligohydramnios (reduced amniotic fluid), for which thick meconium staining is a marker. The objective of this review was to assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome. The Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001) were searched. Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid. Eligibility and trial quality were assessed by one reviewer. Twelve studies, most involving small numbers of participants, were included. Under standard perinatal surveillance, amnioinfusion was associated with a reduction in the following: heavy meconium staining of the liquor (relative risk 0.03, 95% confidence interval 0.01 to 0.15); variable fetal heart rate deceleration (relative risk 0.65, 95% confidence interval 0.49 to 0.88); and reduced caesarean section overall (relative risk 0.82, 95% confidence interval 0.69 to 1.97). No perinatal deaths were reported. Under limited perinatal surveillance, amnioinfusion was associated with a reduction in the following: meconium aspiration syndrome (relative risk 0.24, 95% confidence interval 0.12 to 0.48); neonatal hypoxic ischaemic encephalopathy (relative risk 0.07, 95% confidence interval 0.01 to 0.56) and neonatal ventilation or intensive care unit admission (relative risk 0.56, 95% confidence interval 0.39 to 0.79); there was a trend towards reduced perinatal mortality (relative risk 0.34, 95% confidence interval 0.11 to 1.06). Amnioinfusion is associated with improvements in perinatal outcome, particularly in settings where facilities for perinatal surveillance are limited. The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.
Association between GFR Estimated by Multiple Methods at Dialysis Commencement and Patient Survival

PubMed Central

Wong, Muh Geot; Pollock, Carol A.; Cooper, Bruce A.; Branley, Pauline; Collins, John F.; Craig, Jonathan C.; Kesselhut, Joan; Luxton, Grant; Pilmore, Andrew; Harris, David C.

2014-01-01

Summary Background and objectives The Initiating Dialysis Early and Late study showed that planned early or late initiation of dialysis, based on the Cockcroft and Gault estimation of GFR, was associated with identical clinical outcomes. This study examined the association of all-cause mortality with estimated GFR at dialysis commencement, which was determined using multiple formulas. Design, setting, participants, & measurements Initiating Dialysis Early and Late trial participants were stratified into tertiles according to the estimated GFR measured by Cockcroft and Gault, Modification of Diet in Renal Disease, or Chronic Kidney Disease-Epidemiology Collaboration formula at dialysis commencement. Patient survival was determined using multivariable Cox proportional hazards model regression. Results Only Initiating Dialysis Early and Late trial participants who commenced on dialysis were included in this study (n=768). A total of 275 patients died during the study. After adjustment for age, sex, racial origin, body mass index, diabetes, and cardiovascular disease, no significant differences in survival were observed between estimated GFR tertiles determined by Cockcroft and Gault (lowest tertile adjusted hazard ratio, 1.11; 95% confidence interval, 0.82 to 1.49; middle tertile hazard ratio, 1.29; 95% confidence interval, 0.96 to 1.74; highest tertile reference), Modification of Diet in Renal Disease (lowest tertile hazard ratio, 0.88; 95% confidence interval, 0.63 to 1.24; middle tertile hazard ratio, 1.20; 95% confidence interval, 0.90 to 1.61; highest tertile reference), and Chronic Kidney Disease-Epidemiology Collaboration equations (lowest tertile hazard ratio, 0.93; 95% confidence interval, 0.67 to 1.27; middle tertile hazard ratio, 1.15; 95% confidence interval, 0.86 to 1.54; highest tertile reference). Conclusion Estimated GFR at dialysis commencement was not significantly associated with patient survival, regardless of the formula used. However, a clinically important association cannot be excluded, because observed confidence intervals were wide. PMID:24178976
Bootstrap investigation of the stability of a Cox regression model.

PubMed

Altman, D G; Andersen, P K

1989-07-01

We describe a bootstrap investigation of the stability of a Cox proportional hazards regression model resulting from the analysis of a clinical trial of azathioprine versus placebo in patients with primary biliary cirrhosis. We have considered stability to refer both to the choice of variables included in the model and, more importantly, to the predictive ability of the model. In stepwise Cox regression analyses of 100 bootstrap samples using 17 candidate variables, the most frequently selected variables were those selected in the original analysis, and no other important variable was identified. Thus there was no reason to doubt the model obtained in the original analysis. For each patient in the trial, bootstrap confidence intervals were constructed for the estimated probability of surviving two years. It is shown graphically that these intervals are markedly wider than those obtained from the original model.
Sample size requirements for the design of reliability studies: precision consideration.

PubMed

Shieh, Gwowen

2014-09-01

In multilevel modeling, the intraclass correlation coefficient based on the one-way random-effects model is routinely employed to measure the reliability or degree of resemblance among group members. To facilitate the advocated practice of reporting confidence intervals in future reliability studies, this article presents exact sample size procedures for precise interval estimation of the intraclass correlation coefficient under various allocation and cost structures. Although the suggested approaches do not admit explicit sample size formulas and require special algorithms for carrying out iterative computations, they are more accurate than the closed-form formulas constructed from large-sample approximations with respect to the expected width and assurance probability criteria. This investigation notes the deficiency of existing methods and expands the sample size methodology for the design of reliability studies that have not previously been discussed in the literature.

VizieR Online Data Catalog: Fermi/GBM GRB time-resolved spectral catalog (Yu+, 2016)

NASA Astrophysics Data System (ADS)

Yu, H.-F.; Preece, R. D.; Greiner, J.; Bhat, P. N.; Bissaldi, E.; Briggs, M. S.; Cleveland, W. H.; Connaughton, V.; Goldstein, A.; von Kienlin; A.; Kouveliotou, C.; Mailyan, B.; Meegan, C. A.; Paciesas, W. S.; Rau, A.; Roberts, O. J.; Veres, P.; Wilson-Hodge, C.; Zhang, B.-B.; van Eerten, H. J.

2016-01-01

Time-resolved spectral analysis results of BEST models: for each spectrum GRB name using the Fermi GBM trigger designation, spectrum number within individual burst, start time Tstart and end time Tstop for the time bin, BEST model, best-fit parameters of the BEST model, value of CSTAT per degrees of freedom, 10keV-1MeV photon and energy flux are given. Ep evolutionary trends: for each burst GRB name, number of spectra with Ep, Spearman's Rank Correlation Coefficients between Ep_ and photon flux and 90%, 95%, and 99% confidence intervals, Spearman's Rank Correlation Coefficients between Ep and energy flux and 90%, 95%, and 99% confidence intervals, Spearman's Rank Correlation Coefficient between Ep and time and 90%, 95%, and 99% confidence intervals, trends as determined by computer for 90%, 95%, and 99% confidence intervals, trends as determined by human eyes are given. (2 data files).
Pregnancy and birth outcomes in couples with infertility with and without assisted reproductive technology: with an emphasis on US population-based studies.

PubMed

Luke, Barbara

2017-09-01

Infertility, defined as the inability to conceive within 1 year of unprotected intercourse, affects an estimated 80 million individuals worldwide, or 10-15% of couples of reproductive age. Assisted reproductive technology includes all infertility treatments to achieve conception; in vitro fertilization is the process by which an oocyte is fertilized by semen outside the body; non-in vitro fertilization assisted reproductive technology treatments include ovulation induction, artificial insemination, and intrauterine insemination. Use of assisted reproductive technology has risen steadily in the United States during the past 2 decades due to several reasons, including childbearing at older maternal ages and increasing insurance coverage. The number of in vitro fertilization cycles in the United States has nearly doubled from 2000 through 2013 and currently 1.7% of all live births in the United States are the result of this technology. Since the birth of the first child from in vitro fertilization >35 years ago, >5 million babies have been born from in vitro fertilization, half within the past 6 years. It is estimated that 1% of singletons, 19% of twins, and 25% of triplet or higher multiples are due to in vitro fertilization, and 4%, 21%, and 52%, respectively, are due to non-in vitro fertilization assisted reproductive technology. Higher plurality at birth results in a >10-fold increase in the risks for prematurity and low birthweight in twins vs singletons (adjusted odds ratio, 11.84; 95% confidence interval, 10.56-13.27 and adjusted odds ratio, 10.68; 95% confidence interval, 9.45-12.08, respectively). The use of donor oocytes is associated with increased risks for pregnancy-induced hypertension (adjusted odds ratio, 1.43; 95% confidence interval, 1.14-1.78) and prematurity (adjusted odds ratio, 1.43; 95% confidence interval, 1.11-1.83). The use of thawed embryos is associated with higher risks for pregnancy-induced hypertension (adjusted odds ratio, 1.30; 95% confidence interval, 1.08-1.57) and large-for-gestation birthweight (adjusted odds ratio, 1.74; 95% confidence interval, 1.45-2.08). Among singletons, in vitro fertilization is associated with increased risk of severe maternal morbidity compared with fertile deliveries (vaginal: adjusted odds ratio, 2.27; 95% confidence interval, 1.78-2.88; cesarean: adjusted odds ratio, 1.67; 95% confidence interval, 1.40-1.98, respectively) and subfertile deliveries (vaginal: adjusted odds ratio, 1.97; 95% confidence interval, 1.30-3.00; cesarean: adjusted odds ratio, 1.75; 95% confidence interval, 1.30-2.35, respectively). Among twins, cesarean in vitro fertilization deliveries have significantly greater severe maternal morbidity compared to cesarean fertile deliveries (adjusted odds ratio, 1.48; 95% confidence interval, 1.14-1.93). Subfertility, with or without in vitro fertilization or non-in vitro fertilization infertility treatments to achieve a pregnancy, is associated with increased risks of adverse maternal and perinatal outcomes. The major risk from in vitro fertilization treatments of multiple births (and the associated excess of perinatal morbidity) has been reduced over time, with fewer and better-quality embryos being transferred. Copyright © 2017. Published by Elsevier Inc.
Comparison of the Efficacy and Efficiency of the Use of Virtual Reality Simulation With High-Fidelity Mannequins for Simulation-Based Training of Fiberoptic Bronchoscope Manipulation.

PubMed

Jiang, Bailin; Ju, Hui; Zhao, Ying; Yao, Lan; Feng, Yi

2018-04-01

This study compared the efficacy and efficiency of virtual reality simulation (VRS) with high-fidelity mannequin in the simulation-based training of fiberoptic bronchoscope manipulation in novices. Forty-six anesthesia residents with no experience in fiberoptic intubation were divided into two groups: VRS (group VRS) and mannequin (group M). After a standard didactic teaching session, group VRS trained 25 times on VRS, whereas group M performed the same process on a mannequin. After training, participants' performance was assessed on a mannequin five consecutive times. Procedure times during training were recorded as pooled data to construct learning curves. Procedure time and global rating scale scores of manipulation ability were compared between groups, as well as changes in participants' confidence after training. Plateaus in the learning curves were achieved after 19 (95% confidence interval = 15-26) practice sessions in group VRS and 24 (95% confidence interval = 20-32) in group M. There was no significant difference in procedure time [13.7 (6.6) vs. 11.9 (4.1) seconds, t' = 1.101, P = 0.278] or global rating scale [3.9 (0.4) vs. 3.8 (0.4), t = 0.791, P = 0.433] between groups. Participants' confidence increased after training [group VRS: 1.8 (0.7) vs. 3.9 (0.8), t = 8.321, P < 0.001; group M = 2.0 (0.7) vs. 4.0 (0.6), t = 13.948, P < 0.001] but did not differ significantly between groups. Virtual reality simulation is more efficient than mannequin in simulation-based training of flexible fiberoptic manipulation in novices, but similar effects can be achieved in both modalities after adequate training.
Family environment, hobbies and habits as psychosocial predictors of survival for surgically treated patients with breast cancer.

PubMed

Tominaga, K; Andow, J; Koyama, Y; Numao, S; Kurokawa, E; Ojima, M; Nagai, M

1998-01-01

Many psychosocial factors have been reported to influence the duration of survival of breast cancer patients. We have studied how family members, hobbies and habits of the patients may alter their psychosocial status. Female patients with surgically treated breast cancer diagnosed between 1986 and 1995 at the Tochigi Cancer Center Hospital, who provided information on the above-mentioned factors, were used. Their subsequent physical status was followed up in the outpatients clinic. The Cox regression model was used to evaluate the relationship between the results of the factors examined and the duration of the patients' survival, adjusting for the patients' age, stage of disease at diagnosis and curability, as judged by the physician in charge after the treatment. The following factors were revealed to be significant with regard to the survival of surgically treated breast cancer patients: being a widow (hazard ratio 3.29; 95% confidence interval 1.32-8.20), having a hobby (hazard ratio 0.43; 95% confidence interval 0.23-0.82), number of hobbies (hazard ratio 0.64; 95% confidence interval 0.41-1.00), number of female children (hazard ratio 0.64; 95% confidence interval 0.42-0.98), smoker (hazard ratio 2.08; 95% confidence interval 1.02-4.26) and alcohol consumption (hazard ratio 0.10; 95% confidence interval 0.01-0.72). These results suggest that psychosocial factors, including the family environment, where patients receive emotional support from their spouse and children, hobbies and the patients' habits, may influence the duration of survival in surgically treated breast cancer patients.
Surgical Anatomy of Vaginal Hysterectomy-Impact of a Resident-Constructed Simulation Model.

PubMed

Anand, Mallika; Duffy, Conor P; Vragovic, Olivera; Abbasi, Wafaa; Bell, Shannon L

Obstetrics and gynecology residents are less prepared to perform vaginal hysterectomy (VH), despite its advantages over other hysterectomy routes. The American Congress of Obstetricians and Gynecologists and Council on Resident Education in Obstetrics and Gynecology have prioritized simulation training in VH. Our objective was to improve residents' understanding of surgical anatomy of VH using a resident-constructed, low-cost, low-fidelity model. A single simulation session was held in November 2016. Residents constructed a pelvic model, guided by 2 surgeons. A pretest and a posttest were administered. Experienced-based responses were tabulated for frequencies and contents. Improvement on knowledge-based questions was assessed using McNemar's test. Of 20 residents, 16 completed the pretest and 14 (70%) completed pretests and posttests. One hundred percent of postgraduate year (PGY)-4 had performed greater than 10 VH (11-21) and 75% of PGY-3 had performed 5 to 12 VH. Although 75% of PGY-3 and 100% of PGY-4 felt comfortable performing VH, baseline knowledge of essential surgical anatomy of VH was low (65.8%). The PGY-3 and -4 group (n=8) experienced a mean improvement of 24.4% (mean pretest score 65.8% vs mean posttest score 90%; 95% confidence interval, +14.1% to +33.3%, P=0.0005). The PGY-1 and -2 groups (n=6) experienced a mean improvement of 43.3% (mean pretest score, 41.7% vs mean posttest score, 85%; 95% confidence interval, +26.7% to +59.2%, P=0.001). After the session, all residents reported improved understanding surgical anatomy of VH and "more hands-on sessions" was the most frequently requested teaching aid. Residents desire additional model-based simulation training in VH, and such structured, model-based simulations can identify and address gaps in resident knowledge of surgical anatomy of this important operation.
Taichi exercise for self-rated sleep quality in older people: a systematic review and meta-analysis.

PubMed

Du, Shizheng; Dong, Jianshu; Zhang, Heng; Jin, Shengji; Xu, Guihua; Liu, Zengxia; Chen, Lixia; Yin, Haiyan; Sun, Zhiling

2015-01-01

Self-reported sleep disorders are common in older adults, resulting in serious consequences. Non-pharmacological measures are important complementary interventions, among which Taichi exercise is a popular alternative. Some experiments have been performed; however, the effect of Taichi exercise in improving sleep quality in older people has yet to be validated by systematic review. Using systematic review and meta-analysis, this study aimed to examine the efficacy of Taichi exercise in promoting self-reported sleep quality in older adults. Systematic review and meta-analysis of randomized controlled studies. 4 English databases: Pubmed, Cochrane Library, Web of Science and CINAHL, and 4 Chinese databases: CBMdisc, CNKI, VIP, and Wanfang database were searched through December 2013. Two reviewers independently selected eligible trials, conducted critical appraisal of the methodological quality by using the quality appraisal criteria for randomized controlled studies recommended by Cochrane Handbook. A standardized data form was used to extract information. Meta-analysis was performed. Five randomized controlled studies met inclusion criteria. All suffered from some methodological flaws. The results of this study showed that Taichi has large beneficial effect on sleep quality in older people, as indicated by decreases in the global Pittsburgh Sleep Quality Index score [standardized mean difference=-0.87, 95% confidence intervals (95% confidence interval) (-1.25, -0.49)], as well as its sub-domains of subjective sleep quality [standardized mean difference=-0.83, 95% confidence interval (-1.08, -0.57)], sleep latency [standardized mean difference=-0.75, 95% confidence interval (-1.42, -0.07)], sleep duration [standardized mean difference=-0.55, 95% confidence interval (-0.90, -0.21)], habitual sleep efficiency [standardized mean difference=-0.49, 95% confidence interval (-0.74, -0.23)], sleep disturbance [standardized mean difference=-0.44, 95% confidence interval (-0.69, -0.19)], and daytime dysfunction [standardized mean difference=-0.34, 95% confidence interval (-0.59, -0.09)]. Daytime sleepiness improvement was also observed. Weak evidence shows that Taichi exercise has a beneficial effect in improving self-rated sleep quality for older adults, suggesting that Taichi could be an effective alternative and complementary approach to existing therapies for older people with sleep problems. More rigorous experimental studies are required. Copyright © 2014 Elsevier Ltd. All rights reserved.
Previous treatment, sputum-smear nonconversion, and suburban living: The risk factors of multidrug-resistant tuberculosis among Malaysians.

PubMed

Mohd Shariff, Noorsuzana; Shah, Shamsul Azhar; Kamaludin, Fadzilah

2016-03-01

The number of multidrug-resistant tuberculosis patients is increasing each year in many countries all around the globe. Malaysia has no exception in facing this burdensome health problem. We aimed to investigate the factors that contribute to the occurrence of multidrug-resistant tuberculosis among Malaysian tuberculosis patients. An unmatched case-control study was conducted among tuberculosis patients who received antituberculosis treatments from April 2013 until April 2014. Cases are those diagnosed as pulmonary tuberculosis patients clinically, radiologically, and/or bacteriologically, and who were confirmed to be resistant to both isoniazid and rifampicin through drug-sensitivity testing. On the other hand, pulmonary tuberculosis patients who were sensitive to all first-line antituberculosis drugs and were treated during the same time period served as controls. A total of 150 tuberculosis patients were studied, of which the susceptible cases were 120. Factors found to be significantly associated with the occurrence of multidrug-resistant tuberculosis are being Indian or Chinese (odds ratio 3.17, 95% confidence interval 1.04-9.68; and odds ratio 6.23, 95% confidence interval 2.24-17.35, respectively), unmarried (odds ratio 2.58, 95% confidence interval 1.09-6.09), living in suburban areas (odds ratio 2.58, 95% confidence interval 1.08-6.19), are noncompliant (odds ratio 4.50, 95% confidence interval 1.71-11.82), were treated previously (odds ratio 8.91, 95% confidence interval 3.66-21.67), and showed positive sputum smears at the 2nd (odds ratio 7.00, 95% confidence interval 2.46-19.89) and 6th months of treatment (odds ratio 17.96, 95% confidence interval 3.51-91.99). Living in suburban areas, positive sputum smears in the 2nd month of treatment, and was treated previously are factors that independently contribute to the occurrence of multidrug-resistant tuberculosis. Those with positive smears in the second month of treatment, have a history of previous treatment, and live in suburban areas are found to have a higher probability of becoming multidrug resistant. The results presented here may facilitate improvements in the screening and detection process of drug-resistant patients in Malaysia in the future. Copyright © 2015 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.
Stapled versus handsewn methods for colorectal anastomosis surgery.

PubMed

Lustosa, S A; Matos, D; Atallah, A N; Castro, A A

2001-01-01

Randomized controlled trials comparing stapled with handsewn colorectal anastomosis have not shown either technique to be superior, perhaps because individual studies lacked statistical power. A systematic review, with pooled analysis of results, might provide a more definitive answer. To compare the safety and effectiveness of stapled and handsewn colorectal anastomosis. The following primary hypothesis was tested: the stapled technique is more effective because it decreases the level of complications. The RCT register of the Cochrane Review Group was searched for any trial or reference to a relevant trial (published, in-press, or in progress). All publications were sought through computerised searches of EMBASE, LILACS, MEDLINE, the Cochrane Controlled Clinical Trials Database, and through letters to industrial companies and authors. There were no limits upon language, date, or other criteria. All randomized clinical trials (RCTs) in which stapled and handsewn colorectal anastomosis were compared. Adult patients submitted electively to colorectal anastomosis. Endoluminal circular stapler and handsewn colorectal anastomosis. a) Mortality b) Overall Anastomotic Dehiscence c) Clinical Anastomotic Dehiscence d) Radiological Anastomotic Dehiscence e) Stricture f) Anastomotic Haemorrhage g) Reoperation h) Wound Infection i) Anastomosis Duration j) Hospital Stay. Data were independently extracted by the two reviewers (SASL, DM) and cross-checked. The methodological quality of each trial was assessed by the same two reviewers. Details of the randomization (generation and concealment), blinding, whether an intention-to-treat analysis was done, and the number of patients lost to follow-up were recorded. The results of each RCT were summarised on an intention-to-treat basis in 2 x 2 tables for each outcome. External validity was defined by characteristics of the participants, the interventions and the outcomes. The RCTs were stratified according to the level of colorectal anastomosis. The Risk Difference method (random effects model) and NNT for dichotomous outcomes measures and weighted mean difference for continuous outcomes measures, with the corresponding 95% confidence interval, were presented in this review. Statistical heterogeneity was evaluated by using funnel plot and chi-square testing. Of the 1233 patients enrolled ( in 9 trials), 622 were treated with stapled, and 611 with manual, suture. The following main results were obtained: a) Mortality: result based on 901 patients; Risk Difference - 0.6% Confidence Interval -2.8% to +1.6%. b) Overall Dehiscence: result based on 1233 patients; Risk Difference 0.2%, 95% Confidence Interval -5.0% to +5.3%. c) Clinical Anastomotic Dehiscence : result based on 1233 patients; Risk Difference -1.4%, 95% Confidence Interval -5.2 to +2.3%. d) Radiological Anastomotic Dehiscence : result based on 825 patients; Risk Difference 1.2%, 95% Confidence Interval -4.8% to +7.3%. e) Stricture: result based on 1042 patients; Risk Difference 4.6%, 95% Confidence Interval 1.2% to 8.1%. Number needed to treat 17, 95% confidence interval 12 to 31. f) Anastomotic Hemorrhage: result based on 662 patients; Risk Difference 2.7%, 95% Confidence Interval - 0.1% to +5.5%. g) Reoperation: result based on 544 patients; Risk Difference 3.9%, 95% Confidence Interval 0.3% to 7.4%. h) Wound Infection: result based on 567 patients; Risk Difference 1.0%, 95% Confidence Interval -2.2% to +4.3%. i) Anastomosis duration: result based on one study (159 patients); Weighted Mean Difference -7.6 minutes, 95% Confidence Interval -12.9 to -2.2 minutes. j) Hospital Stay: result based on one study (159 patients), Weighted Mean Difference 2.0 days, 95% Confidence Interval -3.27 to +7.2 days. The evidence found was insufficient to demonstrate any superiority of stapled over handsewn techniques in colorectal anastomosis, regardless of the level of anastomosis.
Asymptotic formulae for likelihood-based tests of new physics

NASA Astrophysics Data System (ADS)

Cowan, Glen; Cranmer, Kyle; Gross, Eilam; Vitells, Ofer

2011-02-01

We describe likelihood-based statistical tests for use in high energy physics for the discovery of new phenomena and for construction of confidence intervals on model parameters. We focus on the properties of the test procedures that allow one to account for systematic uncertainties. Explicit formulae for the asymptotic distributions of test statistics are derived using results of Wilks and Wald. We motivate and justify the use of a representative data set, called the "Asimov data set", which provides a simple method to obtain the median experimental sensitivity of a search or measurement as well as fluctuations about this expectation.
Etiological classifications of transient ischemic attacks: subtype classification by TOAST, CCS and ASCO--a pilot study.

PubMed

Amort, Margareth; Fluri, Felix; Weisskopf, Florian; Gensicke, Henrik; Bonati, Leo H; Lyrer, Philippe A; Engelter, Stefan T

2012-01-01

In patients with transient ischemic attacks (TIA), etiological classification systems are not well studied. The Trial of ORG 10172 in Acute Stroke Treatment (TOAST), the Causative Classification System (CCS), and the Atherosclerosis Small Vessel Disease Cardiac Source Other Cause (ASCO) classification may be useful to determine the underlying etiology. We aimed at testing the feasibility of each of the 3 systems. Furthermore, we studied and compared their prognostic usefulness. In a single-center TIA registry prospectively ascertained over 2 years, we applied 3 etiological classification systems. We compared the distribution of underlying etiologies, the rates of patients with determined versus undetermined etiology, and studied whether etiological subtyping distinguished TIA patients with versus without subsequent stroke or TIA within 3 months. The 3 systems were applicable in all 248 patients. A determined etiology with the highest level of causality was assigned similarly often with TOAST (35.9%), CCS (34.3%), and ASCO (38.7%). However, the frequency of undetermined causes differed significantly between the classification systems and was lowest for ASCO (TOAST: 46.4%; CCS: 37.5%; ASCO: 18.5%; p < 0.001). In TOAST, CCS, and ASCO, cardioembolism (19.4/14.5/18.5%) was the most common etiology, followed by atherosclerosis (11.7/12.9/14.5%). At 3 months, 33 patients (13.3%, 95% confidence interval 9.3-18.2%) had recurrent cerebral ischemic events. These were strokes in 13 patients (5.2%; 95% confidence interval 2.8-8.8%) and TIAs in 20 patients (8.1%, 95% confidence interval 5.0-12.2%). Patients with a determined etiology (high level of causality) had higher rates of subsequent strokes than those without a determined etiology [TOAST: 6.7% (95% confidence interval 2.5-14.1%) vs. 4.4% (95% confidence interval 1.8-8.9%); CSS: 9.3% (95% confidence interval 4.1-17.5%) vs. 3.1% (95% confidence interval 1.0-7.1%); ASCO: 9.4% (95% confidence interval 4.4-17.1%) vs. 2.6% (95% confidence interval 0.7-6.6%)]. However, this difference was only significant in the ASCO classification (p = 0.036). Using ASCO, there was neither an increase in risk of subsequent stroke among patients with incomplete diagnostic workup (at least one subtype scored 9) compared with patients with adequate workup (no subtype scored 9), nor among patients with multiple causes compared with patients with a single cause. In TIA patients, all etiological classification systems provided a similar distribution of underlying etiologies. The increase in stroke risk in TIA patients with determined versus undetermined etiology was most evident using the ASCO classification. Copyright © 2012 S. Karger AG, Basel.
Likelihood-based confidence intervals for estimating floods with given return periods

NASA Astrophysics Data System (ADS)

Martins, Eduardo Sávio P. R.; Clarke, Robin T.

1993-06-01

This paper discusses aspects of the calculation of likelihood-based confidence intervals for T-year floods, with particular reference to (1) the two-parameter gamma distribution; (2) the Gumbel distribution; (3) the two-parameter log-normal distribution, and other distributions related to the normal by Box-Cox transformations. Calculation of the confidence limits is straightforward using the Nelder-Mead algorithm with a constraint incorporated, although care is necessary to ensure convergence either of the Nelder-Mead algorithm, or of the Newton-Raphson calculation of maximum-likelihood estimates. Methods are illustrated using records from 18 gauging stations in the basin of the River Itajai-Acu, State of Santa Catarina, southern Brazil. A small and restricted simulation compared likelihood-based confidence limits with those given by use of the central limit theorem; for the same confidence probability, the confidence limits of the simulation were wider than those of the central limit theorem, which failed more frequently to contain the true quantile being estimated. The paper discusses possible applications of likelihood-based confidence intervals in other areas of hydrological analysis.
Risks of Large Portfolios

PubMed Central

Fan, Jianqing; Liao, Yuan; Shi, Xiaofeng

2014-01-01

The risk of a large portfolio is often estimated by substituting a good estimator of the volatility matrix. However, the accuracy of such a risk estimator is largely unknown. We study factor-based risk estimators under a large amount of assets, and introduce a high-confidence level upper bound (H-CLUB) to assess the estimation. The H-CLUB is constructed using the confidence interval of risk estimators with either known or unknown factors. We derive the limiting distribution of the estimated risks in high dimensionality. We find that when the dimension is large, the factor-based risk estimators have the same asymptotic variance no matter whether the factors are known or not, which is slightly smaller than that of the sample covariance-based estimator. Numerically, H-CLUB outperforms the traditional crude bounds, and provides an insightful risk assessment. In addition, our simulated results quantify the relative error in the risk estimation, which is usually negligible using 3-month daily data. PMID:26195851
RELIABILITY CONCERNS IN THE REPEATED COMPUTERIZED ASSESSMENT OF ATTENTION IN CHILDREN

PubMed Central

Zabel, T. Andrew; von Thomsen, Christian; Cole, Carolyn; Martin, Rebecca; Mahone, E. Mark

2010-01-01

Assessment of attentional processes via computerized assessment is frequently used to quantify intra-individual cognitive improvement or decline in response to treatment. However, assessment of intra-individual change is highly dependent on sufficient test reliability. We examined the test–retest reliability of selected variables from one popular computerized continuous performance test (CPT)—i.e., the Conners’ CPT – Second Edition (CPT-II). Participants were 39 healthy children (20 girls) ages 6–18 without intellectual impairment (mean PPVT-III SS = 102.6), LD, or psychiatric disorders (DICA-IV). Test–retest reliability over the 3–8 month interval (mean = 6 months) was acceptable (Intraclass Correlations [ICC] = .82 to .92) on comparison measures (Beery Test of Visual Perception, WISC-IV Block Design, PPVT-III). In contrast, test–retest reliability was only modest for CPT-II raw scores (ICCs ranging from .62 to .82) and T-scores (ICCs ranging from .33 to .65) for variables of interest (Omissions, Commissions, Variability, Hit Reaction Time, and Attentiveness). Using test–retest reliability information published in the CPT-II manual, 90% confidence intervals based on reliable change index (RCI) methodology were constructed to examine the significance of test–retest difference/change scores. Of the participants in this sample of typically developing youth, 30% generated intra-individual changes in T-scores on the Omissions and Attentiveness variables that exceeded the 90% confidence intervals and qualified as “statistically rare” changes in score. These results suggest a considerable degree of normal variability in CPT-II test scores over extended test–retest intervals, and suggest a need for caution when interpreting test score changes in neurologically unstable clinical populations. PMID:19452302
Estimating equivalence with quantile regression

USGS Publications Warehouse

Cade, B.S.

2011-01-01

Equivalence testing and corresponding confidence interval estimates are used to provide more enlightened statistical statements about parameter estimates by relating them to intervals of effect sizes deemed to be of scientific or practical importance rather than just to an effect size of zero. Equivalence tests and confidence interval estimates are based on a null hypothesis that a parameter estimate is either outside (inequivalence hypothesis) or inside (equivalence hypothesis) an equivalence region, depending on the question of interest and assignment of risk. The former approach, often referred to as bioequivalence testing, is often used in regulatory settings because it reverses the burden of proof compared to a standard test of significance, following a precautionary principle for environmental protection. Unfortunately, many applications of equivalence testing focus on establishing average equivalence by estimating differences in means of distributions that do not have homogeneous variances. I discuss how to compare equivalence across quantiles of distributions using confidence intervals on quantile regression estimates that detect differences in heterogeneous distributions missed by focusing on means. I used one-tailed confidence intervals based on inequivalence hypotheses in a two-group treatment-control design for estimating bioequivalence of arsenic concentrations in soils at an old ammunition testing site and bioequivalence of vegetation biomass at a reclaimed mining site. Two-tailed confidence intervals based both on inequivalence and equivalence hypotheses were used to examine quantile equivalence for negligible trends over time for a continuous exponential model of amphibian abundance. ?? 2011 by the Ecological Society of America.
Fasting glucose levels, incident diabetes, subclinical atherosclerosis and cardiovascular events in apparently healthy adults: A 12-year longitudinal study.

PubMed

Sitnik, Debora; Santos, Itamar S; Goulart, Alessandra C; Staniak, Henrique L; Manson, JoAnn E; Lotufo, Paulo A; Bensenor, Isabela M

2016-11-01

We aimed to study the association between fasting plasma glucose, diabetes incidence and cardiovascular burden after 10-12 years. We evaluated diabetes and cardiovascular events incidences, carotid intima-media thickness and coronary artery calcium scores in ELSA-Brasil (the Brazilian Longitudinal Study of Adult Health) baseline (2008-2010) of 1536 adults without diabetes in 1998. We used regression models to estimate association with carotid intima-media thickness (in mm), coronary artery calcium scores (in Agatston points) and cardiovascular events according to fasting plasma glucose in 1998. Adjusted diabetes incidence rate was 9.8/1000 person-years (95% confidence interval: 7.7-13.6/1000 person-years). Incident diabetes was positively associated with higher fasting plasma glucose. Fasting plasma glucose levels 110-125 mg/dL were associated with higher carotid intima-media thickness (β = 0.028; 95% confidence interval: 0.003-0.053). Excluding those with incident diabetes, there was a borderline association between higher carotid intima-media thickness and fasting plasma glucose 110-125 mg/dL (β = 0.030; 95% confidence interval: -0.005 to 0.065). Incident diabetes was associated with higher carotid intima-media thickness (β = 0.034; 95% confidence interval: 0.015-0.053), coronary artery calcium scores ⩾400 (odds ratio = 2.84; 95% confidence interval: 1.17-6.91) and the combined outcome of a coronary artery calcium scores ⩾400 or incident cardiovascular event (odds ratio = 3.50; 95% confidence interval: 1.60-7.65). In conclusion, fasting plasma glucose in 1998 and incident diabetes were associated with higher cardiovascular burden. © The Author(s) 2016.
Prevalence of infections among residents of Residential Care Homes for the Elderly in Hong Kong.

PubMed

Choy, C Sm; Chen, H; Yau, C Sw; Hsu, E K; Chik, N Y; Wong, A Ty

2016-08-01

A point prevalence study was conducted to study the epidemiology of common infections among residents in Residential Care Homes for the Elderly in Hong Kong and their associated factors. Residential Care Homes for the Elderly in Hong Kong were selected by stratified single-stage cluster random sampling. All residents aged 65 years or above from the recruited homes were surveyed. Infections were identified using standardised definitions. Demographic and health information-including medical history, immunisation record, antibiotic use, and activities of daily living (as measured by Barthel Index)-was collected by a survey team to determine any associated factors. Data were collected from 3857 residents in 46 Residential Care Homes for the Elderly from February to May 2014. A total of 105 residents had at least one type of infection based on the survey definition. The overall prevalence of all infections was 2.7% (95% confidence interval, 2.2%-3.4%). The three most common infections were of the respiratory tract (1.3%; 95% confidence interval, 0.9%-1.9%), skin and soft tissue (0.7%; 95% confidence interval, 0.5%-1.0%), and urinary tract (0.5%; 95% confidence interval, 0.3%-0.9%). Total dependence in activities of daily living, as indicated by low Barthel Index score of 0 to 20 (odds ratio=3.0; 95% confidence interval, 1.4-6.2), and presence of a wound or stoma (odds ratio=2.7; 95% confidence interval, 1.4-4.9) were significantly associated with presence of infection. This survey provides information about infections among residents in Residential Care Homes for the Elderly in the territory. Local data enable us to understand the burden of infections and formulate targeted measures for prevention.
Influence of Objective Three-Dimensional Measures and Movement Images on Surgeon Treatment Planning for Lip Revision Surgery

PubMed Central

Trotman, Carroll-Ann; Phillips, Ceib; Faraway, Julian J.; Hartman, Terry; van Aalst, John A.

2013-01-01

Objective To determine whether a systematic evaluation of facial soft tissues of patients with cleft lip and palate, using facial video images and objective three-dimensional measurements of movement, change surgeons’ treatment plans for lip revision surgery. Design Prospective longitudinal study. Setting The University of North Carolina School of Dentistry. Patients, Participants A group of patients with repaired cleft lip and palate (n = 21), a noncleft control group (n = 37), and surgeons experienced in cleft care. Interventions Lip revision. Main Outcome Measures (1) facial photographic images; (2) facial video images during animations; (3) objective three-dimensional measurements of upper lip movement based on z scores; and (4) objective dynamic and visual three-dimensional measurement of facial soft tissue movement. Results With the use of the video images plus objective three-dimensional measures, changes were made to the problem list of the surgical treatment plan for 86% of the patients (95% confidence interval, 0.64 to 0.97) and the surgical goals for 71% of the patients (95% confidence interval, 0.48 to 0.89). The surgeon group varied in the percentage of patients for whom the problem list was modified, ranging from 24% (95% confidence interval, 8% to 47%) to 48% (95% confidence interval, 26% to 70%) of patients, and the percentage for whom the surgical goals were modified, ranging from 14% (94% confidence interval, 3% to 36%) to 48% (95% confidence interval, 26% to 70%) of patients. Conclusions For all surgeons, the additional assessment components of the systematic valuation resulted in a change in clinical decision making for some patients. PMID:23855676
Lower hospital mortality and complications after pediatric hematopoietic stem cell transplantation.

PubMed

Bratton, Susan L; Van Duker, Heather; Statler, Kimberly D; Pulsipher, Michael A; McArthur, Jennifer; Keenan, Heather T

2008-03-01

To assess protective and risk factors for mortality among pediatric patients during initial care after hematopoietic stem cell transplantation (HSCT) and to evaluate changes in hospital mortality. Retrospective cohort using the 1997, 2000, and 2003 Kids Inpatient Database, a probabilistic sample of children hospitalized in the United States with a procedure code for HSCT. Hospitalized patients in the United States submitted to the database. Age, <19 yrs. None. Hospital mortality significantly decreased from 12% in 1997 to 6% in 2003. Source of stem cells changed with increased use of cord blood. Rates of sepsis, graft versus host disease, and mechanical ventilation significantly decreased. Compared with autologous HSCT, patients who received an allogenic HSCT without T-cell depletion were more likely to die (adjusted odds ratio, 2.4; 95% confidence interval, 1.5, 3.9), while children who received cord blood HSCT were at the greatest risk of hospital death (adjusted odds ratio, 4.8; 95% confidence interval, 2.6, 9.1). Mechanical ventilation (adjusted odds ratio, 26.32; 95% confidence interval, 16.3-42.2), dialysis (adjusted odds ratio, 12.9; 95% confidence interval, 4.7-35.4), and sepsis (adjusted odds ratio, 3.9; 95% confidence interval, 2.5-6.1) were all independently associated with death, while care in 2003 was associated with decreased risk (adjusted odds ratio, 0.4; 95% confidence interval, 0.2-0.7) of death. Hospital mortality after HSCT in children decreased over time as did complications including need for mechanical ventilation, graft versus host disease, and sepsis. Prevention of complications is essential as the need for invasive support continues to be associated with high mortality risk.
High prevalence of refractive errors in a rural population: 'Nooravaran Salamat' Mobile Eye Clinic experience.

PubMed

Hashemi, Hassan; Rezvan, Farhad; Ostadimoghaddam, Hadi; Abdollahi, Majid; Hashemi, Maryam; Khabazkhoob, Mehdi

2013-01-01

The prevalence of myopia and hyperopia and determinants were determined in a rural population of Iran. Population-based cross-sectional study. Using random cluster sampling, 13 of the 83 villages of Khaf County in the north east of Iran were selected. Data from 2001 people over the age of 15 years were analysed. Visual acuity measurement, non-cycloplegic refraction and eye examinations were done at the Mobile Eye Clinic. The prevalence of myopia and hyperopia based on spherical equivalent worse than -0.5 dioptre and +0.5 dioptre, respectively. The prevalence of myopia, hyperopia and anisometropia in the total study sample was 28% (95% confidence interval: 25.9-30.2), 19.2% (95% confidence interval: 17.3-21.1), and 11.5% (95% confidence interval: 10.0-13.1), respectively. In the over 40 population, the prevalence of myopia and hyperopia was 32.5% (95% confidence interval: 28.9-36.1) and 27.9% (95% confidence interval: 24.5-31.3), respectively. In the multiple regression model for this group, myopia strongly correlated with cataract (odds ratio = 1.98 and 95% confidence interval: 1.33-2.93), and hyperopia only correlated with age (P < 0.001). The prevalence of high myopia and high hyperopia was 1.5% and 4.6%. In the multiple regression model, anisometropia significantly correlated with age (odds ratio = 1.04) and cataract (odds ratio = 5.2) (P < 0.001). The prevalence of myopia and anisometropia was higher than that in previous studies in urban population of Iran, especially in the elderly. Cataract was the only variable that correlated with myopia and anisometropia. © 2013 The Authors. Clinical and Experimental Ophthalmology © 2013 Royal Australian and New Zealand College of Ophthalmologists.
The Association Between Maternal Age and Cerebral Palsy Risk Factors.

PubMed

Schneider, Rilla E; Ng, Pamela; Zhang, Xun; Andersen, John; Buckley, David; Fehlings, Darcy; Kirton, Adam; Wood, Ellen; van Rensburg, Esias; Shevell, Michael I; Oskoui, Maryam

2018-05-01

Advanced maternal age is associated with higher frequencies of antenatal and perinatal conditions, as well as a higher risk of cerebral palsy in offspring. We explore the association between maternal age and specific cerebral palsy risk factors. Data were extracted from the Canadian Cerebral Palsy Registry. Maternal age was categorized as ≥35 years of age and less than 20 years of age at the time of birth. Chi-square and multivariate logistic regressions were performed to calculate odds ratios and their 95% confidence intervals. The final sample consisted of 1391 children with cerebral palsy, with 19% of children having mothers aged 35 or older and 4% of children having mothers below the age of 20. Univariate analyses showed that mothers aged 35 or older were more likely to have gestational diabetes (odds ratio 1.9, 95% confidence interval 1.3 to 2.8), to have a history of miscarriage (odds ratio 1.8, 95% confidence interval 1.3 to 2.4), to have undergone fertility treatments (odds ratio 2.4, 95% confidence interval 1.5 to 3.9), and to have delivered by Caesarean section (odds ratio 1.6, 95% confidence interval 1.2 to 2.2). These findings were supported by multivariate analyses. Children with mothers below the age of 20 were more likely to have a congenital malformation (odds ratio 2.4, 95% confidence interval 1.4 to 4.2), which is also supported by multivariate analysis. The risk factor profiles of children with cerebral palsy vary by maternal age. Future studies are warranted to further our understanding of the compound causal pathways leading to cerebral palsy and the observed greater prevalence of cerebral palsy with increasing maternal age. Copyright © 2018 Elsevier Inc. All rights reserved.

Priorities for treatment, care and information if faced with serious illness: a comparative population-based survey in seven European countries.

PubMed

Higginson, Irene J; Gomes, Barbara; Calanzani, Natalia; Gao, Wei; Bausewein, Claudia; Daveson, Barbara A; Deliens, Luc; Ferreira, Pedro L; Toscani, Franco; Gysels, Marjolein; Ceulemans, Lucas; Simon, Steffen T; Cohen, Joachim; Harding, Richard

2014-02-01

Health-care costs are growing, with little population-based data about people's priorities for end-of-life care, to guide service development and aid discussions. We examined variations in people's priorities for treatment, care and information across seven European countries. Telephone survey of a random sample of households; we asked respondents their priorities if 'faced with a serious illness, like cancer, with limited time to live' and used multivariable logistic regressions to identify associated factors. Members of the general public aged ≥ 16 years residing in England, Flanders, Germany, Italy, the Netherlands, Portugal and Spain. In total, 9344 individuals were interviewed. Most people chose 'improve quality of life for the time they had left', ranging from 57% (95% confidence interval: 55%-60%, Italy) to 81% (95% confidence interval: 79%-83%, Spain). Only 2% (95% confidence interval: 1%-3%, England) to 6% (95% confidence interval: 4%-7%, Flanders) said extending life was most important, and 15% (95% confidence interval: 13%-17%, Spain) to 40% (95% confidence interval: 37%-43%, Italy) said quality and extension were equally important. Prioritising quality of life was associated with higher education in all countries (odds ratio = 1.3 (Flanders) to 7.9 (Italy)), experience of caregiving or bereavement (England, Germany, Portugal), prioritising pain/symptom control over having a positive attitude and preferring death in a hospice/palliative care unit. Those prioritising extending life had the highest home death preference of all groups. Health status did not affect priorities. Across all countries, extending life was prioritised by a minority, regardless of health status. Treatment and care needs to be reoriented with patient education and palliative care becoming mainstream for serious conditions such as cancer.
Air pollution attributable postneonatal infant mortality in U.S. metropolitan areas: a risk assessment study

PubMed Central

Kaiser, Reinhard; Romieu, Isabelle; Medina, Sylvia; Schwartz, Joel; Krzyzanowski, Michal; Künzli, Nino

2004-01-01

Background The impact of outdoor air pollution on infant mortality has not been quantified. Methods Based on exposure-response functions from a U.S. cohort study, we assessed the attributable risk of postneonatal infant mortality in 23 U.S. metropolitan areas related to particulate matter <10 μm in diameter (PM10) as a surrogate of total air pollution. Results The estimated proportion of all cause mortality, sudden infant death syndrome (normal birth weight infants only) and respiratory disease mortality (normal birth weight) attributable to PM10 above a chosen reference value of 12.0 μg/m3 PM10 was 6% (95% confidence interval 3–11%), 16% (95% confidence interval 9–23%) and 24% (95% confidence interval 7–44%), respectively. The expected number of infant deaths per year in the selected areas was 106 (95% confidence interval 53–185), 79 (95% confidence interval 46–111) and 15 (95% confidence interval 5–27), respectively. Approximately 75% of cases were from areas where the current levels are at or below the new U.S. PM2.5 standard of 15 μg/m3 (equivalent to 25 μg/m3 PM10). In a country where infant mortality rates and air pollution levels are relatively low, ambient air pollution as measured by particulate matter contributes to a substantial fraction of infant death, especially for those due to sudden infant death syndrome and respiratory disease. Even if all counties would comply to the new PM2.5 standard, the majority of the estimated burden would remain. Conclusion Given the inherent limitations of risk assessments, further studies are needed to support and quantify the relationship between infant mortality and air pollution. PMID:15128459
Assessing Interval Estimation Methods for Hill Model ...

EPA Pesticide Factsheets

The Hill model of concentration-response is ubiquitous in toxicology, perhaps because its parameters directly relate to biologically significant metrics of toxicity such as efficacy and potency. Point estimates of these parameters obtained through least squares regression or maximum likelihood are commonly used in high-throughput risk assessment, but such estimates typically fail to include reliable information concerning confidence in (or precision of) the estimates. To address this issue, we examined methods for assessing uncertainty in Hill model parameter estimates derived from concentration-response data. In particular, using a sample of ToxCast concentration-response data sets, we applied four methods for obtaining interval estimates that are based on asymptotic theory, bootstrapping (two varieties), and Bayesian parameter estimation, and then compared the results. These interval estimation methods generally did not agree, so we devised a simulation study to assess their relative performance. We generated simulated data by constructing four statistical error models capable of producing concentration-response data sets comparable to those observed in ToxCast. We then applied the four interval estimation methods to the simulated data and compared the actual coverage of the interval estimates to the nominal coverage (e.g., 95%) in order to quantify performance of each of the methods in a variety of cases (i.e., different values of the true Hill model paramet
Prevalence of Injury in Occupation and Industry: Role of Obesity in the National Health Interview Survey 2004 to 2013

PubMed Central

Gu, Ja K.; Charles, Luenda E.; Fekedulegn, Desta; Ma, Claudia C.; Andrew, Michael E.; Burchfiel, Cecil M.

2016-01-01

Objectives The aim of this study was to estimate prevalence of injury by occupation and industry and obesity’s role. Methods Self-reported injuries were collected annually for US workers during 2004 to 2013. Prevalence ratios (PRs) and 95% confidence intervals (CIs) were obtained from fitted logistic regression models. Results Overall weighted injury prevalence during the previous three months was 77 per 10,000 workers. Age-adjusted injury prevalence was greatest for Construction and Extraction workers (169.7/10,000) followed by Production (160.6) among occupations, while workers in the Construction industry sector (147.9) had the highest injury prevalence followed by the Agriculture/Forestry/Fishing/Mining/Utilities sector (122.1). Overweight and obese workers were 26% to 45% more likely to experience injuries than normal-weight workers. Conclusion The prevalence of injury, highest for Construction workers, gradually increased as body mass index levels increased in most occupational and industry groups. PMID:27058472
Coefficient Alpha Bootstrap Confidence Interval under Nonnormality

ERIC Educational Resources Information Center

Padilla, Miguel A.; Divers, Jasmin; Newton, Matthew

2012-01-01

Three different bootstrap methods for estimating confidence intervals (CIs) for coefficient alpha were investigated. In addition, the bootstrap methods were compared with the most promising coefficient alpha CI estimation methods reported in the literature. The CI methods were assessed through a Monte Carlo simulation utilizing conditions…
Teach a Confidence Interval for the Median in the First Statistics Course

ERIC Educational Resources Information Center

Howington, Eric B.

2017-01-01

Few introductory statistics courses consider statistical inference for the median. This article argues in favour of adding a confidence interval for the median to the first statistics course. Several methods suitable for introductory statistics students are identified and briefly reviewed.
Dynamic association rules for gene expression data analysis.

PubMed

Chen, Shu-Chuan; Tsai, Tsung-Hsien; Chung, Cheng-Han; Li, Wen-Hsiung

2015-10-14

The purpose of gene expression analysis is to look for the association between regulation of gene expression levels and phenotypic variations. This association based on gene expression profile has been used to determine whether the induction/repression of genes correspond to phenotypic variations including cell regulations, clinical diagnoses and drug development. Statistical analyses on microarray data have been developed to resolve gene selection issue. However, these methods do not inform us of causality between genes and phenotypes. In this paper, we propose the dynamic association rule algorithm (DAR algorithm) which helps ones to efficiently select a subset of significant genes for subsequent analysis. The DAR algorithm is based on association rules from market basket analysis in marketing. We first propose a statistical way, based on constructing a one-sided confidence interval and hypothesis testing, to determine if an association rule is meaningful. Based on the proposed statistical method, we then developed the DAR algorithm for gene expression data analysis. The method was applied to analyze four microarray datasets and one Next Generation Sequencing (NGS) dataset: the Mice Apo A1 dataset, the whole genome expression dataset of mouse embryonic stem cells, expression profiling of the bone marrow of Leukemia patients, Microarray Quality Control (MAQC) data set and the RNA-seq dataset of a mouse genomic imprinting study. A comparison of the proposed method with the t-test on the expression profiling of the bone marrow of Leukemia patients was conducted. We developed a statistical way, based on the concept of confidence interval, to determine the minimum support and minimum confidence for mining association relationships among items. With the minimum support and minimum confidence, one can find significant rules in one single step. The DAR algorithm was then developed for gene expression data analysis. Four gene expression datasets showed that the proposed DAR algorithm not only was able to identify a set of differentially expressed genes that largely agreed with that of other methods, but also provided an efficient and accurate way to find influential genes of a disease. In the paper, the well-established association rule mining technique from marketing has been successfully modified to determine the minimum support and minimum confidence based on the concept of confidence interval and hypothesis testing. It can be applied to gene expression data to mine significant association rules between gene regulation and phenotype. The proposed DAR algorithm provides an efficient way to find influential genes that underlie the phenotypic variance.
Increased calcium supplementation is associated with morbidity and mortality in the infant postoperative cardiac patient.

PubMed

Dyke, Peter C; Yates, Andrew R; Cua, Clifford L; Hoffman, Timothy M; Hayes, John; Feltes, Timothy F; Springer, Michelle A; Taeed, Roozbeh

2007-05-01

The purpose of this study was to assess the association of calcium replacement therapy with morbidity and mortality in infants after cardiac surgery involving cardiopulmonary bypass. Retrospective chart review. The cardiac intensive care unit at a tertiary care children's hospital. Infants undergoing cardiac surgery involving cardiopulmonary bypass between October 2002 and August 2004. None. Total calcium replacement (mg/kg calcium chloride given) for the first 72 postoperative hours was measured. Morbidity and mortality data were collected. The total volume of blood products given during the first 72 hrs was recorded. Infants with confirmed chromosomal deletions at the 22q11 locus were noted. Correlation and logistic regression analyses were used to generate odds ratios and 95% confidence intervals, with p < .05 being significant. One hundred seventy-one infants met inclusion criteria. Age was 4 +/- 3 months and weight was 4.9 +/- 1.7 kg at surgery. Six infants had deletions of chromosome 22q11. Infants who weighed less required more calcium replacement (r = -.28, p < .001). Greater calcium replacement correlated with a longer intensive care unit length of stay (r = .27, p < .001) and a longer total hospital length of stay (r = .23, p = .002). Greater calcium replacement was significantly associated with morbidity (liver dysfunction [odds ratio, 3.9; confidence interval, 2.1-7.3; p < .001], central nervous system complication [odds ratio, 1.8; confidence interval, 1.1-3.0; p = .02], infection [odds ratio, 1.5; confidence interval, 1.0-2.2; p < .04], extracorporeal membrane oxygenation [odds ratio, 5.0; confidence interval, 2.3-10.6; p < .001]) and mortality (odds ratio, 5.8; confidence interval, 5.8-5.9; p < .001). Greater calcium replacement was not associated with renal insufficiency (odds ratio, 1.5; confidence interval, 0.9-2.3; p = .07). Infants with >1 sd above the mean of total calcium replacement received on average fewer blood products than the total study population. Greater calcium replacement is associated with increasing morbidity and mortality. Further investigation of the etiology and therapy of hypocalcemia in this population is warranted.
WITHDRAWN: Amnioinfusion for meconium-stained liquor in labour.

PubMed

Hofmeyr, G Justus

2009-01-21

Amnioinfusion aims to prevent or relieve umbilical cord compression during labour by infusing a solution into the uterine cavity. It is also thought to dilute meconium when present in the amniotic fluid and so reduce the risk of meconium aspiration. However, it may be that the mechanism of effect is that it corrects oligohydramnios (reduced amniotic fluid), for which thick meconium staining is a marker. The objective of this review was to assess the effects of amnioinfusion for meconium-stained liquor on perinatal outcome. The Cochrane Pregnancy and Childbirth Group trials register (October 2001) and the Cochrane Controlled Trials Register (Issue 3, 2001) were searched. Randomised trials comparing amnioinfusion with no amnioinfusion for women in labour with moderate or thick meconium-staining of the amniotic fluid. Eligibility and trial quality were assessed by one reviewer. Twelve studies, most involving small numbers of participants, were included. Under standard perinatal surveillance, amnioinfusion was associated with a reduction in the following: heavy meconium staining of the liquor (relative risk 0.03, 95% confidence interval 0.01 to 0.15); variable fetal heart rate deceleration (relative risk 0.65, 95% confidence interval 0.49 to 0.88); and reduced caesarean section overall (relative risk 0.82, 95% confidence interval 0.69 to 1.97). No perinatal deaths were reported. Under limited perinatal surveillance, amnioinfusion was associated with a reduction in the following: meconium aspiration syndrome (relative risk 0.24, 95% confidence interval 0.12 to 0.48); neonatal hypoxic ischaemic encephalopathy (relative risk 0.07, 95% confidence interval 0.01 to 0.56) and neonatal ventilation or intensive care unit admission (relative risk 0.56, 95% confidence interval 0.39 to 0.79); there was a trend towards reduced perinatal mortality (relative risk 0.34, 95% confidence interval 0.11 to 1.06). Amnioinfusion is associated with improvements in perinatal outcome, particularly in settings where facilities for perinatal surveillance are limited. The trials reviewed are too small to address the possibility of rare but serious maternal adverse effects of amnioinfusion.
Reliability of clinical findings and magnetic resonance imaging for the diagnosis of chondromalacia patellae.

PubMed

Pihlajamäki, Harri K; Kuikka, Paavo-Ilari; Leppänen, Vesa-Veikko; Kiuru, Martti J; Mattila, Ville M

2010-04-01

This diagnostic study was performed to determine the correlation between anterior knee pain and chondromalacia patellae and to define the reliability of magnetic resonance imaging for the diagnosis of chondromalacia patellae. Fifty-six young adults (median age, 19.5 years) with anterior knee pain had magnetic resonance imaging of the knee followed by arthroscopy. The patellar chondral lesions identified by magnetic resonance imaging were compared with the arthroscopic findings. Arthroscopy confirmed the presence of chondromalacia patellae in twenty-five (45%) of the fifty-six knees, a synovial plica in twenty-five knees, a meniscal tear in four knees, and a femorotibial chondral lesion in four knees; normal anatomy was seen in six knees. No association was found between the severity of the chondromalacia patellae seen at arthroscopy and the clinical symptoms of anterior knee pain syndrome (p = 0.83). The positive predictive value for the ability of 1.0-T magnetic resonance imaging to detect chondromalacia patellae was 75% (95% confidence interval, 53% to 89%), the negative predictive value was 72% (95% confidence interval, 56% to 84%), the sensitivity was 60% (95% confidence interval, 41% to 77%), the specificity was 84% (95% confidence interval, 67% to 93%), and the diagnostic accuracy was 73% (95% confidence interval, 60% to 83%). The sensitivity was 13% (95% confidence interval, 2% to 49%) for grade-I lesions and 83% (95% confidence interval, 59% to 94%) for grade-II, III, or IV lesions. Chondromalacia patellae cannot be diagnosed on the basis of symptoms or with current physical examination methods. The present study demonstrated no correlation between the severity of chondromalacia patellae and the clinical symptoms of anterior knee pain syndrome. Thus, symptoms of anterior knee pain syndrome should not be used as an indication for knee arthroscopy. The sensitivity of 1.0-T magnetic resonance imaging was low for grade-I lesions but considerably higher for more severe (grade-II, III, or IV) lesions. Magnetic resonance imaging may be considered an accurate diagnostic tool for identification of more severe cases of chondromalacia patellae.
Asymptomatic Intradialytic Supraventricular Arrhythmias and Adverse Outcomes in Patients on Hemodialysis

PubMed Central

Pérez de Prado, Armando; López-Gómez, Juan M.; Quiroga, Borja; Goicoechea, Marian; García-Prieto, Ana; Torres, Esther; Reque, Javier; Luño, José

2016-01-01

Background and objectives Supraventricular arrhythmias are associated with high morbidity and mortality. Nevertheless, this condition has received little attention in patients on hemodialysis. The objective of this study was to analyze the incidence of intradialysis supraventricular arrhythmia and its long–term prognostic value. Design, setting, participants, & measurements We designed an observational and prospective study in a cohort of patients on hemodialysis with a 10-year follow-up period. All patients were recruited for study participation and were not recruited for clinical indications. The study population comprised 77 patients (42 men and 35 women; mean age =58±15 years old) with sinus rhythm monitored using a Holter electrocardiogram over six consecutive hemodialysis sessions at recruitment. Results Hypertension was present in 68.8% of patients, and diabetes was present in 29.9% of patients. Supraventricular arrhythmias were recorded in 38 patients (49.3%); all of these were short, asymptomatic, and self-limiting. Age (hazard ratio, 1.04 per year; 95% confidence interval, 1.00 to 1.08) and right atrial enlargement (hazard ratio, 4.29; 95% confidence interval, 1.30 to 14.09) were associated with supraventricular arrhythmia in the multivariate analysis. During a median follow-up of 40 months, 57 patients died, and cardiovascular disease was the main cause of death (52.6%). The variables associated with all-cause mortality in the Cox model were age (hazard ratio, 1.04 per year; 95% confidence interval, 1.00 to 1.08), C-reactive protein (hazard ratio, 1.04 per 1 mg/L; 95% confidence interval, 1.00 to 1.08), and supraventricular arrhythmia (hazard ratio, 3.21; 95% confidence interval, 1.29 to 7.96). Patients with supraventricular arrhythmia also had a higher risk of nonfatal cardiovascular events (hazard ratio, 4.32; 95% confidence interval, 2.11 to 8.83) and symptomatic atrial fibrillation during follow-up (hazard ratio, 17.19; 95% confidence interval, 2.03 to 145.15). Conclusions The incidence of intradialysis supraventricular arrhythmia was high in our hemodialysis study population. Supraventricular arrhythmias were short, asymptomatic, and self-limiting, and although silent, these arrhythmias were independently associated with mortality and cardiovascular events. PMID:27697781
Asymptomatic Intradialytic Supraventricular Arrhythmias and Adverse Outcomes in Patients on Hemodialysis.

PubMed

Verde, Eduardo; Pérez de Prado, Armando; López-Gómez, Juan M; Quiroga, Borja; Goicoechea, Marian; García-Prieto, Ana; Torres, Esther; Reque, Javier; Luño, José

2016-12-07

Supraventricular arrhythmias are associated with high morbidity and mortality. Nevertheless, this condition has received little attention in patients on hemodialysis. The objective of this study was to analyze the incidence of intradialysis supraventricular arrhythmia and its long-term prognostic value. We designed an observational and prospective study in a cohort of patients on hemodialysis with a 10-year follow-up period. All patients were recruited for study participation and were not recruited for clinical indications. The study population comprised 77 patients (42 men and 35 women; mean age =58±15 years old) with sinus rhythm monitored using a Holter electrocardiogram over six consecutive hemodialysis sessions at recruitment. Hypertension was present in 68.8% of patients, and diabetes was present in 29.9% of patients. Supraventricular arrhythmias were recorded in 38 patients (49.3%); all of these were short, asymptomatic, and self-limiting. Age (hazard ratio, 1.04 per year; 95% confidence interval, 1.00 to 1.08) and right atrial enlargement (hazard ratio, 4.29; 95% confidence interval, 1.30 to 14.09) were associated with supraventricular arrhythmia in the multivariate analysis. During a median follow-up of 40 months, 57 patients died, and cardiovascular disease was the main cause of death (52.6%). The variables associated with all-cause mortality in the Cox model were age (hazard ratio, 1.04 per year; 95% confidence interval, 1.00 to 1.08), C-reactive protein (hazard ratio, 1.04 per 1 mg/L; 95% confidence interval, 1.00 to 1.08), and supraventricular arrhythmia (hazard ratio, 3.21; 95% confidence interval, 1.29 to 7.96). Patients with supraventricular arrhythmia also had a higher risk of nonfatal cardiovascular events (hazard ratio, 4.32; 95% confidence interval, 2.11 to 8.83) and symptomatic atrial fibrillation during follow-up (hazard ratio, 17.19; 95% confidence interval, 2.03 to 145.15). The incidence of intradialysis supraventricular arrhythmia was high in our hemodialysis study population. Supraventricular arrhythmias were short, asymptomatic, and self-limiting, and although silent, these arrhythmias were independently associated with mortality and cardiovascular events. Copyright © 2016 by the American Society of Nephrology.
Long-term Results of an Obesity Program in an Ethnically Diverse Pediatric Population

PubMed Central

Nowicka, Paulina; Shaw, Melissa; Yu, Sunkyung; Dziura, James; Chavent, Georgia; O'Malley, Grace; Serrecchia, John B.; Tamborlane, William V.; Caprio, Sonia

2011-01-01

OBJECTIVE: To determine if beneficial effects of a weight-management program could be sustained for up to 24 months in a randomized trial in an ethnically diverse obese population. PATIENTS AND METHODS: There were 209 obese children (BMI > 95th percentile), ages 8 to 16 of mixed ethnic backgrounds randomly assigned to the intensive lifestyle intervention or clinic control group. The control group received counseling every 6 months, and the intervention group received a family-based program, which included exercise, nutrition, and behavior modification. Lifestyle intervention sessions occurred twice weekly for the first 6 months, then twice monthly for the second 6 months; for the last 12 months there was no active intervention. There were 174 children who completed the 12 months of the randomized trial. Follow-up data were available for 76 of these children at 24 months. There were no statistical differences in dropout rates among ethnic groups or in any other aspects. RESULTS: Treatment effect was sustained at 24 months in the intervention versus control group for BMI z score (−0.16 [95% confidence interval: −0.23 to −0.09]), BMI (−2.8 kg/m2 [95% confidence interval: −4.0–1.6 kg/m2]), percent body fat (−4.2% [95% confidence interval: −6.4% to −2.0%]), total body fat mass (−5.8 kg [95% confidence interval: −9.1 kg to −2.6 kg]), total cholesterol (−13.0 mg/dL [95% confidence interval: −21.7 mg/dL to −4.2 mg/dL]), low-density lipoprotein cholesterol (−10.4 mg/dL [95% confidence interval: −18.3 mg/dL to −2.4 mg/dL]), and homeostasis model assessment of insulin resistance (−2.05 [95% confidence interval: −2.48 to −1.75]). CONCLUSIONS: This study, unprecedented because of the high degree of obesity and ethnically diverse backgrounds of children, reveals that benefits of an intensive lifestyle program can be sustained 12 months after completing the active intervention phase. PMID:21300674
[Risk factors associated with work-related accidents in the construction industry in the Valley of Mexico].

PubMed

Sarmiento-Salinas, Rodrigo; López-Rojas, Pablo; Marín-Cotoñieto, Irma Araceli; Godínez-Rocha, Arturo; Haro-García, Luis; Salinas-Tovar, Santiago

2004-01-01

Our aim was to describe construction-industry, work-related accident prevalence in, associated factors in, and potential impact on affiliated workers of the Mexican Institute of Social Security (Instituto Mexicano del Seguro Social, IMSS) in the Valley of Mexico. Prevalent cases in a retrospective case-control design. These include 385 construction-industry workers who were found to have construction work-related accidents in 2001. Controls comprised 385 active construction-industry workers without work-related accident background paired by gender, workplace, and worksite. Work-related accident prevalence in construction workers was 5.5%; most important risk factors and etiology fraction (Ef) included the following: age 16-20 years odds ratio, OR = 1.58, 95% confidence interval (95% CI) 1.40-10.7, p = 0.001, Ef 0.36; eventual insurance, OR = 3.7, 95% CI, 2.16-26.45, p = 0.001), Ef, 0.72, and no training for job, OR = 5.3, 95% CI, 4.9-69.2, p = 0.01), Ef: 0.81. Variables not showing significance were included salary, work shift, and workday. Work-related accident prevalence maintains its preponderance in the Valley of Mexico construction industry; identified risk factors are potentially modifiable, among which job training acquires unquestionable relevance.
UK population norms for the modified dental anxiety scale with percentile calculator: adult dental health survey 2009 results

PubMed Central

2013-01-01

Background A recent UK population survey of oral health included questions to assess dental anxiety to provide mean and prevalence estimates of this important psychological construct. Methods A two-stage cluster sample was used for the survey across England, Wales, and Northern Ireland. The survey took place between October-December 2009, and January-April 2010. All interviewers were trained on survey procedures. Within the 7,233 households sampled there were 13,509 adults who were asked to participate in the survey and 11,382 participated (84%). Results The scale was reliable and showed some evidence of unidimensionality. Estimated proportion of participants with high dental anxiety (cut-off score = 19) was 11.6%. Percentiles and confidence intervals were presented and can be estimated for individual patients across various age ranges and gender using an on-line tool. Conclusions The largest reported data set on the MDAS from a representative UK sample was presented. The scale’s psychometrics is supportive for the routine assessment of patient dental anxiety to compare against a number of major demographic groups categorised by age and sex. Practitioners within the UK have a resource to estimate the rarity of a particular patient’s level of dental anxiety, with confidence intervals, when using the on-line percentile calculator. PMID:23799962
Testing for clustering at many ranges inflates family-wise error rate (FWE).

PubMed

Loop, Matthew Shane; McClure, Leslie A

2015-01-15

Testing for clustering at multiple ranges within a single dataset is a common practice in spatial epidemiology. It is not documented whether this approach has an impact on the type 1 error rate. We estimated the family-wise error rate (FWE) for the difference in Ripley's K functions test, when testing at an increasing number of ranges at an alpha-level of 0.05. Case and control locations were generated from a Cox process on a square area the size of the continental US (≈3,000,000 mi2). Two thousand Monte Carlo replicates were used to estimate the FWE with 95% confidence intervals when testing for clustering at one range, as well as 10, 50, and 100 equidistant ranges. The estimated FWE and 95% confidence intervals when testing 10, 50, and 100 ranges were 0.22 (0.20 - 0.24), 0.34 (0.31 - 0.36), and 0.36 (0.34 - 0.38), respectively. Testing for clustering at multiple ranges within a single dataset inflated the FWE above the nominal level of 0.05. Investigators should construct simultaneous critical envelopes (available in spatstat package in R), or use a test statistic that integrates the test statistics from each range, as suggested by the creators of the difference in Ripley's K functions test.
Psychosocial and nonclinical factors predicting hospital utilization in patients of a chronic disease management program: a prospective observational study.

PubMed

Tran, Mark W; Weiland, Tracey J; Phillips, Georgina A

2015-01-01

Psychosocial factors such as marital status (odds ratio, 3.52; 95% confidence interval, 1.43-8.69; P = .006) and nonclinical factors such as outpatient nonattendances (odds ratio, 2.52; 95% confidence interval, 1.22-5.23; P = .013) and referrals made (odds ratio, 1.20; 95% confidence interval, 1.06-1.35; P = .003) predict hospital utilization for patients in a chronic disease management program. Along with optimizing patients' clinical condition by prescribed medical guidelines and supporting patient self-management, addressing psychosocial and nonclinical issues are important in attempting to avoid hospital utilization for people with chronic illnesses.
Confidence Interval Coverage for Cohen's Effect Size Statistic

ERIC Educational Resources Information Center

Algina, James; Keselman, H. J.; Penfield, Randall D.

2006-01-01

Kelley compared three methods for setting a confidence interval (CI) around Cohen's standardized mean difference statistic: the noncentral-"t"-based, percentile (PERC) bootstrap, and biased-corrected and accelerated (BCA) bootstrap methods under three conditions of nonnormality, eight cases of sample size, and six cases of population…
Emergency department patient satisfaction survey in Imam Reza Hospital, Tabriz, Iran

PubMed Central

2011-01-01

Introduction Patient satisfaction is an important indicator of the quality of care and service delivery in the emergency department (ED). The objective of this study was to evaluate patient satisfaction with the Emergency Department of Imam Reza Hospital in Tabriz, Iran. Methods This study was carried out for 1 week during all shifts. Trained researchers used the standard Press Ganey questionnaire. Patients were asked to complete the questionnaire prior to discharge. The study questionnaire included 30 questions based on a Likert scale. Descriptive and analytical statistics were used throughout data analysis in a number of ways using SPSS version 13. Results Five hundred patients who attended our ED were included in this study. The highest satisfaction rates were observed in the terms of physicians' communication with patients (82.5%), security guards' courtesy (78.3%) and nurses' communication with patients (78%). The average waiting time for the first visit to a physician was 24 min 15 s. The overall satisfaction rate was dependent on the mean waiting time. The mean waiting time for a low rate of satisfaction was 47 min 11 s with a confidence interval of (19.31, 74.51), and for very good level of satisfaction it was 14 min 57 s with a (10.58, 18.57) confidence interval. Approximately 63% of the patients rated their general satisfaction with the emergency setting as good or very good. On the whole, the patient satisfaction rate at the lowest level was 7.7 with a confidence interval of (5.1, 10.4), and at the low level it was 5.8% with a confidence interval of (3.7, 7.9). The rate of satisfaction for the mediocre level was 23.3 with a confidence interval of (19.1, 27.5); for the high level of satisfaction it was 28.3 with a confidence interval of (22.9, 32.8), and for the very high level of satisfaction, this rate was 32.9% with a confidence interval of (28.4, 37.4). Conclusion The study findings indicated the need for evidence-based interventions in emergency care services in areas such as medical care, nursing care, courtesy of staff, physical comfort and waiting time. Efforts should focus on shortening waiting intervals and improving patients' perceptions about waiting in the ED, and also improving the overall cleanliness of the emergency room. PMID:21407998
Human responses to augmented virtual scaffolding models.

PubMed

Hsiao, Hongwei; Simeonov, Peter; Dotson, Brian; Ammons, Douglas; Kau, Tsui-Ying; Chiou, Sharon

2005-08-15

This study investigated the effect of adding real planks, in virtual scaffolding models of elevation, on human performance in a surround-screen virtual reality (SSVR) system. Twenty-four construction workers and 24 inexperienced controls performed walking tasks on real and virtual planks at three virtual heights (0, 6 m, 12 m) and two scaffolding-platform-width conditions (30, 60 cm). Gait patterns, walking instability measurements and cardiovascular reactivity were assessed. The results showed differences in human responses to real vs. virtual planks in walking patterns, instability score and heart-rate inter-beat intervals; it appeared that adding real planks in the SSVR virtual scaffolding model enhanced the quality of SSVR as a human - environment interface research tool. In addition, there were significant differences in performance between construction workers and the control group. The inexperienced participants were more unstable as compared to construction workers. Both groups increased their stride length with repetitions of the task, indicating a possibly confidence- or habit-related learning effect. The practical implications of this study are in the adoption of augmented virtual models of elevated construction environments for injury prevention research, and the development of programme for balance-control training to reduce the risk of falls at elevation before workers enter a construction job.

Comparison of WBRT alone, SRS alone, and their combination in the treatment of one or more brain metastases: Review and meta-analysis.

PubMed

Khan, Muhammad; Lin, Jie; Liao, Guixiang; Li, Rong; Wang, Baiyao; Xie, Guozhu; Zheng, Jieling; Yuan, Yawei

2017-07-01

Whole brain radiotherapy has been a standard treatment of brain metastases. Stereotactic radiosurgery provides more focal and aggressive radiation and normal tissue sparing but worse local and distant control. This meta-analysis was performed to assess and compare the effectiveness of whole brain radiotherapy alone, stereotactic radiosurgery alone, and their combination in the treatment of brain metastases based on randomized controlled trial studies. Electronic databases (PubMed, MEDLINE, Embase, and Cochrane Library) were searched to identify randomized controlled trial studies that compared treatment outcome of whole brain radiotherapy and stereotactic radiosurgery. This meta-analysis was performed using the Review Manager (RevMan) software (version 5.2) that is provided by the Cochrane Collaboration. The data used were hazard ratios with 95% confidence intervals calculated for time-to-event data extracted from survival curves and local tumor control rate curves. Odds ratio with 95% confidence intervals were calculated for dichotomous data, while mean differences with 95% confidence intervals were calculated for continuous data. Fixed-effects or random-effects models were adopted according to heterogeneity. Five studies (n = 763) were included in this meta-analysis meeting the inclusion criteria. All the included studies were randomized controlled trials. The sample size ranged from 27 to 331. In total 202 (26%) patients with whole brain radiotherapy alone, 196 (26%) patients receiving stereotactic radiosurgery alone, and 365 (48%) patients were in whole brain radiotherapy plus stereotactic radiosurgery group. No significant survival benefit was observed for any treatment approach; hazard ratio was 1.19 (95% confidence interval: 0.96-1.43, p = 0.12) based on three randomized controlled trials for whole brain radiotherapy only compared to whole brain radiotherapy plus stereotactic radiosurgery and hazard ratio was 1.03 (95% confidence interval: 0.82-1.29, p = 0.81) for stereotactic radiosurgery only compared to combined approach. Local control was best achieved when whole brain radiotherapy was combined with stereotactic radiosurgery. Hazard ratio 2.05 (95% confidence interval: 1.36-3.09, p = 0.0006) and hazard ratio 1.84 (95% confidence interval: 1.26-2.70, p = 0.002) were obtained from comparing whole brain radiotherapy only and stereotactic radiosurgery only to whole brain radiotherapy + stereotactic radiosurgery, respectively. No difference in adverse events for treatment difference; odds ratio 1.16 (95% confidence interval: 0.77-1.76, p = 0.48) and odds ratio 0.92 (95% confidence interval: 0.59-1.42, p = 71) for whole brain radiotherapy + stereotactic radiosurgery versus whole brain radiotherapy only and whole brain radiotherapy + stereotactic radiosurgery versus stereotactic radiosurgery only, respectively. Adding stereotactic radiosurgery to whole brain radiotherapy provides better local control as compared to whole brain radiotherapy only and stereotactic radiosurgery only with no difference in radiation related toxicities.
Maternal and neonatal outcomes after bariatric surgery; a systematic review and meta-analysis: do the benefits outweigh the risks?

PubMed

Kwong, Wilson; Tomlinson, George; Feig, Denice S

2018-02-15

Obesity during pregnancy is associated with a number of adverse obstetric outcomes that include gestational diabetes mellitus, macrosomia, and preeclampsia. Increasing evidence shows that bariatric surgery may decrease the risk of these outcomes. Our aim was to evaluate the benefits and risks of bariatric surgery in obese women according to obstetric outcomes. We performed a systematic literature search using MEDLINE, Embase, Cochrane, Web of Science, and PubMed from inception up to December 12, 2016. Studies were included if they evaluated patients who underwent bariatric surgery, reported subsequent pregnancy outcomes, and compared these outcomes with a control group. Two reviewers extracted study outcomes independently, and risk of bias was assessed with the use of the Newcastle-Ottawa Quality Assessment Scale. Pooled odds ratios for each outcome were estimated with the Dersimonian and Laird random effects model. After a review of 2616 abstracts, 20 cohort studies and approximately 2.8 million subjects (8364 of whom had bariatric surgery) were included in the metaanalysis. In our primary analysis, patients who underwent bariatric surgery showed reduced rates of gestational diabetes mellitus (odds ratio, 0.20; 95% confidence interval, 0.11-0.37, number needed to benefit, 5), large-for-gestational-age infants (odds ratio, 0.31; 95% confidence interval, 0.17-0.59; number needed to benefit, 6), gestational hypertension (odds ratio, 0.38; 95% confidence interval, 0.19-0.76; number needed to benefit, 11), all hypertensive disorders (odds ratio, 0.38; 95% confidence interval, 0.27-0.53; number needed to benefit, 8), postpartum hemorrhage (odds ratio, 0.32; 95% confidence interval, 0.08-1.37; number needed to benefit, 21), and caesarean delivery rates (odds ratio, 0.50; 95% confidence interval, 0.38-0.67; number needed to benefit, 9); however, group of patients showed an increase in small-for-gestational-age infants (odds ratio, 2.16; 95% confidence interval, 1.34-3.48; number needed to harm, 21), intrauterine growth restriction (odds ratio, 2.16; 95% confidence interval, 1.34-3.48; number needed to harm, 66), and preterm deliveries (odds ratio, 1.35; 95% confidence interval, 1.02-1.79; number needed to harm, 35) when compared with control subjects who were matched for presurgery body mass index. There were no differences in rates of preeclampsia, neonatal intensive care unit admissions, stillbirths, malformations, and neonatal death. Malabsorptive surgeries resulted in a greater increase in small-for-gestational-age infants (P=.0466) and a greater decrease in large-for-gestational-age infants (P=<.0001) compared with restrictive surgeries. There were no differences in outcomes when we used administrative databases vs clinical charts. Although bariatric surgery is associated with a reduction in the risk of several adverse obstetric outcomes, there is a potential for an increased risk of other important outcomes that should be considered when bariatric surgery is discussed with reproductive-age women. Copyright © 2018 Elsevier Inc. All rights reserved.
Prey Selection by an Apex Predator: The Importance of Sampling Uncertainty

PubMed Central

Davis, Miranda L.; Stephens, Philip A.; Willis, Stephen G.; Bassi, Elena; Marcon, Andrea; Donaggio, Emanuela; Capitani, Claudia; Apollonio, Marco

2012-01-01

The impact of predation on prey populations has long been a focus of ecologists, but a firm understanding of the factors influencing prey selection, a key predictor of that impact, remains elusive. High levels of variability observed in prey selection may reflect true differences in the ecology of different communities but might also reflect a failure to deal adequately with uncertainties in the underlying data. Indeed, our review showed that less than 10% of studies of European wolf predation accounted for sampling uncertainty. Here, we relate annual variability in wolf diet to prey availability and examine temporal patterns in prey selection; in particular, we identify how considering uncertainty alters conclusions regarding prey selection. Over nine years, we collected 1,974 wolf scats and conducted drive censuses of ungulates in Alpe di Catenaia, Italy. We bootstrapped scat and census data within years to construct confidence intervals around estimates of prey use, availability and selection. Wolf diet was dominated by boar (61.5±3.90 [SE] % of biomass eaten) and roe deer (33.7±3.61%). Temporal patterns of prey densities revealed that the proportion of roe deer in wolf diet peaked when boar densities were low, not when roe deer densities were highest. Considering only the two dominant prey types, Manly's standardized selection index using all data across years indicated selection for boar (mean = 0.73±0.023). However, sampling error resulted in wide confidence intervals around estimates of prey selection. Thus, despite considerable variation in yearly estimates, confidence intervals for all years overlapped. Failing to consider such uncertainty could lead erroneously to the assumption of differences in prey selection among years. This study highlights the importance of considering temporal variation in relative prey availability and accounting for sampling uncertainty when interpreting the results of dietary studies. PMID:23110122
Relation between Birth Weight and Intraoperative Hemorrhage during Cesarean Section in Pregnancy with Placenta Previa

PubMed Central

Ishibashi, Hiroki; Takano, Masashi; Sasa, Hidenori; Furuya, Kenichi

2016-01-01

Background Placenta previa, one of the most severe obstetric complications, carries an increased risk of intraoperative massive hemorrhage. Several risk factors for intraoperative hemorrhage have been identified to date. However, the correlation between birth weight and intraoperative hemorrhage has not been investigated. Here we estimate the correlation between birth weight and the occurrence of intraoperative massive hemorrhage in placenta previa. Materials and Methods We included all 256 singleton pregnancies delivered via cesarean section at our hospital because of placenta previa between 2003 and 2015. We calculated not only measured birth weights but also standard deviation values according to the Japanese standard growth curve to adjust for differences in gestational age. We assessed the correlation between birth weight and the occurrence of intraoperative massive hemorrhage (>1500 mL blood loss). Receiver operating characteristic curves were constructed to determine the cutoff value of intraoperative massive hemorrhage. Results Of 256 pregnant women with placenta previa, 96 (38%) developed intraoperative massive hemorrhage. Receiver-operating characteristic curves revealed that the area under the curve of the combination variables between the standard deviation of birth weight and intraoperative massive hemorrhage was 0.71. The cutoff value with a sensitivity of 81.3% and specificity of 55.6% was −0.33 standard deviation. The multivariate analysis revealed that a standard deviation of >−0.33 (odds ratio, 5.88; 95% confidence interval, 3.04–12.00), need for hemostatic procedures (odds ratio, 3.31; 95% confidence interval, 1.79–6.25), and placental adhesion (odds ratio, 12.68; 95% confidence interval, 2.85–92.13) were independent risk of intraoperative massive hemorrhage. Conclusion In patients with placenta previa, a birth weight >−0.33 standard deviation was a significant risk indicator of massive hemorrhage during cesarean section. Based on this result, further studies are required to investigate whether fetal weight estimated by ultrasonography can predict hemorrhage during cesarean section in patients with placental previa. PMID:27902772
Relation between Birth Weight and Intraoperative Hemorrhage during Cesarean Section in Pregnancy with Placenta Previa.

PubMed

Soyama, Hiroaki; Miyamoto, Morikazu; Ishibashi, Hiroki; Takano, Masashi; Sasa, Hidenori; Furuya, Kenichi

2016-01-01

Placenta previa, one of the most severe obstetric complications, carries an increased risk of intraoperative massive hemorrhage. Several risk factors for intraoperative hemorrhage have been identified to date. However, the correlation between birth weight and intraoperative hemorrhage has not been investigated. Here we estimate the correlation between birth weight and the occurrence of intraoperative massive hemorrhage in placenta previa. We included all 256 singleton pregnancies delivered via cesarean section at our hospital because of placenta previa between 2003 and 2015. We calculated not only measured birth weights but also standard deviation values according to the Japanese standard growth curve to adjust for differences in gestational age. We assessed the correlation between birth weight and the occurrence of intraoperative massive hemorrhage (>1500 mL blood loss). Receiver operating characteristic curves were constructed to determine the cutoff value of intraoperative massive hemorrhage. Of 256 pregnant women with placenta previa, 96 (38%) developed intraoperative massive hemorrhage. Receiver-operating characteristic curves revealed that the area under the curve of the combination variables between the standard deviation of birth weight and intraoperative massive hemorrhage was 0.71. The cutoff value with a sensitivity of 81.3% and specificity of 55.6% was -0.33 standard deviation. The multivariate analysis revealed that a standard deviation of >-0.33 (odds ratio, 5.88; 95% confidence interval, 3.04-12.00), need for hemostatic procedures (odds ratio, 3.31; 95% confidence interval, 1.79-6.25), and placental adhesion (odds ratio, 12.68; 95% confidence interval, 2.85-92.13) were independent risk of intraoperative massive hemorrhage. In patients with placenta previa, a birth weight >-0.33 standard deviation was a significant risk indicator of massive hemorrhage during cesarean section. Based on this result, further studies are required to investigate whether fetal weight estimated by ultrasonography can predict hemorrhage during cesarean section in patients with placental previa.
A growth reference for mid upper arm circumference for age among school age children and adolescents, and validation for mortality: growth curve construction and longitudinal cohort study.

PubMed

Mramba, Lazarus; Ngari, Moses; Mwangome, Martha; Muchai, Lilian; Bauni, Evasius; Walker, A Sarah; Gibb, Diana M; Fegan, Gregory; Berkley, James A

2017-08-03

Objectives To construct growth curves for mid-upper-arm circumference (MUAC)-for-age z score for 5-19 year olds that accord with the World Health Organization growth standards, and to evaluate their discriminatory performance for subsequent mortality. Design Growth curve construction and longitudinal cohort study. Setting United States and international growth data, and cohorts in Kenya, Uganda, and Zimbabwe. Participants The Health Examination Survey (HES)/National Health and Nutrition Examination Survey (NHANES) US population datasets (age 5-25 years), which were used to construct the 2007 WHO growth reference for body mass index in this age group, were merged with an imputed dataset matching the distribution of the WHO 2006 growth standards age 2-6 years. Validation data were from 685 HIV infected children aged 5-17 years participating in the Antiretroviral Research for Watoto (ARROW) trial in Uganda and Zimbabwe; and 1741 children aged 5-13 years discharged from a rural Kenyan hospital (3.8% HIV infected). Both cohorts were followed-up for survival during one year. Main outcome measures Concordance with WHO 2006 growth standards at age 60 months and survival during one year according to MUAC-for-age and body mass index-for-age z scores. Results The new growth curves transitioned smoothly with WHO growth standards at age 5 years. MUAC-for-age z scores of -2 to -3 and less than-3, compared with -2 or more, was associated with hazard ratios for death within one year of 3.63 (95% confidence interval 0.90 to 14.7; P=0.07) and 11.1 (3.40 to 36.0; P<0.001), respectively, among ARROW trial participants; and 2.22 (1.01 to 4.9; P=0.04) and 5.15 (2.49 to 10.7; P<0.001), respectively, among Kenyan children after discharge from hospital. The AUCs for MUAC-for-age and body mass index-for-age z scores for discriminating subsequent mortality were 0.81 (95% confidence interval 0.70 to 0.92) and 0.75 (0.63 to 0.86) in the ARROW trial (absolute difference 0.06, 95% confidence interval -0.032 to 0.16; P=0.2) and 0.73 (0.65 to 0.80) and 0.58 (0.49 to 0.67), respectively, in Kenya (absolute difference in AUC 0.15, 0.07 to 0.23; P=0.0002). Conclusions The MUAC-for-age z score is at least as effective as the body mass index-for-age z score for assessing mortality risks associated with undernutrition among African school aged children and adolescents. MUAC can provide simplified screening and diagnosis within nutrition and HIV programmes, and in research. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions

ERIC Educational Resources Information Center

Padilla, Miguel A.; Divers, Jasmin

2013-01-01

The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…
WASP (Write a Scientific Paper) using Excel - 6: Standard error and confidence interval.

PubMed

Grech, Victor

2018-03-01

The calculation of descriptive statistics includes the calculation of standard error and confidence interval, an inevitable component of data analysis in inferential statistics. This paper provides pointers as to how to do this in Microsoft Excel™. Copyright © 2018 Elsevier B.V. All rights reserved.
Robust Confidence Interval for a Ratio of Standard Deviations

ERIC Educational Resources Information Center

Bonett, Douglas G.

2006-01-01

Comparing variability of test scores across alternate forms, test conditions, or subpopulations is a fundamental problem in psychometrics. A confidence interval for a ratio of standard deviations is proposed that performs as well as the classic method with normal distributions and performs dramatically better with nonnormal distributions. A simple…
The microcomputer scientific software series 2: general linear model--regression.

Treesearch

Harold M. Rauscher

1983-01-01

The general linear model regression (GLMR) program provides the microcomputer user with a sophisticated regression analysis capability. The output provides a regression ANOVA table, estimators of the regression model coefficients, their confidence intervals, confidence intervals around the predicted Y-values, residuals for plotting, a check for multicollinearity, a...
Toward Using Confidence Intervals to Compare Correlations

ERIC Educational Resources Information Center

Zou, Guang Yong

2007-01-01

Confidence intervals are widely accepted as a preferred way to present study results. They encompass significance tests and provide an estimate of the magnitude of the effect. However, comparisons of correlations still rely heavily on significance testing. The persistence of this practice is caused primarily by the lack of simple yet accurate…
Women seeking treatment for advanced pelvic organ prolapse have decreased body image and quality of life.

PubMed

Jelovsek, J Eric; Barber, Matthew D

2006-05-01

Women who seek treatment for pelvic organ prolapse strive for an improvement in quality of life. Body image has been shown to be an important component of differences in quality of life. To date, there are no data on body image in patients with advanced pelvic organ prolapse. Our objective was to compare body image and quality of life in women with advanced pelvic organ prolapse with normal controls. We used a case-control study design. Cases were defined as subjects who presented to a tertiary urogynecology clinic with advanced pelvic organ prolapse (stage 3 or 4). Controls were defined as subjects who presented to a tertiary care gynecology or women's health clinic for an annual visit with normal pelvic floor support (stage 0 or 1) and without urinary incontinence. All patients completed a valid and reliable body image scale and a generalized (Short Form Health Survey) and condition-specific (Pelvic Floor Distress Inventory-20) quality-of-life scale. Linear and logistic regression analyses were performed to adjust for possible confounding variables. Forty-seven case and 51 control subjects were enrolled. After controlling for age, race, parity, previous hysterectomy, and medical comorbidities, subjects with advanced pelvic organ prolapse were more likely to feel self-conscious (adjusted odds ratio 4.7; 95% confidence interval 1.4 to 18, P = .02), less likely to feel physically attractive (adjusted odds ratio 11; 95% confidence interval 2.9 to 51, P < .001), less likely to feel feminine (adjusted odds ratio 4.0; 95% confidence interval 1.2 to 15, P = .03), and less likely to feel sexually attractive (adjusted odds ratio 4.6; 95% confidence interval 1.4 to 17, P = .02) than normal controls. The groups were similar in their feeling of dissatisfaction with appearance when dressed, difficulty looking at themselves naked, avoiding people because of appearance, and overall dissatisfaction with their body. Subjects with advanced pelvic organ prolapse suffered significantly lower quality of life on the physical scale of the SF-12 (mean 42; 95% confidence interval 39 to 45 versus mean 50; 95% confidence interval 47 to 53, P < .009). However, no differences between groups were noted on the mental scale of the SF-12 (mean 51; 95% confidence interval 50 to 54 versus mean 50; 95% confidence interval 47 to 52, P = .56). Additionally, subjects with advanced pelvic organ prolapse scored significantly worse on the prolapse, urinary, and colorectal scales and overall summary score of Pelvic Floor Distress Inventory-20 than normal controls (mean summary score 104; 95% confidence interval 90 to 118 versus mean 29; 95% confidence interval 16 to 43, P < .0001), indicating a decrease in condition-specific quality of life. Worsening body image correlated with lower quality of life on both the physical and mental scales of the SF-12 as well as the prolapse, urinary, and colorectal scales and overall summary score of Pelvic Floor Distress Inventory-20 in subjects with advanced pelvic organ prolapse. Women seeking treatment for advanced pelvic organ prolapse have decreased body image and overall quality of life. Body image may be a key determinant for quality of life in patients with advanced prolapse and may be an important outcome measure for treatment evaluation in clinical trials.
Exercise during pregnancy in normal-weight women and risk of preterm birth: a systematic review and meta-analysis of randomized controlled trials.

PubMed

Di Mascio, Daniele; Magro-Malosso, Elena Rita; Saccone, Gabriele; Marhefka, Gregary D; Berghella, Vincenzo

2016-11-01

Preterm birth is the major cause of perinatal mortality in the United States. In the past, pregnant women have been recommended to not exercise because of presumed risks of preterm birth. Physical activity has been theoretically related to preterm birth because it increases the release of catecholamines, especially norepinephrine, which might stimulate myometrial activity. Conversely, exercise may reduce the risk of preterm birth by other mechanisms such as decreased oxidative stress or improved placenta vascularization. Therefore, the safety of exercise regarding preterm birth and its effects on gestational age at delivery remain controversial. The objective of the study was to evaluate the effects of exercise during pregnancy on the risk of preterm birth. MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID, and Cochrane Library were searched from the inception of each database to April 2016. Selection criteria included only randomized clinical trials of pregnant women randomized before 23 weeks to an aerobic exercise regimen or not. Types of participants included women of normal weight with uncomplicated, singleton pregnancies without any obstetric contraindication to physical activity. The summary measures were reported as relative risk or as mean difference with 95% confidence intervals. The primary outcome was the incidence of preterm birth <37 weeks. Of the 2059 women included in the meta-analysis, 1022 (49.6%) were randomized to the exercise group and 1037 (50.4%) to the control group. Aerobic exercise lasted about 35-90 minutes 3-4 times per week. Women who were randomized to aerobic exercise had a similar incidence of preterm birth of <37 weeks (4.5% vs 4.4%; relative risk, 1.01, 95% confidence interval, 0.68-1.50) and a similar mean gestational age at delivery (mean difference, 0.05 week, 95% confidence interval, -0.07 to 0.17) compared with controls. Women in the exercise group had a significantly higher incidence of vaginal delivery (73.6% vs 67.5%; relative risk, 1.09, 95% confidence interval, 1.04-1.15) and a significantly lower incidence of cesarean delivery (17.9% vs 22%; relative risk, 0.82, 95% confidence interval, 0.69-0.97) compared with controls. The incidence of operative vaginal delivery (12.9% vs 16.5%; relative risk, 0.78, 95% confidence interval, 0.61-1.01) was similar in both groups. Women in the exercise group had a significantly lower incidence of gestational diabetes mellitus (2.9% vs 5.6%; relative risk, 0.51, 95% confidence interval, 0.31-0.82) and a significantly lower incidence of hypertensive disorders (1.0% vs 5.6%; relative risk, 0.21, 95% confidence interval, 0.09-0.45) compared with controls. No differences in low birthweight (5.2% vs 4.7%; relative risk, 1.11, 95% confidence interval, 0.72-1.73) and mean birthweight (mean difference, -10.46 g, 95% confidence interval, -47.10 to 26.21) between the exercise group and controls were found. Aerobic exercise for 35-90 minutes 3-4 times per week during pregnancy can be safely performed by normal-weight women with singleton, uncomplicated gestations because this is not associated with an increased risk of preterm birth or with a reduction in mean gestational age at delivery. Exercise was associated with a significantly higher incidence of vaginal delivery and a significantly lower incidence of cesarean delivery, with a significantly lower incidence of gestational diabetes mellitus and hypertensive disorders and therefore should be encouraged. Copyright © 2016. Published by Elsevier Inc.
A simple method for assessing occupational exposure via the one-way random effects model.

PubMed

Krishnamoorthy, K; Mathew, Thomas; Peng, Jie

2016-11-01

A one-way random effects model is postulated for the log-transformed shift-long personal exposure measurements, where the random effect in the model represents an effect due to the worker. Simple closed-form confidence intervals are proposed for the relevant parameters of interest using the method of variance estimates recovery (MOVER). The performance of the confidence bounds is evaluated and compared with those based on the generalized confidence interval approach. Comparison studies indicate that the proposed MOVER confidence bounds are better than the generalized confidence bounds for the overall mean exposure and an upper percentile of the exposure distribution. The proposed methods are illustrated using a few examples involving industrial hygiene data.
Simulation data for an estimation of the maximum theoretical value and confidence interval for the correlation coefficient.

PubMed

Rocco, Paolo; Cilurzo, Francesco; Minghetti, Paola; Vistoli, Giulio; Pedretti, Alessandro

2017-10-01

The data presented in this article are related to the article titled "Molecular Dynamics as a tool for in silico screening of skin permeability" (Rocco et al., 2017) [1]. Knowledge of the confidence interval and maximum theoretical value of the correlation coefficient r can prove useful to estimate the reliability of developed predictive models, in particular when there is great variability in compiled experimental datasets. In this Data in Brief article, data from purposely designed numerical simulations are presented to show how much the maximum r value is worsened by increasing the data uncertainty. The corresponding confidence interval of r is determined by using the Fisher r → Z transform.
Particle filter based hybrid prognostics for health monitoring of uncertain systems in bond graph framework

NASA Astrophysics Data System (ADS)

Jha, Mayank Shekhar; Dauphin-Tanguy, G.; Ould-Bouamama, B.

2016-06-01

The paper's main objective is to address the problem of health monitoring of system parameters in Bond Graph (BG) modeling framework, by exploiting its structural and causal properties. The system in feedback control loop is considered uncertain globally. Parametric uncertainty is modeled in interval form. The system parameter is undergoing degradation (prognostic candidate) and its degradation model is assumed to be known a priori. The detection of degradation commencement is done in a passive manner which involves interval valued robust adaptive thresholds over the nominal part of the uncertain BG-derived interval valued analytical redundancy relations (I-ARRs). The latter forms an efficient diagnostic module. The prognostics problem is cast as joint state-parameter estimation problem, a hybrid prognostic approach, wherein the fault model is constructed by considering the statistical degradation model of the system parameter (prognostic candidate). The observation equation is constructed from nominal part of the I-ARR. Using particle filter (PF) algorithms; the estimation of state of health (state of prognostic candidate) and associated hidden time-varying degradation progression parameters is achieved in probabilistic terms. A simplified variance adaptation scheme is proposed. Associated uncertainties which arise out of noisy measurements, parametric degradation process, environmental conditions etc. are effectively managed by PF. This allows the production of effective predictions of the remaining useful life of the prognostic candidate with suitable confidence bounds. The effectiveness of the novel methodology is demonstrated through simulations and experiments on a mechatronic system.
Influence of fatigue on construction workers’ physical and cognitive function

PubMed Central

Zhang, M.; Murphy, L. A.; Fang, D.

2015-01-01

Background Despite scientific evidence linking workers’ fatigue to occupational safety (due to impaired physical or cognitive function), little is known about this relationship in construction workers. Aims To assess the association between construction workers’ reported fatigue and their perceived difficulties with physical and cognitive functions. Methods Using data from a convenience sample of US construction workers participating in the 2010–11 National Health Interview Survey two multivariate weighted logistic regression models were built to predict difficulty with physical and with cognitive functions associated with workers’ reported fatigue, while controlling for age, smoking status, alcohol consumption status, sleep hygiene, psychological distress and arthritis status. Results Of 606 construction workers surveyed, 49% reported being ‘tired some days’ in the past 3 months and 10% reported ‘tired most days or every day’. Compared with those feeling ‘never tired’, workers who felt ‘tired some days’ were significantly more likely to report difficulty with physical function (adjusted odds ratio [AOR] = 2.03; 95% confidence interval [CI] 1.17–3.51) and cognitive function (AOR = 2.27; 95% CI 1.06–4.88) after controlling for potential confounders. Conclusions Our results suggest an association between reported fatigue and experiencing difficulties with physical and cognitive functions in construction workers. PMID:25701835
Pregnancy intentions-a complex construct and call for new measures.

PubMed

Mumford, Sunni L; Sapra, Katherine J; King, Rosalind B; Louis, Jean Fredo; Buck Louis, Germaine M

2016-11-01

To estimate the prevalence of unintended pregnancies under relaxed assumptions regarding birth control use compared with a traditional constructed measure. Cross-sectional survey. Not applicable. Nationally representative sample of U.S. women aged 15-44 years. None. Prevalence of intended and unintended pregnancies as estimated by [1] a traditional constructed measure from the National Survey of Family Growth (NSFG), and [2] a constructed measure relaxing assumptions regarding birth control use, reasons for nonuse, and pregnancy timing. The prevalence of unintended pregnancies was 6% higher using the traditional constructed measure as compared with the approach with relaxed assumptions (NSFG: 44%, 95% confidence interval [CI] 41, 46; new construct 38%, 95% CI, 36, 41). Using the NSFG approach, only 92% of women who stopped birth control to become pregnant and 0 women who were not using contraceptives at the time of the pregnancy and reported that they did not mind getting pregnant were classified as having intended pregnancies, compared with 100% using the new construct. Current measures of pregnancy intention may overestimate rates of unintended pregnancy, with over 340,000 pregnancies in the United States misclassified as unintended using the current approach, corresponding to an estimated savings of $678 million in public health-care expenditures. Current constructs make assumptions that may not reflect contemporary reproductive practices, so improved measures are needed. Published by Elsevier Inc.
The use of the dicentric assay for biological dosimetry for radiation accidents in Bulgaria.

PubMed

Hadjidekova, Valeria; Hristova, Rositsa; Ainsbury, Elizabeth A; Atanasova, Petya; Popova, Ljubomira; Staynova, Albena

2010-02-01

This paper details the construction of a 137Cs gamma calibration curve that has been established for dicentric assay and the testing and validation of the curve through biological dosimetry in three situations of suspected workplace overexposure that arose accidentally or through negligence or lack of appropriate safety measures. The three situations were: (1) suspected 137Cs contamination in a factory air supply; (2) suspected exposure to an industrial 192Ir source; and (3) accidental exposure of construction workers to radiation from a 60Co radiotherapy source in a hospital medical physics department. From a total of 24 potentially-exposed subjects, only one worker was found to have a statistically significant dose (0.16 Gy, 95% confidence intervals 0.02-0.43 Gy). In all other cases, the main function of the biological dosimetry was to reassure the subjects that any dose received was low.
Confidence Intervals for Assessing Heterogeneity in Generalized Linear Mixed Models

ERIC Educational Resources Information Center

Wagler, Amy E.

2014-01-01

Generalized linear mixed models are frequently applied to data with clustered categorical outcomes. The effect of clustering on the response is often difficult to practically assess partly because it is reported on a scale on which comparisons with regression parameters are difficult to make. This article proposes confidence intervals for…

Likelihood-Based Confidence Intervals in Exploratory Factor Analysis

ERIC Educational Resources Information Center

Oort, Frans J.

2011-01-01

In exploratory or unrestricted factor analysis, all factor loadings are free to be estimated. In oblique solutions, the correlations between common factors are free to be estimated as well. The purpose of this article is to show how likelihood-based confidence intervals can be obtained for rotated factor loadings and factor correlations, by…
Characterizing the Mathematics Anxiety Literature Using Confidence Intervals as a Literature Review Mechanism

ERIC Educational Resources Information Center

Zientek, Linda Reichwein; Yetkiner, Z. Ebrar; Thompson, Bruce

2010-01-01

The authors report the contextualization of effect sizes within mathematics anxiety research, and more specifically within research using the Mathematics Anxiety Rating Scale (MARS) and the MARS for Adolescents (MARS-A). The effect sizes from 45 studies were characterized by graphing confidence intervals (CIs) across studies involving (a) adults…
Estimating Standardized Linear Contrasts of Means with Desired Precision

ERIC Educational Resources Information Center

Bonett, Douglas G.

2009-01-01

L. Wilkinson and the Task Force on Statistical Inference (1999) recommended reporting confidence intervals for measures of effect sizes. If the sample size is too small, the confidence interval may be too wide to provide meaningful information. Recently, K. Kelley and J. R. Rausch (2006) used an iterative approach to computer-generate tables of…
UNDERSTANDING SYSTEMATIC MEASUREMENT ERROR IN THERMAL-OPTICAL ANALYSIS FOR PM BLACK CARBON USING RESPONSE SURFACES AND SURFACE CONFIDENCE INTERVALS

EPA Science Inventory

Results from a NIST-EPA Interagency Agreement on Understanding Systematic Measurement Error in Thermal-Optical Analysis for PM Black Carbon Using Response Surfaces and Surface Confidence Intervals will be presented at the American Association for Aerosol Research (AAAR) 24th Annu...
The impact of effort-reward imbalance on quality of life among Japanese working men.

PubMed

Watanabe, Mayumi; Tanaka, Katsutoshi; Aratake, Yutaka; Kato, Noritada; Sakata, Yumi

2008-07-01

Health-related quality of life (HRQL) is an important measure of health outcome in working and healthy populations. Here, we investigated the impact of effort-reward imbalance (ERI), a representative work-stress model, on HRQL of Japanese working men. The study targeted 1,096 employees from a manufacturing plant in Japan. To assess HRQL and ERI, participants were surveyed using the Japanese version of the Short-Form 8 Health Survey (SF-8) and effort-reward imbalance model. Of the 1,096 employees, 1,057 provided valid responses to the questionnaire. For physical summary scores, the adjusted effort-reward imbalance odds ratios of middle vs. bottom and top vs. bottom tertiles were 0.24 (95% confidence interval, 0.08-0.70) and 0.09 (95% confidence interval, 0.03-0.28), respectively. For mental summary scores, ratios were 0.21 (95% confidence interval, 0.07-0.63) and 0.07 (95% confidence interval, 0.02-0.25), respectively. These findings demonstrate that effort-reward imbalance is independently associated with HRQL among Japanese employees.
Prevention of falls to a lower level: evaluation of an occupational health and safety intervention via subsidies for the replacement of scaffolding.

PubMed

Rubio-Romero, Juan Carlos; Carrillo-Castrillo, Jesús Antonio; Gibb, Alistair

2015-01-01

The objective of this study is to evaluate the impact of a subsidy policy for construction companies in Andalusia (Spain), which enables them to acquire new scaffolds. The rate of falls from scaffolds within the Andalusian construction sector in the period 2009-2011 was analysed. A randomised controlled trial was not possible as the subsidy was granted according to a public and competitive call. A quasi-experimental design based on an intervention group (subsidised companies) and a control group was chosen. Companies in the control group were selected from the social security census of companies in order to avoid selection bias. The subsidy policy has led to an overall 71% decrease in the rate of accident involving falls to a lower level in the companies that received grants in the period 2009-2011. The confidence interval for the comparison for the before-after difference in rates between the intervention group and the control group is found significant (confidence 95%, p = 0.05). The improvement of scaffolds was effective in reducing rates of accident with falls to a lower level. This intervention should be a priority in public policies. The process of standardisation of equipment with high accident risk should be developed further.
Effect of PR interval prolongation on long-term outcomes in patients with left bundle branch block vs non-left bundle branch block morphologies undergoing cardiac resynchronization therapy.

PubMed

Rickard, John; Karim, Mohammad; Baranowski, Bryan; Cantillon, Daniel; Spragg, David; Tang, W H Wilson; Niebauer, Mark; Grimm, Richard; Trulock, Kevin; Wilkoff, Bruce; Varma, Niraj

2017-10-01

Although the influence of QRS duration (QRSd) and/or bundle branch block morphology on outcomes of cardiac resynchronization therapy (CRT) have been well studied, the effect of PR interval remains uncertain. The purpose of this study was to evaluate the impact of PR prolongation (PRp) before CRT on long-term outcomes, specifically taking into account bundle branch block morphology and QRSd. We extracted clinical data on consecutive patients undergoing CRT. Multivariate models were constructed to analyze the effect of PRp (≥200 ms) on the combined endpoint of death, heart transplant, or left ventricular assist device. Kaplan-Meier curves were constructed stratifying patients based on bundle branch block and QRSd (dichotomized by 150 ms). Of the 472 patients who met inclusion criteria, 197 (41.7%) had PR interval ≥200 ms. During follow-up (mean 5.1 ± 2.6 years) there were 214 endpoints, of which 109 (23.1%) occurred in patients with PRp. In multivariate analysis, PRp was independently associated with worsened outcomes (hazard ratio 1.34, 95% confidence interval 1.01-1.77, P = .04). When stratified by bundle branch block morphology, PRp was significantly associated with worsened outcomes (log-rank P <.001) in patients with LBBB but not in those with non-LBBB (log-rank P = .55). Among patients with LBBB, stratified by QRSd, patients without PRp had improved outcomes compared to those with PRp independent of QRSd (log-rank P <.001). PRp is an independent predictor of impaired long-term outcome after CRT among patients with LBBB but not in non-LBBB patients. Notably, among LBBB patients, PRp is a more important predictor than QRSd in assessing long-term outcomes. Copyright © 2017. Published by Elsevier Inc.
Genetic dissection of quantitative trait locus for ethanol sensitivity in long- and short-sleep mice.

PubMed

Bennett, B; Carosone-Link, P; Beeson, M; Gordon, L; Phares-Zook, N; Johnson, T E

2008-08-01

Interval-specific congenic strains (ISCS) allow fine mapping of a quantitative trait locus (QTL), narrowing its confidence interval by an order of magnitude or more. In earlier work, we mapped four QTL specifying differential ethanol sensitivity, assessed by loss of righting reflex because of ethanol (LORE), in the inbred long-sleep (ILS) and inbred short-sleep (ISS) strains, accounting for approximately 50% of the genetic variance for this trait. Subsequently, we generated reciprocal congenic strains in which each full QTL interval from ILS was bred onto the ISS background and vice versa. An earlier paper reported construction and results of the ISCS on the ISS background; here, we describe this process and report results on the ILS background. We developed multiple ISCS for each Lore QTL in which the QTL interval was broken into a number of smaller intervals. For each of the four QTL regions (chromosomes 1, 2, 11 and 15), we were successful in reducing the intervals significantly. Multiple, positive strains were overlapped to generate a single, reduced interval. Subsequently, this reduced region was overlaid on previous reductions from the ISS background congenics, resulting in substantial reductions in all QTL regions by approximately 75% from the initial mapping study. Genes with sequence or expression polymorphisms in the reduced intervals are potential candidates; evidence for these is presented. Genetic background effects can be important in detection of single QTL; combining this information with the generation of congenics on both backgrounds, as described here, is a powerful approach for fine mapping QTL.
Sex hormones and the risk of type 2 diabetes mellitus: A 9-year follow up among elderly men in Finland.

PubMed

Salminen, Marika; Vahlberg, Tero; Räihä, Ismo; Niskanen, Leo; Kivelä, Sirkka-Liisa; Irjala, Kerttu

2015-05-01

To analyze whether sex hormone levels predict the incidence of type2 diabetes among elderly Finnish men. This was a prospective population-based study, with a 9-year follow up period. The study population in the municipality of Lieto, Finland, consisted of elderly (age ≥64 years) men free of type 2 diabetes at baseline in 1998-1999 (n = 430). Body mass index and cardiovascular disease-adjusted hazard ratios and their 95% confidence intervals for type 2 diabetes predicted by testosterone, free testosterone, sex hormone-binding globulin, luteinizing hormone, and testosterone/luteinizing hormone were estimated. A total of 30 new cases of type 2 diabetes developed during the follow-up period. After adjustment, only higher levels of testosterone (hazard ratio for one-unit increase 0.93, 95% confidence interval 0.87-0.99, P = 0.020) and free testosterone (hazard ratio for 10-unit increase 0.96, 95% confidence interval 0.91-1.00, P = 0.044) were associated with a lower risk of incident type 2 diabetes during the follow up. These associations (0.94, 95% confidence interval 0.87-1.00, P = 0.050 and 0.95, 95% confidence interval 0.90-1.00, P = 0.035, respectively) persisted even after additional adjustment of sex hormone-binding globulin. Higher levels of testosterone and free testosterone independently predicted a reduced risk of type 2 diabetes in the elderly men. © 2014 Japan Geriatrics Society.
N-acetyltransferase 2 gene polymorphism as a biomarker for susceptibility to bladder cancer in Bangladeshi population.

PubMed

Hosen, Md Bayejid; Islam, Jahidul; Salam, Md Abdus; Islam, Md Fakhrul; Hawlader, M Zakir Hossain; Kabir, Yearul

2015-03-01

To investigate the association between the three most common single nucleotide polymorphisms of the N-acetyltransferase 2 gene together with cigarette smoking and the risk of developing bladder cancer and its aggressiveness. A case-control study on 102 bladder cancer patients and 140 control subjects was conducted. The genomic DNA was extracted from peripheral white blood cells and N-acetyltransferase 2 alleles were differentiated by polymerase chain reaction-based restriction fragment length polymorphism methods. Bladder cancer risk was estimated as odds ratio and 95% confidence interval using binary logistic regression models adjusting for age and gender. Overall, N-acetyltransferase 2 slow genotypes were associated with bladder cancer risk (odds ratio=4.45; 95% confidence interval=2.26-8.77). The cigarette smokers with slow genotypes were found to have a sixfold increased risk to develop bladder cancer (odds ratio=6.05; 95% confidence interval=2.23-15.82). Patients with slow acetylating genotypes were more prone to develop high-grade (odds ratio=6.63; 95% confidence interval=1.15-38.13; P<0.05) and invasive (odds ratio=10.6; 95% confidence interval=1.00-111.5; P=0.05) tumor. N-acetyltransferase 2 slow genotype together with tobacco smoking increases bladder cancer risk. Patients with N-acetyltransferase 2 slow genotypes were more likely to develop a high-grade and invasive tumor. N-acetyltransferase 2 slow genotype is an important genetic determinant for bladder cancer in Bangladesh population. © 2014 Wiley Publishing Asia Pty Ltd.
Sodium-glucose cotransporter 2 (SGLT2) inhibitors and fracture risk in patients with type 2 diabetes mellitus: A meta-analysis.

PubMed

Ruanpeng, Darin; Ungprasert, Patompong; Sangtian, Jutarat; Harindhanavudhi, Tasma

2017-09-01

Sodium-glucose cotransporter 2 (SGLT2) inhibitors could potentially alter calcium and phosphate homeostasis and may increase the risk of bone fracture. The current meta-analysis was conducted to investigate the fracture risk among patients with type 2 diabetes mellitus treated with SGLT2 inhibitors. Randomized controlled trials that compared the efficacy of SGLT2 inhibitors to placebo were identified. The risk ratios of fracture among patients who received SGLT2 inhibitors versus placebo were extracted from each study. Pooled risk ratios and 95% confidence intervals were calculated using a random-effect, Mantel-Haenszel analysis. A total of 20 studies with 8286 patients treated with SGLT2 inhibitors were included. The pooled risk ratio of bone fracture in patients receiving SGLT2 inhibitors versus placebo was 0.67 (95% confidence interval, 0.42-1.07). The pooled risk ratio for canagliflozin, dapagliflozin, and empagliflozin was 0.66 (95% confidence interval, 0.37-1.19), 0.84 (95% confidence interval, 0.22-3.18), and 0.57 (95% confidence interval, 0.20-1.59), respectively. Increased risk of bone fracture among patients with type 2 diabetes mellitus treated with SGLT2 inhibitors compared with placebo was not observed in this meta-analysis. However, the results were limited by short duration of treatment/follow-up and low incidence of the event of interest. Copyright © 2017 John Wiley & Sons, Ltd.
Influence of gender role attitudes on smoking and drinking among girls from Jujuy, Argentina.

PubMed

Mejia, Raul; Kaplan, Celia P; Alderete, Ethel; Gregorich, Steven E; Pérez-Stable, Eliseo J

2013-09-01

Evaluate effect of gender role attitudes on tobacco and alcohol use among Argentinean girls. Cross-sectional survey of 10th grade students attending 27 randomly selected schools in Jujuy, Argentina. Questions about tobacco and alcohol use were adapted from global youth surveys. Five items with 5-point response options of agreement-disagreement assessed attitude towards egalitarian (higher score) gender roles. 2133 girls, aged 13-18 years, 71% Indigenous, 22% mixed Indigenous/European, and 7% European responded. Of these, 60% had ever smoked, 32% were current smokers, 58% ever drinkers, 27% drank in previous month, and 13% had ≥5 drinks on one occasion. Mean response to the gender role scale was 3.49 (95% Confidence Intervals = 3.41-3.57) out of 5 tending toward egalitarian attitudes. Logistic regression models using the gender role scale score as the main predictor and adjusting for demographic and social confounders showed that egalitarian gender role was associated with ever smoking (Odds Ratio = 1.25; 95% Confidence Intervals 1.09-1.44), ever drinking (Odds Ratio = 1.24; 95% Confidence Intervals 1.10-1.40), drinking in prior month (Odds Ratio = 1.21; 95% Confidence Intervals 1.07-1.37) and ≥5 drinks on one occasion (Odds Ratio = 1.15; 95% Confidence Intervals 1.00-1.33), but was not significant for current smoking. Girls in Jujuy who reported more egalitarian gender role attitudes had higher odds of smoking or drinking. Copyright © 2013 Elsevier Inc. All rights reserved.
Hostility and the risk of peptic ulcer in the GAZEL cohort.

PubMed

Lemogne, Cédric; Schuster, Jean-Pierre; Levenstein, Susan; Melchior, Maria; Nabi, Hermann; Ducimetière, Pierre; Limosin, Frédéric; Goldberg, Marcel; Zins, Marie; Consoli, Silla M

2015-02-01

Evidence for an association between hostility and peptic ulcer mainly relies on cross-sectional studies. Prospective studies are rare and have not used a validated measure of hostility. This prospective study aimed to examine the association between hostility and peptic ulcer in the large-scale French GAZEL cohort. In 1993, 14,674 participants completed the Buss and Durkee Hostility Inventory. Participants were annually followed-up from 1994 to 2011. Diagnosis of peptic ulcer was self-reported. The association between hostility scores and ulcer incidence was measured by hazard ratios (HR) and 95% confidence intervals computed through Cox regression. Among 13,539 participants free of peptic ulcer history at baseline, 816 reported a peptic ulcer during a mean follow-up of 16.8 years. Adjusting for potential confounders, including smoking, occupational grade, and a proxy for nonsteroidal anti-inflammatory drug exposure, ulcer incidence was positively associated with total hostility (HR per SD: 1.23, confidence interval: 1.14-1.31), behavioral hostility (HR per SD: 1.13, confidence interval: 1.05-1.21), cognitive hostility (HR per SD: 1.26, confidence interval: 1.18-1.35), and irritability (HR per SD: 1.20, confidence interval: 1.12-1.29). The risk of peptic ulcer increased from the lowest to the highest quartile for all hostility measures (p for linear trend < .05). Hostility might be associated with an increased risk of peptic ulcer. Should these results be replicated, further studies would be needed to explore the underlying mechanisms.
Albumin treatment regimen for type 1 hepatorenal syndrome: a dose-response meta-analysis.

PubMed

Salerno, Francesco; Navickis, Roberta J; Wilkes, Mahlon M

2015-11-25

Recommended treatment for type 1 hepatorenal syndrome consists of albumin and vasoconstrictor. The optimal albumin dose remains poorly characterized. This meta-analysis aimed to determine the impact of albumin dose on treatment outcomes. Clinical studies of type 1 hepatorenal syndrome treatment with albumin and vasoconstrictor were sought. Search terms included: hepatorenal syndrome; albumin; vasoconstrictor; terlipressin; midodrine; octreotide; noradrenaline; and norepinephrine. A meta-analysis was performed of hepatorenal syndrome reversal and survival in relation to albumin dose. Nineteen clinical studies with 574 total patients were included, comprising 8 randomized controlled trials, 8 prospective studies and 3 retrospective studies. The pooled percentage of patients achieving hepatorenal syndrome reversal was 49.5% (95% confidence interval, 40.0-59.1%). Increments of 100 g in cumulative albumin dose were accompanied by significantly increased survival (hazard ratio, 1.15; 95% confidence interval, 1.02-1.31; p = 0.023). A non-significant increase of similar magnitude in hepatorenal syndrome reversal was also observed (odds ratio, 1.15; 95% confidence interval, 0.97-1.37; p = 0.10). Expected survival rates at 30 days among patients receiving cumulative albumin doses of 200, 400 and 600 g were 43.2% (95% confidence interval, 36.4-51.3%), 51.4% (95% confidence interval, 46.3-57.1%) and 59.0% (95% confidence interval, 51.9-67.2), respectively. Neither survival nor hepatorenal syndrome reversal was significantly affected by vasoconstrictor dose or type, treatment duration, age, baseline serum creatinine, bilirubin or albumin, baseline mean arterial pressure, or study design, size or time period. This meta-analysis suggests a dose-response relationship between infused albumin and survival in patients with type 1 hepatorenal syndrome. The meta-analysis provides the best current evidence on the potential role of albumin dose selection in improving outcomes of treatment for type 1 HRS and furnishes guidance for the design of future dose-ranging studies.
Prevalence of orofacial clefts and risks for nonsyndromic cleft lip with or without cleft palate in newborns at a university hospital from West Mexico.

PubMed

Corona-Rivera, Jorge Román; Bobadilla-Morales, Lucina; Corona-Rivera, Alfredo; Peña-Padilla, Christian; Olvera-Molina, Sandra; Orozco-Martín, Miriam A; García-Cruz, Diana; Ríos-Flores, Izabel M; Gómez-Rodríguez, Brian Gabriel; Rivas-Soto, Gemma; Pérez-Molina, J Jesús

2018-02-19

We determined the overall prevalence of typical orofacial clefts and the potential risks for nonsyndromic cleft lip with or without cleft palate in a university hospital from West México. For the prevalence, 227 liveborn infants with typical orofacial clefts were included from a total of 81,193 births occurred during the period 2009-2016 at the "Dr. Juan I. Menchaca" Civil Hospital of Guadalajara (Guadalajara, Jalisco, Mexico). To evaluate potential risks, a case-control study was conducted among 420 newborns, including only those 105 patients with nonsyndromic cleft lip with or without cleft palate (cases), and 315 infants without birth defects (controls). Data were analyzed using multivariable logistic regression analysis expressed as adjusted odds ratio with 95% confidence intervals . The overall prevalence for typical orofacial clefts was 28 per 10,000 (95% confidence interval: 24.3-31.6), or 1 per 358 live births. The mean values for the prepregnancy weight, antepartum weight, and pre-pregnancy body mass index were statistically higher among the mothers of cases. Infants with nonsyndromic cleft lip with or without cleft palate had a significantly higher risk for previous history of any type of congenital anomaly (adjusted odds ratio: 2.7; 95% confidence interval: 1.4-5.1), history of a relative with cleft lip with or without cleft palate (adjusted odds ratio: 19.6; 95% confidence interval: 8.2-47.1), and first-trimester exposures to progestogens (adjusted odds ratio: 6.8; 95% CI 1.8-25.3), hyperthermia (adjusted odds ratio: 3.4; 95% confidence interval: 1.1-10.6), and common cold (adjusted odds ratio: 3.6; 95% confidence interval: 1.1-11.9). These risks could have contributed to explain the high prevalence of orofacial clefts in our region of Mexico, emphasizing that except for history of relatives with cleft lip with or without cleft palate, most are susceptible of modification. © 2018 Japanese Teratology Society.
Fixed ratio combinations of glucagon like peptide 1 receptor agonists with basal insulin: a systematic review and meta-analysis.

PubMed

Liakopoulou, Paraskevi; Liakos, Aris; Vasilakou, Despoina; Athanasiadou, Eleni; Bekiari, Eleni; Kazakos, Kyriakos; Tsapas, Apostolos

2017-06-01

Basal insulin controls primarily fasting plasma glucose but causes hypoglycaemia and weight gain, whilst glucagon like peptide 1 receptor agonists induce weight loss without increasing risk for hypoglycaemia. We conducted a systematic review and meta-analysis of randomised controlled trials to investigate the efficacy and safety of fixed ratio combinations of basal insulin with glucagon like peptide 1 receptor agonists. We searched Medline, Embase, and the Cochrane Library as well as conference abstracts up to December 2016. We assessed change in haemoglobin A 1c , body weight, and incidence of hypoglycaemia and gastrointestinal adverse events. We included eight studies with 5732 participants in the systematic review. Switch from basal insulin to fixed ratio combinations with a glucagon like peptide 1 receptor agonist was associated with 0.72% reduction in haemoglobin A 1c [95% confidence interval -1.03 to -0.41; I 2 = 93%] and 2.35 kg reduction in body weight (95% confidence interval -3.52 to -1.19; I 2 = 93%), reducing also risk for hypoglycaemia [odds ratio 0.70; 95% confidence interval 0.57 to 0.86; I 2 = 85%] but increasing incidence of nausea (odds ratio 6.89; 95% confidence interval 3.73-12.74; I 2 = 79%). Similarly, switching patients from treatment with a glucagon like peptide 1 receptor agonist to a fixed ratio combination with basal insulin was associated with 0.94% reduction in haemoglobin A 1c (95% confidence interval -1.11 to -0.77) and an increase in body weight by 2.89 kg (95% confidence interval 2.17-3.61). Fixed ratio combinations of basal insulin with glucagon like peptide 1 receptor agonists improve glycaemic control whilst balancing out risk for hypoglycaemia and gastrointestinal side effects.
Neonatal Infection in Children With Cerebral Palsy: A Registry-Based Cohort Study.

PubMed

Smilga, Anne-Sophie; Garfinkle, Jarred; Ng, Pamela; Andersen, John; Buckley, David; Fehlings, Darcy; Kirton, Adam; Wood, Ellen; van Rensburg, Esias; Shevell, Michael; Oskoui, Maryam

2018-03-01

The goal of this study was to explore the association between neonatal infection and outcomes in children with cerebral palsy. We conducted a retrospective cohort study using the Canadian CP Registry. Neonatal infection was defined as meeting one of the following criteria: (1) septicemia, (2) septic shock, or (3) administration of antibiotics for ≥10 days. Phenotypic profiles of children with cerebral palsy with and without an antecedent neonatal infection were compared. Subgroup analysis was performed, stratified by gestational age (term versus preterm). Of the 1229 registry participants, 505 (41.1%) were preterm, and 192 (15.6%) met the criteria for neonatal infection with 29% of preterm children having a neonatal infection compared with 6.5% in term-born children. Children with prior neonatal infection were more likely to have a white matter injury (odds ratio 2.2, 95% confidence interval 1.5 to 3.2), spastic diplegic neurological subtype (odds ratio 1.6, 95% confidence interval 1.1 to 2.3), and sensorineural auditory impairment (odds ratio 2.1, 95% confidence interval 1.4 to 3.3). Among preterm children, neonatal infection was not associated with a difference in phenotypic profile. Term-born children with neonatal infection were more likely to have spastic triplegia or quadriplegia (odds ratio 2.4, 95% confidence interval 1.3 to 4.3), concomitant white matter and cortical injury (odds ratio 4.1, 95% confidence interval 1.6 to 10.3), and more severe gross motor ability (Gross Motor Function Classification System IV to V) (odds ratio 2.6, 95% confidence interval 1.4 to 4.8) compared with preterm children. Findings suggest a role of systemic infection on the developing brain in term-born infants, and the possibility to develop targeted therapeutic and preventive strategies to reduce cerebral palsy morbidity. Copyright © 2017. Published by Elsevier Inc.
T-category remains an important prognostic factor for oropharyngeal carcinoma in the era of human papillomavirus.

PubMed

Mackenzie, P; Pryor, D; Burmeister, E; Foote, M; Panizza, B; Burmeister, B; Porceddu, S

2014-10-01

To determine prognostic factors for locoregional relapse (LRR), distant relapse and all-cause death in a contemporary cohort of locoregionally advanced oropharyngeal squamous cell carcinoma (OSCC) treated with definitive chemoradiotherapy or radiotherapy alone. OSCC patients treated with definitive radiotherapy between 2005 and 2010 were identified from a prospective head and neck database. Patient age, gender, smoking history, human papillomavirus (HPV) status, T- and N-category, lowest involved nodal level and gross tumour volume of the primary (GTV-p) and nodal (GTV-n) disease were analysed in relation to LRR, distant relapse and death by way of univariate and multivariate analysis. In total, 130 patients were identified, 88 HPV positive, with a median follow-up of 42 months. On multivariate analysis HPV status was a significant predictor of LRR (hazard ratio 0.15; 95% confidence interval 0.05-0.51) and death (hazard ratio 0.29; 95% confidence interval 0.14-0.59) but not distant relapse (hazard ratio 0.53, 95% confidence interval 0.22-1.27). Increasing T-category was associated with a higher risk of LRR (hazard ratio 1.80 for T3/4 versus T1/2; 95% confidence interval 1.08-2.99), death (hazard ratio 1.37, 95% confidence interval 1.06-1.77) and distant relapse (hazard ratio 1.35; 95% confidence interval 1.00-1.83). Increasing GTV-p was associated with increased risk of distant relapse and death. N3 disease and low neck nodes were significant for LRR, distant relapse and death on univariate analysis only. Tumour HPV status was the strongest predictor of LRR and death. T-category is more predictive of distant relapse and may provide additional prognostic value for LRR and death when accounting for HPV status. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
The Hospital Anxiety and Depression Scale (HADS) and the 9-item Patient Health Questionnaire (PHQ-9) as screening instruments for depression in patients with cancer.

PubMed

Hartung, Tim J; Friedrich, Michael; Johansen, Christoffer; Wittchen, Hans-Ulrich; Faller, Herman; Koch, Uwe; Brähler, Elmar; Härter, Martin; Keller, Monika; Schulz, Holger; Wegscheider, Karl; Weis, Joachim; Mehnert, Anja

2017-11-01

Depression screening in patients with cancer is recommended by major clinical guidelines, although the evidence on individual screening tools is limited for this population. Here, the authors assess and compare the diagnostic accuracy of 2 established screening instruments: the depression modules of the 9-item Patient Health Questionnaire (PHQ-9) and the Hospital Anxiety and Depression Scale (HADS-D), in a representative sample of patients with cancer. This multicenter study was conducted with a proportional, stratified, random sample of 2141 patients with cancer across all major tumor sites and treatment settings. The PHQ-9 and HADS-D were assessed and compared in terms of diagnostic accuracy and receiver operating characteristic (ROC) curves for Diagnostic and Statistical Manual of Mental Disorders, 4th edition diagnosis of major depressive disorder using the Composite International Diagnostic Interview for Oncology as the criterion standard. The diagnostic accuracy of the PHQ-9 and HADS-D was fair for diagnosing major depressive disorder, with areas under the ROC curves of 0.78 (95% confidence interval, 0.76-0.79) and 0.75 (95% confidence interval, 0.74-0.77), respectively. The 2 questionnaires did not differ significantly in their areas under the ROC curves (P = .15). The PHQ-9 with a cutoff score ≥7 had the best screening performance, with a sensitivity of 83% (95% confidence interval, 78%-89%) and a specificity of 61% (95% confidence interval, 59%-63%). The American Society of Clinical Oncology guideline screening algorithm had a sensitivity of 44% (95% confidence interval, 36%-51%) and a specificity of 84% (95% confidence interval, 83%-85%). In patients with cancer, the screening performance of both the PHQ-9 and the HADS-D was limited compared with a standardized diagnostic interview. Costs and benefits of routinely screening all patients with cancer should be weighed carefully. Cancer 2017;123:4236-4243. © 2017 American Cancer Society. © 2017 American Cancer Society.
Variable impact on mortality of AIDS-defining events diagnosed during combination antiretroviral therapy: not all AIDS-defining conditions are created equal.

PubMed

Mocroft, Amanda; Sterne, Jonathan A C; Egger, Matthias; May, Margaret; Grabar, Sophie; Furrer, Hansjakob; Sabin, Caroline; Fatkenheuer, Gerd; Justice, Amy; Reiss, Peter; d'Arminio Monforte, Antonella; Gill, John; Hogg, Robert; Bonnet, Fabrice; Kitahata, Mari; Staszewski, Schlomo; Casabona, Jordi; Harris, Ross; Saag, Michael

2009-04-15

The extent to which mortality differs following individual acquired immunodeficiency syndrome (AIDS)-defining events (ADEs) has not been assessed among patients initiating combination antiretroviral therapy. We analyzed data from 31,620 patients with no prior ADEs who started combination antiretroviral therapy. Cox proportional hazards models were used to estimate mortality hazard ratios for each ADE that occurred in >50 patients, after stratification by cohort and adjustment for sex, HIV transmission group, number of antiretroviral drugs initiated, regimen, age, date of starting combination antiretroviral therapy, and CD4+ cell count and HIV RNA load at initiation of combination antiretroviral therapy. ADEs that occurred in <50 patients were grouped together to form a "rare ADEs" category. During a median follow-up period of 43 months (interquartile range, 19-70 months), 2880 ADEs were diagnosed in 2262 patients; 1146 patients died. The most common ADEs were esophageal candidiasis (in 360 patients), Pneumocystis jiroveci pneumonia (320 patients), and Kaposi sarcoma (308 patients). The greatest mortality hazard ratio was associated with non-Hodgkin's lymphoma (hazard ratio, 17.59; 95% confidence interval, 13.84-22.35) and progressive multifocal leukoencephalopathy (hazard ratio, 10.0; 95% confidence interval, 6.70-14.92). Three groups of ADEs were identified on the basis of the ranked hazard ratios with bootstrapped confidence intervals: severe (non-Hodgkin's lymphoma and progressive multifocal leukoencephalopathy [hazard ratio, 7.26; 95% confidence interval, 5.55-9.48]), moderate (cryptococcosis, cerebral toxoplasmosis, AIDS dementia complex, disseminated Mycobacterium avium complex, and rare ADEs [hazard ratio, 2.35; 95% confidence interval, 1.76-3.13]), and mild (all other ADEs [hazard ratio, 1.47; 95% confidence interval, 1.08-2.00]). In the combination antiretroviral therapy era, mortality rates subsequent to an ADE depend on the specific diagnosis. The proposed classification of ADEs may be useful in clinical end point trials, prognostic studies, and patient management.

Out-of-range INR values and outcomes among new warfarin patients with non-valvular atrial fibrillation.

PubMed

Nelson, Winnie W; Wang, Li; Baser, Onur; Damaraju, Chandrasekharrao V; Schein, Jeffrey R

2015-02-01

Although efficacious in stroke prevention in non-valvular atrial fibrillation, many warfarin patients are sub-optimally managed. To evaluate the association of international normalized ratio control and clinical outcomes among new warfarin patients with non-valvular atrial fibrillation. Adult non-valvular atrial fibrillation patients (≥18 years) initiating warfarin treatment were selected from the US Veterans Health Administration dataset between 10/2007 and 9/2012. Valid international normalized ratio values were examined from the warfarin initiation date through the earlier of the first clinical outcome, end of warfarin exposure or death. Each patient contributed multiple in-range and out-of-range time periods. The relative risk ratios of clinical outcomes associated with international normalized ratio control were estimated. 34,346 patients were included for analysis. During the warfarin exposure period, the incidence of events per 100 person-years was highest when patients had international normalized ratio <2:13.66 for acute coronary syndrome; 10.30 for ischemic stroke; 2.93 for transient ischemic attack; 1.81 for systemic embolism; and 4.55 for major bleeding. Poisson regression confirmed that during periods with international normalized ratio <2, patients were at increased risk of developing acute coronary syndrome (relative risk ratio: 7.9; 95 % confidence interval 6.9-9.1), ischemic stroke (relative risk ratio: 7.6; 95 % confidence interval 6.5-8.9), transient ischemic attack (relative risk ratio: 8.2; 95 % confidence interval 6.1-11.2), systemic embolism (relative risk ratio: 6.3; 95 % confidence interval 4.4-8.9) and major bleeding (relative risk ratio: 2.6; 95 % confidence interval 2.2-3.0). During time periods with international normalized ratio >3, patients had significantly increased risk of major bleeding (relative risk ratio: 1.5; 95 % confidence interval 1.2-2.0). In a Veterans Health Administration non-valvular atrial fibrillation population, exposure to out-of-range international normalized ratio values was associated with significantly increased risk of adverse clinical outcomes.
The prevalence of diagnosed tourette syndrome in Canada: A national population-based study.

PubMed

Yang, Jaeun; Hirsch, Lauren; Martino, Davide; Jette, Nathalie; Roberts, Jodie; Pringsheim, Tamara

2016-11-01

The objective of this study was to examine: (1) the prevalence of diagnosed Tourette syndrome in Canada by sex in youth (aged 12-17) and adults and (2) socioeconomic factors in this population. The majority of epidemiological studies of tics have focused on children and youth, with few studies describing the prevalence of tics in adult populations. Canadian data on Tourette syndrome prevalence were derived from the Canadian Community Health Survey 2010 and 2011 cycles, a Statistics Canada population-based cross-sectional survey that collects information related to health status. We determined the prevalence of diagnosed Tourette syndrome and examined sociodemographic factors, including age, sex, education, income, employment, and birthplace. Overall, 122,884 Canadians participated in the surveys, with 122 participants diagnosed with Tourette syndrome. The prevalence of Tourette syndrome was higher in males in youth: 6.03 per 1000 (95% confidence interval: 3.24-8.81) in males versus 0.48 per 1,000 (95% confidence interval: 0.05-0.91) in females, with a prevalence risk ratio of 5.31 (95% confidence interval: 2.38-11.81). In adults, the prevalence of Tourette syndrome was 0.89 per 1,000 (95% confidence interval: 0.48-1.29) in males versus 0.44 (95% confidence interval: 0.16.0-0.71) in females, with a prevalence risk ratio of 1.93 (95% confidence interval: 1.21-3.08). After adjusting for age and sex, adults with Tourette syndrome had lower odds of receiving postsecondary education or being employed and higher odds of having income lower than the median and receiving governmental support. Data on the prevalence of Tourette syndrome in adults are scarce because most studies focus on children. Our data demonstrate a decreasing prevalence risk ratio for sex in adults compared to children. A diagnosis of Tourette syndrome is associated with lower education, income, and employment in adulthood. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.
Stroke preparedness in children: translating knowledge into behavioral intent: a systematic review and meta-analysis.

PubMed

Ottawa, Cassandra; Sposato, Luciano A; Nabbouh, Fadl; Saposnik, Gustavo

2015-10-01

If translated into behavioral intent, improving stroke knowledge may potentially impact on better outcomes. Children are an attractive target population since they can drive familial behavioral changes. However, the impact of interventions on stroke knowledge among children is unclear. We performed a systematic review and meta-analysis to investigate whether educational interventions targeting children improve stroke knowledge and lead to behavioral changes. We searched Ovid, PubMed, and Embase between January 2000 and December 2014. We included studies written in English reporting the number of children aged 6-15 years undergoing educational interventions on stroke and providing the results for baseline and early and late postintervention tests. We compared the proportion of correct answers between baseline, early, and late responses for two endpoints: knowledge and behavioral intent. Of the initial 58 articles found, we included nine that met the inclusion criteria. Compared with baseline tests (51·7%, 95% confidence interval 40·9-62·4), there was improvement in stroke knowledge in early (74·0%, 95% confidence interval 64·4-82·5, P = 0·002) and late (67·3%, 95% confidence interval 55·4-78·2, P = 0·027) responses. There was improvement in the early (92·1%, 95% confidence interval 86·0-96·6, P < 0·001) and late (83·9%, 95% confidence interval 73·5-92·1, P = 0·001) responses for behavioral intent compared with the baseline assessment (63·8%, 95% confidence interval 53·5-73·4). Children are a potentially attractive target population for improvement in stroke knowledge and behavioral intent, both in the short and long term. Our findings may support the implementation of large-scale stroke educational initiatives targeting children. © 2015 World Stroke Organization.
Suicide in patients with gastric cancer: a population-based study.

PubMed

Sugawara, Akitomo; Kunieda, Etsuo

2016-09-01

We conducted this study to examine the rate of suicide in patients with gastric cancer and to identify factors associated with increased risk of suicide using the Surveillance, Epidemiology, and End Results database. The database was queried for patients who were diagnosed with gastric cancer from 1998 to 2011. The rate of suicide and standardized mortality ratio were calculated. Multivariable analyses were conducted to identify factors associated with increased risk of suicide. A total of 65 535 patients with 109 597 person-years of follow-up were included. A total of 68 patients died of suicide. The age-adjusted rate of suicide was 34.6 per 100 000 person-years (standardized mortality ratios, 4.07; 95% confidence interval, 3.18-5.13). The rate of suicide was highest within the first 3 months after cancer diagnosis (standardized mortality ratios, 67.67; 95% confidence interval, 40.74-106.15). Results of multivariable analyses showed that male sex (incidence rate ratio, 7.15; 95% confidence interval, 3.05-16.78; P < 0.0001), White race (incidence rate ratio, 3.23; 95% confidence interval, 1.00-10.35; P = 0.0491), unmarried status (incidence rate ratio, 2.01; 95% confidence interval, 1.22-3.30; P = 0.0060) and distant stage disease (incidence rate ratio, 2.90; 95% confidence interval, 1.72-4.92; P < 0.0001) were significantly associated with increased risk of suicide. Patients with gastric cancer have an ~4-fold higher risk of suicide compared with the general US population. The suicide risk is highest within the first 3 months after diagnosis. Male sex, White race, unmarried status and distant stage disease are significantly associated with increased risk of suicide. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Integrating palliative care across settings: A retrospective cohort study of a hospice home care programme for cancer patients.

PubMed

Tan, Woan Shin; Lee, Angel; Yang, Sze Yee; Chan, Susan; Wu, Huei Yaw; Ng, Charis Wei Ling; Heng, Bee Hoon

2016-07-01

Terminally ill patients at the end-of-life do transit between care settings due to their complex care needs. Problems of care fragmentation could result in poor quality of care. We aimed to evaluate the impact of an integrated hospice home care programme on acute care service usage and on the share of home deaths. The retrospective study cohort comprised patients who were diagnosed with cancer, had an expected prognosis of 1 year or less, and were referred to a home hospice. The intervention group comprised deceased patients enrolled in the integrated hospice home care programme between September 2012 and June 2014. The historical comparison group comprised deceased patients who were referred to other home hospices between January 2007 and January 2011. There were 321 cases and 593 comparator subjects. Relative to the comparator group, the share of hospital deaths was significantly lower for programme participants (12.1% versus 42.7%). After adjusting for differences at baseline, the intervention group had statistically significantly lower emergency department visits at 30 days (incidence rate ratio: 0.38; 95% confidence interval: 0.31-0.47), 60 days (incidence rate ratio: 0.61; 95% confidence interval: 0.54-0.69) and 90 days (incidence rate ratio: 0.69; 95% confidence interval: 0.62-0.77) prior to death. Similar results held for the number of hospitalisations at 30 days (incidence rate ratio: 0.48; 95% confidence interval: 0.40-0.58), 60 days (incidence rate ratio: 0.71; 95% confidence interval: 0.62-0.82) and 90 days (incidence rate ratio: 0.77; 95% confidence interval: 0.68-0.88) prior to death. Our results demonstrated that by integrating services between acute care and home hospice care, a reduction in acute care service usage could occur. © The Author(s) 2016.
Prevalence of dry eye syndrome in an adult population.

PubMed

Hashemi, Hassan; Khabazkhoob, Mehdi; Kheirkhah, Ahmad; Emamian, Mohammad Hassan; Mehravaran, Shiva; Shariati, Mohammad; Fotouhi, Akbar

2014-04-01

To determine the prevalence of dry eye syndrome in the general 40- to 64-year-old population of Shahroud, Iran. Population-based cross-sectional study. Through cluster sampling, 6311 people were selected and 5190 participated. Assessment of dry eye was done in a random subsample of 1008 people. Subjective assessment for dry eye syndrome was performed using Ocular Surface Disease Index questionnaire. In addition, the following objective tests of dry eye syndrome were employed: Schirmer test, tear break-up time, and fluorescein and Rose Bengal staining using the Oxford grading scheme. Those with an Ocular Surface Disease Index score ≥23 were considered symptomatic, and dry eye syndrome was defined as having symptoms and at least one positive objective sign. The prevalence of dry eye syndrome was 8.7% (95% confidence interval 6.9-10.6). Assessment of signs showed an abnormal Schirmer score in 17.8% (95% confidence interval 15.5-20.0), tear break-up time in 34.2% (95% confidence interval 29.5-38.8), corneal fluorescein staining (≥1) in 11.3% (95% confidence interval 8.5-14.1) and Rose Bengal staining (≥3 for cornea and/or conjunctiva) in 4.9% (95% confidence interval 3.4-6.5). According to the Ocular Surface Disease Index scores, 18.3% (95% confidence interval 15.9-20.6) had dry eye syndrome symptoms. The prevalence of dry eye syndrome was significantly higher in women (P = 0.010) and not significantly associated with age (P = 0.291). The objective dry eye syndrome signs significantly increased with age. Based on the findings, the prevalence of dry eye syndrome in the studied population is in the mid-range. The prevalence is higher in women. Also, objective tests tend to turn abnormal at higher age. Pterygium is associated with dry eye syndrome and increased its symptoms. © 2013 Royal Australian and New Zealand College of Ophthalmologists.
The diagnostic value of narrow-band imaging for early and invasive lung cancer: a meta-analysis.

PubMed

Zhu, Juanjuan; Li, Wei; Zhou, Jihong; Chen, Yuqing; Zhao, Chenling; Zhang, Ting; Peng, Wenjia; Wang, Xiaojing

2017-07-01

This study aimed to compare the ability of narrow-band imaging to detect early and invasive lung cancer with that of conventional pathological analysis and white-light bronchoscopy. We searched the PubMed, EMBASE, Sinomed, and China National Knowledge Infrastructure databases for relevant studies. Meta-disc software was used to perform data analysis, meta-regression analysis, sensitivity analysis, and heterogeneity testing, and STATA software was used to determine if publication bias was present, as well as to calculate the relative risks for the sensitivity and specificity of narrow-band imaging vs those of white-light bronchoscopy for the detection of early and invasive lung cancer. A random-effects model was used to assess the diagnostic efficacy of the above modalities in cases in which a high degree of between-study heterogeneity was noted with respect to their diagnostic efficacies. The database search identified six studies including 578 patients. The pooled sensitivity and specificity of narrow-band imaging were 86% (95% confidence interval: 83-88%) and 81% (95% confidence interval: 77-84%), respectively, and the pooled sensitivity and specificity of white-light bronchoscopy were 70% (95% confidence interval: 66-74%) and 66% (95% confidence interval: 62-70%), respectively. The pooled relative risks for the sensitivity and specificity of narrow-band imaging vs the sensitivity and specificity of white-light bronchoscopy for the detection of early and invasive lung cancer were 1.33 (95% confidence interval: 1.07-1.67) and 1.09 (95% confidence interval: 0.84-1.42), respectively, and sensitivity analysis showed that narrow-band imaging exhibited good diagnostic efficacy with respect to detecting early and invasive lung cancer and that the results of the study were stable. Narrow-band imaging was superior to white light bronchoscopy with respect to detecting early and invasive lung cancer; however, the specificities of the two modalities did not differ significantly.
Antecedents and neuroimaging patterns in cerebral palsy with epilepsy and cognitive impairment: a population-based study in children born at term.

PubMed

Ahlin, Kristina; Jacobsson, Bo; Nilsson, Staffan; Himmelmann, Kate

2017-07-01

Antecedents of accompanying impairments in cerebral palsy and their relation to neuroimaging patterns need to be explored. A population-based study of 309 children with cerebral palsy born at term between 1983 and 1994. Prepartum, intrapartum, and postpartum variables previously studied as antecedents of cerebral palsy type and motor severity were analyzed in children with cerebral palsy and cognitive impairment and/or epilepsy, and in children with cerebral palsy without these accompanying impairments. Neuroimaging patterns and their relation to identified antecedents were analyzed. Data were retrieved from the cerebral palsy register of western Sweden, and from obstetric and neonatal records. Children with cerebral palsy and accompanying impairments more often had low birthweight (kg) (odds ratio 0.5, 95% confidence interval 0.3-0.8), brain maldevelopment known at birth (p = 0.007, odds ratio ∞) and neonatal infection (odds ratio 5.4, 95% confidence interval 1.04-28.4). Moreover, neuroimaging patterns of maldevelopment (odds ratio 7.2, 95% confidence interval 2.9-17.2), cortical/subcortical lesions (odds ratio 5.3, 95% confidence interval 2.3-12.2) and basal ganglia lesions (odds ratio 7.6, 95% confidence interval 1.4-41.3) were more common, wheras white matter injury was found significantly less often (odds ratio 0.2, 95% confidence interval 0.1-0.5). In most children with maldevelopment, the intrapartum and postpartum periods were uneventful (p < 0.05). Cerebral maldevelopment was associated with prepartum antecedents, whereas subcortical/cortical and basal ganglia lesions were associated with intrapartum and postpartum antecedents. No additional factor other than those related to motor impairment was associated with epilepsy and cognitive impairment in cerebral palsy. Timing of antecedents deemed important for the development of cerebral palsy with accompanying impairments were supported by neuroimaging patterns. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.
Breast cancer biology varies by method of detection and may contribute to overdiagnosis.

PubMed

Hayse, Brandon; Hooley, Regina J; Killelea, Brigid K; Horowitz, Nina R; Chagpar, Anees B; Lannin, Donald R

2016-08-01

Recently, it has been suggested that screening mammography may result in some degree of overdiagnosis (ie, detection of breast cancers that would never become clinically important within the lifespan of the patient). The extent and biology of these overdiagnosed cancers, however, is not well understood, and the effect of newer screening modalities on overdiagnosis is unknown. We performed a retrospective review of a prospectively collected database of breast cancers diagnosed at the Yale Breast Center from 2004-2014. The mode of initial presentation was categorized into 5 groups: screening mammogram, screening magnetic resonance imaging, screening ultrasonography, self-detected masses, and physician-detected masses. Compared with cancers presenting with masses, cancers detected by image-based screening were more likely to present with ductal carcinoma-in-situ or T1 cancers (P < .001). In addition to a simple stage shift, however, cancers detected by image-based screening were also more likely to be luminal and low-grade cancers; symptomatic cancers were more likely high-grade and triple-negative (P < .001, respectively). On a multivariate analysis, adjusting for age, race, and tumor size, cancers detected by mammogram, US, and magnetic resonance imaging had greater odds of being luminal (odds ratio 1.8, 95% confidence interval, 1.5-2.3; odds ratio 2.2, 95% confidence interval, 1.1-4.7; and odds ratio 4.7, 95% confidence interval, 2.1-10.6, respectively), and low-grade (odds ratio 2.2, 95% confidence interval, 1.6-2.9; odds ratio 4.9, 95% confidence interval, 2.7-8.9; and odds ratio 4.6, 95% confidence interval, 2.6-8.1, respectively) compared with cancers presenting with self-detected masses. Screening detects cancers with more indolent biology, potentially contributing to the observed rate of overdiagnosis. With magnetic resonance imaging and US being used more commonly for screening, the rate of overdiagnosis may increase further. Copyright © 2016. Published by Elsevier Inc.
Peritoneal Dialysis Access Revision in Children: Causes, Interventions, and Outcomes.

PubMed

Borzych-Duzalka, Dagmara; Aki, T Fazil; Azocar, Marta; White, Colin; Harvey, Elizabeth; Mir, Sevgi; Adragna, Marta; Serdaroglu, Erkin; Sinha, Rajiv; Samaille, Charlotte; Vanegas, Juan Jose; Kari, Jameela; Barbosa, Lorena; Bagga, Arvind; Galanti, Monica; Yavascan, Onder; Leozappa, Giovanna; Szczepanska, Maria; Vondrak, Karel; Tse, Kei-Chiu; Schaefer, Franz; Warady, Bradley A

2017-01-06

Little published information is available about access failure in children undergoing chronic peritoneal dialysis. Our objectives were to evaluate frequency, risk factors, interventions, and outcome of peritoneal dialysis access revision. Data were derived from 824 incident and 1629 prevalent patients from 105 pediatric nephrology centers enrolled in the International Pediatric Peritoneal Dialysis Network Registry between 2007 and 2015. In total, 452 access revisions were recorded in 321 (13%) of 2453 patients over 3134 patient-years of follow-up, resulting in an overall access revision rate of 0.14 per treatment year. Among 824 incident patients, 186 (22.6%) underwent 188 access revisions over 1066 patient-years, yielding an access revision rate of 0.17 per treatment year; 83% of access revisions in incident patients were reported within the first year of peritoneal dialysis treatment. Catheter survival rates in incident patients were 84%, 80%, 77%, and 73% at 12, 24, 36, and 48 months, respectively. By multivariate logistic regression analysis, risk of access revision was associated with younger age (odds ratio, 0.93; 95% confidence interval, 0.92 to 0.95; P<0.001), diagnosis of congenital anomalies of the kidney and urinary tract (odds ratio, 1.28; 95% confidence interval, 1.03 to 1.59; P=0.02), coexisting ostomies (odds ratio, 1.42; 95% confidence interval, 1.07 to 1.87; P=0.01), presence of swan neck tunnel with curled intraperitoneal portion (odds ratio, 1.30; 95% confidence interval, 1.04 to 1.63; P=0.02), and high gross national income (odds ratio, 1.10; 95% confidence interval, 1.02 to 1.19; P=0.01). Main reasons for access revisions included mechanical malfunction (60%), peritonitis (16%), exit site infection (12%), and leakage (6%). Need for access revision increased the risk of peritoneal dialysis technique failure or death (hazard ratio, 1.35; 95% confidence interval, 1.10 to 1.65; P=0.003). Access dysfunction due to mechanical causes doubled the risk of technique failure compared with infectious causes (hazard ratio, 1.95; 95% confidence interval, 1.20 to 2.30; P=0.03). Peritoneal dialysis catheter revisions are common in pediatric patients on peritoneal dialysis and complicate provision of chronic peritoneal dialysis. Attention to potentially modifiable risk factors by pediatric nephrologists and pediatric surgeons should be encouraged. Copyright © 2016 by the American Society of Nephrology.
Peritoneal Dialysis Access Revision in Children: Causes, Interventions, and Outcomes

PubMed Central

Aki, T. Fazil; Azocar, Marta; White, Colin; Harvey, Elizabeth; Mir, Sevgi; Adragna, Marta; Serdaroglu, Erkin; Sinha, Rajiv; Samaille, Charlotte; Vanegas, Juan Jose; Kari, Jameela; Barbosa, Lorena; Bagga, Arvind; Galanti, Monica; Yavascan, Onder; Leozappa, Giovanna; Szczepanska, Maria; Vondrak, Karel; Tse, Kei-Chiu; Schaefer, Franz; Warady, Bradley A.

2017-01-01

Background and objectives Little published information is available about access failure in children undergoing chronic peritoneal dialysis. Our objectives were to evaluate frequency, risk factors, interventions, and outcome of peritoneal dialysis access revision. Design, setting, participants, & measurements Data were derived from 824 incident and 1629 prevalent patients from 105 pediatric nephrology centers enrolled in the International Pediatric Peritoneal Dialysis Network Registry between 2007 and 2015. Results In total, 452 access revisions were recorded in 321 (13%) of 2453 patients over 3134 patient-years of follow-up, resulting in an overall access revision rate of 0.14 per treatment year. Among 824 incident patients, 186 (22.6%) underwent 188 access revisions over 1066 patient-years, yielding an access revision rate of 0.17 per treatment year; 83% of access revisions in incident patients were reported within the first year of peritoneal dialysis treatment. Catheter survival rates in incident patients were 84%, 80%, 77%, and 73% at 12, 24, 36, and 48 months, respectively. By multivariate logistic regression analysis, risk of access revision was associated with younger age (odds ratio, 0.93; 95% confidence interval, 0.92 to 0.95; P<0.001), diagnosis of congenital anomalies of the kidney and urinary tract (odds ratio, 1.28; 95% confidence interval, 1.03 to 1.59; P=0.02), coexisting ostomies (odds ratio, 1.42; 95% confidence interval, 1.07 to 1.87; P=0.01), presence of swan neck tunnel with curled intraperitoneal portion (odds ratio, 1.30; 95% confidence interval, 1.04 to 1.63; P=0.02), and high gross national income (odds ratio, 1.10; 95% confidence interval, 1.02 to 1.19; P=0.01). Main reasons for access revisions included mechanical malfunction (60%), peritonitis (16%), exit site infection (12%), and leakage (6%). Need for access revision increased the risk of peritoneal dialysis technique failure or death (hazard ratio, 1.35; 95% confidence interval, 1.10 to 1.65; P=0.003). Access dysfunction due to mechanical causes doubled the risk of technique failure compared with infectious causes (hazard ratio, 1.95; 95% confidence interval, 1.20 to 2.30; P=0.03). Conclusions Peritoneal dialysis catheter revisions are common in pediatric patients on peritoneal dialysis and complicate provision of chronic peritoneal dialysis. Attention to potentially modifiable risk factors by pediatric nephrologists and pediatric surgeons should be encouraged. PMID:27899416
Toxoplasma gondii exposure and epilepsy: A matched case-control study in a public hospital in northern Mexico.

PubMed

Alvarado-Esquivel, Cosme; Rico-Almochantaf, Yazmin Del Rosario; Hernández-Tinoco, Jesús; Quiñones-Canales, Gerardo; Sánchez-Anguiano, Luis Francisco; Torres-González, Jorge; Ramírez-Valles, Eda Guadalupe; Minjarez-Veloz, Andrea

2018-01-01

This study aimed to determine the association between infection with Toxoplasma gondii and epilepsy in patients attended to in a public hospital in the northern Mexican city of Durango. We performed an age- and gender-matched case-control study of 99 patients suffering from epilepsy and 99 without epilepsy. Sera of participants were analyzed for anti- T. gondii IgG and IgM antibodies using commercially available enzyme-linked immunoassays. Seropositive samples to T. gondii were further analyzed for detection of T. gondii DNA by polymerase chain reaction. Anti- T. gondii IgG antibodies were found in 10 (10.1%) of the 99 cases and in 6 (6.1%) of the 99 controls (odds ratio = 1.74; 95% confidence interval: 0.60-4.99; p = 0.43). High (> 150 IU/mL) levels of anti- T. gondii IgG antibodies were found in 6 of the 99 cases and in 4 of the 99 controls (odds ratio = 1.53; 95% confidence interval: 0.41-5.60; p = 0.74). Anti- T. gondii IgM antibodies were found in 2 of the 10 IgG seropositive cases, and in 2 of the 6 IgG seropositive controls (odds ratio = 0.50; 95% confidence interval: 0.05-4.97; p = 0.60). T. gondii DNA was not found in any of the 10 anti- T. gondii IgG positive patients. Bivariate analysis of IgG seropositivity to T. gondii and International Statistical Classification of Diseases and related Health Problems, 10th Edition codes of epilepsy showed an association between seropositivity and G40.1 code (odds ratio = 22.0; 95% confidence interval: 2.59-186.5; p = 0.008). Logistic regression analysis showed an association between T. gondii infection and consumption of goat meat (odds ratio = 6.5; 95% confidence interval: 1.22-34.64; p = 0.02), unwashed raw vegetables (odds ratio = 26.3; 95% confidence interval: 2.61-265.23; p = 0.006), and tobacco use (odds ratio = 6.2; 95% confidence interval: 1.06-36.66; p = 0.04). Results suggest that T. gondii infection does not increase the risk of epilepsy in our setting; however, infection might be linked to specific types of epilepsy. Factors associated with T. gondii infection found in this study may aid in the design of preventive measures against toxoplasmosis.
Association of protein tyrosine phosphatase, non-receptor type 22 +1858C→T polymorphism and susceptibility to vitiligo: Systematic review and meta-analysis.

PubMed

Agarwal, Silky; Changotra, Harish

2017-01-01

Protein tyrosine phosphatase, non-receptor type 22 gene, which translates to lymphoid tyrosine phosphatase, is considered to be a susceptibility gene marker associated with several autoimmune diseases. Several studies have demonstrated the association of protein tyrosine phosphatase, non-receptor type 22 +1858C→T polymorphism with vitiligo. However, these studies showed conflicting results. Meta-analysis of the same was conducted earlier that included fewer number of publications in their study. We performed a meta-analysis of a total of seven studies consisting of 2094 cases and 3613 controls to evaluate the possible association of protein tyrosine phosphatase, non-receptor type 22 +1858C>T polymorphism with vitiligo susceptibility. We conducted a literature search in PubMed, Google Scholar and Dogpile for all published paper on protein tyrosine phosphatase, non-receptor type 22 +1858C→T polymorphism and vitiligo risk till June 2016. Data analysis was performed by RevMan 5.3 and comprehensive meta-analysis v3.0 software. Meta-analysis showed an overall significant association of protein tyrosine phosphatase, non- receptor type 22 +1858C→T polymorphism with vitiligo in all models (allelic model [T vs. C]: odds ratio = 1.50, 95% confidence interval [1.32-1.71], P< 0.001; dominant model [TT + CT vs. CC]: odds ratio = 1.61, 95% confidence interval [1.16-2.24], P = 0.004; recessive model [TT vs. CT + CC]: odds ratio = 4.82, 95% confidence interval [1.11-20.92], P = 0.04; homozygous model [TT vs. CC]: odds ratio = 5.34, 95% confidence interval [1.23-23.24], P = 0.03; co-dominant model [CT vs. CC]: odds ratio = 1.52, 95% confidence interval [1.09-2.13], P = 0.01). No publication bias was detected in the funnel plot study. Limited ethnic-based studies, unable to satisfy data by gender or vitiligo-type are some limitations of the present meta-analysis. Stratifying data by ethnicity showed an association of protein tyrosine phosphatase, non-receptor type 22 +1858C→T with vitiligo in European population (odds ratio = 1.53, 95% confidence interval [1.34-1.75], P< 0.001) but not in Asian population (odds ratio = 0.59, 95% confidence interval [0.26-1.32], P = 0.2). In conclusion, protein tyrosine phosphatase, non-receptor type 22 +1858 T allele predisposes European individuals to vitiligo.
Characterization of Myocardial Repolarization Reserve in Adolescent Females With Anorexia Nervosa.

PubMed

Padfield, Gareth J; Escudero, Carolina A; DeSouza, Astrid M; Steinberg, Christian; Gibbs, Karen; Puyat, Joseph H; Lam, Pei Yoong; Sanatani, Shubhayan; Sherwin, Elizabeth; Potts, James E; Sandor, George; Krahn, Andrew D

2016-02-09

Patients with anorexia nervosa exhibit abnormal myocardial repolarization and are susceptible to sudden cardiac death. Exercise testing is useful in unmasking QT prolongation in disorders associated with abnormal repolarization. We characterized QT adaptation during exercise in anorexia. Sixty-one adolescent female patients with anorexia nervosa and 45 age- and sex-matched healthy volunteers performed symptom-limited cycle ergometry during 12-lead ECG monitoring. Changes in the QT interval during exercise were measured, and QT/RR-interval slopes were determined by using mixed-effects regression modeling. Patients had significantly lower body mass index than controls; however, resting heart rates and QT/QTc intervals were similar at baseline. Patients had shorter exercise times (13.7±4.5 versus 20.6±4.5 minutes; P<0.001) and lower peak heart rates (159±20 versus 184±9 beats/min; P<0.001). The mean QTc intervals were longer at peak exercise in patients (442±29 versus 422±19 ms; P<0.001). During submaximal exertion at comparable heart rates (114±6 versus 115±11 beats/min; P=0.54), the QTc interval had prolonged significantly more in patients than controls (37±28 versus 24±25 ms; P<0.016). The RR/QT slope, best described by a curvilinear relationship, was more gradual in patients than in controls (13.4; 95% confidence interval, 12.8-13.9 versus 15.8; 95% confidence interval, 15.3-16.4 ms QT change per 10% change in RR interval; P<0.001) and steepest in patients within the highest body mass index tertile versus the lowest (13.9; 95% confidence interval, 12.9-14.9 versus 12.3; 95% confidence interval, 11.3-13.3; P=0.026). Despite the absence of manifest QT prolongation, adolescent anorexic females have impaired repolarization reserve in comparison with healthy controls. Further study may identify impaired QT dynamics as a risk factor for arrhythmias in anorexia nervosa. © 2016 American Heart Association, Inc.
Accuracy assessment of percent canopy cover, cover type, and size class

Treesearch

H. T. Schreuder; S. Bain; R. C. Czaplewski

2003-01-01

Truth for vegetation cover percent and type is obtained from very large-scale photography (VLSP), stand structure as measured by size classes, and vegetation types from a combination of VLSP and ground sampling. We recommend using the Kappa statistic with bootstrap confidence intervals for overall accuracy, and similarly bootstrap confidence intervals for percent...
Confidence Intervals for Effect Sizes: Compliance and Clinical Significance in the "Journal of Consulting and Clinical Psychology"

ERIC Educational Resources Information Center

Odgaard, Eric C.; Fowler, Robert L.

2010-01-01

Objective: In 2005, the "Journal of Consulting and Clinical Psychology" ("JCCP") became the first American Psychological Association (APA) journal to require statistical measures of clinical significance, plus effect sizes (ESs) and associated confidence intervals (CIs), for primary outcomes (La Greca, 2005). As this represents the single largest…
Optimal and Most Exact Confidence Intervals for Person Parameters in Item Response Theory Models

ERIC Educational Resources Information Center

Doebler, Anna; Doebler, Philipp; Holling, Heinz

2013-01-01

The common way to calculate confidence intervals for item response theory models is to assume that the standardized maximum likelihood estimator for the person parameter [theta] is normally distributed. However, this approximation is often inadequate for short and medium test lengths. As a result, the coverage probabilities fall below the given…
SIMREL: Software for Coefficient Alpha and Its Confidence Intervals with Monte Carlo Studies

ERIC Educational Resources Information Center

Yurdugul, Halil

2009-01-01

This article describes SIMREL, a software program designed for the simulation of alpha coefficients and the estimation of its confidence intervals. SIMREL runs on two alternatives. In the first one, if SIMREL is run for a single data file, it performs descriptive statistics, principal components analysis, and variance analysis of the item scores…
Performing Contrast Analysis in Factorial Designs: From NHST to Confidence Intervals and Beyond

ERIC Educational Resources Information Center

Wiens, Stefan; Nilsson, Mats E.

2017-01-01

Because of the continuing debates about statistics, many researchers may feel confused about how to analyze and interpret data. Current guidelines in psychology advocate the use of effect sizes and confidence intervals (CIs). However, researchers may be unsure about how to extract effect sizes from factorial designs. Contrast analysis is helpful…
Planck intermediate results. XVI. Profile likelihoods for cosmological parameters

NASA Astrophysics Data System (ADS)

Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bonaldi, A.; Bond, J. R.; Bouchet, F. R.; Burigana, C.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Couchot, F.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dupac, X.; Enßlin, T. A.; Eriksen, H. K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; González-Nuevo, J.; Górski, K. M.; Gregorio, A.; Gruppuso, A.; Hansen, F. K.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lawrence, C. R.; Leonardi, R.; Liddle, A.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski∗, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Puget, J.-L.; Rachen, J. P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rouillé d'Orfeuil, B.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Savelainen, M.; Savini, G.; Spencer, L. D.; Spinelli, M.; Starck, J.-L.; Sureau, F.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; White, M.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-06-01

We explore the 2013 Planck likelihood function with a high-precision multi-dimensional minimizer (Minuit). This allows a refinement of the ΛCDM best-fit solution with respect to previously-released results, and the construction of frequentist confidence intervals using profile likelihoods. The agreement with the cosmological results from the Bayesian framework is excellent, demonstrating the robustness of the Planck results to the statistical methodology. We investigate the inclusion of neutrino masses, where more significant differences may appear due to the non-Gaussian nature of the posterior mass distribution. By applying the Feldman-Cousins prescription, we again obtain results very similar to those of the Bayesian methodology. However, the profile-likelihood analysis of the cosmic microwave background (CMB) combination (Planck+WP+highL) reveals a minimum well within the unphysical negative-mass region. We show that inclusion of the Planck CMB-lensing information regularizes this issue, and provide a robust frequentist upper limit ∑ mν ≤ 0.26 eV (95% confidence) from the CMB+lensing+BAO data combination.

Identification of stable QTLs for seed oil content by combined linkage and association mapping in Brassica napus.

PubMed

Sun, Fengming; Liu, Jing; Hua, Wei; Sun, Xingchao; Wang, Xinfa; Wang, Hanzhong

2016-11-01

Seed oil content is an important agricultural trait in rapeseed breeding. Although numerous quantitative trait locus (QTL) have been identified, most of them cannot be applied in practical breeding mainly due to environmental instability or large confidence intervals. The purpose of this study was to identify and validate high quality and more stable QTLs by combining linkage mapping and genome-wide association study (GWAS). For linkage mapping, we constructed two F 2 populations from crosses of high-oil content (∼50%) lines 6F313 and 61616 with a low-oil content (∼40%) line 51070. Two high density linkage maps spanned 1987cM (1659 bins) and 1856cM (1746 bins), respectively. For GWAS, we developed more than 34,000 high-quality SNP markers based on 227 accessions. Finally, 40 QTLs and 29 associations were established by linkage and association mapping in different environments. After merging the results, 32 consensus QTLs were obtained and 7 of them were identified by both mapping methods. Seven overlapping QTLs covered an average confidence interval of 183kb and explained the phenotypic variation of 10.23 to 24.45%. We further developed allele-specific PCR primers to identify each of the seven QTLs. These stable QTLs should be useful in gene cloning and practical breeding application. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Occupational correlates of low back pain among U.S. Marines following combat deployment.

PubMed

MacGregor, Andrew J; Dougherty, Amber L; Mayo, Jonathan A; Rauh, Mitchell J; Galarneau, Michael R

2012-07-01

Many U.S. Marines have experienced routine combat deployments during Operation Iraqi Freedom, which present numerous occupational hazards that may result in low back pain (LBP). The objective of this retrospective cohort study was to identify new-onset LBP among Marines following initial deployment to Operation Iraqi Freedom. Active duty Marines deployed to Iraq or Kuwait between 2005 and 2008 were identified from deployment records and linked to medical databases (n = 36,680). The outcome of interest was an International Classification of Diseases, 9th Revision, Clinical Modification code indicating LBP (724.2) within 1 year postdeployment. Multivariate logistic regression examined the effect of occupation on LBP. Overall, 4.1% (n = 1,517) of Marines were diagnosed with LBP. After adjusting for covariates, the service/supply (odds ratio 1.33, 95% confidence interval, 1.12-1.59) and electrical/mechanical/craftsworker occupations (odds ratio 1.31, 95% confidence interval, 1.12-1.53) had higher odds of LBP when compared to the administrative/other referent group. Within these groups, the highest LBP prevalence was in the construction (8.6%) and law enforcement (6.2%) subgroups. Although infantry occupations purposefully engage the enemy and often face sustained physical rigors of combat, LBP was most prevalent in noninfantry occupations. Future studies should include detailed exposure histories to elucidate occupation-specific etiologies of LBP in order to guide prevention efforts.
Inconsistent survey reporting in anesthesia journals.

PubMed

Story, David A; Gin, Veronica; na Ranong, Vanida; Poustie, Stephanie; Jones, Daryl

2011-09-01

As with other types of research, there are concerns about reporting of survey research in anesthesia journals. We hypothesized that use of survey reporting items would be inconsistent in survey research reported in anesthesia journals. After a literature review we constructed a 17-item reporting list for a limited systematic review of survey reporting in 6 anesthesia journals. We identified survey reports by MEDLINE (PubMed) search for January 2000 to April 2009. The initial search identified 347 publications. Of these, we excluded 107 because they were not questionnaire surveys (often audits), were reviews, or were letters. We therefore identified 240 surveys published as full survey reports. From the 17-item reporting list, the median number of items recorded was 9 (interquartile range: 7 to 10; range 2 to 15). The number (and percentage) of surveys reporting specific items ranged widely for different items: from 9 surveys (4%; 95% confidence interval [CI]: 2% to 7%) for sample size to 240 surveys (100%; 95% CI: 98% to 100%) for response rate. In addition to sample size, the 5 least frequently reported items included the following: reporting confidence intervals, 21 surveys (9%; 95% CI: 6% to 13%); stating a hypothesis, 23 of 240 surveys (10%; 95% CI: 7% to 14%); accounting for nonresponders, 61 surveys (25%; 95% CI: 20% to 31%); and survey design, 67 surveys (28%; 95% CI: 33% to 34%). Inconsistent reporting may compromise the transparency and reproducibility of survey reports.
Initial Validation of NDVI time seriesfrom AVHRR, VEGETATION, and MODIS

NASA Technical Reports Server (NTRS)

Morisette, Jeffrey T.; Pinzon, Jorge E.; Brown, Molly E.; Tucker, Jim; Justice, Christopher O.

2004-01-01

The paper will address Theme 7: Multi-sensor opportunities for VEGETATION. We present analysis of a long-term vegetation record derived from three moderate resolution sensors: AVHRR, VEGETATION, and MODIS. While empirically based manipulation can ensure agreement between the three data sets, there is a need to validate the series. This paper uses atmospherically corrected ETM+ data available over the EOS Land Validation Core Sites as an independent data set with which to compare the time series. We use ETM+ data from 15 globally distributed sites, 7 of which contain repeat coverage in time. These high-resolution data are compared to the values of each sensor by spatially aggregating the ETM+ to each specific sensors' spatial coverage. The aggregated ETM+ value provides a point estimate for a specific site on a specific date. The standard deviation of that point estimate is used to construct a confidence interval for that point estimate. The values from each moderate resolution sensor are then evaluated with respect to that confident interval. Result show that AVHRR, VEGETATION, and MODIS data can be combined to assess temporal uncertainties and address data continuity issues and that the atmospherically corrected ETM+ data provide an independent source with which to compare that record. The final product is a consistent time series climate record that links historical observations to current and future measurements.
Frequency of depression in type 2 diabetes mellitus and an analysis of predictive factors.

PubMed

Arshad, Abdul Rehman; Alvi, Kamran Yousaf

2016-04-01

To determine frequency of depression in patients with diabetes mellitus type 2 and to identify predictive factors. The observational study was carried out at 1 Mountain Medical Battalion, Bagh, Azad Kashmir, Pakistan, from June 2013 to May 2014, and comprised type 2 diabetic patients who were not using anti-depressants and did not have history of other psychiatric illnesses. Demographic data, duration of diabetes, presence of hypertension and type of treatment were recorded and body mass index was calculated. Patient Health Questionnaire-9, translated into Urdu, was administered during face-to-face interviews. Scores >5 indicated depression, which was classified into different grades of severity using standard cut-off values. Of the 133 patients, 51(38.35%) were depressed. Depression was mild in 34(26%), moderate in 12(9.6%), moderately severe in 4(2.9%) and severe in 1(0.7%) patient. On univariate binary logistic regression, female gender (odds ratio=3.07; 95% confidence interval = 1.43, 6.59), lesser education (odds ratio = 0.90; 95% confidence interval 0.84, 0.97) shorter duration of diabetes (odds ratio=0.87; 95% confidence interval = 0.80, 0.96) and higher body mass index (odds ratio=1.41; 95% confidence interval = 1.05, 1.25) were significantly associated with depression. Only shorter duration of diabetes (odds ratio=0.90; 95% confidence interval = 0.82, 0.99) remained significant after adjustment for confounders. Age, level of education, glycaemic control and type of treatment did not predict depression. A significant proportion of type 2 diabetics were depressed. Shorter duration of diabetes reliably predicted depression in these patients.
EXACT DISTRIBUTIONS OF INTRACLASS CORRELATION AND CRONBACH'S ALPHA WITH GAUSSIAN DATA AND GENERAL COVARIANCE.

PubMed

Kistner, Emily O; Muller, Keith E

2004-09-01

Intraclass correlation and Cronbach's alpha are widely used to describe reliability of tests and measurements. Even with Gaussian data, exact distributions are known only for compound symmetric covariance (equal variances and equal correlations). Recently, large sample Gaussian approximations were derived for the distribution functions. New exact results allow calculating the exact distribution function and other properties of intraclass correlation and Cronbach's alpha, for Gaussian data with any covariance pattern, not just compound symmetry. Probabilities are computed in terms of the distribution function of a weighted sum of independent chi-square random variables. New F approximations for the distribution functions of intraclass correlation and Cronbach's alpha are much simpler and faster to compute than the exact forms. Assuming the covariance matrix is known, the approximations typically provide sufficient accuracy, even with as few as ten observations. Either the exact or approximate distributions may be used to create confidence intervals around an estimate of reliability. Monte Carlo simulations led to a number of conclusions. Correctly assuming that the covariance matrix is compound symmetric leads to accurate confidence intervals, as was expected from previously known results. However, assuming and estimating a general covariance matrix produces somewhat optimistically narrow confidence intervals with 10 observations. Increasing sample size to 100 gives essentially unbiased coverage. Incorrectly assuming compound symmetry leads to pessimistically large confidence intervals, with pessimism increasing with sample size. In contrast, incorrectly assuming general covariance introduces only a modest optimistic bias in small samples. Hence the new methods seem preferable for creating confidence intervals, except when compound symmetry definitely holds.
A prospective observational cohort study to assess the incidence of acute otitis media among children 0-5 years of age in Southern Brazil.

PubMed

Lanzieri, Tatiana M; Cunha, Clóvis Arns da; Cunha, Rejane B; Arguello, D Fermin; Devadiga, Raghavendra; Sanchez, Nervo; Barria, Eduardo Ortega

To estimate acute otitis media incidence among young children and impact on quality of life of parents/caregivers in a southern Brazilian city. Prospective cohort study including children 0-5 years of age registered at a private pediatric practice. Acute otitis media episodes diagnosed by a pediatrician and impact on quality of life of parents/caregivers were assessed during a 12-month follow-up. During September 2008-March 2010, of 1,136 children enrolled in the study, 1074 (95%) were followed: 55.0% were ≤2 years of age, 52.3% males, 94.7% white, and 69.2% had previously received pneumococcal vaccine in private clinics. Acute otitis media incidence per 1000 person-years was 95.7 (95% confidence interval: 77.2-117.4) overall, 105.5 (95% confidence interval: 78.3-139.0) in children ≤2 years of age and 63.6 (95% confidence interval: 43.2-90.3) in children 3-5 years of age. Acute otitis media incidence per 1000 person-years was 86.3 (95% confidence interval: 65.5-111.5) and 117.1 (95% confidence interval: 80.1-165.3) among vaccinated and unvaccinated children, respectively. Nearly 68.9% of parents reported worsening of their overall quality of life. Acute otitis media incidence among unvaccinated children in our study may be useful as baseline data to assess impact of pneumococcal vaccine introduction in the Brazilian National Immunization Program in April 2010. Copyright © 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.
Risk factors for gametocyte carriage in uncomplicated falciparum malaria in children before and after artemisinin-based combination treatments.

PubMed

Sowunmi, Akintunde; Okuboyejo, Titilope M; Gbotosho, Grace O; Happi, Christian T

2011-01-01

Artemisinin-based combination treatments (ACTs) are the recommended first-line antimalarials globally, but their influence on the risk factors associated with gametocyte carriage has had little evaluation in endemic areas. The risk factors associated with gametocytaemia at presentation and after ACTs were evaluated in 835 children assigned to artesunate, artesunate-amodiaquine, artesunate-mefloquine or artemether-lumefantrine. Gametocyte carriage at enrolment was 8.4%. During follow-up, 24 patients (2.8%) developed gametocytaemia, which in 83% (20 patients) had developed by day 7 following treatment. In a multiple regression model, 2 factors were independent risk factors for the presence of gametocytaemia at enrolment, namely age <3 years (adjusted odds ratio 2.03, 95% confidence interval 1.01-4.05; p = 0.04) and enrolment before 2009 (adjusted odds ratio 4.2, 95% confidence interval 2.09-8.44; p < 0.001). Haematocrit <25% and parasitaemia <50,000/μl blood were associated with an increased risk of gametocytaemia. Following treatment, 3 factors were independent risk factors for gametocytaemia, namely gametocytaemia at enrolment (adjusted odds ratio 46.39, 95% confidence interval 22.3-96.46; p < 0.0001) and treatment with artesunate (adjusted odds ratio 6.74, 95% confidence interval 1.79-25.27; p = 0.005) or artesunate-mefloquine (adjusted odds ratio 9.66, 95% confidence interval 2.87-32.46; p < 0.0.0001) relative to other ACTs. ACTs modified the risk factors associated with gametocyte carriage after use. Copyright © 2012 S. Karger AG, Basel.
Weighted regression analysis and interval estimators

Treesearch

Donald W. Seegrist

1974-01-01

A method for deriving the weighted least squares estimators for the parameters of a multiple regression model. Confidence intervals for expected values, and prediction intervals for the means of future samples are given.
Applications of asymptotic confidence intervals with continuity corrections for asymmetric comparisons in noninferiority trials.

PubMed

Soulakova, Julia N; Bright, Brianna C

2013-01-01

A large-sample problem of illustrating noninferiority of an experimental treatment over a referent treatment for binary outcomes is considered. The methods of illustrating noninferiority involve constructing the lower two-sided confidence bound for the difference between binomial proportions corresponding to the experimental and referent treatments and comparing it with the negative value of the noninferiority margin. The three considered methods, Anbar, Falk-Koch, and Reduced Falk-Koch, handle the comparison in an asymmetric way, that is, only the referent proportion out of the two, experimental and referent, is directly involved in the expression for the variance of the difference between two sample proportions. Five continuity corrections (including zero) are considered with respect to each approach. The key properties of the corresponding methods are evaluated via simulations. First, the uncorrected two-sided confidence intervals can, potentially, have smaller coverage probability than the nominal level even for moderately large sample sizes, for example, 150 per group. Next, the 15 testing methods are discussed in terms of their Type I error rate and power. In the settings with a relatively small referent proportion (about 0.4 or smaller), the Anbar approach with Yates' continuity correction is recommended for balanced designs and the Falk-Koch method with Yates' correction is recommended for unbalanced designs. For relatively moderate (about 0.6) and large (about 0.8 or greater) referent proportion, the uncorrected Reduced Falk-Koch method is recommended, although in this case, all methods tend to be over-conservative. These results are expected to be used in the design stage of a noninferiority study when asymmetric comparisons are envisioned. Copyright © 2013 John Wiley & Sons, Ltd.
Intraclass Correlation Coefficients in Hierarchical Design Studies with Discrete Response Variables: A Note on a Direct Interval Estimation Procedure

ERIC Educational Resources Information Center

Raykov, Tenko; Marcoulides, George A.

2015-01-01

A latent variable modeling procedure that can be used to evaluate intraclass correlation coefficients in two-level settings with discrete response variables is discussed. The approach is readily applied when the purpose is to furnish confidence intervals at prespecified confidence levels for these coefficients in setups with binary or ordinal…
Monte Carlo simulation of parameter confidence intervals for non-linear regression analysis of biological data using Microsoft Excel.

PubMed

Lambert, Ronald J W; Mytilinaios, Ioannis; Maitland, Luke; Brown, Angus M

2012-08-01

This study describes a method to obtain parameter confidence intervals from the fitting of non-linear functions to experimental data, using the SOLVER and Analysis ToolPaK Add-In of the Microsoft Excel spreadsheet. Previously we have shown that Excel can fit complex multiple functions to biological data, obtaining values equivalent to those returned by more specialized statistical or mathematical software. However, a disadvantage of using the Excel method was the inability to return confidence intervals for the computed parameters or the correlations between them. Using a simple Monte-Carlo procedure within the Excel spreadsheet (without recourse to programming), SOLVER can provide parameter estimates (up to 200 at a time) for multiple 'virtual' data sets, from which the required confidence intervals and correlation coefficients can be obtained. The general utility of the method is exemplified by applying it to the analysis of the growth of Listeria monocytogenes, the growth inhibition of Pseudomonas aeruginosa by chlorhexidine and the further analysis of the electrophysiological data from the compound action potential of the rodent optic nerve. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Influences of the Tamarisk Leaf Beetle (Diorhabda carinulata) on the diet of insectivorous birds along the Dolores River in Southwestern Colorado

USGS Publications Warehouse

Puckett, Sarah L.; van Riper, Charles

2014-01-01

We examined the effects of a biologic control agent, the tamarisk leaf beetle (Diorhabda carinulata), on native avifauna in southwestern Colorado, specifically, addressing whether and to what degree birds eat tamarisk leaf beetles. In 2010, we documented avian foraging behavior, characterized the arthropod community, sampled bird diets, and undertook an experiment to determine whether tamarisk leaf beetles are palatable to birds. We observed that tamarisk leaf beetles compose 24.0 percent (95-percent-confidence interval, 19.9-27.4 percent) and 35.4 percent (95-percent-confidence interval, 32.4-45.1 percent) of arthropod abundance and biomass in the study area, respectively. Birds ate few tamarisk leaf beetles, despite a superabundance of D. carinulata in the environment. The frequency of occurrence of tamarisk leaf beetles in bird diets was 2.1 percent (95-percent-confidence interval, 1.3- 2.9 percent) by abundance and 3.4 percent (95-percent-confidence interval, 2.6-4.2 percent) by biomass. Thus, tamarisk leaf beetles probably do not contribute significantly to the diets of birds in areas where biologic control of tamarisk is being applied.
Post-traumatic stress disorder in adolescents after a hurricane.

PubMed

Garrison, C Z; Weinrich, M W; Hardin, S B; Weinrich, S; Wang, L

1993-10-01

A school-based study conducted in 1990, 1 year after Hurricane Hugo, investigated the frequency and correlates of post-traumatic stress disorder (PTSD) in 1,264 adolescents aged 11-17 years residing in selected South Carolina communities. Data were collected via a 174-item self-administered questionnaire that included a PTSD symptom scale. A computer algorithm that applied decision rules of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised to the symptoms reported was used to assign a diagnosis of PTSD and to designate the number of individuals who met the reexperiencing (20%), avoidance (9%), and arousal (18%) criteria. Rates of PTSD were lowest in black males (1.5%) and higher, but similar, in the remaining groups (3.8-6.2%). Results from a multivariable logistic model indicated that exposure to the hurricane (odds ratio (OR) = 1.26, 95% confidence interval 1.13-1.41), experiencing other violent traumatic events (OR = 2.46, 95% confidence interval 1.75-3.44), being white (OR = 2.03, 95% confidence interval 1.12-3.69) and being female (OR = 2.17, 95% confidence interval 1.15-4.10) were significant correlates of PTSD.
Bendectin and human congenital malformations.

PubMed

Shiono, P H; Klebanoff, M A

1989-08-01

The relationship between Bendectin exposure during the first trimester of pregnancy and the occurrence of congenital malformations was prospectively studied in 31,564 newborns registered in the Northern California Kaiser Permanente Birth Defects Study. The odds ratio for any major malformation and Bendectin use was 1.0 (95% confidence interval 0.8-1.4). There were 58 categories of congenital malformations; three of them were statistically associated with Bendectin exposure (microcephaly--odds ratio = 5.3, 95% confidence interval = 1.8-15.6; congenital cataract--odds ratio = 5.3, 95% confidence interval = 1.2-24.3; lung malformations (ICD-8 codes 484.4-484.8)--odds ratio = 4.6, 95% confidence interval = 1.9-10.9). This is exactly the number of associations that would be expected by chance. An independent study (the Collaborative Perinatal Project) was used to determine whether vomiting during pregnancy in the absence of Bendectin use was associated with these three malformations. Two of the three (microcephaly and cataract) had strong positive associations with vomiting in the absence of Bendectin use. We conclude that there is no increase in the overall rate of major malformations after exposure to Bendectin and that the three associations found between Bendectin and individual malformations are unlikely to be causal.
Confidence intervals for expected moments algorithm flood quantile estimates

USGS Publications Warehouse

Cohn, Timothy A.; Lane, William L.; Stedinger, Jery R.

2001-01-01

Historical and paleoflood information can substantially improve flood frequency estimates if appropriate statistical procedures are properly applied. However, the Federal guidelines for flood frequency analysis, set forth in Bulletin 17B, rely on an inefficient “weighting” procedure that fails to take advantage of historical and paleoflood information. This has led researchers to propose several more efficient alternatives including the Expected Moments Algorithm (EMA), which is attractive because it retains Bulletin 17B's statistical structure (method of moments with the Log Pearson Type 3 distribution) and thus can be easily integrated into flood analyses employing the rest of the Bulletin 17B approach. The practical utility of EMA, however, has been limited because no closed‐form method has been available for quantifying the uncertainty of EMA‐based flood quantile estimates. This paper addresses that concern by providing analytical expressions for the asymptotic variance of EMA flood‐quantile estimators and confidence intervals for flood quantile estimates. Monte Carlo simulations demonstrate the properties of such confidence intervals for sites where a 25‐ to 100‐year streamgage record is augmented by 50 to 150 years of historical information. The experiments show that the confidence intervals, though not exact, should be acceptable for most purposes.
The role of attitudes about vaccine safety, efficacy, and value in explaining parents' reported vaccination behavior.

PubMed

Lavail, Katherine Hart; Kennedy, Allison Michelle

2013-10-01

To explain vaccine confidence as it related to parents' decisions to vaccinate their children with recommended vaccines, and to develop a confidence measure to efficiently and effectively predict parents' self-reported vaccine behaviors. A sample of parents with at least one child younger than 6 years (n = 376) was analyzed using data from the HealthStyles 2010 survey. Questions were grouped into block variables to create three confidence constructs: value, safety, and efficacy. Regression equations controlling for demographic characteristics were used to identify the confidence construct(s) that best predicted parents' self-reported vaccination decisions (accept all, some, or none of the recommended childhood vaccines). Among the three constructs evaluated, confidence in the value of vaccines, that is the belief that vaccines are important and vaccinating one's children is the right thing to do, was the best predictor of parents' vaccine decisions, F(2, 351) = 119.199, p < .001. When combined into a block variable for analysis, two survey items measuring confidence in the value of vaccines accounted for 40% of the variance in parents' self-reported vaccine decisions. Confidence in the safety or efficacy of vaccines failed to account for additional significant variance in parent-reported vaccination behavior. Confidence in the value of vaccines is a helpful predictor of parent-reported vaccination behavior. Attitudinal constructs of confidence in the safety and efficacy of vaccines failed to account for additional significant variance in parents' vaccination behaviors. Future research should assess the role of vaccine knowledge and tangible barriers, such as access and cost, to further explain parents' vaccination behaviors.
Associations between maternal periconceptional exposure to secondhand tobacco smoke and major birth defects.

PubMed

Hoyt, Adrienne T; Canfield, Mark A; Romitti, Paul A; Botto, Lorenzo D; Anderka, Marlene T; Krikov, Sergey V; Tarpey, Morgan K; Feldkamp, Marcia L

2016-11-01

While associations between secondhand smoke and a few birth defects (namely, oral clefts and neural tube defects) have been noted in the scientific literature, to our knowledge, there is no single or comprehensive source of population-based information on its associations with a range of birth defects among nonsmoking mothers. We utilized data from the National Birth Defects Prevention Study, a large population-based multisite case-control study, to examine associations between maternal reports of periconceptional exposure to secondhand smoke in the household or workplace/school and major birth defects. The multisite National Birth Defects Prevention Study is the largest case-control study of birth defects to date in the United States. We selected cases from birth defect groups having >100 total cases, as well as all nonmalformed controls (10,200), from delivery years 1997 through 2009; 44 birth defects were examined. After excluding cases and controls from multiple births and whose mothers reported active smoking or pregestational diabetes, we analyzed data on periconceptional secondhand smoke exposure-encompassing the period 1 month prior to conception through the first trimester. For the birth defect craniosynostosis, we additionally examined the effect of exposure in the second and third trimesters as well due to the potential sensitivity to teratogens for this defect throughout pregnancy. Covariates included in all final models of birth defects with ≥5 exposed mothers were study site, previous live births, time between estimated date of delivery and interview date, maternal age at estimated date of delivery, race/ethnicity, education, body mass index, nativity, household income divided by number of people supported by this income, periconceptional alcohol consumption, and folic acid supplementation. For each birth defect examined, we used logistic regression analyses to estimate both crude and adjusted odds ratios and 95% confidence intervals for both isolated and total case groups for various sources of exposure (household only; workplace/school only; household and workplace/school; household or workplace/school). The prevalence of secondhand smoke exposure only across all sources ranged from 12.9-27.8% for cases and 14.5-15.8% for controls. The adjusted odds ratios for any vs no secondhand smoke exposure in the household or workplace/school and isolated birth defects were significantly elevated for neural tube defects (anencephaly: adjusted odds ratio, 1.66; 95% confidence interval, 1.22-2.25; and spina bifida: adjusted odds ratio, 1.49; 95% confidence interval, 1.20-1.86); orofacial clefts (cleft lip without cleft palate: adjusted odds ratio, 1.41; 95% confidence interval, 1.10-1.81; cleft lip with or without cleft palate: adjusted odds ratio, 1.24; 95% confidence interval, 1.05-1.46; cleft palate alone: adjusted odds ratio, 1.31; 95% confidence interval, 1.06-1.63); bilateral renal agenesis (adjusted odds ratio, 1.99; 95% confidence interval, 1.05-3.75); amniotic band syndrome-limb body wall complex (adjusted odds ratio, 1.66; 95% confidence interval, 1.10-2.51); and atrial septal defects, secundum (adjusted odds ratio, 1.37; 95% confidence interval, 1.09-1.72). There were no significant inverse associations observed. Additional studies replicating the findings are needed to better understand the moderate positive associations observed between periconceptional secondhand smoke and several birth defects in this analysis. Increased odds ratios resulting from chance (eg, multiple comparisons) or recall bias cannot be ruled out. Copyright © 2016 Elsevier Inc. All rights reserved.
Multiple imputation methods for nonparametric inference on cumulative incidence with missing cause of failure

PubMed Central

Lee, Minjung; Dignam, James J.; Han, Junhee

2014-01-01

We propose a nonparametric approach for cumulative incidence estimation when causes of failure are unknown or missing for some subjects. Under the missing at random assumption, we estimate the cumulative incidence function using multiple imputation methods. We develop asymptotic theory for the cumulative incidence estimators obtained from multiple imputation methods. We also discuss how to construct confidence intervals for the cumulative incidence function and perform a test for comparing the cumulative incidence functions in two samples with missing cause of failure. Through simulation studies, we show that the proposed methods perform well. The methods are illustrated with data from a randomized clinical trial in early stage breast cancer. PMID:25043107
Generalized likelihood ratios for quantitative diagnostic test scores.

PubMed

Tandberg, D; Deely, J J; O'Malley, A J

1997-11-01

The reduction of quantitative diagnostic test scores to the dichotomous case is a wasteful and unnecessary simplification in the era of high-speed computing. Physicians could make better use of the information embedded in quantitative test results if modern generalized curve estimation techniques were applied to the likelihood functions of Bayes' theorem. Hand calculations could be completely avoided and computed graphical summaries provided instead. Graphs showing posttest probability of disease as a function of pretest probability with confidence intervals (POD plots) would enhance acceptance of these techniques if they were immediately available at the computer terminal when test results were retrieved. Such constructs would also provide immediate feedback to physicians when a valueless test had been ordered.

Pregnancy intentions – a complex construct and call for new measures

PubMed Central

Mumford, Sunni L.; Sapra, Katherine J.; King, Rosalind B.; Louis, Jean Fredo; Buck Louis, Germaine M.

2016-01-01

Objective To estimate the prevalence of unintended pregnancies under relaxed assumptions regarding birth control use compared with a traditional constructed measure. Design Cross-sectional survey. Setting Not applicable. Patients Nationally representative sample of U.S. females aged 15–44 years. Intervention(s) None. Main Outcome Measure(s) The prevalence of intended and unintended pregnancies as estimated by 1) a traditional constructed measure from the National Survey of Family Growth (NSFG), and 2) a constructed measure relaxing assumptions regarding birth control use, reasons for non-use, and pregnancy timing. Results The prevalence of unintended pregnancies was 6% higher using the traditional constructed measure as compared to the approach with relaxed assumptions (NSFG: 44%, 95% confidence interval [CI] 41, 46; new construct 38%, 95% CI 36, 41). Using the NSFG approach only 92% of women who stopped birth control to become pregnant and 0% of women who were not using contraceptives at the time of the pregnancy and reported that they did not mind getting pregnant were classified as having intended pregnancies, compared to 100% using the new construct. Conclusion Current measures of pregnancy intention may overestimate rates of unintended pregnancy, with over 340,000 pregnancies in the United States misclassified as unintended using the current approach, corresponding to an estimated savings of $678 million in public health care expenditures. Current constructs make assumptions that may not reflect contemporary reproductive practices and improved measures are needed. PMID:27490044
Pulmonary disease in cystic fibrosis: assessment with chest CT at chest radiography dose levels.

PubMed

Ernst, Caroline W; Basten, Ines A; Ilsen, Bart; Buls, Nico; Van Gompel, Gert; De Wachter, Elke; Nieboer, Koenraad H; Verhelle, Filip; Malfroot, Anne; Coomans, Danny; De Maeseneer, Michel; de Mey, Johan

2014-11-01

To investigate a computed tomographic (CT) protocol with iterative reconstruction at conventional radiography dose levels for the assessment of structural lung abnormalities in patients with cystic fibrosis ( CF cystic fibrosis ). In this institutional review board-approved study, 38 patients with CF cystic fibrosis (age range, 6-58 years; 21 patients <18 years and 17 patients >18 years) underwent investigative CT (at minimal exposure settings combined with iterative reconstruction) as a replacement of yearly follow-up posteroanterior chest radiography. Verbal informed consent was obtained from all patients or their parents. CT images were randomized and rated independently by two radiologists with use of the Bhalla scoring system. In addition, mosaic perfusion was evaluated. As reference, the previous available conventional chest CT scan was used. Differences in Bhalla scores were assessed with the χ(2) test and intraclass correlation coefficients ( ICC intraclass correlation coefficient s). Radiation doses for CT and radiography were assessed for adults (>18 years) and children (<18 years) separately by using technical dose descriptors and estimated effective dose. Differences in dose were assessed with the Mann-Whitney U test. The median effective dose for the investigative protocol was 0.04 mSv (95% confidence interval [ CI confidence interval ]: 0.034 mSv, 0.10 mSv) for children and 0.05 mSv (95% CI confidence interval : 0.04 mSv, 0.08 mSv) for adults. These doses were much lower than those with conventional CT (median: 0.52 mSv [95% CI confidence interval : 0.31 mSv, 3.90 mSv] for children and 1.12 mSv [95% CI confidence interval : 0.57 mSv, 3.15 mSv] for adults) and of the same order of magnitude as those for conventional radiography (median: 0.012 mSv [95% CI confidence interval : 0.006 mSv, 0.022 mSv] for children and 0.012 mSv [95% CI confidence interval : 0.005 mSv, 0.031 mSv] for adults). All images were rated at least as diagnostically acceptable. Very good agreement was found in overall Bhalla score ( ICC intraclass correlation coefficient , 0.96) with regard to the severity of bronchiectasis ( ICC intraclass correlation coefficient , 0.87) and sacculations and abscesses ( ICC intraclass correlation coefficient , 0.84). Interobserver agreement was excellent ( ICC intraclass correlation coefficient , 0.86-1). For patients with CF cystic fibrosis , a dedicated chest CT protocol can replace the two yearly follow-up chest radiographic examinations without major dose penalty and with similar diagnostic quality compared with conventional CT.
Cancer-related Concerns of Spouses of Women with Breast Cancer

PubMed Central

Fletcher, Kristin A.; Lewis, Frances Marcus; Haberman, Mel R.

2009-01-01

Objective To describe spouses' reported cancer-related demands attributed to their wife's breast cancer and to test the construct and predictive validity of a brief standardized measure of these demands. Methods Cross-sectional and longitudinal data were obtained from 151 spouses of women newly diagnosed with non-metastatic breast cancer. Descriptive statistics were computed to describe spouses' dominant cancer-related demands and multivariate regression analyses tested the construct and predictive validity of the standardized measure. Results Five categories of spouses' cancer-related demands were identified, such as concerns about: spouses' own functioning; wife's well being and response to treatment; couples' sexual activities; the family's and children's well-being; and the spouses' role in supporting their wives. A 33-item short version of the standardized measure of cancer demands demonstrated construct and predictive validity that was comparable to a 123-item version of the same questionnaire. Greater numbers of illness demands occurred when spouses were more depressed and had less confidence in their ability to manage the impact of the cancer (F=18.08 (3, 103), p<.001). Predictive validity was established by the short form's ability to significantly predict the quality of marital communication and spouses' self-efficacy at a two-month interval. Conclusion The short-version of the standardized measure of cancer-related demands shows promise for future application in clinic settings. Additional testing of the questionnaire is warranted. Spouses' breast cancer-related demands deserve attention by providers. In the absence of assisting them, spouses' illness pressures have deleterious consequences for the quality of marital communication and spouses' self-confidence. PMID:20014184
Influence of fatigue on construction workers' physical and cognitive function.

PubMed

Zhang, M; Murphy, L A; Fang, D; Caban-Martinez, A J

2015-04-01

Despite scientific evidence linking workers' fatigue to occupational safety (due to impaired physical or cognitive function), little is known about this relationship in construction workers. To assess the association between construction workers' reported fatigue and their perceived difficulties with physical and cognitive functions. Using data from a convenience sample of US construction workers participating in the 2010-11 National Health Interview Survey two multivariate weighted logistic regression models were built to predict difficulty with physical and with cognitive functions associated with workers' reported fatigue, while controlling for age, smoking status, alcohol consumption status, sleep hygiene, psychological distress and arthritis status. Of 606 construction workers surveyed, 49% reported being 'tired some days' in the past 3 months and 10% reported 'tired most days or every day'. Compared with those feeling 'never tired', workers who felt 'tired some days' were significantly more likely to report difficulty with physical function (adjusted odds ratio [AOR] = 2.03; 95% confidence interval [CI] 1.17-3.51) and cognitive function (AOR = 2.27; 95% CI 1.06-4.88) after controlling for potential confounders. Our results suggest an association between reported fatigue and experiencing difficulties with physical and cognitive functions in construction workers. © The Author 2015. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Confidence Intervals for the Probability of Superiority Effect Size Measure and the Area under a Receiver Operating Characteristic Curve

ERIC Educational Resources Information Center

Ruscio, John; Mullen, Tara

2012-01-01

It is good scientific practice to the report an appropriate estimate of effect size and a confidence interval (CI) to indicate the precision with which a population effect was estimated. For comparisons of 2 independent groups, a probability-based effect size estimator (A) that is equal to the area under a receiver operating characteristic curve…
The bacterial meningitis score to distinguish bacterial from aseptic meningitis in children from Sao Paulo, Brazil.

PubMed

Mekitarian Filho, Eduardo; Horita, Sérgio Massaru; Gilio, Alfredo Elias; Alves, Anna Cláudia Dominguez; Nigrovic, Lise E

2013-09-01

In a retrospective cohort of 494 children with meningitis in Sao Paulo, Brazil, the Bacterial Meningitis Score identified all the children with bacterial meningitis (sensitivity 100%, 95% confidence interval: 92-100% and negative predictive value 100%, 95% confidence interval: 98-100%). Addition of cerebrospinal fluid lactate to the score did not improve clinical prediction rule performance.
Spacecraft utility and the development of confidence intervals for criticality of anomalies

NASA Technical Reports Server (NTRS)

Williams, R. E.

1980-01-01

The concept of spacecraft utility, a measure of its performance in orbit, is discussed and its formulation is described. Performance is defined in terms of the malfunctions that occur and the criticality to the mission of these malfunctions. Different approaches to establishing average or expected values of criticality are discussed and confidence intervals are developed for parameters used in the computation of utility.
Prevalence Estimates of Complicated Syphilis.

PubMed

Dombrowski, Julia C; Pedersen, Rolf; Marra, Christina M; Kerani, Roxanne P; Golden, Matthew R

2015-12-01

We reviewed 68 cases of possible neurosyphilis among 573 syphilis cases in King County, WA, from 3rd January 2012 to 30th September 2013; 7.9% (95% confidence interval, 5.8%-10.5%) had vision or hearing changes, and 3.5% (95% confidence interval, 2.2%-5.4%) had both symptoms and objective confirmation of complicated syphilis with either abnormal cerebrospinal fluid or an abnormal ophthalmologic examination.
Speech and language adverse effects after thalamotomy and deep brain stimulation in patients with movement disorders: A meta-analysis.

PubMed

Alomar, Soha; King, Nicolas K K; Tam, Joseph; Bari, Ausaf A; Hamani, Clement; Lozano, Andres M

2017-01-01

The thalamus has been a surgical target for the treatment of various movement disorders. Commonly used therapeutic modalities include ablative and nonablative procedures. A major clinical side effect of thalamic surgery is the appearance of speech problems. This review summarizes the data on the development of speech problems after thalamic surgery. A systematic review and meta-analysis was performed using nine databases, including Medline, Web of Science, and Cochrane Library. We also checked for articles by searching citing and cited articles. We retrieved studies between 1960 and September 2014. Of a total of 2,320 patients, 19.8% (confidence interval: 14.8-25.9) had speech difficulty after thalamotomy. Speech difficulty occurred in 15% (confidence interval: 9.8-22.2) of those treated with a unilaterally and 40.6% (confidence interval: 29.5-52.8) of those treated bilaterally. Speech impairment was noticed 2- to 3-fold more commonly after left-sided procedures (40.7% vs. 15.2%). Of the 572 patients that underwent DBS, 19.4% (confidence interval: 13.1-27.8) experienced speech difficulty. Subgroup analysis revealed that this complication occurs in 10.2% (confidence interval: 7.4-13.9) of patients treated unilaterally and 34.6% (confidence interval: 21.6-50.4) treated bilaterally. After thalamotomy, the risk was higher in Parkinson's patients compared to patients with essential tremor: 19.8% versus 4.5% in the unilateral group and 42.5% versus 13.9% in the bilateral group. After DBS, this rate was higher in essential tremor patients. Both lesioning and stimulation thalamic surgery produce adverse effects on speech. Left-sided and bilateral procedures are approximately 3-fold more likely to cause speech difficulty. This effect was higher after thalamotomy compared to DBS. In the thalamotomy group, the risk was higher in Parkinson's patients, whereas in the DBS group it was higher in patients with essential tremor. Understanding the pathophysiology of speech disturbance after thalamic procedures is a priority. © 2017 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.
Outcomes after helicopter versus ground emergency medical services for major trauma--propensity score and instrumental variable analyses: a retrospective nationwide cohort study.

PubMed

Tsuchiya, Asuka; Tsutsumi, Yusuke; Yasunaga, Hideo

2016-11-29

Because of a lack of randomized controlled trials and the methodological weakness of currently available observational studies, the benefits of helicopter emergency medical services (HEMS) over ground emergency medical services (GEMS) for major trauma patients remain uncertain. The aim of this retrospective nationwide cohort study was to compare the mortality of adults with serious traumatic injuries who were transported by HEMS and GEMS, and to analyze the effects of HEMS in various subpopulations. Using the Japan Trauma Data Bank, we evaluated all adult patients who had an injury severity score ≥ 16 transported by HEMS or GEMS during the daytime between 2004 and 2014. We compared in-hospital mortality between patients transported by HEMS and GEMS using propensity score matching, inverse probability of treatment weighting and instrumental variable analyses to adjust for measured and unmeasured confounding factors. Eligible patients (n = 21,286) from 192 hospitals included 4128 transported by HEMS and 17,158 transported by GEMS. In the propensity score-matched model, there was a significant difference in the in-hospital mortality between HEMS and GEMS groups (22.2 vs. 24.5%, risk difference -2.3% [95% confidence interval, -4.2 to -0.5]; number needed to treat, 43 [95% confidence interval, 24 to 220]). The inverse probability of treatment weighting (20.8% vs. 23.9%; risk difference, -3.9% [95% confidence interval, -5.7 to -2.1]; number needed to treat, 26 [95% confidence interval, 17 to 48]) and instrumental variable analyses showed similar results (risk difference, -6.5% [95% confidence interval, -9.2 to -3.8]; number needed to treat, 15 [95% confidence interval, 11 to 27]). HEMS transport was significantly associated with lower in-hospital mortality after falls, compression injuries, severe chest injuries, extremity (including pelvic) injuries, and traumatic arrest on arrival to the emergency department. HEMS was associated with a significantly lower mortality than GEMS in adult patients with major traumatic injuries after adjusting for measured and unmeasured confounders.
Determinants of waterpipe use amongst adolescents in Northern Sweden: a survey of use pattern, risk perception, and environmental factors.

PubMed

Ramji, Rathi; Arnetz, Judy; Nilsson, Maria; Jamil, Hikmet; Norström, Fredrik; Maziak, Wasim; Wiklund, Ywonne; Arnetz, Bengt

2015-09-15

Determinants of waterpipe use in adolescents are believed to differ from those for other tobacco products, but there is a lack of studies of possible social, cultural, or psychological aspects of waterpipe use in this population. This study applied a socioecological model to explore waterpipe use, and its relationship to other tobacco use in Swedish adolescents. A total of 106 adolescents who attended an urban high-school in northern Sweden responded to an anonymous questionnaire. Prevalence rates for waterpipe use were examined in relation to socio-demographics, peer pressure, sensation seeking behavior, harm perception, environmental factors, and depression. Thirty-three percent reported ever having smoked waterpipe (ever use), with 30% having done so during the last 30 days (current use). Among waterpipe ever users, 60% had ever smoked cigarettes in comparison to 32% of non-waterpipe smokers (95% confidence interval 1.4-7.9). The odds of having ever smoked waterpipe were three times higher among male high school seniors as well as students with lower grades. Waterpipe ever users had three times higher odds of having higher levels of sensation-seeking (95% confidence interval 1.2-9.5) and scored high on the depression scales (95% confidence interval 1.6-6.8) than non-users. The odds of waterpipe ever use were four times higher for those who perceived waterpipe products to have pleasant smell compared to cigarettes (95% confidence interval 1.7-9.8). Waterpipe ever users were twice as likely to have seen waterpipe use on television compared to non-users (95% confidence interval 1.1-5.7). The odds of having friends who smoked regularly was eight times higher for waterpipe ever users than non-users (95% confidence interval 2.1-31.2). The current study reports a high use of waterpipe in a select group of students in northern Sweden. The study adds the importance of looking at socioecological determinants of use, including peer pressure and exposure to media marketing, as well as mental health among users.
To be involved or not to be involved: a survey of public preferences for self-involvement in decision-making involving mental capacity (competency) within Europe.

PubMed

Daveson, Barbara A; Bausewein, Claudia; Murtagh, Fliss E M; Calanzani, Natalia; Higginson, Irene J; Harding, Richard; Cohen, Joachim; Simon, Steffen T; Deliens, Luc; Bechinger-English, Dorothee; Hall, Sue; Koffman, Jonathan; Ferreira, Pedro Lopes; Toscani, Franco; Gysels, Marjolein; Ceulemans, Lucas; Haugen, Dagny F; Gomes, Barbara

2013-05-01

The Council of Europe has recommended that member states of European Union encourage their citizens to make decisions about their healthcare before they lose capacity to do so. However, it is unclear whether the public wants to make such decisions beforehand. To examine public preferences for self-involvement in end-of-life care decision-making and identify associated factors. A population-based survey with 9344 adults in England, Belgium, Germany, Italy, the Netherlands, Portugal and Spain. Across countries, 74% preferred self-involvement when capable; 44% preferred self-involvement when incapable through, for example, a living will. Four factors were associated with a preference for self-involvement across capacity and incapacity scenarios, respectively: higher educational attainment ((odds ratio = 1.93-2.77), (odds ratio = 1.33-1.80)); female gender ((odds ratio = 1.27, 95% confidence interval = 1.14-1.41), (odds ratio = 1.30, 95% confidence interval = 1.20-1.42)); younger-middle age ((30-59 years: odds ratio = 1.24-1.40), (50-59 years: odds ratio = 1.23, 95% confidence interval = 1.04-1.46)) and valuing quality over quantity of life or valuing both equally ((odds ratio = 1.49-1.58), (odds ratio = 1.35-1.53)). Those with increased financial hardship (odds ratio = 0.64-0.83) and a preference to die in hospital (not a palliative care unit) (odds ratio = 0.73, 95% confidence interval = 0.60-0.88), a nursing home or residential care (odds ratio = 0.73, 95% confidence interval = 0.54-0.99) were less likely to prefer self-involvement when capable. For the incapacity scenario, single people were more likely to prefer self-involvement (odds ratio = 1.34, 95% confidence interval = 1.18-1.53). Self-involvement in decision-making is important to the European public. However, a large proportion of the public prefer to not make decisions about their care in advance of incapacity. Financial hardship, educational attainment, age, and preferences regarding quality and quantity of life require further examination; these factors should be considered in relation to policy.
Practice Patterns and Outcomes for Pemetrexed Plus Platinum Doublet as Neoadjuvant Chemotherapy in Adenocarcinomas of Lung: Looking Beyond the Usual Paradigm.

PubMed

Noronha, V; Zanwar, S; Joshi, A; Patil, V M; Mahajan, A; Janu, A; Agarwal, J P; Bhargava, P; Kapoor, A; Prabhash, K

2018-01-01

Neoadjuvant chemotherapy (NACT) is the standard of care in non-small cell lung cancers (NSCLC) with locally advanced N2 disease. There is a scarcity of data for the pemetrexed-platinum regimen as NACT. Also, apart from N2 disease, the role of NACT in locally advanced NSCLCs for tumour downstaging is unclear. Non-metastatic adenocarcinomas of lung treated with pemetrexed-platinum-based NACT were analysed. The patients with locoregionally advanced N2 disease and those who were borderline candidates for upfront definitive treatment were planned for NACT after discussion in a multidisciplinary clinic. In total, four cycles of 3-weekly pemetrexed and platinum were delivered in the combined neoadjuvant and adjuvant setting. A response assessment was carried out using RECIST criteria. Progression-free (PFS) and overall survival were calculated using the Kaplan-Meier method. Of 114 patients, 96 evaluable patients received NACT with pemetrexed-platinum. The most common indication for NACT was N2 disease at baseline (46.8%). The objective response rate was 36.4% (95% confidence interval 22-52%), including two complete and 32 partial responses, whereas 12.5% of patients had progressive disease on NACT. The median PFS was 14 months (95% confidence interval 10.7-17.3) and the median overall survival was 22 months (95% confidence interval 15.6-28.4) at a median follow-up of 16 months. There was a significant improvement in the overall survival of patients undergoing definitive therapy versus no definitive therapy (median overall survival 25 months [95% confidence interval 19.6-30.4] versus 12 months [95% confidence interval 3.2-20.7], respectively; P = 0.015, hazard ratio 0.56 [95% confidence interval 0.3-0.9]). Among patients who could not undergo definitive chemoradiation upfront due to dosimetric constraints (n = 34), 24 (70.6%) patients finally underwent definitive therapy after NACT. Pemetrexed-platinum-based NACT seems to be an effective option and many borderline cases, where upfront definitive therapy is not feasible, may become amenable to the same after incorporation of NACT. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Provider use of a participatory decision-making style with youth and caregivers and satisfaction with pediatric asthma visits.

PubMed

Sleath, Betsy; Carpenter, Delesha M; Coyne, Imelda; Davis, Scott A; Hayes Watson, Claire; Loughlin, Ceila E; Garcia, Nacire; Reuland, Daniel S; Tudor, Gail E

2018-01-01

We conducted a randomized controlled trial to test the effectiveness of an asthma question prompt list with video intervention to engage the youth during clinic visits. We examined whether the intervention was associated with 1) providers including youth and caregiver inputs more into asthma treatment regimens, 2) youth and caregivers rating providers as using more of a participatory decision-making style, and 3) youth and caregivers being more satisfied with visits. English- or Spanish-speaking youth aged 11-17 years with persistent asthma and their caregivers were recruited from four pediatric clinics and randomized to the intervention or usual care groups. The youth in the intervention group watched the video with their caregivers on an iPad and completed a one-page asthma question prompt list before their clinic visits. All visits were audiotaped. Generalized estimating equations were used to analyze the data. Forty providers and their patients (n=359) participated in this study. Providers included youth input into the asthma management treatment regimens during 2.5% of visits and caregiver input during 3.3% of visits. The youth in the intervention group were significantly more likely to rate their providers as using more of a participatory decision-making style (odds ratio=1.7, 95% confidence interval=1.1, 2.5). White caregivers were significantly more likely to rate the providers as more participatory (odds ratio=2.3, 95% confidence interval=1.2, 4.4). Youth (beta=4.9, 95% confidence interval=3.3, 6.5) and caregivers (beta=7.5, 95% confidence interval=3.1, 12.0) who rated their providers as being more participatory were significantly more satisfied with their visits. Youth (beta=-1.9, 95% confidence interval=-3.4, -0.4) and caregivers (beta=-8.8, 95% confidence interval=-16.2, -1.3) who spoke Spanish at home were less satisfied with visits. The intervention did not increase the inclusion of youth and caregiver inputs into asthma treatment regimens. However, it did increase the youth's perception of participatory decision-making style of the providers, and this in turn was associated with greater satisfaction.
Clinical impact and predictors of complete ST segment resolution after primary percutaneous coronary intervention: A subanalysis of the ATLANTIC Trial.

PubMed

Fabris, Enrico; van 't Hof, Arnoud; Hamm, Christian W; Lapostolle, Frédéric; Lassen, Jens F; Goodman, Shaun G; Ten Berg, Jurriën M; Bolognese, Leonardo; Cequier, Angel; Chettibi, Mohamed; Hammett, Christopher J; Huber, Kurt; Janzon, Magnus; Merkely, Béla; Storey, Robert F; Zeymer, Uwe; Cantor, Warren J; Tsatsaris, Anne; Kerneis, Mathieu; Diallo, Abdourahmane; Vicaut, Eric; Montalescot, Gilles

2017-08-01

In the ATLANTIC (Administration of Ticagrelor in the catheterization laboratory or in the Ambulance for New ST elevation myocardial Infarction to open the Coronary artery) trial the early use of aspirin, anticoagulation, and ticagrelor coupled with very short medical contact-to-balloon times represent good indicators of optimal treatment of ST-elevation myocardial infarction and an ideal setting to explore which factors may influence coronary reperfusion beyond a well-established pre-hospital system. This study sought to evaluate predictors of complete ST-segment resolution after percutaneous coronary intervention in ST-elevation myocardial infarction patients enrolled in the ATLANTIC trial. ST-segment analysis was performed on electrocardiograms recorded at the time of inclusion (pre-hospital electrocardiogram), and one hour after percutaneous coronary intervention (post-percutaneous coronary intervention electrocardiogram) by an independent core laboratory. Complete ST-segment resolution was defined as ≥70% ST-segment resolution. Complete ST-segment resolution occurred post-percutaneous coronary intervention in 54.9% ( n=800/1456) of patients and predicted lower 30-day composite major adverse cardiovascular and cerebrovascular events (odds ratio 0.35, 95% confidence interval 0.19-0.65; p<0.01), definite stent thrombosis (odds ratio 0.18, 95% confidence interval 0.02-0.88; p=0.03), and total mortality (odds ratio 0.43, 95% confidence interval 0.19-0.97; p=0.04). In multivariate analysis, independent negative predictors of complete ST-segment resolution were the time from symptoms to pre-hospital electrocardiogram (odds ratio 0.91, 95% confidence interval 0.85-0.98; p<0.01) and diabetes mellitus (odds ratio 0.6, 95% confidence interval 0.44-0.83; p<0.01); pre-hospital ticagrelor treatment showed a favorable trend for complete ST-segment resolution (odds ratio 1.22, 95% confidence interval 0.99-1.51; p=0.06). This study confirmed that post-percutaneous coronary intervention complete ST-segment resolution is a valid surrogate marker for cardiovascular clinical outcomes. In the current era of ST-elevation myocardial infarction reperfusion, patients' delay and diabetes mellitus are independent predictors of poor reperfusion and need specific attention in the future.
Circulating tocopherols and risk of coronary artery disease: A systematic review and meta-analysis.

PubMed

Li, Guangxiao; Li, Ying; Chen, Xin; Sun, Hao; Hou, Xiaowen; Shi, Jingpu

2016-05-01

Circulating level of tocopherols was supposed to be associated with risk of coronary artery disease. However, the results from previous studies remain controversial. Therefore, we conducted a meta-analysis based on observational studies to evaluate the association between circulating tocopherols and coronary artery disease risk for the first time. Meta-analysis. PubMed, Embase and Cochrane databases were searched to retrieve articles published during January 1995 and May 2015. Articles were included if they provided sufficient information to calculate the weighted mean difference and its corresponding 95% confidence interval. Circulating level of total tocopherols was significantly lower in coronary artery disease patients than that in controls (weighted mean difference -4.33 μmol/l, 95% confidence interval -6.74 to -1.91, P < 0.01). However, circulating α-tocopherol alone was not significantly associated with coronary artery disease risk. Results from subgroup analyses showed that a lower level of circulating total tocopherols was merely associated with higher coronary artery disease risk in studies with higher sex ratio in cases (<2, weighted mean difference -0.07 μmol/l, 95% confidence interval -1.15 to 1.00, P = 0.90; ≥ 2, weighted mean difference -6.00 μmol/l, 95% confidence interval -9.76 to -2.22, P < 0.01). Similarly, a lower level of circulating total tocopherols was associated with early onset coronary artery disease rather than late onset coronary artery disease (<60 years, weighted mean difference -5.40 μmol/l, 95% confidence interval -9.22 to -1.57, P < 0.01; ≥ 60 years, weighted mean difference -1.37 μmol/l, 95% confidence interval -3.48 to 0.74, P = 0.20). We also found some discrepancies in circulating total tocopherols when the studies were stratified by matching status and assay methods. Our findings suggest that a deficiency in circulating total tocopherols might be associated with higher coronary artery disease risk. Whereas circulating α-tocopherol alone could not protect us from developing coronary artery disease. Further prospective studies were warranted to confirm our findings. © The European Society of Cardiology 2015.
Association of Preoperative Urinary Uromodulin with AKI after Cardiac Surgery.

PubMed

Garimella, Pranav S; Jaber, Bertrand L; Tighiouart, Hocine; Liangos, Orfeas; Bennett, Michael R; Devarajan, Prasad; El-Achkar, Tarek M; Sarnak, Mark J

2017-01-06

AKI is a serious complication after cardiac surgery. Although high urinary concentrations of the tubular protein uromodulin, a marker of tubular health, are associated with less AKI in animal models, its relationship in humans is unknown. A post hoc analysis of a prospective cohort study of 218 adults undergoing on-pump cardiac surgery between 2004 and 2011 was conducted. Multivariable logistic and linear regression analyses were used to evaluate the associations of preoperative urinary uromodulin-to-creatinine ratio with postoperative AKI (defined as a rise in serum creatinine of >0.3 mg/dl or >1.5 times baseline); severe AKI (doubling of creatinine or need for dialysis) and peak postoperative serum creatinine over the first 72 hours. Mean age was 68 years, 27% were women, 95% were white, and the median uromodulin-to-creatinine ratio was 10.0 μg/g. AKI developed in 64 (29%) patients. Lower urinary uromodulin-to-creatinine ratio was associated with higher odds for AKI (odds ratio, 1.49 per 1-SD lower uromodulin; 95% confidence interval, 1.04 to 2.13), which was marginally attenuated after multivariable adjustment (odds ratio, 1.43; 95% confidence interval, 0.99 to 2.07). The lowest uromodulin-to-creatinine ratio quartile was also associated with higher odds for AKI relative to the highest quartile (odds ratio, 2.94; 95% confidence interval, 1.19 to 7.26), which was slightly attenuated after multivariable adjustment (odds ratio, 2.43; 95% confidence interval, 0.91 to 6.48). A uromodulin-to-creatinine ratio below the median was associated with higher adjusted odds for severe AKI, although this did not reach statistical significance (odds ratio, 4.03; 95% confidence interval, 0.87 to 18.70). Each 1-SD lower uromodulin-to-creatinine ratio was associated with a higher adjusted mean peak serum creatinine (0.07 mg/dl per SD; 95% confidence interval, 0.02 to 0.13). Lower uromodulin-to-creatinine ratio is associated with higher odds of AKI and higher peak serum creatinine after cardiac surgery. Additional studies are needed to confirm these preliminary results. Copyright © 2016 by the American Society of Nephrology.
Association of Preoperative Urinary Uromodulin with AKI after Cardiac Surgery

PubMed Central

Garimella, Pranav S.; Jaber, Bertrand L.; Tighiouart, Hocine; Liangos, Orfeas; Bennett, Michael R.; Devarajan, Prasad; El-Achkar, Tarek M.

2017-01-01

Background and objectives AKI is a serious complication after cardiac surgery. Although high urinary concentrations of the tubular protein uromodulin, a marker of tubular health, are associated with less AKI in animal models, its relationship in humans is unknown. Design, setting, participants, & measurements A post hoc analysis of a prospective cohort study of 218 adults undergoing on–pump cardiac surgery between 2004 and 2011 was conducted. Multivariable logistic and linear regression analyses were used to evaluate the associations of preoperative urinary uromodulin-to-creatinine ratio with postoperative AKI (defined as a rise in serum creatinine of >0.3 mg/dl or >1.5 times baseline); severe AKI (doubling of creatinine or need for dialysis) and peak postoperative serum creatinine over the first 72 hours. Results Mean age was 68 years, 27% were women, 95% were white, and the median uromodulin-to-creatinine ratio was 10.0 μg/g. AKI developed in 64 (29%) patients. Lower urinary uromodulin-to-creatinine ratio was associated with higher odds for AKI (odds ratio, 1.49 per 1-SD lower uromodulin; 95% confidence interval, 1.04 to 2.13), which was marginally attenuated after multivariable adjustment (odds ratio, 1.43; 95% confidence interval, 0.99 to 2.07). The lowest uromodulin-to-creatinine ratio quartile was also associated with higher odds for AKI relative to the highest quartile (odds ratio, 2.94; 95% confidence interval, 1.19 to 7.26), which was slightly attenuated after multivariable adjustment (odds ratio, 2.43; 95% confidence interval, 0.91 to 6.48). A uromodulin-to-creatinine ratio below the median was associated with higher adjusted odds for severe AKI, although this did not reach statistical significance (odds ratio, 4.03; 95% confidence interval, 0.87 to 18.70). Each 1-SD lower uromodulin-to-creatinine ratio was associated with a higher adjusted mean peak serum creatinine (0.07 mg/dl per SD; 95% confidence interval, 0.02 to 0.13). Conclusions Lower uromodulin-to-creatinine ratio is associated with higher odds of AKI and higher peak serum creatinine after cardiac surgery. Additional studies are needed to confirm these preliminary results. PMID:27797887
Association of CKD with Outcomes Among Patients Undergoing Transcatheter Aortic Valve Implantation

PubMed Central

Kaier, Klaus; Kaleschke, Gerrit; Gebauer, Katrin; Meyborg, Matthias; Malyar, Nasser M.; Freisinger, Eva; Baumgartner, Helmut; Reinecke, Holger; Reinöhl, Jochen

2017-01-01

Background and objectives Despitethe multiple depicted associations of CKD with reduced cardiovascular and overall prognoses, the association of CKD with outcome of patients undergoing transcatheter aortic valve implantation has still not been well described. Design, setting, participants, & measurements Data from all hospitalized patients who underwent transcatheter aortic valve implantation procedures between January 1, 2010 and December 31, 2013 in Germany were evaluated regarding influence of CKD, even in the earlier stages, on morbidity, in-hospital outcomes, and costs. Results A total of 28,716 patients were treated with transcatheter aortic valve implantation. A total of 11,189 (39.0%) suffered from CKD. Patients with CKD were predominantly women; had higher rates of comorbidities, such as coronary artery disease, heart failure at New York Heart Association 3/4, peripheral artery disease, and diabetes; and had a 1.3-fold higher estimated logistic European System for Cardiac Operative Risk Evaluation value. In-hospital mortality was independently associated with CKD stage ≥3 (up to odds ratio, 1.71; 95% confidence interval, 1.35 to 2.17; P<0.05), bleeding was independently associated with CKD stage ≥4 (up to odds ratio, 1.82; 95% confidence interval, 1.47 to 2.24; P<0.001), and AKI was independently associated with CKD stages 3 (odds ratio, 1.83; 95% confidence interval, 1.62 to 2.06) and 4 (odds ratio, 2.33; 95% confidence interval, 1.92 to 2.83 both P<0.001). The stroke risk, in contrast, was lower for patients with CKD stages 4 (odds ratio, 0.23; 95% confidence interval, 0.16 to 0.33) and 5 (odds ratio, 0.24; 95% confidence interval, 0.15 to 0.39; both P<0.001). Lengths of hospital stay were, on average, 1.2-fold longer, whereas reimbursements were, on average, only 1.03-fold higher in patients who suffered from CKD. Conclusions This analysis illustrates for the first time on a nationwide basis the association of CKD with adverse outcomes in patients who underwent transcatheter aortic valve implantation. Thus, classification of CKD stages before transcatheter aortic valve implantation is important for appropriate risk stratification. PMID:28289067
Association of CKD with Outcomes Among Patients Undergoing Transcatheter Aortic Valve Implantation.

PubMed

Lüders, Florian; Kaier, Klaus; Kaleschke, Gerrit; Gebauer, Katrin; Meyborg, Matthias; Malyar, Nasser M; Freisinger, Eva; Baumgartner, Helmut; Reinecke, Holger; Reinöhl, Jochen

2017-05-08

Despitethe multiple depicted associations of CKD with reduced cardiovascular and overall prognoses, the association of CKD with outcome of patients undergoing transcatheter aortic valve implantation has still not been well described. Data from all hospitalized patients who underwent transcatheter aortic valve implantation procedures between January 1, 2010 and December 31, 2013 in Germany were evaluated regarding influence of CKD, even in the earlier stages, on morbidity, in-hospital outcomes, and costs. A total of 28,716 patients were treated with transcatheter aortic valve implantation. A total of 11,189 (39.0%) suffered from CKD. Patients with CKD were predominantly women; had higher rates of comorbidities, such as coronary artery disease, heart failure at New York Heart Association 3/4, peripheral artery disease, and diabetes; and had a 1.3-fold higher estimated logistic European System for Cardiac Operative Risk Evaluation value. In-hospital mortality was independently associated with CKD stage ≥3 (up to odds ratio, 1.71; 95% confidence interval, 1.35 to 2.17; P <0.05), bleeding was independently associated with CKD stage ≥4 (up to odds ratio, 1.82; 95% confidence interval, 1.47 to 2.24; P <0.001), and AKI was independently associated with CKD stages 3 (odds ratio, 1.83; 95% confidence interval, 1.62 to 2.06) and 4 (odds ratio, 2.33; 95% confidence interval, 1.92 to 2.83 both P <0.001). The stroke risk, in contrast, was lower for patients with CKD stages 4 (odds ratio, 0.23; 95% confidence interval, 0.16 to 0.33) and 5 (odds ratio, 0.24; 95% confidence interval, 0.15 to 0.39; both P <0.001). Lengths of hospital stay were, on average, 1.2-fold longer, whereas reimbursements were, on average, only 1.03-fold higher in patients who suffered from CKD. This analysis illustrates for the first time on a nationwide basis the association of CKD with adverse outcomes in patients who underwent transcatheter aortic valve implantation. Thus, classification of CKD stages before transcatheter aortic valve implantation is important for appropriate risk stratification. Copyright © 2017 by the American Society of Nephrology.

Combined metformin-clomiphene in clomiphene-resistant polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials.

PubMed

Abu Hashim, Hatem; Foda, Osama; Ghayaty, Essam

2015-09-01

Our objective was to compare the effectiveness of metformin plus clomiphene citrate vs. gonadotrophins, laparoscopic ovarian diathermy, aromatase inhibitors, N-acetyl-cysteine and other insulin sensitizers+clomiphene for improving fertility outcomes in women with clomiphene-resistant polycystic ovary syndrome. PubMed, SCOPUS and CENTRAL databases were searched until April 2014 with the key words: PCOS, polycystic ovary syndrome, metformin, clomiphene citrate, ovulation induction and pregnancy. The search was limited to articles conducted with humans and published in English. The PRISMA statement was followed. Twelve randomized controlled trials (n = 1411 women) were included. Ovulation and clinical pregnancy rates per woman randomized. Compared with gonadotrophins, the metformin+clomiphene combination resulted in significantly fewer ovulations (odds ratio 0.25; 95% confidence interval 0.15-0.41; p < 0.00001, 3 trials, I(2) = 85%, n = 323) and pregnancies (odds ratio 0.45; 95% confidence interval 0.27-0.75; p = 0.002, 3 trials, I(2) = 0%, n = 323). No significant differences were found when metformin+clomiphene was compared with laparoscopic ovarian diathermy (odds ratio 0.88; 95% confidence interval 0.53-1.47; p = 0.62, 1 trial, n = 282; odds ratio 0.96; 95% confidence interval 0.60-1.54; p = 0.88, 2 trials, I(2) = 0%, n = 332, for ovulation and pregnancy rates, respectively). Likewise, no differences were observed in comparison with aromatase inhibitors (odds ratio 0.88; 95% confidence interval 0.58-1.34; p = 0.55, 3 trials, I(2) = 3%, n = 409; odds ratio 0.85; 95% confidence interval 0.53-1.36; p = 0.50, 2 trials, n = 309, for ovulation and pregnancy rates, respectively). There is evidence for the superiority of gonadotrophins, but the metformin+clomiphene combination is mainly relevant for clomiphene-resistant polycystic ovary syndrome patients and, if not effective, a next step could be gonadotrophins. More attempts with metformin+clomiphene are only relevant if there is limited access to gonadotrophins. © 2015 Nordic Federation of Societies of Obstetrics and Gynecology.
[Uncertainty characterization approaches for ecological risk assessment of polycyclic aromatic hydrocarbon in Taihu Lake].

PubMed

Guo, Guang-Hui; Wu, Feng-Chang; He, Hong-Ping; Feng, Cheng-Lian; Zhang, Rui-Qing; Li, Hui-Xian

2012-04-01

Probabilistic approaches, such as Monte Carlo Sampling (MCS) and Latin Hypercube Sampling (LHS), and non-probabilistic approaches, such as interval analysis, fuzzy set theory and variance propagation, were used to characterize uncertainties associated with risk assessment of sigma PAH8 in surface water of Taihu Lake. The results from MCS and LHS were represented by probability distributions of hazard quotients of sigma PAH8 in surface waters of Taihu Lake. The probabilistic distribution of hazard quotient were obtained from the results of MCS and LHS based on probabilistic theory, which indicated that the confidence intervals of hazard quotient at 90% confidence level were in the range of 0.000 18-0.89 and 0.000 17-0.92, with the mean of 0.37 and 0.35, respectively. In addition, the probabilities that the hazard quotients from MCS and LHS exceed the threshold of 1 were 9.71% and 9.68%, respectively. The sensitivity analysis suggested the toxicity data contributed the most to the resulting distribution of quotients. The hazard quotient of sigma PAH8 to aquatic organisms ranged from 0.000 17 to 0.99 using interval analysis. The confidence interval was (0.001 5, 0.016 3) at the 90% confidence level calculated using fuzzy set theory, and the confidence interval was (0.000 16, 0.88) at the 90% confidence level based on the variance propagation. These results indicated that the ecological risk of sigma PAH8 to aquatic organisms were low. Each method has its own set of advantages and limitations, which was based on different theory; therefore, the appropriate method should be selected on a case-by-case to quantify the effects of uncertainties on the ecological risk assessment. Approach based on the probabilistic theory was selected as the most appropriate method to assess the risk of sigma PAH8 in surface water of Taihu Lake, which provided an important scientific foundation of risk management and control for organic pollutants in water.
Parental self-efficacy in childhood overweight: validation of the Lifestyle Behavior Checklist in the Netherlands.

PubMed

Gerards, Sanne M P L; Hummel, Karin; Dagnelie, Pieter C; de Vries, Nanne K; Kremers, Stef P J

2013-01-18

Evaluating whether parental challenges and self-efficacy toward managing children's lifestyle behaviors are successfully addressed by interventions requires valid instruments. The Lifestyle Behavior Checklist (LBC) has recently been developed in the Australian context. It consists of two subscales: the Problem scale, which measures parental perceptions of children's behavioral problems related to overweight and obesity, and the Confidence scale, measuring parental self-efficacy in dealing with these problems. The aim of the current study was to systematically translate the questionnaire into Dutch and to evaluate its internal consistency, construct validity and test-retest reliability. The LBC was systematically translated by four experts at Maastricht University. In total, 392 parents of 3-to13-year-old children were invited to fill out two successive online questionnaires with a two-week interval. Of these, 273 parents responded to the first questionnaire (test, response rate = 69.6%), and of the 202 who could be invited for the second questionnaire (retest), 100 responded (response rate = 49.5%). We assessed the questionnaire's internal consistency (Cronbach's α), construct validity (Spearman's Rho correlation tests, using the criterion measures: restrictiveness, nurturance, and psychological control), and test-retest reliability (Spearman's Rho correlation tests). Both scales had high internal consistency (Cronbach's α ≥ 0.90). Spearman correlation coefficients indicated acceptable test-retest reliability for both the Problem scale (rs = 0.74) and the Confidence scale (rs = 0.70). The LBC Problem scale was significantly correlated to all criterion scales (nurturance, restrictiveness, psychological control) in the hypothesized direction, and the LBC Confidence scale was significantly correlated with nurturance and psychological control in the hypothesized direction, but not with restrictiveness. The Dutch translation of the LBC was found to be a reliable and reasonably valid questionnaire to measure parental perceptions of children's weight-related problem behavior and the extent to which parents feel confident to manage these problems.
Associations of High-Grade Glioma With Glioma Risk Alleles and Histories of Allergy and Smoking

PubMed Central

Lachance, Daniel H.; Yang, Ping; Johnson, Derek R.; Decker, Paul A.; Kollmeyer, Thomas M.; McCoy, Lucie S.; Rice, Terri; Xiao, Yuanyuan; Ali-Osman, Francis; Wang, Frances; Stoddard, Shawn M.; Sprau, Debra J.; Kosel, Matthew L.; Wiencke, John K.; Wiemels, Joseph L.; Patoka, Joseph S.; Davis, Faith; McCarthy, Bridget; Rynearson, Amanda L.; Worra, Joel B.; Fridley, Brooke L.; O’Neill, Brian Patrick; Buckner, Jan C.; Il’yasova, Dora; Jenkins, Robert B.; Wrensch, Margaret R.

2011-01-01

Glioma risk has consistently been inversely associated with allergy history but not with smoking history despite putative biologic plausibility. Data from 855 high-grade glioma cases and 1,160 controls from 4 geographic regions of the United States during 1997–2008 were analyzed for interactions between allergy and smoking histories and inherited variants in 5 established glioma risk regions: 5p15.3 (TERT), 8q24.21 (CCDC26/MLZE), 9p21.3 (CDKN2B), 11q23.3 (PHLDB1/DDX6), and 20q13.3 (RTEL1). The inverse relation between allergy and glioma was stronger among those who did not (odds ratioallergy-glioma = 0.40, 95% confidence interval: 0.28, 0.58) versus those who did (odds ratioallergy-glioma = 0.76, 95% confidence interval: 0.59, 0.97; Pinteraction = 0.02) carry the 9p21.3 risk allele. However, the inverse association with allergy was stronger among those who carried (odds ratioallergy-glioma = 0.44, 95% confidence interval: 0.29, 0.68) versus those who did not carry (odds ratioallergy-glioma = 0.68, 95% confidence interval: 0.54, 0.86) the 20q13.3 glioma risk allele, but this interaction was not statistically significant (P = 0.14). No relation was observed between glioma risk and smoking (odds ratio = 0.92, 95% confidence interval: 0.77, 1.10; P = 0.37), and there were no interactions for glioma risk of smoking history with any of the risk alleles. The authors’ observations are consistent with a recent report that the inherited glioma risk variants in chromosome regions 9p21.3 and 20q13.3 may modify the inverse association of allergy and glioma. PMID:21742680
Gastric dilation-volvulus in dogs attending UK emergency-care veterinary practices: prevalence, risk factors and survival.

PubMed

O'Neill, D G; Case, J; Boag, A K; Church, D B; McGreevy, P D; Thomson, P C; Brodbelt, D C

2017-11-01

To report prevalence, risk factors and clinical outcomes for presumptive gastric dilation-volvulus diagnosed among an emergency-care population of UK dogs. The study used a cross-sectional design using emergency-care veterinary clinical records from the VetCompass Programme spanning September 1, 2012 to February 28, 2014 and risk factor analysis using multivariable logistic regression modelling. The study population comprised 77,088 dogs attending 50 Vets Now clinics. Overall, 492 dogs had presumptive gastric dilation-volvulus diagnoses, giving a prevalence of 0·64% (95% Confidence interval: 0·58 to 0·70%). Compared with cross-bred dogs, breeds with the highest odds ratios for the diagnosis of presumptive gastric dilation-volvulus were the great Dane (odds ratio: 114·3, 95% Confidence interval 55·1 to 237·1, P<0·001), akita (odds ratio: 84·4, 95% Confidence interval 33·6 to 211·9, P<0·001) and dogue de Bordeaux (odds ratio: 82·9, 95% Confidence interval 39·0 to 176·3, P<0·001). Odds increased as dogs aged up to 12 years and neutered male dogs had 1·3 (95% Confidence interval 1·0 to 1·8, P=0·041) times the odds compared with entire females. Of the cases that were presented alive, 49·7% survived to discharge overall, but 79·3% of surgical cases survived to discharge. Approximately 80% of surgically managed cases survived to discharge. Certain large breeds were highly predisposed. © 2017 British Small Animal Veterinary Association.
Diagnostic accuracy of intracellular mycobacterium tuberculosis detection for tuberculous meningitis.

PubMed

Feng, Guo-dong; Shi, Ming; Ma, Lei; Chen, Ping; Wang, Bing-ju; Zhang, Min; Chang, Xiao-lin; Su, Xiu-chu; Yang, Yi-ning; Fan, Xin-hong; Dai, Wen; Liu, Ting-ting; He, Ying; Bian, Ting; Duan, Li-xin; Li, Jin-ge; Hao, Xiao-ke; Liu, Jia-yun; Xue, Xin; Song, Yun-zhang; Wu, Hai-qin; Niu, Guo-qiang; Zhang, Li; Han, Cui-juan; Lin, Hong; Lin, Zhi-hui; Liu, Jian-jun; Jian, Qian; Zhang, Jin-she; Tian, Ye; Zhou, Bai-yu; Wang, Jing; Xue, Chang-hu; Han, Xiao-fang; Wang, Jian-feng; Wang, Shou-lian; Thwaites, Guy E; Zhao, Gang

2014-02-15

Early diagnosis and treatment of tuberculous meningitis saves lives, but current laboratory diagnostic tests lack sensitivity. We investigated whether the detection of intracellular bacteria by a modified Ziehl-Neelsen stain and early secretory antigen target (ESAT)-6 in cerebrospinal fluid leukocytes improves tuberculous meningitis diagnosis. Cerebrospinal fluid specimens from patients with suspected tuberculous meningitis were stained by conventional Ziehl-Neelsen stain, a modified Ziehl-Neelsen stain involving cytospin slides with Triton processing, and an ESAT-6 immunocytochemical stain. Acid-fast bacteria and ESAT-6-expressing leukocytes were detected by microscopy. All tests were performed prospectively in a central laboratory by experienced technicians masked to the patients' final diagnosis. Two hundred and eighty patients with suspected tuberculous meningitis were enrolled. Thirty-seven had Mycobacterium tuberculosis cultured from cerebrospinal fluid; 40 had a microbiologically confirmed alternative diagnosis; the rest had probable or possible tuberculous meningitis according to published criteria. Against a clinical diagnostic gold standard the sensitivity of conventional Ziehl-Neelsen stain was 3.3% (95% confidence interval, 1.6-6.7%), compared with 82.9% (95% confidence interval, 77.4-87.3%) for modified Ziehl-Neelsen stain and 75.1% (95% confidence interval, 68.8-80.6%) for ESAT-6 immunostain. Intracellular bacteria were seen in 87.8% of the slides positive by the modified Ziehl-Neelsen stain. The specificity of modified Ziehl-Neelsen and ESAT-6 stain was 85.0% (95% confidence interval, 69.4-93.8%) and 90.0% (95% confidence interval, 75.4-96.7%), respectively. Enhanced bacterial detection by simple modification of the Ziehl-Neelsen stain and an ESAT-6 intracellular stain improve the laboratory diagnosis of tuberculous meningitis.
Dietary acid, age, and serum bicarbonate levels among adults in the United States.

PubMed

Amodu, Afolarin; Abramowitz, Matthew K

2013-12-01

Greater dietary acid has been associated with lower serum bicarbonate levels in patients with CKD. Whether this association extends to the general population and if it is modified by age are unknown. This study examined the association of the dietary acid load, estimated by net endogenous acid production, with serum bicarbonate levels in adult participants in the National Health and Nutrition Examination Survey 1999-2004. The mean serum bicarbonate was 24.9 mEq/L (SEM=0.1), and the mean estimated net endogenous acid production was 57.4 mEq/d (SEM=0.4). Serum bicarbonate was linearly associated with age, such that the oldest participants had the highest serum bicarbonate levels. After multivariable adjustment, participants in the highest quartile of net endogenous acid production had 0.40 mEq/L (95% confidence interval, -0.55 to -0.26) lower serum bicarbonate and a 33% (95% confidence interval, 3 to 72) higher likelihood of acidosis compared with those participants in the lowest quartile. There was a significant interaction by age of the association of net endogenous acid production with serum bicarbonate (P=0.005). Among participants 20-39, 40-59, and ≥60 years old, those participants in the highest net endogenous acid production quartile had 0.26 (95% confidence interval, -0.49 to -0.03), 0.60 (95% confidence interval, -0.92 to -0.29), and 0.49 (95% confidence interval, -0.84 to -0.14) mEq/L lower serum bicarbonate, respectively, compared with participants in the lowest quartile. Greater dietary acid is associated with lower serum bicarbonate in the general US population, and the magnitude of this association is greater among middle-aged and elderly persons than younger adults.
Bootstrap confidence intervals and bias correction in the estimation of HIV incidence from surveillance data with testing for recent infection.

PubMed

Carnegie, Nicole Bohme

2011-04-15

The incidence of new infections is a key measure of the status of the HIV epidemic, but accurate measurement of incidence is often constrained by limited data. Karon et al. (Statist. Med. 2008; 27:4617–4633) developed a model to estimate the incidence of HIV infection from surveillance data with biologic testing for recent infection for newly diagnosed cases. This method has been implemented by public health departments across the United States and is behind the new national incidence estimates, which are about 40 per cent higher than previous estimates. We show that the delta method approximation given for the variance of the estimator is incomplete, leading to an inflated variance estimate. This contributes to the generation of overly conservative confidence intervals, potentially obscuring important differences between populations. We demonstrate via simulation that an innovative model-based bootstrap method using the specified model for the infection and surveillance process improves confidence interval coverage and adjusts for the bias in the point estimate. Confidence interval coverage is about 94–97 per cent after correction, compared with 96–99 per cent before. The simulated bias in the estimate of incidence ranges from −6.3 to +14.6 per cent under the original model but is consistently under 1 per cent after correction by the model-based bootstrap. In an application to data from King County, Washington in 2007 we observe correction of 7.2 per cent relative bias in the incidence estimate and a 66 per cent reduction in the width of the 95 per cent confidence interval using this method. We provide open-source software to implement the method that can also be extended for alternate models.
Comparative factor analysis of the effect of postoperative peripheral parenteral nutrition on recovery of right lobe liver donors.

PubMed

Hsieh, Chia-En; Lin, Kuo-Hua; Lin, Chia-Cheng; Hwu, Yueh-Juen; Lin, Ping-Yi; Lin, Hui-Chuan; Ko, Chih-Jan; Wang, Su-Han; Chen, Yao-Li

2015-04-01

Intensive nutritional support can reduce the catabolic response, improve protein synthesis, and promote liver regeneration. This study examined whether postoperative peripheral parenteral nutrition may improve recovery and reduce the length of hospital stay in right lobe liver donors. In this retrospective study, we enrolled liver donors with residual liver volume < 50%. Donors were classified into 2 groups: donors who received (n = 44) or did not receive (n = 40) postoperative peripheral parenteral nutrition. Liver function tests included alanine aminotransferase and total bilirubin levels, and postoperative complications included pleural effusion, atelectasis, and wound complications. Hospital length of stay was included as a potential risk factor for the evaluation of the effect of postoperative peripheral parenteral nutrition on recovery of right lobe liver donors. Male sex (β, 22.04; 95% confidence interval: 6.22 - 37.86) was a significant predictor of changes in postoperative alanine aminotransferase level. Male sex (β, 0.045; 95% confidence interval: 0.16 - 37.86) and receipt of peripheral parenteral nutrition (β, -0.045; 95% confidence interval: -0.72 - 0.17) were significant predictors of changes in total bilirubin level. Postoperative atelectasis (P < .001), pleural effusion (P < .011), and total complications (P = .015) had significantly lower incidence in the peripheral parenteral nutrition than control group. Multivariate logistic regression showed that recipients of peripheral parenteral nutrition (odds ratio, 0.161; 95% confidence interval: 0.043 - 0.598) and age (odds ratio, 0.870; 95% confidence interval: 0.782 - 0.968) were significant preoperative risk factors for postoperative complications. Postoperative peripheral parenteral nutrition is associated with a lower incidence of pleural effusion and atelectasis, a more rapid recovery of hyperbilirubinemia, and shorter length of stay in right lobe liver donors.
Intrauterine fetal death and risk of shoulder dystocia at delivery.

PubMed

Larsen, Sandra; Dobbin, Joanna; McCallion, Oliver; Eskild, Anne

2016-12-01

Vaginal delivery is recommended after intrauterine fetal death. However, little is known about the risk of shoulder dystocia in these deliveries. We studied whether intrauterine fetal death increases the risk of shoulder dystocia at delivery. In this population-based register study using the Medical Birth Registry of Norway, we included all singleton pregnancies with vaginal delivery of offspring in cephalic presentation in Norway during the period 1967-2012 (n = 2 266 118). Risk of shoulder dystocia was estimated as absolute risk (%) and odds ratio with 95% confidence interval. Adjustment was made for offspring birthweight (in grams). We performed sub-analyses within categories of birthweight (<4000 and ≥4000 g) and in pregnancies with maternal diabetes. Shoulder dystocia occurred in 1.1% of pregnancies with intrauterine fetal death and in 0.8% of pregnancies without intrauterine fetal death (p < 0.0001) (crude odds ratio 1.5, 95% confidence interval 1.2-4.9). After adjustment for birthweight, the odds ratio was 5.9 (95% confidence interval 4.7-7.4). In pregnancies with birthweight ≥4000 g, shoulder dystocia occurred in 14.6% of pregnancies with intrauterine fetal death and in 2.8% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 5.9, 95% confidence interval 4.5-7.9). In pregnancies with birthweight ≥4000 g and concurrent maternal diabetes, shoulder dystocia occurred in 57.1% of pregnancies with intrauterine fetal death and 9.6% of pregnancies without intrauterine fetal death (p < 0.001) (crude odds ratio 12.6, 95% confidence interval 5.9-26.9). Intrauterine fetal death increased the risk of shoulder dystocia at delivery, and the absolute risk of shoulder dystocia was particularly high if offspring birthweight was high and the mother had diabetes. © 2016 Nordic Federation of Societies of Obstetrics and Gynecology.
Prediction of posttraumatic stress disorder symptomatology after childbirth - A Croatian longitudinal study.

PubMed

Srkalović Imširagić, Azijada; Begić, Dražen; Šimičević, Livija; Bajić, Žarko

2017-02-01

Following childbirth, a vast number of women experience some degree of mood swings, while some experience symptoms of postpartum posttraumatic stress disorder. Using a biopsychosocial model, the primary aim of this study was to identify predictors of posttraumatic stress disorder and its symptomatology following childbirth. This observational, longitudinal study included 372 postpartum women. In order to explore biopsychosocial predictors, participants completed several questionnaires 3-5 days after childbirth: the Impact of Events Scale Revised, the Big Five Inventory, The Edinburgh Postnatal Depression Scale, breastfeeding practice and social and demographic factors. Six to nine weeks after childbirth, participants re-completed the questionnaires regarding psychiatric symptomatology and breastfeeding practice. Using a multivariate level of analysis, the predictors that increased the likelihood of postpartum posttraumatic stress disorder symptomatology at the first study phase were: emergency caesarean section (odds ratio 2.48; confidence interval 1.13-5.43) and neuroticism personality trait (odds ratio 1.12; confidence interval 1.05-1.20). The predictor that increased the likelihood of posttraumatic stress disorder symptomatology at the second study phase was the baseline Impact of Events Scale Revised score (odds ratio 12.55; confidence interval 4.06-38.81). Predictors that decreased the likelihood of symptomatology at the second study phase were life in a nuclear family (odds ratio 0.27; confidence interval 0.09-0.77) and life in a city (odds ratio 0.29; confidence interval 0.09-0.94). Biopsychosocial theory is applicable to postpartum psychiatric disorders. In addition to screening for depression amongst postpartum women, there is a need to include other postpartum psychiatric symptomatology screenings in routine practice. Copyright © 2016 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.
The association between the metabolic syndrome and metabolic syndrome score and pulmonary function in non-smoking adults.

PubMed

Yoon, Hyun; Gi, Mi Young; Cha, Ju Ae; Yoo, Chan Uk; Park, Sang Muk

2018-03-01

This study assessed the association of metabolic syndrome and metabolic syndrome score with the predicted forced vital capacity and predicted forced expiratory volume in 1 s (predicted forced expiratory volume in 1 s) values in Korean non-smoking adults. We analysed data obtained from 6684 adults during the 2013-2015 Korean National Health and Nutrition Examination Survey. After adjustment for related variables, metabolic syndrome ( p < 0.001) and metabolic syndrome score ( p < 0.001) were found to be inversely associated with the predicted forced vital capacity and forced expiratory volume in 1 s values. The odds ratios of restrictive pulmonary disease (the predicted forced vital capacity < 80.0% with forced expiratory volume in 1 s/FVC ⩾ 70.0%) by metabolic syndrome score with metabolic syndrome score 0 as a reference group showed no significance for metabolic syndrome score 1 [1.061 (95% confidence interval, 0.755-1.490)] and metabolic syndrome score 2 [1.247 (95% confidence interval, 0.890-1.747)], but showed significant for metabolic syndrome score 3 [1.433 (95% confidence interval, 1.010-2.033)] and metabolic syndrome score ⩾ 4 [1.760 (95% confidence interval, 1.216-2.550)]. In addition, the odds ratio of restrictive pulmonary disease of the metabolic syndrome [1.360 (95% confidence interval, 1.118-1.655)] was significantly higher than those of non-metabolic syndrome. Metabolic syndrome and metabolic syndrome score were inversely associated with the predicted forced vital capacity and forced expiratory volume in 1 s values in Korean non-smoking adults. In addition, metabolic syndrome and metabolic syndrome score were positively associated with the restrictive pulmonary disease.
Prevalence of vision impairment and refractive error in school children in Ba Ria – Vung Tau province, Vietnam

PubMed Central

Paudel, Prakash; Ramson, Prasidh; Naduvilath, Thomas; Wilson, David; Phuong, Ha Thanh; Ho, Suit M; Giap, Nguyen V

2014-01-01

Background To assess the prevalence of vision impairment and refractive error in school children 12–15 years of age in Ba Ria – Vung Tau province, Vietnam. Design Prospective, cross-sectional study. Participants 2238 secondary school children. Methods Subjects were selected based on stratified multistage cluster sampling of 13 secondary schools from urban, rural and semi-urban areas. The examination included visual acuity measurements, ocular motility evaluation, cycloplegic autorefraction, and examination of the external eye, anterior segment, media and fundus. Main Outcome Measures Visual acuity and principal cause of vision impairment. Results The prevalence of uncorrected and presenting visual acuity ≤6/12 in the better eye were 19.4% (95% confidence interval, 12.5–26.3) and 12.2% (95% confidence interval, 8.8–15.6), respectively. Refractive error was the cause of vision impairment in 92.7%, amblyopia in 2.2%, cataract in 0.7%, retinal disorders in 0.4%, other causes in 1.5% and unexplained causes in the remaining 2.6%. The prevalence of vision impairment due to myopia in either eye (–0.50 diopter or greater) was 20.4% (95% confidence interval, 12.8–28.0), hyperopia (≥2.00 D) was 0.4% (95% confidence interval, 0.0–0.7) and emmetropia with astigmatism (≥0.75 D) was 0.7% (95% confidence interval, 0.2–1.2). Vision impairment due to myopia was associated with higher school grade and increased time spent reading and working on a computer. Conclusions Uncorrected refractive error, particularly myopia, among secondary school children in Vietnam is a major public health problem. School-based eye health initiative such as refractive error screening is warranted to reduce vision impairment. PMID:24299145
Prevalence of vision impairment and refractive error in school children in Ba Ria - Vung Tau province, Vietnam.

PubMed

Paudel, Prakash; Ramson, Prasidh; Naduvilath, Thomas; Wilson, David; Phuong, Ha Thanh; Ho, Suit M; Giap, Nguyen V

2014-04-01

To assess the prevalence of vision impairment and refractive error in school children 12-15 years of age in Ba Ria - Vung Tau province, Vietnam. Prospective, cross-sectional study. 2238 secondary school children. Subjects were selected based on stratified multistage cluster sampling of 13 secondary schools from urban, rural and semi-urban areas. The examination included visual acuity measurements, ocular motility evaluation, cycloplegic autorefraction, and examination of the external eye, anterior segment, media and fundus. Visual acuity and principal cause of vision impairment. The prevalence of uncorrected and presenting visual acuity ≤6/12 in the better eye were 19.4% (95% confidence interval, 12.5-26.3) and 12.2% (95% confidence interval, 8.8-15.6), respectively. Refractive error was the cause of vision impairment in 92.7%, amblyopia in 2.2%, cataract in 0.7%, retinal disorders in 0.4%, other causes in 1.5% and unexplained causes in the remaining 2.6%. The prevalence of vision impairment due to myopia in either eye (-0.50 diopter or greater) was 20.4% (95% confidence interval, 12.8-28.0), hyperopia (≥2.00 D) was 0.4% (95% confidence interval, 0.0-0.7) and emmetropia with astigmatism (≥0.75 D) was 0.7% (95% confidence interval, 0.2-1.2). Vision impairment due to myopia was associated with higher school grade and increased time spent reading and working on a computer. Uncorrected refractive error, particularly myopia, among secondary school children in Vietnam is a major public health problem. School-based eye health initiative such as refractive error screening is warranted to reduce vision impairment. © 2013 The Authors. Clinical & Experimental Ophthalmology published by Wiley Publishing Asia Pty Ltd on behalf of Royal Australian and New Zealand College of Ophthalmologists.
Impact of Time to Treatment Initiation in Patients with Human Papillomavirus-positive and -negative Oropharyngeal Squamous Cell Carcinoma.

PubMed

Grønhøj, C; Jensen, D; Dehlendorff, C; Nørregaard, C; Andersen, E; Specht, L; Charabi, B; von Buchwald, C

2018-06-01

The distinct difference in disease phenotype of human papillomavirus-positive (HPV+) and -negative (HPV-) oropharyngeal squamous cell cancer (OPSCC) patients might also be apparent when assessing the effect of time to treatment initiation (TTI). We assessed the overall survival and progression-free survival (PFS) effect from increasing TTI for HPV+ and HPV- OPSCC patients. We examined patients who received curative-intended therapy for OPSCC in eastern Denmark between 2000 and 2014. TTI was the number of days from diagnosis to the initiation of curative treatment. Overall survival and PFS were measured from the start of treatment and estimated with the Kaplan-Meier estimator. Hazard ratios and 95% confidence intervals were estimated with Cox proportional hazard regression. At a median follow-up of 3.6 years (interquartile range 1.86-6.07 years), 1177 patients were included (59% HPV+). In the adjusted analysis for the HPV+ and HPV- patient population, TTI influenced overall survival and PFS, most evident in the HPV- group, where TTI >60 days statistically significantly influenced overall survival but not PFS (overall survival: hazard ratio 1.60; 95% confidence interval 1.04-2.45; PFS: hazard ratio 1.46; 95% confidence interval 0.96-2.22). For patients with a TTI >60 days in the HPV+ group, TTI affected overall survival and PFS similarly, with slightly lower hazard ratio estimates of 1.44 (95% confidence interval 0.83-2.51) and 1.15 (95% confidence interval 0.70-1.88), respectively. For patients treated for a HPV+ or HPV- OPSCC, TTI affects outcome, with the strongest effect for overall survival among HPV- patients. Reducing TTI is an important tool to improve the prognosis. Copyright © 2018. Published by Elsevier Ltd.
Gene polymorphisms in folate metabolizing enzymes in adult acute lymphoblastic leukemia: effects on methotrexate-related toxicity and survival

PubMed Central

Ongaro, Alessia; De Mattei, Monica; Della Porta, Matteo Giovanni; Rigolin, GianMatteo; Ambrosio, Cristina; Di Raimondo, Francesco; Pellati, Agnese; Masieri, Federica Francesca; Caruso, Angelo; Catozzi, Linda; Gemmati, Donato

2009-01-01

Background The antifolate agent methotrexate is an important component of maintenance therapy in acute lymphoblastic leukemia, although methotrexate-related toxicity is often a reason for interruption of chemotherapy. Prediction of toxicity is difficult because of inter-individual variability susceptibility to antileukemic agents. Methotrexate interferes with folate metabolism leading to depletion of reduced folates. Design and Methods The aim of this study was to investigate the influence of polymorphisms for folate metabolizing enzymes with respect to toxicity and survival in adult patients with acute lymphoblastic leukemia treated with methotrexate maintenance therapy. To this purpose, we evaluated possible associations between genotype and hematologic and non-hematologic toxicity and effects on survival at 2 years of follow-up in patients with acute lymphoblastic leukemia. Results Polymorphisms in the genes encoding for methylenetetrahydrofolate reductase (MTHFR 677C>T) and in dihydrofolate reductase (DHFR 19 bp deletion) significantly increased the risk of hepatotoxicity in single (odds ratio 5.23, 95% confidence interval 1.13–21.95 and odds ratio 4.57, 95% confidence interval 1.01–20.77, respectively) and in combined analysis (odds ratio 6.82, 95% confidence interval 1.38–33.59). MTHFR 677C>T also increased the risk of leukopenia and gastrointestinal toxicity, whilst thymidylate synthase 28 bp repeat polymorphism increased the risk of anemia (odds ratio 8.48, 95% confidence interval 2.00–36.09). Finally, patients with MTHFR 677TT had a decreased overall survival rate (hazard ratio 2.37, 95% confidence interval 1.46–8.45). Conclusions Genotyping of folate polymorphisms might be useful in adult acute lymphoblastic leukemia to optimize methotrexate therapy, reducing the associated toxicity with possible effects on survival. PMID:19648163
The thresholds for statistical and clinical significance – a five-step procedure for evaluation of intervention effects in randomised clinical trials

PubMed Central

2014-01-01

Background Thresholds for statistical significance are insufficiently demonstrated by 95% confidence intervals or P-values when assessing results from randomised clinical trials. First, a P-value only shows the probability of getting a result assuming that the null hypothesis is true and does not reflect the probability of getting a result assuming an alternative hypothesis to the null hypothesis is true. Second, a confidence interval or a P-value showing significance may be caused by multiplicity. Third, statistical significance does not necessarily result in clinical significance. Therefore, assessment of intervention effects in randomised clinical trials deserves more rigour in order to become more valid. Methods Several methodologies for assessing the statistical and clinical significance of intervention effects in randomised clinical trials were considered. Balancing simplicity and comprehensiveness, a simple five-step procedure was developed. Results For a more valid assessment of results from a randomised clinical trial we propose the following five-steps: (1) report the confidence intervals and the exact P-values; (2) report Bayes factor for the primary outcome, being the ratio of the probability that a given trial result is compatible with a ‘null’ effect (corresponding to the P-value) divided by the probability that the trial result is compatible with the intervention effect hypothesised in the sample size calculation; (3) adjust the confidence intervals and the statistical significance threshold if the trial is stopped early or if interim analyses have been conducted; (4) adjust the confidence intervals and the P-values for multiplicity due to number of outcome comparisons; and (5) assess clinical significance of the trial results. Conclusions If the proposed five-step procedure is followed, this may increase the validity of assessments of intervention effects in randomised clinical trials. PMID:24588900
Parental use of sun protection for their children-does skin color matter?

PubMed

Tan, Marcus G; Nag, Shudeshna; Weinstein, Miriam

2018-03-01

Excessive sun exposure during childhood is a risk factor for skin cancer. This study aimed to compare the frequency of ideal sun protection use between parents with lighter- and darker-skinned children and explore their attitudes and beliefs on sun safety and their choice of sun protection. Parents of children aged 6 months to 6 years completed self-administered questionnaires about sun protection practices for their children. Parents assessed their child's Fitzpatrick phototype and were divided into lighter- (Fitzpatrick phototype I-III) and darker-skinned (Fitzpatrick phototype IV-VI) groups. Sun safety guidelines from the Canadian Dermatology Association were used to qualify ideal sun protection. A total of 183 parents were included. Overall, 31 parents (17%) used ideal sun protection for their children. As their children grew older, parents were less likely to use ideal sun protection (odds ratio = 0.69, 95% confidence interval = 0.53-0.90). Parents in the lighter-skinned group were more likely to use ideal sun protection for their children (odds ratio = 7.4, 95% confidence interval = 2.7-20.1), believe that sun exposure was harmful (odds ratio = 17.2, 95% confidence interval = 4.0-74.9), and perceive value in sun protection (odds ratio = 11.4, 95% confidence interval = 3.3-39.0); the darker-skinned group believed that darker skin tones provided more sun protection (odds ratio = 12.4, 95% confidence interval = 6.1-25.4). Ideal parental sun protection efforts are overall low, particularly in parents of darker-skinned children. The identified attitudes toward and beliefs about sun safety may aid in delivery of future sun protection interventions, especially in multiracial populations. © 2018 Wiley Periodicals, Inc.
Dietary Pattern and Risk of Hodgkin Lymphoma in a Population-Based Case-Control Study

PubMed Central

Epstein, Mara M.; Chang, Ellen T.; Zhang, Yawei; Fung, Teresa T.; Batista, Julie L.; Ambinder, Richard F.; Zheng, Tongzhang; Mueller, Nancy E.; Birmann, Brenda M.

2015-01-01

Classic Hodgkin lymphoma (cHL) has few known modifiable risk factors, and the relationship between diet and cHL risk is unclear. We performed the first investigation of an association between dietary pattern and cHL risk in 435 cHL cases and 563 population-based controls from Massachusetts and Connecticut (1997–2000) who completed baseline diet questionnaires. We identified 4 major dietary patterns (“vegetable,” “high meat,” “fruit/low-fat dairy,” “desserts/sweets”) using principal components analysis. We computed multivariable odds ratios and 95% confidence intervals for associations of dietary pattern score (quartiles) with younger-adult (age <50 years), older-adult (age ≥50 years), and overall cHL risk. Secondary analyses examined associations by histological subtype and tumor Epstein-Barr virus (EBV) status. A diet high in desserts/sweets was associated with younger-adult (odds ratio(quartile 4 vs. quartile 1) = 1.60, 95% confidence interval: 1.05, 2.45; Ptrend = 0.008) and EBV-negative, younger-adult (odds ratio = 2.11, 95% confidence interval: 1.31, 3.41; Ptrend = 0.007) cHL risk. A high meat diet was associated with older-adult (odds ratio = 3.34, 95% confidence interval: 1.02, 10.91; Ptrend = 0.04) and EBV-negative, older-adult (odds ratio = 4.64, 95% confidence interval: 1.03, 20.86; Ptrend = 0.04) cHL risk. Other dietary patterns were not clearly associated with cHL. We report the first evidence for a role of dietary pattern in cHL etiology. Diets featuring high intake of meat or desserts and sweets may increase cHL risk. PMID:26182945
Dietary pattern and risk of hodgkin lymphoma in a population-based case-control study.

PubMed

Epstein, Mara M; Chang, Ellen T; Zhang, Yawei; Fung, Teresa T; Batista, Julie L; Ambinder, Richard F; Zheng, Tongzhang; Mueller, Nancy E; Birmann, Brenda M

2015-09-01

Classic Hodgkin lymphoma (cHL) has few known modifiable risk factors, and the relationship between diet and cHL risk is unclear. We performed the first investigation of an association between dietary pattern and cHL risk in 435 cHL cases and 563 population-based controls from Massachusetts and Connecticut (1997-2000) who completed baseline diet questionnaires. We identified 4 major dietary patterns ("vegetable," "high meat," "fruit/low-fat dairy," "desserts/sweets") using principal components analysis. We computed multivariable odds ratios and 95% confidence intervals for associations of dietary pattern score (quartiles) with younger-adult (age <50 years), older-adult (age ≥50 years), and overall cHL risk. Secondary analyses examined associations by histological subtype and tumor Epstein-Barr virus (EBV) status. A diet high in desserts/sweets was associated with younger-adult (odds ratio(quartile 4 vs. quartile 1) = 1.60, 95% confidence interval: 1.05, 2.45; Ptrend = 0.008) and EBV-negative, younger-adult (odds ratio = 2.11, 95% confidence interval: 1.31, 3.41; Ptrend = 0.007) cHL risk. A high meat diet was associated with older-adult (odds ratio = 3.34, 95% confidence interval: 1.02, 10.91; Ptrend = 0.04) and EBV-negative, older-adult (odds ratio = 4.64, 95% confidence interval: 1.03, 20.86; Ptrend = 0.04) cHL risk. Other dietary patterns were not clearly associated with cHL. We report the first evidence for a role of dietary pattern in cHL etiology. Diets featuring high intake of meat or desserts and sweets may increase cHL risk. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Educational achievement among long-term survivors of congenital heart defects: a Danish population-based follow-up study.

PubMed

Olsen, Morten; Hjortdal, Vibeke E; Mortensen, Laust H; Christensen, Thomas D; Sørensen, Henrik T; Pedersen, Lars

2011-04-01

Congenital heart defect patients may experience neurodevelopmental impairment. We investigated their educational attainments from basic schooling to higher education. Using administrative databases, we identified all Danish patients with a cardiac defect diagnosis born from 1 January, 1977 to 1 January, 1991 and alive at age 13 years. As a comparison cohort, we randomly sampled 10 persons per patient. We obtained information on educational attainment from Denmark's Database for Labour Market Research. The study population was followed until achievement of educational levels, death, emigration, or 1 January, 2006. We estimated the hazard ratio of attaining given educational levels, conditional on completing preceding levels, using discrete-time Cox regression and adjusting for socio-economic factors. Analyses were repeated for a sub-cohort of patients and controls born at term and without extracardiac defects or chromosomal anomalies. We identified 2986 patients. Their probability of completing compulsory basic schooling was approximately 10% lower than that of control individuals (adjusted hazard ratio = 0.79, ranged from 0.75 to 0.82 0.79; 95% confidence interval: 0.75-0.82). Their subsequent probability of completing secondary school was lower than that of the controls, both for all patients (adjusted hazard ratio = 0.74; 95% confidence interval: 0.69-0.80) and for the sub-cohort (adjusted hazard ratio = 0.80; 95% confidence interval: 0.73-0.86). The probability of attaining a higher degree, conditional on completion of youth education, was affected both for all patients (adjusted hazard ratio = 0.88; 95% confidence interval: 0.76-1.01) and for the sub-cohort (adjusted hazard ratio = 0.92; 95% confidence interval: 0.79-1.07). The probability of educational attainment was reduced among long-term congenital heart defect survivors.
A numerical approach to 14C wiggle-match dating of organic deposits: best fits and confidence intervals

NASA Astrophysics Data System (ADS)

Blaauw, Maarten; Heuvelink, Gerard B. M.; Mauquoy, Dmitri; van der Plicht, Johannes; van Geel, Bas

2003-06-01

14C wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between 14C age and calendar age to match the shape of a sequence of closely spaced peat 14C dates with the 14C calibration curve. A numerical approach to WMD enables the quantitative assessment of various possible wiggle-match solutions and of calendar year confidence intervals for sequences of 14C dates. We assess the assumptions, advantages, and limitations of the method. Several case-studies show that WMD results in more precise chronologies than when individual 14C dates are calibrated. WMD is most successful during periods with major excursions in the 14C calibration curve (e.g., in one case WMD could narrow down confidence intervals from 230 to 36 yr).
Prioritization of Candidate Genes in QTL Regions for Physiological and Biochemical Traits Underlying Drought Response in Barley (Hordeum vulgare L.)

PubMed Central

Gudys, Kornelia; Guzy-Wrobelska, Justyna; Janiak, Agnieszka; Dziurka, Michał A.; Ostrowska, Agnieszka; Hura, Katarzyna; Jurczyk, Barbara; Żmuda, Katarzyna; Grzybkowska, Daria; Śróbka, Joanna; Urban, Wojciech; Biesaga-Koscielniak, Jolanta; Filek, Maria; Koscielniak, Janusz; Mikołajczak, Krzysztof; Ogrodowicz, Piotr; Krystkowiak, Karolina; Kuczyńska, Anetta; Krajewski, Paweł; Szarejko, Iwona

2018-01-01

Drought is one of the most adverse abiotic factors limiting growth and productivity of crops. Among them is barley, ranked fourth cereal worldwide in terms of harvested acreage and production. Plants have evolved various mechanisms to cope with water deficit at different biological levels, but there is an enormous challenge to decipher genes responsible for particular complex phenotypic traits, in order to develop drought tolerant crops. This work presents a comprehensive approach for elucidation of molecular mechanisms of drought tolerance in barley at the seedling stage of development. The study includes mapping of QTLs for physiological and biochemical traits associated with drought tolerance on a high-density function map, projection of QTL confidence intervals on barley physical map, and the retrievement of positional candidate genes (CGs), followed by their prioritization based on Gene Ontology (GO) enrichment analysis. A total of 64 QTLs for 25 physiological and biochemical traits that describe plant water status, photosynthetic efficiency, osmoprotectant and hormone content, as well as antioxidant activity, were positioned on a consensus map, constructed using RIL populations developed from the crosses between European and Syrian genotypes. The map contained a total of 875 SNP, SSR and CGs, spanning 941.86 cM with resolution of 1.1 cM. For the first time, QTLs for ethylene, glucose, sucrose, maltose, raffinose, α-tocopherol, γ-tocotrienol content, and catalase activity, have been mapped in barley. Based on overlapping confidence intervals of QTLs, 11 hotspots were identified that enclosed more than 60% of mapped QTLs. Genetic and physical map integration allowed the identification of 1,101 positional CGs within the confidence intervals of drought response-specific QTLs. Prioritization resulted in the designation of 143 CGs, among them were genes encoding antioxidants, carboxylic acid biosynthesis enzymes, heat shock proteins, small auxin up-regulated RNAs, nitric oxide synthase, ATP sulfurylases, and proteins involved in regulation of flowering time. This global approach may be proposed for identification of new CGs that underlies QTLs responsible for complex traits. PMID:29946328
A statistical approach to identify, monitor, and manage incomplete curated data sets.

PubMed

Howe, Douglas G

2018-04-02

Many biological knowledge bases gather data through expert curation of published literature. High data volume, selective partial curation, delays in access, and publication of data prior to the ability to curate it can result in incomplete curation of published data. Knowing which data sets are incomplete and how incomplete they are remains a challenge. Awareness that a data set may be incomplete is important for proper interpretation, to avoiding flawed hypothesis generation, and can justify further exploration of published literature for additional relevant data. Computational methods to assess data set completeness are needed. One such method is presented here. In this work, a multivariate linear regression model was used to identify genes in the Zebrafish Information Network (ZFIN) Database having incomplete curated gene expression data sets. Starting with 36,655 gene records from ZFIN, data aggregation, cleansing, and filtering reduced the set to 9870 gene records suitable for training and testing the model to predict the number of expression experiments per gene. Feature engineering and selection identified the following predictive variables: the number of journal publications; the number of journal publications already attributed for gene expression annotation; the percent of journal publications already attributed for expression data; the gene symbol; and the number of transgenic constructs associated with each gene. Twenty-five percent of the gene records (2483 genes) were used to train the model. The remaining 7387 genes were used to test the model. One hundred and twenty-two and 165 of the 7387 tested genes were identified as missing expression annotations based on their residuals being outside the model lower or upper 95% confidence interval respectively. The model had precision of 0.97 and recall of 0.71 at the negative 95% confidence interval and precision of 0.76 and recall of 0.73 at the positive 95% confidence interval. This method can be used to identify data sets that are incompletely curated, as demonstrated using the gene expression data set from ZFIN. This information can help both database resources and data consumers gauge when it may be useful to look further for published data to augment the existing expertly curated information.
Confidence intervals in Flow Forecasting by using artificial neural networks

NASA Astrophysics Data System (ADS)

Panagoulia, Dionysia; Tsekouras, George

2014-05-01

One of the major inadequacies in implementation of Artificial Neural Networks (ANNs) for flow forecasting is the development of confidence intervals, because the relevant estimation cannot be implemented directly, contrasted to the classical forecasting methods. The variation in the ANN output is a measure of uncertainty in the model predictions based on the training data set. Different methods for uncertainty analysis, such as bootstrap, Bayesian, Monte Carlo, have already proposed for hydrologic and geophysical models, while methods for confidence intervals, such as error output, re-sampling, multi-linear regression adapted to ANN have been used for power load forecasting [1-2]. The aim of this paper is to present the re-sampling method for ANN prediction models and to develop this for flow forecasting of the next day. The re-sampling method is based on the ascending sorting of the errors between real and predicted values for all input vectors. The cumulative sample distribution function of the prediction errors is calculated and the confidence intervals are estimated by keeping the intermediate value, rejecting the extreme values according to the desired confidence levels, and holding the intervals symmetrical in probability. For application of the confidence intervals issue, input vectors are used from the Mesochora catchment in western-central Greece. The ANN's training algorithm is the stochastic training back-propagation process with decreasing functions of learning rate and momentum term, for which an optimization process is conducted regarding the crucial parameters values, such as the number of neurons, the kind of activation functions, the initial values and time parameters of learning rate and momentum term etc. Input variables are historical data of previous days, such as flows, nonlinearly weather related temperatures and nonlinearly weather related rainfalls based on correlation analysis between the under prediction flow and each implicit input variable of different ANN structures [3]. The performance of each ANN structure is evaluated by the voting analysis based on eleven criteria, which are the root mean square error (RMSE), the correlation index (R), the mean absolute percentage error (MAPE), the mean percentage error (MPE), the mean percentage error (ME), the percentage volume in errors (VE), the percentage error in peak (MF), the normalized mean bias error (NMBE), the normalized root mean bias error (NRMSE), the Nash-Sutcliffe model efficiency coefficient (E) and the modified Nash-Sutcliffe model efficiency coefficient (E1). The next day flow for the test set is calculated using the best ANN structure's model. Consequently, the confidence intervals of various confidence levels for training, evaluation and test sets are compared in order to explore the generalisation dynamics of confidence intervals from training and evaluation sets. [1] H.S. Hippert, C.E. Pedreira, R.C. Souza, "Neural networks for short-term load forecasting: A review and evaluation," IEEE Trans. on Power Systems, vol. 16, no. 1, 2001, pp. 44-55. [2] G. J. Tsekouras, N.E. Mastorakis, F.D. Kanellos, V.T. Kontargyri, C.D. Tsirekis, I.S. Karanasiou, Ch.N. Elias, A.D. Salis, P.A. Kontaxis, A.A. Gialketsi: "Short term load forecasting in Greek interconnected power system using ANN: Confidence Interval using a novel re-sampling technique with corrective Factor", WSEAS International Conference on Circuits, Systems, Electronics, Control & Signal Processing, (CSECS '10), Vouliagmeni, Athens, Greece, December 29-31, 2010. [3] D. Panagoulia, I. Trichakis, G. J. Tsekouras: "Flow Forecasting via Artificial Neural Networks - A Study for Input Variables conditioned on atmospheric circulation", European Geosciences Union, General Assembly 2012 (NH1.1 / AS1.16 - Extreme meteorological and hydrological events induced by severe weather and climate change), Vienna, Austria, 22-27 April 2012.
Razonamiento de Estudiantes Universitarios sobre Variabilidad e Intervalos de Confianza en un Contexto Inferencial Informal = University Students' Reasoning on Variability and Confidence Intervals in Inferential Informal Context

ERIC Educational Resources Information Center

Inzunsa Cazares, Santiago

2016-01-01

This article presents the results of a qualitative research with a group of 15 university students of social sciences on informal inferential reasoning developed in a computer environment on concepts involved in the confidence intervals. The results indicate that students developed a correct reasoning about sampling variability and visualized…
40 CFR Appendix D to Part 52 - Determination of Sulfur Dioxide Emissions From Stationary Sources by Continuous Monitors

Code of Federal Regulations, 2012 CFR

2012-07-01

... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean value... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean and... operation when the pollutant concentration at the time for the measurement is zero. 1.6Calibration Drift...
40 CFR Appendix D to Part 52 - Determination of Sulfur Dioxide Emissions From Stationary Sources by Continuous Monitors

Code of Federal Regulations, 2014 CFR

2014-07-01

... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean value... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean and... operation when the pollutant concentration at the time for the measurement is zero. 1.6Calibration Drift...
40 CFR Appendix D to Part 52 - Determination of Sulfur Dioxide Emissions From Stationary Sources by Continuous Monitors

Code of Federal Regulations, 2013 CFR

2013-07-01

... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean value... confidence interval using Equations D-1 and D-2. Report the zero drift as the sum of the absolute mean and... operation when the pollutant concentration at the time for the measurement is zero. 1.6Calibration Drift...
Lower Plasma Fetuin-A Levels Are Associated With a Higher Mortality Risk in Patients With Coronary Artery Disease.

PubMed

Chen, Xuechen; Zhang, Yuan; Chen, Qian; Li, Qing; Li, Yanping; Ling, Wenhua

2017-11-01

The present study was designed to evaluate the association of circulating fetuin-A with cardiovascular disease (CVD) and all-cause mortality. We measured plasma fetuin-A in 1620 patients using an enzyme-linked immunosorbent assay kit. The patients were members of the Guangdong coronary artery disease cohort and were recruited between October 2008 and December 2011. Cox regression models were used to estimate the association between plasma fetuin-A and the risk of mortality. A total of 206 deaths were recorded during a median follow-up of 5.9 years, 146 of whom died from CVD. The hazard ratios for the second and third tertiles of the fetuin-A levels (using the first tertile as a reference) were 0.65 (95% confidence interval, 0.44-0.96) and 0.51 (95% confidence interval, 0.33-0.78) for CVD mortality ( P =0.005) and 0.65 (95% confidence interval, 0.47-0.91) and 0.48 (95% confidence interval, 0.33-0.70) for all-cause mortality ( P <0.001), respectively. Lower plasma fetuin-A levels were associated with an increased risk of all-cause and CVD mortality in patients with coronary artery disease independently of traditional CVD risk factors. © 2017 American Heart Association, Inc.
Physical activity and mortality: is the association explained by genetic selection?

PubMed

Carlsson, Sofia; Andersson, Tomas; Lichtenstein, Paul; Michaëlsson, Karl; Ahlbom, Anders

2007-08-01

Public health recommendations promote physical activity to improve health and longevity. Recent data suggest that the association between physical activity and mortality may be due to genetic selection. Using data on twins, the authors investigated whether genetic selection explains the association between physical activity and mortality. Data were based on a postal questionnaire answered by 13,109 Swedish twin pairs in 1972. The national Cause of Death Register was used for information about all-cause mortality (n=1,800) and cardiovascular disease mortality (n=638) during 1975-2004. The risk of death was reduced by 34% for men (relative risk=0.64, 95% confidence interval: 0.50, 0.83) and by 25% for women (relative risk=0.75, 95% confidence interval: 0.50, 1.14) reporting high physical activity levels. Within-pair comparisons of monozygotic twins showed that, compared with their less active co-twin, the more active twin had a 20% (odds ratio=0.80, 95% confidence interval: 0.65, 0.99) reduced risk of all-cause mortality and a 32% (odds ratio=0.68, 95% confidence interval: 0.49, 0.95) reduced risk of cardiovascular disease mortality. Results indicate that physical activity is associated with a reduced risk of mortality not due to genetic selection. This finding supports a causal link between physical activity and mortality.
Quantifying uncertainty on sediment loads using bootstrap confidence intervals

NASA Astrophysics Data System (ADS)

Slaets, Johanna I. F.; Piepho, Hans-Peter; Schmitter, Petra; Hilger, Thomas; Cadisch, Georg

2017-01-01

Load estimates are more informative than constituent concentrations alone, as they allow quantification of on- and off-site impacts of environmental processes concerning pollutants, nutrients and sediment, such as soil fertility loss, reservoir sedimentation and irrigation channel siltation. While statistical models used to predict constituent concentrations have been developed considerably over the last few years, measures of uncertainty on constituent loads are rarely reported. Loads are the product of two predictions, constituent concentration and discharge, integrated over a time period, which does not make it straightforward to produce a standard error or a confidence interval. In this paper, a linear mixed model is used to estimate sediment concentrations. A bootstrap method is then developed that accounts for the uncertainty in the concentration and discharge predictions, allowing temporal correlation in the constituent data, and can be used when data transformations are required. The method was tested for a small watershed in Northwest Vietnam for the period 2010-2011. The results showed that confidence intervals were asymmetric, with the highest uncertainty in the upper limit, and that a load of 6262 Mg year-1 had a 95 % confidence interval of (4331, 12 267) in 2010 and a load of 5543 Mg an interval of (3593, 8975) in 2011. Additionally, the approach demonstrated that direct estimates from the data were biased downwards compared to bootstrap median estimates. These results imply that constituent loads predicted from regression-type water quality models could frequently be underestimating sediment yields and their environmental impact.
A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals

NASA Technical Reports Server (NTRS)

Grimes-Ledesma, Lorie; Murthy, Pappu L. N.; Phoenix, S. Leigh; Glaser, Ronald

2007-01-01

In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Overwrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter uncertainties are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.
On the log-normality of historical magnetic-storm intensity statistics: implications for extreme-event probabilities

USGS Publications Warehouse

Love, Jeffrey J.; Rigler, E. Joshua; Pulkkinen, Antti; Riley, Pete

2015-01-01

An examination is made of the hypothesis that the statistics of magnetic-storm-maximum intensities are the realization of a log-normal stochastic process. Weighted least-squares and maximum-likelihood methods are used to fit log-normal functions to −Dst storm-time maxima for years 1957-2012; bootstrap analysis is used to established confidence limits on forecasts. Both methods provide fits that are reasonably consistent with the data; both methods also provide fits that are superior to those that can be made with a power-law function. In general, the maximum-likelihood method provides forecasts having tighter confidence intervals than those provided by weighted least-squares. From extrapolation of maximum-likelihood fits: a magnetic storm with intensity exceeding that of the 1859 Carrington event, −Dst≥850 nT, occurs about 1.13 times per century and a wide 95% confidence interval of [0.42,2.41] times per century; a 100-yr magnetic storm is identified as having a −Dst≥880 nT (greater than Carrington) but a wide 95% confidence interval of [490,1187] nT.
Dust Exposure and Coccidioidomycosis Prevention Among Solar Power Farm Construction Workers in California.

PubMed

Sondermeyer Cooksey, Gail L; Wilken, Jason A; McNary, Jennifer; Gilliss, Debra; Shusterman, Dennis; Materna, Barbara L; Vugia, Duc J

2017-08-01

To investigate if work activities, dust exposure, and protection measures were associated with a 2011 to 2014 coccidioidomycosis outbreak among workers constructing 2 solar farms in California. In 2013, we mailed self-administered questionnaires to employees who were onsite at the solar farms where the outbreak occurred to identify cases of clinical coccidioidomycosis and compare with asymptomatic workers by using multivariate logistic regression. When we compared 89 workers with clinical coccidioidomycosis to 325 asymptomatic workers, frequently being in a dust cloud or storm (odds ratio [OR] = 5.93; 95% confidence interval [CI] = 3.18, 11.06) significantly increased the odds of clinical coccidioidomycosis, whereas frequently wetting soil before soil-disturbing activity (OR = 0.42; 95% CI = 0.24, 0.75) was protective. When we controlled for being in a dust cloud or storm, frequent soil disturbance significantly increased the odds of clinical coccidioidomycosis only among those who reported wearing a respirator infrequently (OR = 2.31; 95% CI = 1.27, 4.21). Utilization of personal and employer-driven safety practices and increased coccidioidomycosis awareness among construction workers should be considered during the planning of any construction work in coccidioidomycosis-endemic regions to prevent occupational infections and outbreaks.
Acute toxicity of diazinon is similar for eight stocks of bobwhite

USGS Publications Warehouse

Hill, E.F.; Camardese, M.B.; Heinz, G.H.; Spann, J.W.; DeBevec, A.B.

1984-01-01

Nine-week-old bobwhite (Colinus virginianus) from eight different game farms were tested for their sensitivity to an acute oral exposure of technical-grade diazinon (phosphorothioic acid O, O-diethyl-O-[6-methyl- 2-(1 -methylethy 1)-4-pyrimidinyl]ester). Extraneous variables associated with interlaboratory differences in husbandry were eliminated by incubating eggs and rearing chicks to test age for all stocks simultaneously in the same facilities at the Patuxent Wildlife Research Center. Under this single set of conditions, the responses of the eight stocks of bobwhite to diazinon were statistically inseparable, with LD50 values varying from 13 mg/kg (95% confidence interval, 8-21 mg/kg) to 17 mg/kg (95% confidence interval, 11-25 mg/kg). The pooled LD50 for the eight stocks was 14.7 mg/kg (95% confidence interval,13.1-16.5 mg/kg).
Relationship Between Maximum Tsunami Amplitude and Duration of Signal

NASA Astrophysics Data System (ADS)

Kim, Yoo Yin; Whitmore, Paul M.

2014-12-01

All available tsunami observations at tide gauges situated along the North American coast were examined to determine if there is any clear relationship between maximum amplitude and signal duration. In total, 89 historical tsunami recordings generated by 13 major earthquakes between 1952 and 2011 were investigated. Tidal variations were filtered out of the signal and the duration between the arrival time and the time at which the signals drops and stays below 0.3 m amplitude was computed. The processed tsunami time series were evaluated and a linear least-squares fit with a 95 % confidence interval was examined to compare tsunami durations with maximum tsunami amplitude in the study region. The confidence interval is roughly 20 h over the range of maximum tsunami amplitudes in which we are interested. This relatively large confidence interval likely results from variations in local resonance effects, late-arriving reflections, and other effects.
Return on Investment of a Work-Family Intervention: Evidence From the Work, Family, and Health Network.

PubMed

Barbosa, Carolina; Bray, Jeremy W; Dowd, William N; Mills, Michael J; Moen, Phyllis; Wipfli, Brad; Olson, Ryan; Kelly, Erin L

2015-09-01

To estimate the return on investment (ROI) of a workplace initiative to reduce work-family conflict in a group-randomized 18-month field experiment in an information technology firm in the United States. Intervention resources were micro-costed; benefits included medical costs, productivity (presenteeism), and turnover. Regression models were used to estimate the ROI, and cluster-robust bootstrap was used to calculate its confidence interval. For each participant, model-adjusted costs of the intervention were $690 and company savings were $1850 (2011 prices). The ROI was 1.68 (95% confidence interval, -8.85 to 9.47) and was robust in sensitivity analyses. The positive ROI indicates that employers' investment in an intervention to reduce work-family conflict can enhance their business. Although this was the first study to present a confidence interval for the ROI, results are comparable with the literature.
Predictors of successful closure of patent ductus arteriosus with indomethacin.

PubMed

Ahamed, M F; Verma, P; Lee, S; Vega, M; Wang, D; Kim, M; Fuloria, M

2015-09-01

To determine whether platelet counts can predict the likelihood of successful closure of patent ductus arteriosus (PDA) with indomethacin. This was a retrospective cohort study of infants <32 weeks' gestational age (GA) and birth weight <1500 g with PDA. Clinical characteristics between infants who achieved ductal closure with indomethacin and those who failed were compared. Multivariable logistic regression was used to identify predictors of successful ductal closure. In infants with hemodynamically significant PDA, older GA (odds ratio=1.54; 95% confidence interval: 1.12 to 2.13), male gender (odds ratio=3.02; 95% confidence interval: 1.08 to 8.49) and higher platelet count (odds ratio=1.5; 95% confidence interval: 1.04 to 2.17) prior to indomethacin treatment were associated with successful ductal closure with indomethacin. Older GA, male gender and higher platelet count at time of treatment of hemodynamically significant PDA are predictors of successful ductal closure with indomethacin.
Fibroblast Growth Factor 23 and Kidney Disease Progression in Autosomal Dominant Polycystic Kidney Disease.

PubMed

Chonchol, Michel; Gitomer, Berenice; Isakova, Tamara; Cai, Xuan; Salusky, Isidro; Pereira, Renata; Abebe, Kaleab; Torres, Vicente; Steinman, Theodor I; Grantham, Jared J; Chapman, Arlene B; Schrier, Robert W; Wolf, Myles

2017-09-07

Increases in fibroblast growth factor 23 precede kidney function decline in autosomal dominant polycystic kidney disease; however, the role of fibroblast growth factor 23 in autosomal dominant polycystic kidney disease has not been well characterized. We measured intact fibroblast growth factor 23 levels in baseline serum samples from 1002 participants in the HALT-PKD Study A ( n =540; mean eGFR =91±17 ml/min per 1.73 m 2 ) and B ( n =462; mean eGFR =48±12 ml/min per 1.73 m 2 ). We used linear mixed and Cox proportional hazards models to test associations between fibroblast growth factor 23 and eGFR decline, percentage change in height-adjusted total kidney volume, and composite of time to 50% reduction in eGFR, onset of ESRD, or death. Median (interquartile range) intact fibroblast growth factor 23 was 44 (33-56) pg/ml in HALT-PKD Study A and 69 (50-93) pg/ml in Study B. In adjusted models, annualized eGFR decline was significantly faster in the upper fibroblast growth factor 23 quartile (Study A: quartile 4, -3.62; 95% confidence interval, -4.12 to -3.12 versus quartile 1, -2.51; 95% confidence interval, -2.71 to -2.30 ml/min per 1.73 m 2 ; P for trend <0.001; Study B: quartile 4, -3.74; 95% confidence interval, -4.14 to -3.34 versus quartile 1, -2.78; 95% confidence interval, -2.92 to -2.63 ml/min per 1.73 m 2 ; P for trend <0.001). In Study A, higher fibroblast growth factor 23 quartiles were associated with greater longitudinal percentage increase in height-adjusted total kidney volume in adjusted models (quartile 4, 6.76; 95% confidence interval, 5.57 to 7.96 versus quartile 1, 6.04; 95% confidence interval, 5.55 to 6.54; P for trend =0.03). In Study B, compared with the lowest quartile, the highest fibroblast growth factor 23 quartile was associated with elevated risk for the composite outcome (hazard ratio, 3.11; 95% confidence interval, 1.84 to 5.25). Addition of fibroblast growth factor 23 to a model of annualized decline in eGFR≥3.0 ml/min per 1.73 m 2 did not improve risk prediction. Higher serum fibroblast growth factor 23 concentration was associated with kidney function decline, height-adjusted total kidney volume percentage increase, and death in patients with autosomal dominant polycystic kidney disease. However, fibroblast growth factor 23 did not substantially improve prediction of rapid kidney function decline. Copyright © 2017 by the American Society of Nephrology.

Effect of modified bridge exercise on trunk muscle activity in healthy adults: a cross sectional study.

PubMed

Yoon, Jeong-Oh; Kang, Min-Hyeok; Kim, Jun-Seok; Oh, Jae-Seop

This is a cross-sectional study. University research laboratory. Fifteen healthy adults (mean age: 27.47 years) volunteered for this study. The individuals performed standard bridge exercise and modified bridge exercises with right leg-lift (single-leg-lift bridge exercise, single-leg-lift bridge exercise on an unstable surface, and single-leg-lift hip abduction bridge exercise). During the bridge exercises, electromyography of the rectus abdominis, internal oblique, erector spinae, and multifidus muscles was recorded using a wireless surface electromyography system. Two-way repeated-measures analysis of variance (exercise by side) with post hoc pairwise comparisons using Bonferroni correction was used to compare the electromyography data collected from each muscle. Bilateral internal oblique muscle activities showed significantly greater during single-leg-lift bridge exercise (95% confidence interval: right internal oblique=-8.99 to -1.08, left internal oblique=-6.84 to -0.10), single-leg-lift bridge exercise on an unstable surface (95% confidence interval: right internal oblique=-7.32 to -1.78, left internal oblique=-5.34 to -0.99), and single-leg-lift hip abduction bridge exercise (95% confidence interval: right internal oblique=-17.13 to -0.89, left internal oblique=-8.56 to -0.60) compared with standard bridge exercise. Bilateral rectus abdominis showed greater electromyography activity during single-leg-lift bridge exercise on an unstable surface (95% confidence interval: right rectus abdominis=-9.33 to -1.13, left rectus abdominis=-4.80 to -0.64) and single-leg-lift hip abduction bridge exercise (95% confidence interval: right rectus abdominis=-14.12 to -1.84, left rectus abdominis=-6.68 to -0.16) compared with standard bridge exercise. In addition, the right rectus abdominis muscle activity was greater during single-leg-lift hip abduction bridge exercise compared with single-leg-lift bridge exercise on an unstable surface (95% confidence interval=-7.51 to -0.89). For erector spinae, muscle activity was greater in right side compared with left side during all exercises (95% confidence interval: standard bridge exercise=0.19-4.53, single-leg-lift bridge exercise=0.24-10.49, single-leg-lift bridge exercise on an unstable surface=0.74-8.55, single-leg-lift hip abduction bridge exercise=0.47-11.43). There was no significant interaction and main effect for multifidus. Adding hip abduction and unstable conditions to bridge exercises may be useful strategy to facilitate the co-activation of trunk muscles. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.
Cost-effectiveness of surgical decompression for space-occupying hemispheric infarction.

PubMed

Hofmeijer, Jeannette; van der Worp, H Bart; Kappelle, L Jaap; Eshuis, Sara; Algra, Ale; Greving, Jacoba P

2013-10-01

Surgical decompression reduces mortality and increases the probability of a favorable functional outcome after space-occupying hemispheric infarction. Its cost-effectiveness is uncertain. We assessed clinical outcomes, costs, and cost-effectiveness for the first 3 years in patients who were randomized to surgical decompression or best medical treatment within 48 hours after symptom onset in the Hemicraniectomy After Middle Cerebral Artery Infarction With Life-Threatening Edema Trial (HAMLET). Data on medical consumption were derived from case record files, hospital charts, and general practitioners. We calculated costs per quality-adjusted life year (QALY). Uncertainty was assessed with bootstrapping. A Markov model was constructed to estimate costs and health outcomes after 3 years. Of 39 patients enrolled within 48 hours, 21 were randomized to surgical decompression. After 3 years, 5 surgical (24%) and 14 medical patients (78%) had died. In the first 3 years after enrollment, operated patients had more QALYs than medically treated patients (mean difference, 1.0 QALY [95% confidence interval, 0.6-1.4]), but at higher costs (mean difference, €127,000 [95% confidence interval, 73,100-181,000]), indicating incremental costs of €127,000 per QALY gained. Ninety-eight percent of incremental cost-effectiveness ratios replicated by bootstrapping were >€80,000 per QALY gained. Markov modeling suggested costs of ≈€60,000 per QALY gained for a patient's lifetime. Surgical decompression for space-occupying infarction results in an increase in QALYs, but at very high costs. http://www.controlled-trials.com. Unique identifier: ISRCTN94237756.
Design, analysis, and interpretation of field quality-control data for water-sampling projects

USGS Publications Warehouse

Mueller, David K.; Schertz, Terry L.; Martin, Jeffrey D.; Sandstrom, Mark W.

2015-01-01

The report provides extensive information about statistical methods used to analyze quality-control data in order to estimate potential bias and variability in environmental data. These methods include construction of confidence intervals on various statistical measures, such as the mean, percentiles and percentages, and standard deviation. The methods are used to compare quality-control results with the larger set of environmental data in order to determine whether the effects of bias and variability might interfere with interpretation of these data. Examples from published reports are presented to illustrate how the methods are applied, how bias and variability are reported, and how the interpretation of environmental data can be qualified based on the quality-control analysis.
The Energy Employees Occupational Illness Compensation Program Act: new legislation to compensate affected employees.

PubMed

Silver, Ken

2005-06-01

Nurses make a bureaucracy work on behalf of clients. Occupational health nurses who are already versed in basic concepts applicable to EEOICPA--confidence intervals, occupational histories, exposure assessment, and dose response--can play constructive, caring roles in assisting claimants in securing benefits under this landmark program. Occupational health nurses know that chronically ill employees have a finite number of hours a week to make phone calls, visit providers, and advocate on their own behalf. Thoughtful referrals to occupational health providers who are both experienced and supportive can come from an occupational health nurse or a family physician. Involvement of university-based programs in projects to empower organizations representing EEOICP claimants would be a welcome development.
Patients with recurrent falls attending Accident & Emergency benefit from multifactorial intervention--a randomised controlled trial.

PubMed

Davison, John; Bond, John; Dawson, Pamela; Steen, I Nicholas; Kenny, Rose Anne

2005-03-01

To determine the effectiveness of multifactorial intervention to prevent falls in cognitively intact older persons with recurrent falls. Randomised controlled trial of multifactorial (medical, physiotherapy and occupational therapy) post-fall assessment and intervention compared with conventional care. Accident & Emergency departments in a university teaching hospital and associated district general hospital. 313 cognitively intact men and women aged over 65 years presenting to Accident & Emergency with a fall or fall-related injury and at least one additional fall in the preceding year; 159 randomised to assessment and intervention and 154 to conventional care. primary outcome was the number of falls and fallers in 1 year after recruitment. Secondary outcomes included injury rates, fall-related hospital admissions, mortality and fear of falling. There were 36% fewer falls in the intervention group (relative risk 0.64, 95% confidence interval 0.46-0.90). The proportion of subjects continuing to fall (65% (94/144) compared with 68% (102/149) relative risk 0.95, 95% confidence interval 0.81-1.12), and the number of fall-related attendances and hospital admissions was not different between groups. Duration of hospital admission was reduced (mean difference admission duration 3.6 days, 95% confidence interval 0.1-7.6) and falls efficacy was better in the intervention group (mean difference in Activities Specific Balance Confidence Score of 7.5, 95% confidence interval 0.72-14.2). Multifactorial intervention is effective at reducing the fall burden in cognitively intact older persons with recurrent falls attending Accident & Emergency, but does not reduce the proportion of subjects still falling.
A Prospective, Randomized Trial of Routine Duplex Ultrasound Surveillance on Arteriovenous Fistula Maturation.

PubMed

Han, Ahram; Min, Seung-Kee; Kim, Mi-Sook; Joo, Kwon Wook; Kim, Jungsun; Ha, Jongwon; Lee, Joongyub; Min, Sang-Il

2016-10-07

Use of arteriovenous fistulas, the most preferred type of access for hemodialysis, is limited by their high maturation failure rate. The aim of this study was to assess whether aggressive surveillance with routine duplex ultrasound and intervention can decrease the maturation failure rate of arteriovenous fistulas. We conducted a single-center, parallel-group, randomized, controlled trial of patients undergoing autogenous arteriovenous fistula. Patients were randomly assigned (1:1) to either the routine duplex or selective duplex group. In the routine duplex group, duplex ultrasound and physical examination were performed 2, 4, and 8 weeks postoperatively. In the selective duplex group, duplex examination was performed only when physical examination detected an abnormality. The primary end point was the maturation failure rate 8 weeks after fistula creation. Maturation failure was defined as the inability to achieve clinical maturation ( i.e. , a successful first use) and failure to achieve sonographic maturation (fistula flow >500 ml/min and diameter >6 mm) within 8 weeks. Between June 14, 2012, and June 25, 2014, 150 patients were enrolled (75 patients in each group), and 118 of those were included in the final analysis. The maturation failure rate was lower in the routine duplex group (8 of 59; 13.6%) than in the selective duplex group (15 of 59; 25.4%), but the difference was not statistically significant (odds ratio, 0.46; 95% confidence interval, 0.18 to 1.19; P =0.10). Factors associated with maturation failure were women (odds ratio, 3.84; 95% confidence interval, 1.05 to 14.06; P =0.04), coronary artery disease (odds ratio, 6.36; 95% confidence interval, 1.62 to 24.95; P <0.01), diabetes (odds ratio, 6.10; 95% confidence interval, 1.76 to 21.19; P <0.01), and the preoperative cephalic vein diameter (odds ratio, 0.30; 95% confidence interval, 0.13 to 0.71; P <0.01). Postoperative routine duplex surveillance failed to prove superiority compared with selective duplex after physical examination for reducing arteriovenous fistula maturation failure. However, the wide 95% confidence interval for the effect of intervention precludes a firm conclusion that routine duplex surveillance was not beneficial. Copyright © 2016 by the American Society of Nephrology.
Quantitative fetal fibronectin and cervical length to predict preterm birth in asymptomatic women with previous cervical surgery.

PubMed

Vandermolen, Brooke I; Hezelgrave, Natasha L; Smout, Elizabeth M; Abbott, Danielle S; Seed, Paul T; Shennan, Andrew H

2016-10-01

Quantitative fetal fibronectin testing has demonstrated accuracy for prediction of spontaneous preterm birth in asymptomatic women with a history of preterm birth. Predictive accuracy in women with previous cervical surgery (a potentially different risk mechanism) is not known. We sought to compare the predictive accuracy of cervicovaginal fluid quantitative fetal fibronectin and cervical length testing in asymptomatic women with previous cervical surgery to that in women with 1 previous preterm birth. We conducted a prospective blinded secondary analysis of a larger observational study of cervicovaginal fluid quantitative fetal fibronectin concentration in asymptomatic women measured with a Hologic 10Q system (Hologic, Marlborough, MA). Prediction of spontaneous preterm birth (<30, <34, and <37 weeks) with cervicovaginal fluid quantitative fetal fibronectin concentration in primiparous women who had undergone at least 1 invasive cervical procedure (n = 473) was compared with prediction in women who had previous spontaneous preterm birth, preterm prelabor rupture of membranes, or late miscarriage (n = 821). Relationship with cervical length was explored. The rate of spontaneous preterm birth <34 weeks in the cervical surgery group was 3% compared with 9% in previous spontaneous preterm birth group. Receiver operating characteristic curves comparing quantitative fetal fibronectin for prediction at all 3 gestational end points were comparable between the cervical surgery and previous spontaneous preterm birth groups (34 weeks: area under the curve, 0.78 [95% confidence interval 0.64-0.93] vs 0.71 [95% confidence interval 0.64-0.78]; P = .39). Prediction of spontaneous preterm birth using cervical length compared with quantitative fetal fibronectin for prediction of preterm birth <34 weeks of gestation offered similar prediction (area under the curve, 0.88 [95% confidence interval 0.79-0.96] vs 0.77 [95% confidence interval 0.62-0.92], P = .12 in the cervical surgery group; and 0.77 [95% confidence interval 0.70-0.84] vs 0.74 [95% confidence interval 0.67-0.81], P = .32 in the previous spontaneous preterm birth group). Prediction of spontaneous preterm birth using cervicovaginal fluid quantitative fetal fibronectin in asymptomatic women with cervical surgery is valid, and has comparative accuracy to that in women with a history of spontaneous preterm birth. Copyright © 2016 Elsevier Inc. All rights reserved.
Quantitative Myocardial Perfusion Imaging Versus Visual Analysis in Diagnosing Myocardial Ischemia: A CE-MARC Substudy.

PubMed

Biglands, John D; Ibraheem, Montasir; Magee, Derek R; Radjenovic, Aleksandra; Plein, Sven; Greenwood, John P

2018-05-01

This study sought to compare the diagnostic accuracy of visual and quantitative analyses of myocardial perfusion cardiovascular magnetic resonance against a reference standard of quantitative coronary angiography. Visual analysis of perfusion cardiovascular magnetic resonance studies for assessing myocardial perfusion has been shown to have high diagnostic accuracy for coronary artery disease. However, only a few small studies have assessed the diagnostic accuracy of quantitative myocardial perfusion. This retrospective study included 128 patients randomly selected from the CE-MARC (Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease) study population such that the distribution of risk factors and disease status was proportionate to the full population. Visual analysis results of cardiovascular magnetic resonance perfusion images, by consensus of 2 expert readers, were taken from the original study reports. Quantitative myocardial blood flow estimates were obtained using Fermi-constrained deconvolution. The reference standard for myocardial ischemia was a quantitative coronary x-ray angiogram stenosis severity of ≥70% diameter in any coronary artery of >2 mm diameter, or ≥50% in the left main stem. Diagnostic performance was calculated using receiver-operating characteristic curve analysis. The area under the curve for visual analysis was 0.88 (95% confidence interval: 0.81 to 0.95) with a sensitivity of 81.0% (95% confidence interval: 69.1% to 92.8%) and specificity of 86.0% (95% confidence interval: 78.7% to 93.4%). For quantitative stress myocardial blood flow the area under the curve was 0.89 (95% confidence interval: 0.83 to 0.96) with a sensitivity of 87.5% (95% confidence interval: 77.3% to 97.7%) and specificity of 84.5% (95% confidence interval: 76.8% to 92.3%). There was no statistically significant difference between the diagnostic performance of quantitative and visual analyses (p = 0.72). Incorporating rest myocardial blood flow values to generate a myocardial perfusion reserve did not significantly increase the quantitative analysis area under the curve (p = 0.79). Quantitative perfusion has a high diagnostic accuracy for detecting coronary artery disease but is not superior to visual analysis. The incorporation of rest perfusion imaging does not improve diagnostic accuracy in quantitative perfusion analysis. Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Factors influencing repeated teenage pregnancy: a review and meta-analysis.

PubMed

Maravilla, Joemer C; Betts, Kim S; Couto E Cruz, Camila; Alati, Rosa

2017-11-01

Existing evidence of predictors of repeated teenage pregnancy has not been assessed rigorously. This systematic review provides a comprehensive evaluation of protective and risk factors that are associated with repeated teenage pregnancy through a metaanalytical consensus. We used PubMed, EMBASE, CINAHL, ProQuest, PsychINFO, ScienceDirect, Scopus, and Web of Science databases from 1997-2015 and the reference list of other relevant research papers and related reviews. Eligibility criteria included (1) epidemiologic studies that analyzed factors associated with repeated pregnancy or birth among adolescents <20 years of age who were nulliparous or experienced at least 1 pregnancy, and (2) experimental studies with an observational component that was adjusted for the intervention. We performed narrative synthesis of study characteristics, participant characteristics, study results, and quality assessment. We also conducted random-effects and quality-effects metaanalyses with meta-regression to obtain pooled odds ratios of identified factors and to determine sources of between-study heterogeneity. Twenty-six eligible epidemiologic studies, most from the United States (n=24), showed >47 factors with no evidence of publication bias for each metaanalysis. Use of contraception (pooled odds ratio, 0.60; 95% confidence interval, 0.35-1.02), particularly long-acting reversible contraceptives (pooled odds ratio, 0.19; 95% confidence interval, 0.08-0.45), considerably reduced repeated teenage pregnancy risk. Among studies about contraception, the number of follow-up visits (adjusted coefficient, 0.72; P=.102) and country of study (unadjusted coefficient, 2.57; permuted P=.071) explained between-study heterogeneity. Education-related factors, which included higher level of education (pooled odds ratio, 0.74; 95% confidence interval, 0.60-0.91) and school continuation (pooled odds ratio, 0.53; 95% confidence interval, 0.33-0.84), were found to be protective. Conversely, depression (pooled odds ratio, 1.46; 95% confidence interval, 1.14-1.87), history of abortion (pooled odds ratio, 1.66; 95% confidence interval, 1.08-2.54), and relationship factors, such as partner support, increased the repeated teenage pregnancy risk. Contraceptive use, educational factors, depression, and a history of abortion are the highly influential predictors of repeated teenage pregnancy. However, there is a lack of epidemiologic studies in low- and middle-income countries to measure the extent and characteristics of repeated teenage pregnancy across more varied settings. Copyright © 2017 Elsevier Inc. All rights reserved.
Provider use of a participatory decision-making style with youth and caregivers and satisfaction with pediatric asthma visits

PubMed Central

Sleath, Betsy; Carpenter, Delesha M; Coyne, Imelda; Davis, Scott A; Hayes Watson, Claire; Loughlin, Ceila E; Garcia, Nacire; Reuland, Daniel S; Tudor, Gail E

2018-01-01

Background We conducted a randomized controlled trial to test the effectiveness of an asthma question prompt list with video intervention to engage the youth during clinic visits. We examined whether the intervention was associated with 1) providers including youth and caregiver inputs more into asthma treatment regimens, 2) youth and caregivers rating providers as using more of a participatory decision-making style, and 3) youth and caregivers being more satisfied with visits. Methods English- or Spanish-speaking youth aged 11–17 years with persistent asthma and their caregivers were recruited from four pediatric clinics and randomized to the intervention or usual care groups. The youth in the intervention group watched the video with their caregivers on an iPad and completed a one-page asthma question prompt list before their clinic visits. All visits were audiotaped. Generalized estimating equations were used to analyze the data. Results Forty providers and their patients (n=359) participated in this study. Providers included youth input into the asthma management treatment regimens during 2.5% of visits and caregiver input during 3.3% of visits. The youth in the intervention group were significantly more likely to rate their providers as using more of a participatory decision-making style (odds ratio=1.7, 95% confidence interval=1.1, 2.5). White caregivers were significantly more likely to rate the providers as more participatory (odds ratio=2.3, 95% confidence interval=1.2, 4.4). Youth (beta=4.9, 95% confidence interval=3.3, 6.5) and caregivers (beta=7.5, 95% confidence interval=3.1, 12.0) who rated their providers as being more participatory were significantly more satisfied with their visits. Youth (beta=−1.9, 95% confidence interval=−3.4, −0.4) and caregivers (beta=−8.8, 95% confidence interval=−16.2, −1.3) who spoke Spanish at home were less satisfied with visits. Conclusion The intervention did not increase the inclusion of youth and caregiver inputs into asthma treatment regimens. However, it did increase the youth’s perception of participatory decision-making style of the providers, and this in turn was associated with greater satisfaction. PMID:29785146
Epidemiology of 1.6 million pediatric soccer-related injuries presenting to US emergency departments from 1990 to 2003.

PubMed

Leininger, Robert E; Knox, Christy L; Comstock, R Dawn

2007-02-01

As soccer participation in the United States increases, so does the number of children at risk for injury. To examine pediatric soccer-related injuries presenting to US emergency departments from 1990 to 2003. Descriptive epidemiology study. A descriptive analysis of nationally representative, pediatric, soccer-related injury data from the US Consumer Product Safety Commission's National Electronic Injury Surveillance System. Among those 2 to 18 years of age, a nationally estimated 1597528 soccer-related injuries presented to US emergency departments from 1990 to 2003. Mean age was 13.2 years (range, 2-18 years); 58.6% were male. From 1990 to 2003, there was an increase in the absolute number of injuries among girls (P < .0001). The wrist/finger/hand (20.3%), ankle (18.2%), and knee (11.4%) were the most commonly injured body parts. The most common diagnoses were sprain/strain (35.9%), contusion/abrasion (24.1%), and fracture (23.2%). Boys were more likely to have face and head/neck injuries (17.7%; relative risk, 1.40; 95% confidence interval, 1.32-1.49; P < .01) and lacerations/punctures (7.5%; relative risk, 3.31; 95% confidence interval, 2.93-3.74; P < .01) than were girls (12.7% and 2.3%, respectively). Girls were more likely to have ankle injuries (21.8%; relative risk, 1.38; 95% confidence interval, 1.33-1.45; P < .01) and knee injuries (12.9%; relative risk, 1.25; 95% confidence interval, 1.15-1.35; P < .01) than were boys (15.7% and 10.4%, respectively). Girls were more likely to have sprains or strains (42.4%) than were boys (31.3%; relative risk, 1.36; 95% confidence interval, 1.31-1.40; P < .01). Children 2 to 4 years old sustained a higher proportion of face and head/neck injuries (41.0%) than did older children (15.5%; relative risk, 2.65; 95% confidence interval, 2.09-3.36; P < .01). When comparing these data to available national statistics that estimate participation in youth soccer, true injury rates may actually be decreasing for boys and girls. Young children should be closely supervised because of risk of head injuries and rate of hospitalization. The establishment of a national database of soccer participation and injury data is needed to better identify injury risks.
Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease, and cancer: systematic review and meta-analysis.

PubMed

Ma, Chenhan; Avenell, Alison; Bolland, Mark; Hudson, Jemma; Stewart, Fiona; Robertson, Clare; Sharma, Pawana; Fraser, Cynthia; MacLennan, Graeme

2017-11-14

Objective To assess whether weight loss interventions for adults with obesity affect all cause, cardiovascular, and cancer mortality, cardiovascular disease, cancer, and body weight. Design Systematic review and meta-analysis of randomised controlled trials (RCTs) using random effects, estimating risk ratios, and mean differences. Heterogeneity investigated using Cochran's Q and I 2 statistics. Quality of evidence assessed by GRADE criteria. Data sources Medline, Embase, the Cochrane Central Register of Controlled Trials, and full texts in our trials' registry for data not evident in databases. Authors were contacted for unpublished data. Eligibility criteria for selecting studies RCTs of dietary interventions targeting weight loss, with or without exercise advice or programmes, for adults with obesity and follow-up ≥1 year. Results 54 RCTs with 30 206 participants were identified. All but one trial evaluated low fat, weight reducing diets. For the primary outcome, high quality evidence showed that weight loss interventions decrease all cause mortality (34 trials, 685 events; risk ratio 0.82, 95% confidence interval 0.71 to 0.95), with six fewer deaths per 1000 participants (95% confidence interval two to 10). For other primary outcomes moderate quality evidence showed an effect on cardiovascular mortality (eight trials, 134 events; risk ratio 0.93, 95% confidence interval 0.67 to 1.31), and very low quality evidence showed an effect on cancer mortality (eight trials, 34 events; risk ratio 0.58, 95% confidence interval 0.30 to 1.11). Twenty four trials (15 176 participants) reported high quality evidence on participants developing new cardiovascular events (1043 events; risk ratio 0.93, 95% confidence interval 0.83 to 1.04). Nineteen trials (6330 participants) provided very low quality evidence on participants developing new cancers (103 events; risk ratio 0.92, 95% confidence interval 0.63 to 1.36). Conclusions Weight reducing diets, usually low in fat and saturated fat, with or without exercise advice or programmes, may reduce premature all cause mortality in adults with obesity. Systematic review registration PROSPERO CRD42016033217. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Prospective study of physical activity and risk of postmenopausal breast cancer

PubMed Central

Leitzmann, Michael F; Moore, Steven C; Peters, Tricia M; Lacey, James V; Schatzkin, Arthur; Schairer, Catherine; Brinton, Louise A; Albanes, Demetrius

2008-01-01

Introduction To prospectively examine the relation of total, vigorous and non-vigorous physical activity to postmenopausal breast cancer risk. Methods We studied 32,269 women enrolled in the Breast Cancer Detection Demonstration Project Follow-up Study. Usual physical activity (including household, occupational and leisure activities) throughout the previous year was assessed at baseline using a self-administered questionnaire. Postmenopausal breast cancer cases were identified through self-reports, death certificates and linkage to state cancer registries. A Cox proportional hazards regression was used to estimate the relative risk and 95% confidence intervals of postmenopausal breast cancer associated with physical activity. Results During 269,792 person-years of follow-up from 1987 to 1998, 1506 new incident cases of postmenopausal breast cancer were ascertained. After adjusting for potential risk factors of breast cancer, a weak inverse association between total physical activity and postmenopausal breast cancer was suggested (relative risk comparing extreme quintiles = 0.87; 95% confidence interval = 0.74 to 1.02; p for trend = 0.21). That relation was almost entirely contributed by vigorous activity (relative risk comparing extreme categories = 0.87; 95% confidence interval = 0.74 to 1.02; p for trend = 0.08). The inverse association with vigorous activity was limited to women who were lean (ie, body mass index <25.0 kg/m2: relative risk = 0.68; 95% confidence interval = 0.54 to 0.85). In contrast, no association with vigorous activity was noted among women who were overweight or obese (ie, body mass index ≥ 25.0 kg/m2: relative risk = 1.18; 95% confidence interval = 0.93 to 1.49; p for interaction = 0.008). Non-vigorous activity showed no relation to breast cancer (relative risk comparing extreme quintiles = 1.02; 95% confidence interval = 0.87 to 1.19; p for trend = 0.86). The physical activity and breast cancer relation was not specific to a certain hormone receptor subtype. Conclusions In this cohort of postmenopausal women, breast cancer risk reduction appeared to be limited to vigorous forms of activity; it was apparent among normal weight women but not overweight women, and the relation did not vary by hormone receptor status. Our findings suggest that physical activity acts through underlying biological mechanisms that are independent of body weight control. PMID:18976449
Contraceptive confidence and timing of first birth in Moldova: an event history analysis of retrospective data.

PubMed

Lyons-Amos, Mark; Padmadas, Sabu S; Durrant, Gabriele B

2014-08-11

To test the contraceptive confidence hypothesis in a modern context. The hypothesis is that women using effective or modern contraceptive methods have increased contraceptive confidence and hence a shorter interval between marriage and first birth than users of ineffective or traditional methods. We extend the hypothesis to incorporate the role of abortion, arguing that it acts as a substitute for contraception in the study context. Moldova, a country in South-East Europe. Moldova exhibits high use of traditional contraceptive methods and abortion compared with other European countries. Data are from a secondary analysis of the 2005 Moldovan Demographic and Health Survey, a nationally representative sample survey. 5377 unmarried women were selected. The outcome measure was the interval between marriage and first birth. This was modelled using a piecewise-constant hazard regression, with abortion and contraceptive method types as primary variables along with relevant sociodemographic controls. Women with high contraceptive confidence (modern method users) have a higher cumulative hazard of first birth 36 months following marriage (0.88 (0.87 to 0.89)) compared with women with low contraceptive confidence (traditional method users, cumulative hazard: 0.85 (0.84 to 0.85)). This is consistent with the contraceptive confidence hypothesis. There is a higher cumulative hazard of first birth among women with low (0.80 (0.79 to 0.80)) and moderate abortion propensities (0.76 (0.75 to 0.77)) than women with no abortion propensity (0.73 (0.72 to 0.74)) 24 months after marriage. Effective contraceptive use tends to increase contraceptive confidence and is associated with a shorter interval between marriage and first birth. Increased use of abortion also tends to increase contraceptive confidence and shorten birth duration, although this effect is non-linear-women with a very high use of abortion tend to have lengthy intervals between marriage and first birth. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
The confidence-accuracy relationship for eyewitness identification decisions: Effects of exposure duration, retention interval, and divided attention.

PubMed

Palmer, Matthew A; Brewer, Neil; Weber, Nathan; Nagesh, Ambika

2013-03-01

Prior research points to a meaningful confidence-accuracy (CA) relationship for positive identification decisions. However, there are theoretical grounds for expecting that different aspects of the CA relationship (calibration, resolution, and over/underconfidence) might be undermined in some circumstances. This research investigated whether the CA relationship for eyewitness identification decisions is affected by three, forensically relevant variables: exposure duration, retention interval, and divided attention at encoding. In Study 1 (N = 986), a field experiment, we examined the effects of exposure duration (5 s vs. 90 s) and retention interval (immediate testing vs. a 1-week delay) on the CA relationship. In Study 2 (N = 502), we examined the effects of attention during encoding on the CA relationship by reanalyzing data from a laboratory experiment in which participants viewed a stimulus video under full or divided attention conditions and then attempted to identify two targets from separate lineups. Across both studies, all three manipulations affected identification accuracy. The central analyses concerned the CA relation for positive identification decisions. For the manipulations of exposure duration and retention interval, overconfidence was greater in the more difficult conditions (shorter exposure; delayed testing) than the easier conditions. Only the exposure duration manipulation influenced resolution (which was better for 5 s than 90 s), and only the retention interval manipulation affected calibration (which was better for immediate testing than delayed testing). In all experimental conditions, accuracy and diagnosticity increased with confidence, particularly at the upper end of the confidence scale. Implications for theory and forensic settings are discussed.
Microcephaly Case Fatality Rate Associated with Zika Virus Infection in Brazil: Current Estimates.

PubMed

Cunha, Antonio José Ledo Alves da; de Magalhães-Barbosa, Maria Clara; Lima-Setta, Fernanda; Medronho, Roberto de Andrade; Prata-Barbosa, Arnaldo

2017-05-01

Considering the currently confirmed cases of microcephaly and related deaths associated with Zika virus in Brazil, the estimated case fatality rate is 8.3% (95% confidence interval: 7.2-9.6). However, a third of the reported cases remain under investigation. If the confirmation rates of cases and deaths are the same in the future, the estimated case fatality rate will be as high as 10.5% (95% confidence interval: 9.5-11.7).
The role of latex agglutination test for the etiological diagnosis of pleural effusion in children and adolescents.

PubMed

Camargos, Paulo; Fonseca, Ana Cristina; Amantéa, Sérgio; Oliveira, Elizabeth; Benfica, Maria das Graças; Chamone, Chequer

2017-05-01

The etiological diagnosis of pleural effusion is a difficult task because the diagnostic tools can only establish a definitive etiological diagnosis in at most 76% of cases. To verify the diagnostic accuracy of the latex agglutination test (LAT) for the etiological diagnosis of pleural effusions caused by Streptococcus pneumoniae and Haemophilus influenzae type b. After thoracocentesis, paired fresh samples of pleural fluid from 418 children and adolescents were included in this investigation. They were tested blindly and simultaneously through counterimmunoelectrophoresis (CIE) and LAT for both bacteria. Sensitivity, specificity, predictive values and likelihood ratios (LR) were calculated taking CIE as a reference standard. The sensitivity and specificity of LAT was 100% (95% confidence interval, 94.4%-100%) and 83.3% (95% confidence interval, 79.0%-87.0%), respectively, whereas the positive (calculated from Bayes' theorem) and negative predictive values were, respectively, lower than 1% and 100% (95% confidence interval, 98.8%-100%). Positive and negative LR were 6.0 (95% confidence interval, 4.7-7.6) and zero, respectively. Our results suggest that LAT is a useful tool for the etiological diagnosis of pleural effusion. It is a reliable, rapid, simple to perform and shows an excellent yield in our studied population, helping to prescribe appropriate antibiotics for this clinical condition. © 2015 John Wiley & Sons Ltd.
Physician-led, hospital-linked, birth care centers can decrease cesarean section rates without increasing rates of adverse events.

PubMed

O'Hara, Margaret H; Frazier, Linda M; Stembridge, Travis W; McKay, Robert S; Mohr, Sandra N; Shalat, Stuart L

2013-09-01

This study compares outcomes at a hospital-linked, physician-led, birthing center to a traditional hospital labor and delivery service. Using de-identified electronic medical records, a retrospective cohort design was employed to evaluate 32,174 singleton births during 1998-2005. Compared with hospital service, birth care center delivery was associated with a lower rate of cesarean sections (adjusted Relative Risk = 0.73, 95% confidence interval 0.59-0.91; p < 0.001) without an increased rate of operative vaginal delivery (adjusted Relative Risk = 1.04, 95% confidence interval 0.97-1.13; p = 0.25) and a higher initiation of breastfeeding (adjusted Relative Risk = 1.28, 95% confidence interval 1.25-1.30; p ≤ 0.001). A maternal length of stay greater than 72 hours occurred less frequently in the birth care center (adjusted Relative Risk = 0.60, 95% confidence interval 0.55-0.66; p < 0.001). Comparing only women without major obstetrical risk factors, the differences in outcomes were reduced but not eliminated. Adverse maternal and infant outcomes were not increased at the birth care center. A hospital-linked, physician-led, birth care center has the potential to lower rates of cesarean sections without increasing rates of operative vaginal delivery or other adverse maternal and infant outcomes. © 2013, Copyright the Authors Journal compilation © 2013, Wiley Periodicals, Inc.
Amnioinfusion for preterm rupture of membranes.

PubMed

Hofmeyr, G J

2000-01-01

Preterm rupture of membranes places a fetus at risk of cord compression and amnionitis. Amnioinfusion aims to prevent or relieve umbilical cord compression by infusing a solution into the uterine cavity. The objective of this review was to assess the effects of amnioinfusion for preterm rupture of membranes on maternal and perinatal outcomes. The Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register were searched. Randomised trials of amnioinfusion compared to no amnioinfusion in women with preterm rupture of membranes. Eligibility and trial quality were assessed by the reviewer. One trial of 66 women was included. It had some methodological flaws. No significant differences between amnioinfusion and no amnioinfusion were detected for caesarean section (relative risk 0.32, 95% confidence interval 0.07 to 1.40); low Apgar scores (relative risk 0.28, 95% confidence interval 0.03 to 2.33) or neonatal death (relative risk 0.55, 95% confidence interval 0.05 to 5.77). In the amnioinfusion group, the number of severe fetal heart rate decelerations per hour during the first stage of labour were reduced (weighted mean difference -1.20, 95% confidence interval -1.83 to -0.57). These outcomes are consistent with those found in the Cochrane review on amnioinfusion for cord compression. There is not enough evidence concerning the use of amnioinfusion for preterm rupture of membranes.
A randomized clinical trial with two doses of an enteral diabetes-specific suplements in elderly patients with diabetes mellitus type 2.

PubMed

de Luis, D A; Izaola, O; de la Fuente, B; Terroba, M C; Cuellar, L; Cabezas, G

2013-06-01

The aim of our study was to investigate whether two different daily doses of a high monounsaturated fatty acid (MUFA) specific diabetes enteral formula could improve nutritional variables as well as metabolic parameters. We conducted a randomized, open-label, multicenter, parallel group study. 27 patients with diabetes mellitus type 2 with recent weight loss were randomized to one of two study groups: group 1 (two cans per day) and group 2 (three cans per day) for a ten week period. A significative decrease of HbA1c was detected in both groups. The decrease 0.98% (confidence interval 95% 0.19-1.88) was higher in group 2 than group 1 0.60% (confidence interval 95% 0.14-1.04). A significant increase of weight, body mass index, fat mass, albumin, prealbumin and transferrin was observed in both groups without statistical differences in this improvement between both groups. The increase of weight 4.59kg (confidence interval 95% 1.71-9.49) was higher in group 2 than group 1 1.46% (confidence interval 95% 0.39-2.54). Gastrointestinal tolerance (diarrhea episodes) with both formulas was good, without statistical differences (7.60% vs 7.14%: ns). A high monounsaturated fatty acid diabetes-specific supplement improved HbA1c and nutritional status. These improvements were higher with three supplements than with two per day.

Prevalence of tics in schoolchildren in central Spain: a population-based study.

PubMed

Cubo, Esther; Gabriel y Galán, José María Trejo; Villaverde, Vanesa Ausín; Velasco, Sara Sáez; Benito, Vanesa Delgado; Macarrón, Jesús Vicente; Guevara, José Cordero; Louis, Elan D; Benito-León, Julián

2011-08-01

Tic disorders constitute a neurodevelopmental disorder of childhood. This study sought to determine the prevalence of tic disorders in a school-based sample. A randomized sample of 1158 schoolchildren, based on clusters (classrooms) in the province of Burgos (Spain), was identified on a stratified sampling frame combining types of educational center and setting (mainstream schools and special education), using a two-phase approach (screening and diagnosis ascertainment by a neurologist). Tics with/without impairment criterion were diagnosed according to Diagnostic and Statistical Manual of Mental Disorders criteria. In mainstream schools, tics were observed in 125/741 students (16.86%; 95% confidence interval, 14.10-19.63), and were more frequent in boys (87/448, 19.42%; 95% confidence interval, 15.64-23.19) compared with girls (38/293, 12.96%; 95% confidence interval, 8.95-16.98; P = 0.03). In special education centers, tics disorders were observed in 11/54 of children (20.37%; 95% confidence interval, 8.70-32.03). Overall, tics with impairment criteria were less frequent than tics without impairment criteria (4.65% vs 11.85%, P < 0.0001). The most frequent diagnoses involved chronic motor tics (6.07%) and Tourette syndrome (5.26%). Tic disorders are common in childhood, and the use or nonuse of impairment criteria exerts a significant impact on tic prevalence estimates. Copyright © 2011 Elsevier Inc. All rights reserved.
Vitrification versus slow freezing gives excellent survival, post warming embryo morphology and pregnancy outcomes for human cleaved embryos.

PubMed

Rezazadeh Valojerdi, Mojtaba; Eftekhari-Yazdi, Poopak; Karimian, Leila; Hassani, Fatemeh; Movaghar, Bahar

2009-06-01

The objective of this retrospective study was to evaluate the efficacy of vitrification and slow freezing for the cryopreservation of human cleavage stage embryos in terms of post-warming survival rate, post-warming embryo morphology and clinical outcomes. The embryos of 305 patients at cleavage stages were cryopreserved either with vitrification (153 patients) or slow-freezing (152 patients) methods. After warming; the survival rate, post-warmed embryo morphology, clinical pregnancy and implantation rates were evaluated and compared between the two groups. In the vitrification group versus slow freezing group, the survival rate (96.9% vs. 82.8%) and the post-warmed excellent morphology with all blastomeres intact (91.8% vs. 56.2%) were higher with an odds ratio of 6.607 (95% confidence interval; 4.184-10.434) and 8.769 (95% confidence interval; 6.460-11.904), respectively. In this group, the clinical pregnancy rate (40.5% vs. 21.4%) and the implantation rate (16.6% vs. 6.8%) were also higher with an odds ratio of 2.427 (95%confidence interval; 1.461-4.033) and 2.726 (95% confidence interval; 1.837-4.046), respectively. Vitrification in contrast to slow freezing is an efficient method for cryopreservation of human cleavage stage embryos. Vitrification provides a higher survival rate, minimal deleterious effects on post-warming embryo morphology and it can improve clinical outcomes.
New-onset diabetes after pancreatoduodenectomy: A systematic review and meta-analysis.

PubMed

Scholten, Lianne; Mungroop, Timothy H; Haijtink, Simone A L; Issa, Yama; van Rijssen, L Bengt; Koerkamp, Bas Groot; van Eijck, Casper H; Busch, Olivier R; DeVries, J Hans; Besselink, Marc G

2018-05-17

Pancreatoduodenectomy may lead to new-onset diabetes mellitus, also known as type 3c diabetes, but the exact risk of this complication is unknown. The aim of this review was to assess the risk of new-onset diabetes mellitus after pancreatoduodenectomy. A literature search was performed in PubMed, Embase (Ovid), and the Cochrane Library for English articles published from March 1993 until March 2017 (PROSPERO registry number: CRD42016039784). Studies reporting on the risk of new-onset diabetes mellitus after pancreatoduodenectomy were included. For meta-analysis, studies were pooled using the random-effects model. All studies were appraised according to the Newcastle-Ottawa Scale. After screening 1,523 studies, 22 studies involving 1,121 patients were eligible. The mean weighted overall proportion of new-onset diabetes mellitus after pancreatoduodenectomy was 16% (95% confidence interval, 12%-20%). We found no significant difference in risk of new-onset diabetes mellitus when pancreatoduodenectomy was performed for nonmalignant disease after excluding patients with chronic pancreatitis (19% risk; 95% confidence interval, 7%-43%; 6 studies) or for malignant disease (22% risk; 95% confidence interval, 14%-32%; 11 studies), P = .71. Among all patients, 6% (95% confidence interval, 4%-10%) developed insulin-dependent new-onset diabetes mellitus. This systematic review identified a clinically relevant risk of new-onset diabetes mellitus after pancreatoduodenectomy of which patients should be informed preoperatively. Copyright © 2018 Elsevier Inc. All rights reserved.
The Valsalva manoeuvre versus tourniquet for venipuncture.

PubMed

Villa, Gianluca; Chelazzi, Cosimo; Giua, Rosa; Lavacchini, Laura; Tofani, Lorenzo; Zagli, Giovanni; Barbani, Francesco; De Gaudio, A Raffaele; Romagnoli, Stefano; Pinelli, Fulvio

2018-03-01

During ultrasound-guided cannulation, venous filling is required for venipuncture. Tourniquet with an elastic tube at the axilla is the most common method to induce venous stasis for cannulation of the deep veins of the arm. Although effective, this method might be associated with short- and long-term complications. Valsalva manoeuvre has been used to produce venous filling in other extrathoracic veins. The aim of this observational study is to demonstrate the effect of Valsalva manoeuvre in respect of the elastic tourniquet on venous distention during echography-guided cannulation of the deep veins of the arm. Sixty-nine patients scheduled for cannulation of basilic or brachial vein were prospectively observed. Vein diameters were recorded at rest and after 10 s of Valsalva or tourniquet placement. The mean difference between basilic vein diameters during tourniquet and Valsalva manoeuvre was 0.006 mm (95% confidence interval = -inf, 0.09) with a standard deviation of 0.5 mm (95% confidence interval = 0.5, 0.7; p > 0.01). The mean difference between brachial vein diameters during tourniquet and Valsalva manoeuvre was 0.04 mm (95% confidence interval = -0.23, 0.15) with a standard deviation of 0.8 mm (95% confidence interval = 0.7, 0.9; p > 0.01). This increase in cross-sectional basilic and brachial vein diameters was not different to that obtained with the elastic tube tourniquet.
Disordered eating in entry-level military personnel.

PubMed

Warner, Christopher; Warner, Carolynn; Matuszak, Theresa; Rachal, James; Flynn, Julianne; Grieger, Thomas A

2007-02-01

The goal was to determine the prevalence of and risk factors for disordered eating in an entry-level U.S. Army population. A cross-sectional survey of advanced individual training U.S. Army soldiers at Aberdeen Proving Ground, Maryland, was performed with an anonymous self-report survey containing demographic factors, history (including abuse and psychiatric treatment), and Eating Attitudes Test-26. Of 1,184 advanced individual training soldiers approached, 1090 participated. The response rate was 91.2% (955 men and 135 women). Forty percent were overweight (body mass index of > or =25), 11% reported a psychiatric history, 26% reported a history of abuse, and 9.8% endorsed disordered eating (male, 7.0%; female, 29.6%), as defined by Eating Attitudes Test-26. Factors that placed soldiers at higher risk for disordered eating were female gender (odds ratio, 5.63; 95% confidence interval, 3.32-9.57; p < 0.00005), overweight (odds ratio, 3.06; 95% confidence interval, 1.92-4.89; p < 0.00005), previous psychiatric treatment (odds ratio, 1.87; 95% confidence interval, 1.04-3.36; p = 0.035), and history of verbal abuse (odds ratio, 2.02; 95% confidence interval, 1.16-3.51; p = 0.014). Our study shows a higher than expected rate of disordered eating in advanced individual training soldiers with identifiable risk factors. This indicates an important need for further study, effective screening, preventive counseling, and early intervention for treatment.
Is complexity of work associated with risk of dementia? The Canadian Study of Health And Aging.

PubMed

Kröger, Edeltraut; Andel, Ross; Lindsay, Joan; Benounissa, Zohra; Verreault, René; Laurin, Danielle

2008-04-01

The authors evaluated the association of complexity of work with data, people, and things with the incidence of dementia, Alzheimer's disease, and vascular dementia in the Canadian Study of Health and Aging, while adjusting for work-related physical activity. The Canadian Study of Health and Aging is a 10-year population study, from 1991 to 2001, of a representative sample of persons aged 65 years or older. Lifetime job history allowed application of complexity scores and classification of work-related physical activity. Analyses included 3,557 subjects, of whom 400 were incident dementia cases, including 299 with Alzheimer's disease and 93 with vascular dementia. In fully adjusted Cox regression models, high complexity of work with people or things reduced risk of dementia (hazard ratios were 0.66 (95% confidence interval: 0.44, 0.98) and 0.72 (95% confidence interval: 0.52, 0.99), respectively) but not Alzheimer's disease. For vascular dementia, hazard ratios were 0.36 (95% confidence interval: 0.15, 0.90) for high complexity of work with people and 0.50 (95% confidence interval: 0.25, 1.00) for high complexity of work with things. Subgroup analyses according to median duration (23 years) of principal occupation showed that associations with complexity varied according to duration of employment. High complexity of work appears to be associated with risk of dementia, but effects may vary according to subtype.
Daytime Napping, Nighttime Sleeping, and Parkinson Disease

PubMed Central

Gao, Jianjun; Huang, Xuemei; Park, Yikyung; Hollenbeck, Albert; Blair, Aaron; Schatzkin, Arthur; Chen, Honglei

2011-01-01

Preliminary evidence suggests that daytime sleepiness may predate clinical diagnosis of Parkinson disease. The authors examined daytime napping and nighttime sleeping durations, reported in 1996–1997 by 220,934 US NIH-AARP Diet and Health Study participants, in relation to Parkinson disease diagnoses at 3 clinical stages: established (cases diagnosed before 1995, n = 267), recent (1995–1999, n = 396), and prediagnostic (2000 and after, n = 770). Odds ratios and 95% confidence intervals were derived from multivariate logistic regression models. Longer daytime napping was associated with higher odds of Parkinson disease at all 3 clinical stages: the odds ratios comparing long nappers (>1 hour/day) with nonnappers were 3.9 (95% confidence interval: 2.8, 5.6) for established cases, 2.2 (95% confidence interval: 1.7, 3.0) for recent cases, and 1.5 (95% confidence interval: 1.2, 1.9) for prediagnostic cases. Further control for health status or nighttime sleeping duration attenuated the association for established cases but made little difference for recent or prediagnostic cases. In the nighttime sleeping analysis, a clear U-shaped association with Parkinson disease was observed for established cases; however, this association was attenuated markedly for recent cases and disappeared for prediagnostic cases. This study supports the notion that daytime sleepiness, but not nighttime sleeping duration, is one of the early nonmotor symptoms of Parkinson disease. PMID:21402730
Aortic stiffness and the balance between cardiac oxygen supply and demand: the Rotterdam Study.

PubMed

Guelen, Ilja; Mattace-Raso, Francesco Us; van Popele, Nicole M; Westerhof, Berend E; Hofman, Albert; Witteman, Jacqueline Cm; Bos, Willem Jan W

2008-06-01

Aortic stiffness is an independent predictor of cardiovascular morbidity and mortality. We investigated whether aortic stiffness, estimated as aortic pulse wave velocity, is associated with decreased perfusion pressure estimated as the cardiac oxygen supply potential. Aortic stiffness and aortic pressure waves, reconstructed from finger blood pressure waves, were obtained in 2490 older adults within the framework of the Rotterdam Study, a large population-based study. Cardiac oxygen supply and demand were estimated using pulse wave analysis techniques, and related to aortic stiffness by linear regression analyses after adjustment for age, sex, mean arterial pressure and heart rate. Cardiac oxygen demand, estimated as the Systolic Pressure Time Index and the Rate Pressure Product, increased with increasing aortic stiffness [0.27 mmHg s (95% confidence interval: 0.21; 0.34)] and [42.2 mmHg/min (95% confidence interval: 34.1; 50.3)], respectively. Cardiac oxygen supply potential estimated as the Diastolic Pressure Time Index decreased [-0.70 mmHg s (95% confidence interval: -0.86; -0.54)] with aortic stiffening. Accordingly, the supply/demand ratio Diastolic Pressure Time Index/Systolic Pressure Time Index -1.11 (95% confidence interval: -0.14; -0.009) decreased with increasing aortic stiffness. Aortic stiffness is associated with estimates of increased cardiac oxygen demand and a decreased cardiac oxygen supply potential. These results may offer additional explanation for the relation between aortic stiffness and cardiovascular morbidity and mortality.
Traffic-related air pollution: Exposure and health effects in Copenhagen street cleaners and cemetery workers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raaschou-Nielsen, O.; Nielsen, M.L.; Gehl, J.

This questionaire-based study found a significantly higher prevalence of chronic bronchitis, asthma, and several other symptoms in 116 Copenhagen street cleaners who were exposed to traffic-related air pollution at levels that were slightly lower than the 1987 World Health Organization-recommended threshold values, compared with 115 Copenhagen cemetery workers exposed to lower pollution levels. Logistic regression analysis, controlling for age and smoking, was conducted, and odds ratios and 95% confidence intervals were calculated to be 2.5 for chronic bronchitis (95% confidence interval = 1.2-5.1), 2.3 for asthma (95% confidence interval = 1.0-5.1), and 1.8-7.9 for other symptoms (95% confidence interval =more » 1.0-28.2). Except for exposure to air pollution, the two groups were comparable, i.e., they had similar terms of employment and working conditions. the exposure ranges during an 8-h work day, averaged from readings taken at five monitored street positions, were: 41-257 ppb nitric oxide (1-h max: 865 ppb); 23-43 ppb nitrogen dioxide (1-h max: 208 ppb); 1.0-4.3 ppm carbon monoxide (8-h max: 7.1 ppm); 14-28 ppb sulfur dioxide (1-h max; 112 ppb); and 10-38 ppb ozone (1-h max: 72 ppb). 33 refs., 7 tabs.« less
Parametric methods outperformed non-parametric methods in comparisons of discrete numerical variables.

PubMed

Fagerland, Morten W; Sandvik, Leiv; Mowinckel, Petter

2011-04-13

The number of events per individual is a widely reported variable in medical research papers. Such variables are the most common representation of the general variable type called discrete numerical. There is currently no consensus on how to compare and present such variables, and recommendations are lacking. The objective of this paper is to present recommendations for analysis and presentation of results for discrete numerical variables. Two simulation studies were used to investigate the performance of hypothesis tests and confidence interval methods for variables with outcomes {0, 1, 2}, {0, 1, 2, 3}, {0, 1, 2, 3, 4}, and {0, 1, 2, 3, 4, 5}, using the difference between the means as an effect measure. The Welch U test (the T test with adjustment for unequal variances) and its associated confidence interval performed well for almost all situations considered. The Brunner-Munzel test also performed well, except for small sample sizes (10 in each group). The ordinary T test, the Wilcoxon-Mann-Whitney test, the percentile bootstrap interval, and the bootstrap-t interval did not perform satisfactorily. The difference between the means is an appropriate effect measure for comparing two independent discrete numerical variables that has both lower and upper bounds. To analyze this problem, we encourage more frequent use of parametric hypothesis tests and confidence intervals.
Blood transfusion for preventing primary and secondary stroke in people with sickle cell disease.

PubMed

Estcourt, Lise J; Fortin, Patricia M; Hopewell, Sally; Trivella, Marialena; Wang, Winfred C

2017-01-17

Sickle cell disease is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. Sickle cell disease can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Stroke affects around 10% of children with sickle cell anaemia (HbSS). Chronic blood transfusions may reduce the risk of vaso-occlusion and stroke by diluting the proportion of sickled cells in the circulation.This is an update of a Cochrane Review first published in 2002, and last updated in 2013. To assess risks and benefits of chronic blood transfusion regimens in people with sickle cell disease for primary and secondary stroke prevention (excluding silent cerebral infarcts). We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 04 April 2016.We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register: 25 April 2016. Randomised controlled trials comparing red blood cell transfusions as prophylaxis for stroke in people with sickle cell disease to alternative or standard treatment. There were no restrictions by outcomes examined, language or publication status. Two authors independently assessed trial eligibility and the risk of bias and extracted data. We included five trials (660 participants) published between 1998 and 2016. Four of these trials were terminated early. The vast majority of participants had the haemoglobin (Hb)SS form of sickle cell disease.Three trials compared regular red cell transfusions to standard care in primary prevention of stroke: two in children with no previous long-term transfusions; and one in children and adolescents on long-term transfusion.Two trials compared the drug hydroxyurea (hydroxycarbamide) and phlebotomy to long-term transfusions and iron chelation therapy: one in primary prevention (children); and one in secondary prevention (children and adolescents).The quality of the evidence was very low to moderate across different outcomes according to GRADE methodology. This was due to the trials being at a high risk of bias due to lack of blinding, indirectness and imprecise outcome estimates. Red cell transfusions versus standard care Children with no previous long-term transfusionsLong-term transfusions probably reduce the incidence of clinical stroke in children with a higher risk of stroke (abnormal transcranial doppler velocities or previous history of silent cerebral infarct), risk ratio 0.12 (95% confidence interval 0.03 to 0.49) (two trials, 326 participants), moderate quality evidence.Long-term transfusions may: reduce the incidence of other sickle cell disease-related complications (acute chest syndrome, risk ratio 0.24 (95% confidence interval 0.12 to 0.48)) (two trials, 326 participants); increase quality of life (difference estimate -0.54, 95% confidence interval -0.92 to -0.17) (one trial, 166 participants); but make little or no difference to IQ scores (least square mean: 1.7, standard error 95% confidence interval -1.1 to 4.4) (one trial, 166 participants), low quality evidence.We are very uncertain whether long-term transfusions: reduce the risk of transient ischaemic attacks, Peto odds ratio 0.13 (95% confidence interval 0.01 to 2.11) (two trials, 323 participants); have any effect on all-cause mortality, no deaths reported (two trials, 326 participants); or increase the risk of alloimmunisation, risk ratio 3.16 (95% confidence interval 0.18 to 57.17) (one trial, 121 participants), very low quality evidence. Children and adolescents with previous long-term transfusions (one trial, 79 participants)We are very uncertain whether continuing long-term transfusions reduces the incidence of: stroke, risk ratio 0.22 (95% confidence interval 0.01 to 4.35); or all-cause mortality, Peto odds ratio 8.00 (95% confidence interval 0.16 to 404.12), very low quality evidence.Several review outcomes were only reported in one trial arm (sickle cell disease-related complications, alloimmunisation, transient ischaemic attacks).The trial did not report neurological impairment, or quality of life. Hydroxyurea and phlebotomy versus red cell transfusions and chelationNeither trial reported on neurological impairment, alloimmunisation, or quality of life. Primary prevention, children (one trial, 121 participants)Switching to hydroxyurea and phlebotomy may have little or no effect on liver iron concentrations, mean difference -1.80 mg Fe/g dry-weight liver (95% confidence interval -5.16 to 1.56), low quality evidence.We are very uncertain whether switching to hydroxyurea and phlebotomy has any effect on: risk of stroke (no strokes); all-cause mortality (no deaths); transient ischaemic attacks, risk ratio 1.02 (95% confidence interval 0.21 to 4.84); or other sickle cell disease-related complications (acute chest syndrome, risk ratio 2.03 (95% confidence interval 0.39 to 10.69)), very low quality evidence. Secondary prevention, children and adolescents (one trial, 133 participants)Switching to hydroxyurea and phlebotomy may: increase the risk of sickle cell disease-related serious adverse events, risk ratio 3.10 (95% confidence interval 1.42 to 6.75); but have little or no effect on median liver iron concentrations (hydroxyurea, 17.3 mg Fe/g dry-weight liver (interquartile range 10.0 to 30.6)); transfusion 17.3 mg Fe/g dry-weight liver (interquartile range 8.8 to 30.7), low quality evidence.We are very uncertain whether switching to hydroxyurea and phlebotomy: increases the risk of stroke, risk ratio 14.78 (95% confidence interval 0.86 to 253.66); or has any effect on all-cause mortality, Peto odds ratio 0.98 (95% confidence interval 0.06 to 15.92); or transient ischaemic attacks, risk ratio 0.66 (95% confidence interval 0.25 to 1.74), very low quality evidence. There is no evidence for managing adults, or children who do not have HbSS sickle cell disease.In children who are at higher risk of stroke and have not had previous long-term transfusions, there is moderate quality evidence that long-term red cell transfusions reduce the risk of stroke, and low quality evidence they also reduce the risk of other sickle cell disease-related complications.In primary and secondary prevention of stroke there is low quality evidence that switching to hydroxyurea with phlebotomy has little or no effect on the liver iron concentration.In secondary prevention of stroke there is low-quality evidence that switching to hydroxyurea with phlebotomy increases the risk of sickle cell disease-related events.All other evidence in this review is of very low quality.
Blood transfusion for preventing primary and secondary stroke in people with sickle cell disease

PubMed Central

Estcourt, Lise J; Fortin, Patricia M; Hopewell, Sally; Trivella, Marialena; Wang, Winfred C

2017-01-01

Background Sickle cell disease is one of the commonest severe monogenic disorders in the world, due to the inheritance of two abnormal haemoglobin (beta globin) genes. Sickle cell disease can cause severe pain, significant end-organ damage, pulmonary complications, and premature death. Stroke affects around 10% of children with sickle cell anaemia (HbSS). Chronic blood transfusions may reduce the risk of vaso-occlusion and stroke by diluting the proportion of sickled cells in the circulation. This is an update of a Cochrane Review first published in 2002, and last updated in 2013. Objectives To assess risks and benefits of chronic blood transfusion regimens in people with sickle cell disease for primary and secondary stroke prevention (excluding silent cerebral infarcts). Search methods We searched for relevant trials in the Cochrane Library, MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1980), and ongoing trial databases; all searches current to 04 April 2016. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register: 25 April 2016. Selection criteria Randomised controlled trials comparing red blood cell transfusions as prophylaxis for stroke in people with sickle cell disease to alternative or standard treatment. There were no restrictions by outcomes examined, language or publication status. Data collection and analysis Two authors independently assessed trial eligibility and the risk of bias and extracted data. Main results We included five trials (660 participants) published between 1998 and 2016. Four of these trials were terminated early. The vast majority of participants had the haemoglobin (Hb)SS form of sickle cell disease. Three trials compared regular red cell transfusions to standard care in primary prevention of stroke: two in children with no previous long-term transfusions; and one in children and adolescents on long-term transfusion. Two trials compared the drug hydroxyurea (hydroxycarbamide) and phlebotomy to long-term transfusions and iron chelation therapy: one in primary prevention (children); and one in secondary prevention (children and adolescents). The quality of the evidence was very low to moderate across different outcomes according to GRADE methodology. This was due to the trials being at a high risk of bias due to lack of blinding, indirectness and imprecise outcome estimates. Red cell transfusions versus standard care Children with no previous long-term transfusions Long-term transfusions probably reduce the incidence of clinical stroke in children with a higher risk of stroke (abnormal transcranial doppler velocities or previous history of silent cerebral infarct), risk ratio 0.12 (95% confidence interval 0.03 to 0.49) (two trials, 326 participants), moderate quality evidence. Long-term transfusions may: reduce the incidence of other sickle cell disease-related complications (acute chest syndrome, risk ratio 0.24 (95% confidence interval 0.12 to 0.48)) (two trials, 326 participants); increase quality of life (difference estimate -0.54, 95% confidence interval -0.92 to -0.17) (one trial, 166 participants); but make little or no difference to IQ scores (least square mean: 1.7, standard error 95% confidence interval -1.1 to 4.4) (one trial, 166 participants), low quality evidence. We are very uncertain whether long-term transfusions: reduce the risk of transient ischaemic attacks, Peto odds ratio 0.13 (95% confidence interval 0.01 to 2.11) (two trials, 323 participants); have any effect on all-cause mortality, no deaths reported (two trials, 326 participants); or increase the risk of alloimmunisation, risk ratio 3.16 (95% confidence interval 0.18 to 57.17) (one trial, 121 participants), very low quality evidence. Children and adolescents with previous long-term transfusions (one trial, 79 participants) We are very uncertain whether continuing long-term transfusions reduces the incidence of: stroke, risk ratio 0.22 (95% confidence interval 0.01 to 4.35); or all-cause mortality, Peto odds ratio 8.00 (95% confidence interval 0.16 to 404.12), very low quality evidence. Several review outcomes were only reported in one trial arm (sickle cell disease-related complications, alloimmunisation, transient ischaemic attacks). The trial did not report neurological impairment, or quality of life. Hydroxyurea and phlebotomy versus red cell transfusions and chelation Neither trial reported on neurological impairment, alloimmunisation, or quality of life. Primary prevention, children (one trial, 121 participants) Switching to hydroxyurea and phlebotomy may have little or no effect on liver iron concentrations, mean difference -1.80 mg Fe/g dry-weight liver (95% confidence interval -5.16 to 1.56), low quality evidence. We are very uncertain whether switching to hydroxyurea and phlebotomy has any effect on: risk of stroke (no strokes); all-cause mortality (no deaths); transient ischaemic attacks, risk ratio 1.02 (95% confidence interval 0.21 to 4.84); or other sickle cell disease-related complications (acute chest syndrome, risk ratio 2.03 (95% confidence interval 0.39 to 10.69)), very low quality evidence. Secondary prevention, children and adolescents (one trial, 133 participants) Switching to hydroxyurea and phlebotomy may: increase the risk of sickle cell disease-related serious adverse events, risk ratio 3.10 (95% confidence interval 1.42 to 6.75); but have little or no effect on median liver iron concentrations (hydroxyurea, 17.3 mg Fe/g dry-weight liver (interquartile range 10.0 to 30.6)); transfusion 17.3 mg Fe/g dry-weight liver (interquartile range 8.8 to 30.7), low quality evidence. We are very uncertain whether switching to hydroxyurea and phlebotomy: increases the risk of stroke, risk ratio 14.78 (95% confidence interval 0.86 to 253.66); or has any effect on all-cause mortality, Peto odds ratio 0.98 (95% confidence interval 0.06 to 15.92); or transient ischaemic attacks, risk ratio 0.66 (95% confidence interval 0.25 to 1.74), very low quality evidence. Authors’ conclusions There is no evidence for managing adults, or children who do not have HbSS sickle cell disease. In children who are at higher risk of stroke and have not had previous long-term transfusions, there is moderate quality evidence that long-term red cell transfusions reduce the risk of stroke, and low quality evidence they also reduce the risk of other sickle cell disease-related complications. In primary and secondary prevention of stroke there is low quality evidence that switching to hydroxyurea with phlebotomy has little or no effect on the liver iron concentration. In secondary prevention of stroke there is low-quality evidence that switching to hydroxyurea with phlebotomy increases the risk of sickle cell disease-related events. All other evidence in this review is of very low quality. PMID:24226646
Consequences of Recipient Obesity on Postoperative Outcomes in a Renal Transplant: A Systematic Review and Meta-Analysis.

PubMed

Sood, Anshuman; Hakim, David N; Hakim, Nadey S

2016-04-01

The prevalence of obesity is increasing rapidly and globally, yet systemic reviews on this topic are scarce. Our meta-analysis and systemic review aimed to assess how obesity affects 5 postoperative outcomes: biopsy-proven acute rejection, patient death, allograft loss, type 2 diabetes mellitus after transplant, and delayed graft function. We evaluated peer-reviewed literature from 22 medical databases. Studies were included if they were conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology criteria, only examined postoperative outcomes in adult patients, only examined the relation between recipient obesity at time of transplant and our 5 postoperative outcomes, and had a minimum score of > 5 stars on the Newcastle-Ottawa scale for nonrandomized studies. Reliable conclusions were ensured by having our studies examined against 2 internationally known scoring systems. Obesity was defined in accordance with the World Health Organization as having a body mass index of > 30 kg/m(2). All obese recipients were compared versus "healthy" recipients (body mass index of 18.5-24.9 kg/m(2)). Hazard ratios were calculated for biopsy-proven acute rejection, patient death, allograft loss, and type 2 diabetes mellitus after transplant. An odds ratio was calculated for delayed graft function. We assessed 21 retrospective observational studies in our meta-analysis (N = 241 381 patients). In obese transplant recipients, hazard ratios were 1.51 (95% confidence interval, 1.24-1.78) for presence of biopsy-proven acute rejection, 1.19 (95% confidence interval, 1.10-1.31) for patient death, 1.54 (95% confidence interval, 1.38-1.68) for allograft loss, and 1.01 (95% confidence interval, 0.98-1.07) for development of type 2 diabetes mellitus. The odds ratio for delayed graft function was 1.81 (95% confidence interval, 1.51-2.13). Our meta-analysis clearly demonstrated greater risks for obese renal transplant recipients and poorer postoperative outcomes with obesity. We confidently recommend renal transplant candidates seek medically supervised weight loss before transplant.
Association between gestational weight gain and perinatal outcomes in women with chronic hypertension.

PubMed

Yee, Lynn M; Caughey, Aaron B; Cheng, Yvonne W

2017-09-01

Gestational weight gain above or below the 2009 National Academy of Medicine guidelines has been associated with adverse maternal and neonatal outcomes. Although it has been well established that excess gestational weight gain is associated with the development of gestational hypertension and preeclampsia, the relationship between gestational weight gain and adverse perinatal outcomes among women with pregestational (chronic) hypertension is less clear. The objective of this study was to examine the relationship between gestational weight gain above and below National Academy of Medicine guidelines and perinatal outcomes in a large, population-based cohort of women with chronic hypertension. This is a population-based retrospective cohort study of women with chronic hypertension who had term, singleton, vertex births in the United States from 2012 through 2014. Prepregnancy body mass index was calculated using self-reported prepregnancy weight and height. Women were categorized into 4 groups based on gestational weight gain and prepregnancy body mass index: (1) weight gain less than, (2) weight gain within, (3) weight gain 1-19 lb in excess of, and (4) weight gain ≥20 lb in excess of the National Academy of Medicine guidelines. The χ 2 tests and multivariable logistic regression analysis were used for statistical comparisons. Stratified analyses by body mass index category were additionally performed. In this large birth cohort, 101,259 women met criteria for inclusion. Compared to hypertensive women who had gestational weight gain within guidelines, hypertensive women with weight gain ≥20 lb over National Academy of Medicine guidelines were more likely to have eclampsia (adjusted odds ratio, 1.93; 95% confidence interval, 1.54-2.42) and cesarean delivery (adjusted odds ratio, 1.60; 95% confidence interval, 1.50-1.70). Excess weight gain ≥20 lb over National Academy of Medicine guidelines was also associated with increased odds of 5-minute Apgar <7 (adjusted odds ratio, 1.29; 95% confidence interval, 1.13-1.47), neonatal intensive care unit admission (adjusted odds ratio, 1.23; 95% confidence interval, 1.14-1.33), and large-for-gestational-age neonates (adjusted odds ratio, 2.41; 95% confidence interval, 2.27-2.56) as well as decreased odds of small-for-gestational-age status (adjusted odds ratio, 0.52; 95% confidence interval, 0.46-0.58). Weight gain 1-19 lb over guidelines was associated with similar fetal growth outcomes although with a smaller effect size. In contrast, weight gain less than National Academy of Medicine guidelines was not associated with adverse maternal outcomes but was associated with increased odds of small for gestational age (adjusted odds ratio, 1.31; 95% confidence interval, 1.21-1.52) and decreased odds of large-for-gestational-age status (adjusted odds ratio, 0.86; 95% confidence interval, 0.81-0.92). Analysis of maternal and neonatal outcomes stratified by body mass index demonstrated similar findings. Women with chronic hypertension who gain less weight than National Academy of Medicine guidelines experience increased odds of small-for-gestational-age neonates, whereas excess weight gain ≥20 lb over National Academy of Medicine guidelines is associated with cesarean delivery, eclampsia, 5-minute Apgar <7, neonatal intensive care unit admission, and large-for-gestational-age neonates. Copyright © 2017 Elsevier Inc. All rights reserved.
Longitudinal study of changing psychological outcomes following the Victorian Black Saturday bushfires.

PubMed

Bryant, Richard A; Gibbs, Lisa; Gallagher, Hugh Colin; Pattison, Phillipa; Lusher, Dean; MacDougall, Colin; Harms, Louise; Block, Karen; Sinnott, Vikki; Ireton, Greg; Richardson, John; Forbes, David

2017-06-01

To map the changing prevalence and predictors of psychological outcomes in affected communities 5 years following the Black Saturday bushfires in Victoria. Follow-up assessment of longitudinal cohort study in high, medium and non-affected communities in Victoria, Australia. Participants included 1017 respondents (Wave 1) interviewed via telephone and web-based survey between December 2011 and January 2013, and 735 (76.1%) eligible participants were retested between July and November 2014 (Wave 2). The survey included measures of fire-related and subsequent stressful events, probable posttraumatic stress disorder, major depressive episode, alcohol use and severe distress. There were reduced rates of fire-related posttraumatic stress disorder (8.7% vs 12.1%), general posttraumatic stress disorder (14.7% vs 18.2%), major depressive episode (9.0% vs 10.9%) and serious mental illness (5.4% vs 7.8%). Rates of resilience increased over time (81.8% vs 77.1%), and problem alcohol use remained high across Wave 1 (22.1%) and Wave 2 (21.4%). The most robust predictor of later development of fire-related posttraumatic stress disorder (odds ratio: 2.11; 95% confidence interval: [1.22, 3.65]), general posttraumatic stress disorder (odds ratio: 3.15; 95% confidence interval: [1.98, 5.02]), major depressive episode (odds ratio: 2.86; 95% confidence interval: [1.74, 4.70]), serious mental illness (odds ratio: 2.67; 95% confidence interval: [0.57, 1.72]) or diminished resilience (odds ratio: 2.01; 95% confidence interval: [1.32, 3.05]) was extent of recent life stressors. Although rates of mental health problems diminished over time, they remained higher than national levels. Findings suggest that policy-makers need to recognize that the mental health consequences of disasters can persist for many years after the event and need to allocate resources towards those who are most at risk as a result of substantive losses and ongoing life stressors.
Absorbable synthetic versus catgut suture material for perineal repair

PubMed Central

Kettle, Christine

2014-01-01

Background Approximately 70% of women will experience some degree of perineal trauma following vaginal delivery and will require stitches. This may result in perineal pain and superficial dyspareunia. Objectives The objective of this review was to assess the effects of absorbable synthetic suture material as compared with catgut on the amount of short and long term pain experienced by mothers following perineal repair. Search strategy We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register. Selection criteria Randomised trials comparing absorbable synthetic (polyglycolic acid and polyglactin) with plain or chromic catgut suture for perineal repair in mothers after vaginal delivery. Data collection and analysis Trial quality was assessed independently by two reviewers. Data were extracted by one reviewer and checked by the second reviewer. Main results Eight trials were included. Compared with catgut, the polyglycolic acid and polyglactin groups were associated with less pain in first three days (odds ratio 0.62, 95% confidence interval 0.54 to 0.71). There was also less need for analgesia (odds ratio 0.63, 95% confidence interval 0.52 to 0.77) and less suture dehiscence (odds ratio 0.45, 95% confidence interval 0.29 to 0.70). There was no significant difference in long term pain (odds ratio 0.81, 95% confidence interval 0.61 to 1.08). Removal of suture material was significantly more common in the polyglycolic acid and polyglactin groups (odds ratio 2.01, 95% confidence interval 1.56 to 2.58). There was no difference in the amount of dyspareunia experienced by women. Authors’ conclusions Absorbable synthetic suture material (in the form of polyglycolic acid and polyglactin sutures) for perineal repair following childbirth appears to decrease women’s experience of short-term pain. The length of time taken for the synthetic material to be absorbed is of concern. A trial addressing the use of polyglactin has recently been completed and this has been included in this updated review. PMID:10796081
Fluorine 18 fluorodeoxyglucose PET/CT volume-based indices in locally advanced non-small cell lung cancer: prediction of residual viable tumor after induction chemotherapy.

PubMed

Soussan, Michael; Cyrta, Joanna; Pouliquen, Christelle; Chouahnia, Kader; Orlhac, Fanny; Martinod, Emmanuel; Eder, Véronique; Morère, Jean-François; Buvat, Irène

2014-09-01

To study whether volume-based indices of fluorine 18 fluorodeoxyglucose positron emission tomographic (PET)/computed tomographic (CT) imaging is an accurate tool to predict the amount of residual viable tumor after induction chemotherapy in patients with locally advanced non-small cell lung cancer (NSCLC). This study was approved by institutional review board with waivers of informed consent. Twenty-two patients with locally advanced NSCLC underwent surgery after induction chemotherapy. All had pre- and posttreatment FDG PET/CT scans. CT largest diameter, CT volume, maximum standardized uptake value (SUVmax), mean SUV (SUVmean), metabolic tumor volume (TV), and total lesion glycolysis of primary tumor were calculated. Changes in tumor measurements were determined by dividing follow-up by baseline measurement (ratio index). Amounts of residual viable tumor, necrosis, fibrous tissue, inflammatory infiltrate, and Ki-67 proliferative index were estimated on resected tumor. Correlations between imaging indices and histologic parameters were estimated by using Spearman correlation coefficients or Mann-Whitney tests. No baseline or posttreatment indices correlated with percentage of residual viable tumor. TV ratio was the only index that correlated with percentage of residual viable tumor (r = 0.61 [95% confidence interval: 0.24, 0.81]; P = .003). Conversely, SUVmax and SUVmean ratios were only indices correlated with Ki-67 (r = 0.62 [95% confidence interval: 0.24, 0.82]; P = .003; and r = 0.60 [95% confidence interval: 0.21, 0.81]; P = .004, respectively). Total lesion glycolysis ratio was moderately correlated with residual viable tumor (r = 0.53 [95% confidence interval: 0.13, 0.78]; P = .01) and with Ki-67 (r = 0.57 [95% confidence interval: 0.18, 0.80]; P = .006). No ratios were correlated with presence of inflammatory infiltrate or foamy macrophages. TV and total lesion glycolysis ratios were the only indices correlated with residual viable tumor after induction chemotherapy in locally advanced NSCLC.
Dietary Acid, Age, and Serum Bicarbonate Levels among Adults in the United States

PubMed Central

Amodu, Afolarin

2013-01-01

Summary Background and objectives Greater dietary acid has been associated with lower serum bicarbonate levels in patients with CKD. Whether this association extends to the general population and if it is modified by age are unknown. Design, setting, participants, & measurements This study examined the association of the dietary acid load, estimated by net endogenous acid production, with serum bicarbonate levels in adult participants in the National Health and Nutrition Examination Survey 1999–2004. Results The mean serum bicarbonate was 24.9 mEq/L (SEM=0.1), and the mean estimated net endogenous acid production was 57.4 mEq/d (SEM=0.4). Serum bicarbonate was linearly associated with age, such that the oldest participants had the highest serum bicarbonate levels. After multivariable adjustment, participants in the highest quartile of net endogenous acid production had 0.40 mEq/L (95% confidence interval, −0.55 to −0.26) lower serum bicarbonate and a 33% (95% confidence interval, 3 to 72) higher likelihood of acidosis compared with those participants in the lowest quartile. There was a significant interaction by age of the association of net endogenous acid production with serum bicarbonate (P=0.005). Among participants 20–39, 40–59, and ≥60 years old, those participants in the highest net endogenous acid production quartile had 0.26 (95% confidence interval, −0.49 to −0.03), 0.60 (95% confidence interval, −0.92 to −0.29), and 0.49 (95% confidence interval, −0.84 to −0.14) mEq/L lower serum bicarbonate, respectively, compared with participants in the lowest quartile. Conclusion Greater dietary acid is associated with lower serum bicarbonate in the general US population, and the magnitude of this association is greater among middle-aged and elderly persons than younger adults. PMID:24052219
Blockade of the angiotensin system improves mental health domain of quality of life: A meta-analysis of randomized clinical trials.

PubMed

Brownstein, Daniel J; Salagre, Estela; Köhler, Cristiano; Stubbs, Brendon; Vian, João; Pereira, Ciria; Chavarria, Victor; Karmakar, Chandan; Turner, Alyna; Quevedo, João; Carvalho, André F; Berk, Michael; Fernandes, Brisa S

2018-01-01

It is unclear whether blockade of the angiotensin system has effects on mental health. Our objective was to determine the impact of angiotensin converting enzyme inhibitors and angiotensin II type 1 receptor (AT1R) blockers on mental health domain of quality of life. Meta-analysis of published literature. PubMed and clinicaltrials.gov databases. The last search was conducted in January 2017. Randomized controlled trials comparing any angiotensin converting enzyme inhibitor or AT1R blocker versus placebo or non-angiotensin converting enzyme inhibitor or non-AT1R blocker were selected. Study participants were adults without any major physical symptoms. We adhered to meta-analysis reporting methods as per PRISMA and the Cochrane Collaboration. Eleven studies were included in the analysis. When compared with placebo or other antihypertensive medications, AT1R blockers and angiotensin converting enzyme inhibitors were associated with improved overall quality of life (standard mean difference = 0.11, 95% confidence interval = [0.08, 0.14], p < 0.0001), positive wellbeing (standard mean difference = 0.11, 95% confidence interval = [0.05, 0.17], p < 0.0001), mental (standard mean difference = 0.15, 95% confidence interval = [0.06, 0.25], p < 0.0001), and anxiety (standard mean difference = 0.08, 95% confidence interval = [0.01, 0.16], p < 0.0001) domains of QoL. No significant difference was found for the depression domain (standard mean difference = 0.05, 95% confidence interval = [0.02, 0.12], p = 0.15). Use of angiotensin blockers and inhibitors for the treatment of hypertension in otherwise healthy adults is associated with improved mental health domains of quality of life. Mental health quality of life was a secondary outcome in the included studies. Research specifically designed to analyse the usefulness of drugs that block the angiotensin system is necessary to properly evaluate this novel psychiatric target.
Preemptive Deceased Donor Kidney Transplantation: Considerations of Equity and Utility

PubMed Central

Chen, B. Po-Han; Coresh, Josef; Segev, Dorry L.

2013-01-01

Summary Background and objectives There exists gross disparity in national deceased donor kidney transplant availability and practice: waiting times exceed 6 years in some regions, but some patients receive kidneys before they require dialysis. This study aimed to quantify and characterize preemptive deceased donor kidney transplant recipients and compare their outcomes with patients transplanted shortly after dialysis initiation. Design, setting, participants, & measurements Using the Scientific Registry of Transplant Recipients database, first-time adult deceased donor kidney transplant recipients between 1995 and 2011 were classified as preemptive, early (on dialysis≤1 year), or late recipients. Random effects logistic regression and multivariate Cox proportional hazards regression were used to identify characteristics of preemptive deceased donor kidney transplant and evaluate survival in preemptive and early recipients, respectively. Results Preemptive recipients were 9.0% of the total recipient population. Patients with private insurance (adjusted odds ratio=3.15, 95% confidence interval=3.01–3.29, P<0.001), previous (nonkidney) transplant (adjusted odds ratio=1.94, 95% confidence interval=1.67–2.26, P<0.001), and zero-antigen mismatch (adjusted odds ratio=1.45, 95% confidence interval=1.37–1.54, P<0.001; Caucasians only) were more likely to receive preemptive deceased donor kidney transplant, even after accounting for center-level clustering. African Americans were less likely to receive preemptive deceased donor kidney transplant (adjusted odds ratio=0.44, 95% confidence interval=0.41–0.47, P<0.001). Overall, patients transplanted preemptively had similar survival compared with patients transplanted within 1 year after initiating dialysis (adjusted hazard ratio=1.06, 95% confidence interval=0.99–1.12, P=0.07). Conclusions Preemptive deceased donor kidney transplant occurs most often among Caucasians with private insurance, and survival is fairly similar to survival of recipients on dialysis for <1 year. PMID:23371953

Prevalence and associated risk factors of necrotic enteritis on broiler farms in the United Kingdom; a cross-sectional survey.

PubMed

Hermans, P G; Morgan, K L

2007-02-01

In order to determine the prevalence and risk factors for necrotic enteritis in broilers, a cross-sectional survey was conducted among 857 farms, rearing broilers for nine UK poultry companies. The main data collection tool was a postal questionnaire directed at farm managers. Additional information on disease occurrence on the farm was collected from veterinary postmortem reports. The response rate to the questionnaire was 75%, ranging from 54% to 90% within companies. During 2001, 32.8% of the respondents indicated that they had observed a case of necrotic enteritis (95% confidence interval, 29.1 to 36.8) in at least one flock. The disease was most often reported during the months October to February. The point prevalence (necrotic enteritis occurrence in the most recently reared flock) reported by farm managers was 12.3% (95% confidence interval, 9.8 to 15.2). Multilevel logistic regression was performed with the poultry company as the random effect, using the occurrence of necrotic enteritis in the farm's most recently reared flock as the dependent variable. Strong associations were found between the outcome variable and the occurrence of wet litter (odds ratio, 2.39; 95% confidence interval, 1.27 to 4.52; P = 0.007) and coccidiosis (odds ratio, 4.68; 95% confidence interval, 1.74 to 12.55; P = 0.002). In addition, the use of ammonia as a disinfectant for coccidial oocysts appeared to be an independent risk factor (odds ratio, 3.44; 95% confidence interval, 1.53 to 7.71; P = 0.003). Finally, the positive association between the use of plasterboard walls in poultry houses and the occurrence of necrotic enteritis might point to an important role of cleaning and disinfection in the epidemiology of this disease (odds ratio, 3.72; 1.38 to 10.00; P = 0.009).
Involving American Indians and medically underserved rural populations in cancer clinical trials.

PubMed

Guadagnolo, B Ashleigh; Petereit, Daniel G; Helbig, Petra; Koop, David; Kussman, Patricia; Fox Dunn, Emily; Patnaik, Asha

2009-12-01

To assess cancer clinical trial recruitment and reasons for nonaccrual among a rural, medically underserved population served by a community-based cancer care center. We prospectively tracked clinical trial enrollment incidence among all new patients presenting at the Rapid City Regional Cancer Care Institute. Evaluating physicians completed questionnaires for each patient regarding clinical trial enrollment status and primary reasons for nonenrollment. Patients who identified as American Indian were referred to a program where patients were assisted in navigating the medical system by trained, culturally competent staff. Between September 2006 and January 2008, 891 new cancer patients were evaluated. Seventy-eight patients (9%; 95% confidence intervals, 7-11%) were enrolled on a clinical treatment trial. For 73% (95% confidence intervals, 69-75%) of patients (646 of 891) lack of relevant protocol availability or protocol inclusion criteria restrictiveness was the reason for nonenrollment. Only 45 (5%; 95% confidence intervals, 4-7%) patients refused enrollment on a trial. Of the 78 enrolled on a trial, 6 (8%; 95% confidence intervals, 3-16%) were American Indian. Three additional American Indian patients were enrolled under a nontreatment cancer control trial, bringing the total percentage enrolled of the 94 American Indians who presented to the clinic to 10% (95% confidence intervals, 5-17%). Eligibility rates were unable to be calculated and cross validation of the number in the cohort via registries or ICD-9 codes was not performed. Clinical trial participation in this medically underserved population was low overall, but approximately 3-fold higher than reported national accrual rates. Lack of availability of protocols for common cancer sites as well as stringent protocol inclusion criteria were the primary obstacles to clinical trial enrollment. Targeted interventions using a Patient Navigation program were used to engage AI patients and may have resulted in higher clinical trial enrollment among this racial/ethnic group.
Involving American Indians and medically underserved rural populations in cancer clinical trials

PubMed Central

Guadagnolo, B Ashleigh; Petereit, Daniel G; Helbig, Petra; Koop, David; Kussman, Patricia; Dunn, Emily Fox; Patnaik, Asha

2010-01-01

Purpose To assess cancer clinical trial recruitment and reasons for nonaccrual among a rural, medically underserved population served by a community-based cancer care center. Methods We prospectively tracked clinical trial enrollment incidence among all new patients presenting at the Rapid City Regional Cancer Care Institute. Evaluating physicians completed questionnaires for each patient regarding clinical trial enrollment status and primary reasons for nonenrollment. Patients who identified as American Indian were referred to a program where patients were assisted in navigating the medical system by trained, culturally competent staff. Results Between September 2006 and January 2008, 891 new cancer patients were evaluated. Seventy-eight patients (9%; 95% confidence intervals, 7–11%) were enrolled on a clinical treatment trial. For 73% (95% confidence intervals, 69–75%) of patients (646 of 891) lack of relevant protocol availability or protocol inclusion criteria restrictiveness was the reason for nonenrollment. Only 45 (5%; 95% confidence intervals, 4–7%) patients refused enrollment on a trial. Of the 78 enrolled on a trial, 6 (8%; 95% confidence intervals, 3–16%) were American Indian. Three additional American Indian patients were enrolled under a nontreatment cancer control trial, bringing the total percentage enrolled of the 94 American Indians who presented to the clinic to 10% (95% confidence intervals, 5–17%). Limitations Eligibility rates were unable to be calculated and cross validation of the number in the cohort via registries or ICD-9 codes was not performed. Conclusion Clinical trial participation in this medically underserved population was low overall, but approximately 3-fold higher than reported national accrual rates. Lack of availability of protocols for common cancer sites as well as stringent protocol inclusion criteria were the primary obstacles to clinical trial enrollment. Targeted interventions using a Patient Navigation program were used to engage AI patients and may have resulted in higher clinical trial enrollment among this racial/ethnic group. PMID:19933720
Effect of increased exercise in school children on physical fitness and endothelial progenitor cells: a prospective randomized trial.

PubMed

Walther, Claudia; Gaede, Luise; Adams, Volker; Gelbrich, Götz; Leichtle, Alexander; Erbs, Sandra; Sonnabend, Melanie; Fikenzer, Kati; Körner, Antje; Kiess, Wieland; Bruegel, Mathias; Thiery, Joachim; Schuler, Gerhard

2009-12-01

The aim of this prospective, randomized study was to examine whether additional school exercise lessons would result in improved peak oxygen uptake (primary end point) and body mass index-standard deviation score, motor and coordinative abilities, circulating progenitor cells, and high-density lipoprotein cholesterol (major secondary end points). Seven sixth-grade classes (182 children, aged 11.1+/-0.7 years) were randomized to an intervention group (4 classes with 109 students) with daily school exercise lessons for 1 year and a control group (3 classes with 73 students) with regular school sports twice weekly. The significant effects of intervention estimated from ANCOVA adjusted for intraclass correlation were the following: increase of peak o(2) (3.7 mL/kg per minute; 95% confidence interval, 0.3 to 7.2) and increase of circulating progenitor cells evaluated by flow cytometry (97 cells per 1 x 10(6) leukocytes; 95% confidence interval, 13 to 181). No significant difference was seen for body mass index-standard deviation score (-0.08; 95% confidence interval, -0.28 to 0.13); however, there was a trend to reduction of the prevalence of overweight and obese children in the intervention group (from 12.8% to 7.3%). No treatment effect was seen for motor and coordinative abilities (4; 95% confidence interval, -1 to 8) and high-density lipoprotein cholesterol (0.03 mmol/L; 95% confidence interval, -0.08 to 0.14). Regular physical activity by means of daily school exercise lessons has a significant positive effect on physical fitness (o(2)max). Furthermore, the number of circulating progenitor cells can be increased, and there is a positive trend in body mass index-standard deviation score reduction and motor ability improvement. Therefore, we conclude that primary prevention by means of increasing physical activity should start in childhood. URL: http://www.clinicaltrials.gov. Identifier: NCT00176371.
Association of time-to-surgery with outcomes in clinical stage I-II pancreatic adenocarcinoma treated with upfront surgery.

PubMed

Swords, Douglas S; Zhang, Chong; Presson, Angela P; Firpo, Matthew A; Mulvihill, Sean J; Scaife, Courtney L

2018-04-01

Time-to-surgery from cancer diagnosis has increased in the United States. We aimed to determine the association between time-to-surgery and oncologic outcomes in patients with resectable pancreatic ductal adenocarcinoma undergoing upfront surgery. The 2004-2012 National Cancer Database was reviewed for patients undergoing curative-intent surgery without neoadjuvant therapy for clinical stage I-II pancreatic ductal adenocarcinoma. A multivariable Cox model with restricted cubic splines was used to define time-to-surgery as short (1-14 days), medium (15-42), and long (43-120). Overall survival was examined using Cox shared frailty models. Secondary outcomes were examined using mixed-effects logistic regression models. Of 16,763 patients, time-to-surgery was short in 34.4%, medium in 51.6%, and long in 14.0%. More short time-to-surgery patients were young, privately insured, healthy, and treated at low-volume hospitals. Adjusted hazards of mortality were lower for medium (hazard ratio 0.94, 95% confidence interval, .90, 0.97) and long time-to-surgery (hazard ratio 0.91, 95% confidence interval, 0.86, 0.96) than short. There were no differences in adjusted odds of node positivity, clinical to pathologic upstaging, being unresectable or stage IV at exploration, and positive margins. Medium time-to-surgery patients had higher adjusted odds (odds ratio 1.11, 95% confidence interval, 1.03, 1.20) of receiving an adequate lymphadenectomy than short. Ninety-day mortality was lower in medium (odds ratio 0.75, 95% confidence interval, 0.65, 0.85) and long time-to-surgery (odds ratio 0.72, 95% confidence interval, 0.60, 0.88) than short. In this observational analysis, short time-to-surgery was associated with slightly shorter OS and higher perioperative mortality. These results may suggest that delays for medical optimization and referral to high volume surgeons are safe. Published by Elsevier Inc.
Association of urinary calcium excretion with serum calcium and vitamin D levels.

PubMed

Rathod, Anita; Bonny, Olivier; Guessous, Idris; Suter, Paolo M; Conen, David; Erne, Paul; Binet, Isabelle; Gabutti, Luca; Gallino, Augusto; Muggli, Franco; Hayoz, Daniel; Péchère-Bertschi, Antoinette; Paccaud, Fred; Burnier, Michel; Bochud, Murielle

2015-03-06

Population-based data on urinary calcium excretion are scarce. The association of serum calcium and circulating levels of vitamin D [25(OH)D2 or D3] with urinary calcium excretion in men and women from a population-based study was explored. Multivariable linear regression was used to explore factors associated with square root-transformed 24-hour urinary calcium excretion (milligrams per 24 hours) taken as the dependent variable with a focus on month-specific vitamin D tertiles and serum calcium in the Swiss Survey on Salt Study. In total, 624 men and 669 women were studied with mean ages of 49.2 and 47.0 years, respectively (age range=15-95 years). Mean urinary calcium excretion was higher in men than in women (183.05 versus 144.60 mg/24 h; P<0.001). In adjusted models, the association (95% confidence interval) of square root urinary calcium excretion with protein-corrected serum calcium was 1.78 (95% confidence interval, 1.21 to 2.34) mg/24 h per milligram per deciliter in women and 0.59 (95% confidence interval, -0.11 to 1.29) mg/24 h per milligram per deciliter in men. Men in the third 25(OH)D3 tertile had higher square root urinary calcium excretion than men in the first tertile (0.99; 95% confidence interval, 0.36 to 1.63 mg/24 h per nanogram per milliliter), and the corresponding association was 0.32 (95% confidence interval, -0.22 to 0.85) mg/24 h per nanogram per milliliter in women. These sex differences were more marked under conditions of high urinary sodium or urea excretions. There was a positive association of serum calcium with urinary calcium excretion in women but not men. Vitamin 25(OH)D3 was associated with urinary calcium excretion in men but not women. These results suggest important sex differences in the hormonal and dietary control of urinary calcium excretion. Copyright © 2015 by the American Society of Nephrology.
Home care by general practitioners for cancer patients in the last 3 months of life: An epidemiological study of quality and associated factors

PubMed Central

Pivodic, Lara; Harding, Richard; Calanzani, Natalia; McCrone, Paul; Hall, Sue; Deliens, Luc; Higginson, Irene J; Gomes, Barbara

2016-01-01

Background: Stronger generalist end-of-life care at home for people with cancer is called for but the quality of end-of-life care delivered by general practitioners has been questioned. Aim: To determine the degree of and factors associated with bereaved relatives’ satisfaction with home end-of-life care delivered by general practitioners to cancer patients. Design: Population-based mortality followback survey. Setting/participants: Bereaved relatives of people who died of cancer in London, United Kingdom (identified from death registrations in 2009–2010), were invited to complete a postal questionnaire surveying the deceased’s final 3 months of life. Results: Questionnaires were completed for 596 decedents of whom 548 spent at least 1 day at home in the last 3 months of life. Of the respondents, 55% (95% confidence interval: 51%–59%) reported excellent/very good home care by general practitioners, compared with 78% (95% confidence interval: 74%–82%) for specialist palliative care providers and 68% (95% confidence interval: 64%–73%) for district/community/private nurses. The odds of high satisfaction (excellent/very good) with end-of-life care by general practitioners doubled if general practitioners made three or more compared with one or no home visits in the patient’s last 3 months of life (adjusted odds ratio: 2.54 (95% confidence interval: 1.52–4.24)) and halved if the patient died at hospital rather than at home (adjusted odds ratio: 0.55 (95% confidence interval: 0.31–0.998)). Conclusion: There is considerable room for improvement in the satisfaction with home care provided by general practitioners to terminally ill cancer patients. Ensuring an adequate offer of home visits by general practitioners may help to achieve this goal. PMID:26036688
Periodontal treatment during pregnancy and birth outcomes: a meta-analysis of randomised trials.

PubMed

George, Ajesh; Shamim, Simin; Johnson, Maree; Ajwani, Shilpi; Bhole, Sameer; Blinkhorn, Anthony; Ellis, Sharon; Andrews, Karen

2011-06-01

The objective of this review was to conduct a meta-analysis of all up-to-date randomised control trials to determine whether periodontal treatment during pregnancy has the potential of reducing preterm birth and low birth weight incidence. Bibliographic databases MEDLINE (1966-present), EMBASE (1980-present), CINAHL (1982-present) and the Cochrane library up to and including 2010 Issue 10 were searched. The reference list of included studies and reviews were also searched for additional literature. Eligible studies were, published and ongoing randomised control trials that compared pregnancy outcomes for pregnant women who received periodontal treatment during the prenatal period. Two of the investigators independently assessed the studies and then extracted and summarised data from eligible trials. Extracted data were entered into Review Manager software and analysed. A total of 5645 pregnant women participated in the 10 eligible trials. Meta-analysis found that periodontal treatment significantly lowered preterm birth (odd ratio 0.65; 95% confidence interval, 0.45-0.93; P = 0.02) and low birth weight (odd ratio 0.53; 95% confidence interval, 0.31-0.92; P = 0.02) rates while no significant difference was found for spontaneous abortion/stillbirth (odd ratio 0.71; 95% confidence interval, 0.43-1.16; P = 0.17). Moderate heterogeneity was observed among the studies for preterm birth and low birth weight. Subgroup analysis showed significant effect of periodontal treatment in pregnant women with low rate of previous preterm birth/low birth weight (odd ratio 0.35; 95% confidence interval, 017-0.70; P = 0.003) and less severe periodontal disease (odd ratio 0.49; confidence interval, 028-0.87; P = 0.01) as defined by probing depth. The cumulative evidence suggests that periodontal treatment during pregnancy may reduce preterm birth and low birth weight incidence. However, these findings need to be further validated through larger more targeted randomised control trials. © 2011 The Authors. International Journal of Evidence-Based Healthcare © 2011 The Joanna Briggs Institute.
Water, sanitation and hygiene related risk factors for soil-transmitted helminth and Giardia duodenalis infections in rural communities in Timor-Leste.

PubMed

Campbell, Suzy J; Nery, Susana V; D'Este, Catherine A; Gray, Darren J; McCarthy, James S; Traub, Rebecca J; Andrews, Ross M; Llewellyn, Stacey; Vallely, Andrew J; Williams, Gail M; Amaral, Salvador; Clements, Archie C A

2016-11-01

There is little evidence on prevalence or risk factors for soil transmitted helminth infections in Timor-Leste. This study describes the epidemiology, water, sanitation and hygiene, and socioeconomic risk factors of STH and intestinal protozoa amongst communities in Manufahi District, Timor-Leste. As part of a cluster randomised controlled trial, a baseline cross-sectional survey was conducted across 18 villages, with data from six additional villages. Stool samples were assessed for soil transmitted helminth and protozoal infections using quantitative PCR (qPCR) and questionnaires administered to collect water, sanitation and hygiene and socioeconomic data. Risk factors for infection were assessed using multivariable mixed-effects logistic regression, stratified by age group (preschool, school-aged and adult). Overall, soil transmitted helminth prevalence was 69% (95% Confidence Interval 67-71%), with Necator americanus being most common (60%; 95% Confidence Interval 58-62%) followed by Ascaris spp. (24%; 95% Confidence Interval 23-26%). Ascaris-N. americanus co-infection was common (17%; 95% Confidence Interval 15%-18%). Giardia duodenalis was the main protozoan identified (13%; 95% Confidence Interval 11-14%). Baseline water, sanitation and hygiene infrastructure and behaviours were poor. Although risk factors varied by age of participants and parasite species, risk factors for N. americanus infection included, generally, age in years, male sex, and socioeconomic quintile. Risk factors for Ascaris included age in years for children, and piped water to the yard for adults. In this first known assessment of community-based prevalence and associated risk factors in Timor-Leste, soil transmitted helminth infections were highly prevalent, indicating a need for soil transmitted helminth control. Few associations with water, sanitation and hygiene were evident, despite water, sanitation and hygiene being generally poor. In our water, sanitation and hygiene we will investigate implications of improving WASH on soil transmitted helminth infection in impoverished communities. Copyright © 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.
Impact of age-related macular degeneration in patients with glaucoma: understanding the patients' perspective.

PubMed

Skalicky, Simon E; Fenwick, Eva; Martin, Keith R; Crowston, Jonathan; Goldberg, Ivan; McCluskey, Peter

2016-07-01

The aim of the study is to measure the impact of age-related macular degeneration on vision-related activity limitation and preference-based status for glaucoma patients. This was a cross-sectional study. Two-hundred glaucoma patients of whom 73 had age-related macular degeneration were included in the research. Sociodemographic information, visual field parameters and visual acuity were collected. Age-related macular degeneration was scored using the Age-Related Eye Disease Study system. The Rasch-analysed Glaucoma Activity Limitation-9 and the Visual Function Questionnaire Utility Index measured vision-related activity limitation and preference-based status, respectively. Regression models determined factors predictive of vision-related activity limitation and preference-based status. Differential item functioning compared Glaucoma Activity Limitation-9 item difficulty for those with and without age-related macular degeneration. Mean age was 73.7 (±10.1) years. Lower better eye mean deviation (β: 1.42, 95% confidence interval: 1.24-1.63, P < 0.001) and age-related macular degeneration (β: 1.26 95% confidence interval: 1.10-1.44, P = 0.001) were independently associated with worse vision-related activity limitation. Worse eye visual acuity (β: 0.978, 95% confidence interval: 0.961-0.996, P = 0.018), high risk age-related macular degeneration (β: 0.981, 95% confidence interval: 0.965-0.998, P = 0.028) and severe glaucoma (β: 0.982, 95% confidence interval: 0.966-0.998, P = 0.032) were independently associated with worse preference-based status. Glaucoma patients with age-related macular degeneration found using stairs, walking on uneven ground and judging distances of foot to step/curb significantly more difficult than those without age-related macular degeneration. Vision-related activity limitation and preference-based status are negatively impacted by severe glaucoma and age-related macular degeneration. Patients with both conditions perceive increased difficulty walking safely compared with patients with glaucoma alone. © 2015 Royal Australian and New Zealand College of Ophthalmologists.
Confidence bounds for normal and lognormal distribution coefficients of variation

Treesearch

Steve Verrill

2003-01-01

This paper compares the so-called exact approach for obtaining confidence intervals on normal distribution coefficients of variation to approximate methods. Approximate approaches were found to perform less well than the exact approach for large coefficients of variation and small sample sizes. Web-based computer programs are described for calculating confidence...
Microvascular anastomosis simulation using a chicken thigh model: Interval versus massed training.

PubMed

Schoeff, Stephen; Hernandez, Brian; Robinson, Derek J; Jameson, Mark J; Shonka, David C

2017-11-01

To compare the effectiveness of massed versus interval training when teaching otolaryngology residents microvascular suturing on a validated microsurgical model. Otolaryngology residents were placed into interval (n = 7) or massed (n = 7) training groups. The interval group performed three separate 30-minute practice sessions separated by at least 1 week, and the massed group performed a single 90-minute practice session. Both groups viewed a video demonstration and recorded a pretest prior to the first training session. A post-test was administered following the last practice session. At an academic medical center, 14 otolaryngology residents were assigned using stratified randomization to interval or massed training. Blinded evaluators graded performance using a validated microvascular Objective Structured Assessment of Technical Skill tool. The tool is comprised of two major components: task-specific score (TSS) and global rating scale (GRS). Participants also received pre- and poststudy surveys to compare subjective confidence in multiple aspects of microvascular skill acquisition. Overall, all residents showed increased TSS and GRS on post- versus pretest. After completion of training, the interval group had a statistically significant increase in both TSS and GRS, whereas the massed group's increase was not significant. Residents in both groups reported significantly increased levels of confidence after completion of the study. Self-directed learning using a chicken thigh artery model may benefit microsurgical skills, competence, and confidence for resident surgeons. Interval training results in significant improvement in early development of microvascular anastomosis skills, whereas massed training does not. NA. Laryngoscope, 127:2490-2494, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.
Adjusted Wald Confidence Interval for a Difference of Binomial Proportions Based on Paired Data

ERIC Educational Resources Information Center

Bonett, Douglas G.; Price, Robert M.

2012-01-01

Adjusted Wald intervals for binomial proportions in one-sample and two-sample designs have been shown to perform about as well as the best available methods. The adjusted Wald intervals are easy to compute and have been incorporated into introductory statistics courses. An adjusted Wald interval for paired binomial proportions is proposed here and…
Overconfidence in Interval Estimates: What Does Expertise Buy You?

ERIC Educational Resources Information Center

McKenzie, Craig R. M.; Liersch, Michael J.; Yaniv, Ilan

2008-01-01

People's 90% subjective confidence intervals typically contain the true value about 50% of the time, indicating extreme overconfidence. Previous results have been mixed regarding whether experts are as overconfident as novices. Experiment 1 examined interval estimates from information technology (IT) professionals and UC San Diego (UCSD) students…
The Relationship Between Hospital Construction and High-Risk Infant Auditory Function at NICU Discharge: A Retrospective Descriptive Cohort Study.

PubMed

Willis, Valerie

2018-04-01

To describe the difference in auditory function at neonatal intensive care unit (NICU) discharge between high-risk infant cases exposed to hospital construction during NICU stay and those not exposed. Noise produced by routine NICU caregiving exceeds recommended intensity. As California hospitals undergo construction to meet seismic safety regulations, vulnerable neonates are potentially exposed to even higher levels of noise. Ramifications are unknown. Retrospective data-based descriptive cohort design was used to compare high-risk infant auditory function at NICU discharge between hospital construction exposed and unexposed groups. N = 540 infant cases (243 construction exposed and 297 unexposed controls). Infant cases born and discharged from the study site NICU in the year 2010 (unexposed) and year 2015 (exposed) and received a newborn hearing screening by automated auditory brainstem evoked response (ABER) prior to discharge with results reported. Infant cases excluded: hearing screen results by ABER unavailable, potentially confounding characteristics (congenital infection, major anomalies including cleft lip and/or palate), and transferred into or out of the study site. ABER. descriptive statistics (SPSS Version 24.0), hypothesis testing, correlation, and logistic regression. The difference in auditory function at NICU discharge between high-risk infant cases exposed to hospital construction noise and those unexposed was statistically insignificant, χ 2 = 1.666, df = 4, p = .1968, 95% confidence interval [-0.635, 2.570]. More research is needed to better understand whether hospital construction exposure during NICU admission negatively affects high-risk infant auditory function. Findings may catalyze theory development, future research, and child health policy.
Proceedings of the Conference on the Design of Experiments in Army Research Development and Testing (34th) Held in Las Cruces, New Mexico on 19-21 October 1988

DTIC Science & Technology

1989-07-01

Webb and Linda L.C. Moss.............,,...,....., 27 COMPARISON OF RELIABILITY CONFIDENCE INTERVALS Paul H . Thrasher. ......... . 0 1...Webb and Linda L.C. Moss, U.S. Army Ballistic Research Laboratory COMPARISON OF RELIABILITY CONFIDENCE INTERVALS Paul H. Thrasher, White Sands Missile...RELEVANT Paul H. Thrasher, White Sands Missile Range 0930 - 1000 BREAK 1000 - 1130 GENERAL SESSION III Chairperson: Douglas B. Tang, Valter Reed Army
Diagnostic accuracy of cerebrospinal fluid gram stain in children with suspected bacterial meningitis.

PubMed

Brizzi, Kate; Hines, Elizabeth M; McGowan, Karin L; Shah, Samir S

2012-02-01

This cross-sectional study included 1938 children undergoing lumbar puncture; 21 (1.1%) cases were classified as definite (n = 17) or probable (n = 4) bacterial meningitis. Gram stain sensitivity was 94.1% (95% confidence interval, 71.3%-99.9%) for those with definite meningitis; the positive predictive value was 47.1% (95% confidence interval, 29.8%-64.9%). The sensitivity was 95.2% for those with definite or probable meningitis. Antibiotic pretreatment did not affect results.
Procedures for estimating confidence intervals for selected method performance parameters.

PubMed

McClure, F D; Lee, J K

2001-01-01

Procedures for estimating confidence intervals (CIs) for the repeatability variance (sigmar2), reproducibility variance (sigmaR2 = sigmaL2 + sigmar2), laboratory component (sigmaL2), and their corresponding standard deviations sigmar, sigmaR, and sigmaL, respectively, are presented. In addition, CIs for the ratio of the repeatability component to the reproducibility variance (sigmar2/sigmaR2) and the ratio of the laboratory component to the reproducibility variance (sigmaL2/sigmaR2) are also presented.
VizieR Online Data Catalog: TROY project. I. (Lillo-Box+, 2018)

NASA Astrophysics Data System (ADS)

Lillo-Box, J.; Barrado, D.; Figueira, P.; Leleu, A.; Santos, N. C.; Correia, A. C. M.; Robutel, P.; Faria, J. P.

2017-11-01

tablea4.dat: Posterior confidence intervals of the parameters explored to fit the radial velocity data according to equation 9 in the paper. tablea6.dat: Maximum mass of possible trojan bodies for the six tested models assuming their presence. We present the 95% confidence intervals of the mass computed from random samplings of the radial velocity semi-amplitude K2, the inclination i, the eccentricity e (when applicable), and the stellar mass obtained from the literature. (2 data files).
Empirical likelihood-based confidence intervals for the sensitivity of a continuous-scale diagnostic test at a fixed level of specificity.

PubMed

Gengsheng Qin; Davis, Angela E; Jing, Bing-Yi

2011-06-01

For a continuous-scale diagnostic test, it is often of interest to find the range of the sensitivity of the test at the cut-off that yields a desired specificity. In this article, we first define a profile empirical likelihood ratio for the sensitivity of a continuous-scale diagnostic test and show that its limiting distribution is a scaled chi-square distribution. We then propose two new empirical likelihood-based confidence intervals for the sensitivity of the test at a fixed level of specificity by using the scaled chi-square distribution. Simulation studies are conducted to compare the finite sample performance of the newly proposed intervals with the existing intervals for the sensitivity in terms of coverage probability. A real example is used to illustrate the application of the recommended methods.

Funding policies and postabortion long-acting reversible contraception: results from a cluster randomized trial.

PubMed

Rocca, Corinne H; Thompson, Kirsten M J; Goodman, Suzan; Westhoff, Carolyn L; Harper, Cynthia C

2016-06-01

Almost one-half of women having an abortion in the United States have had a previous procedure, which highlights a failure to provide adequate preventive care. Provision of intrauterine devices and implants, which have high upfront costs, can be uniquely challenging in the abortion care setting. We conducted a study of a clinic-wide training intervention on long-acting reversible contraception and examined the effect of the intervention, insurance coverage, and funding policies on the use of long-acting contraceptives after an abortion. This subanalysis of a cluster, randomized trial examines data from the 648 patients who had undergone an abortion who were recruited from 17 reproductive health centers across the United States. The trial followed participants 18-25 years old who did not desire pregnancy for a year. We measured the effect of the intervention, health insurance, and funding policies on contraceptive outcomes, which included intrauterine device and implant counseling and selection at the abortion visit, with the use of logistic regression with generalized estimating equations for clustering. We used survival analysis to model the actual initiation of these methods over 1 year. Women who obtained abortion care at intervention sites were more likely to report intrauterine device and implant counseling (70% vs 41%; adjusted odds ratio, 3.83; 95% confidence interval, 2.37-6.19) and the selection of these methods (36% vs 21%; adjusted odds ratio, 2.11; 95% confidence interval, 1.39-3.21). However, the actual initiation of methods was similar between study arms (22/100 woman-years each; adjusted hazard ratio, 0.88; 95% confidence interval, 0.51-1.51). Health insurance and funding policies were important for the initiation of intrauterine devices and implants. Compared with uninsured women, those women with public health insurance had a far higher initiation rate (adjusted hazard ratio, 2.18; 95% confidence interval, 1.31-3.62). Women at sites that provide state Medicaid enrollees abortion coverage also had a higher initiation rate (adjusted hazard ratio, 1.73; 95% confidence interval, 1.04-2.88), as did those at sites with state mandates for private health insurance to cover contraception (adjusted hazard ratio, 1.80; 95% confidence interval, 1.06-3.07). Few of the women with private insurance used it to pay for the abortion (28%), but those who did initiated long-acting contraceptive methods at almost twice the rate as women who paid for it themselves or with donated funds (adjusted hazard ratio, 1.94; 95% confidence interval, 1.10-3.43). The clinic-wide training increased long-acting reversible contraceptive counseling and selection but did not change initiation for abortion patients. Long-acting method use after abortion was associated strongly with funding. Restrictions on the coverage of abortion and contraceptives in abortion settings prevent the initiation of desired long-acting methods. Copyright © 2015 Elsevier Inc. All rights reserved.
The association of drinking water quality and sewage disposal with Helicobacter pylori incidence in infants: the potential role of water-borne transmission.

PubMed

Travis, Penny B; Goodman, Karen J; O'Rourke, Kathleen M; Groves, Frank D; Sinha, Debajyoti; Nicholas, Joyce S; VanDerslice, Jim; Lackland, Daniel; Mena, Kristina D

2010-03-01

The mode of transmission of Helicobacter pylori, a bacterium causing gastric cancer and peptic ulcer disease, is unknown although waterborne transmission is a likely pathway. This study investigated the hypothesis that access to treated water and a sanitary sewerage system reduces the H. pylori incidence rate, using data from 472 participants in a cohort study that followed children in Juarez, Mexico, and El Paso, Texas, from April 1998, with caretaker interviews and the urea breath test for detecting H. pylori infection at target intervals of six months from birth through 24 months of age. The unadjusted hazard ratio comparing bottled/vending machine water to a municipal water supply was 0.71 (95% confidence interval (CI): 0.50, 1.01) and comparing a municipal sewer connection to a septic tank or cesspool, 0.85 (95% CI: 0.60, 1.20). After adjustment for maternal education and country, the hazard ratios decreased slightly to 0.70 (95% confidence interval: 0.49, 1.00) and 0.77 (95% confidence interval: 0.50, 1.21), respectively. These results provide moderate support for potential waterborne transmission of H. pylori.
Asymptotic confidence intervals for the Pearson correlation via skewness and kurtosis.

PubMed

Bishara, Anthony J; Li, Jiexiang; Nash, Thomas

2018-02-01

When bivariate normality is violated, the default confidence interval of the Pearson correlation can be inaccurate. Two new methods were developed based on the asymptotic sampling distribution of Fisher's z' under the general case where bivariate normality need not be assumed. In Monte Carlo simulations, the most successful of these methods relied on the (Vale & Maurelli, 1983, Psychometrika, 48, 465) family to approximate a distribution via the marginal skewness and kurtosis of the sample data. In Simulation 1, this method provided more accurate confidence intervals of the correlation in non-normal data, at least as compared to no adjustment of the Fisher z' interval, or to adjustment via the sample joint moments. In Simulation 2, this approximate distribution method performed favourably relative to common non-parametric bootstrap methods, but its performance was mixed relative to an observed imposed bootstrap and two other robust methods (PM1 and HC4). No method was completely satisfactory. An advantage of the approximate distribution method, though, is that it can be implemented even without access to raw data if sample skewness and kurtosis are reported, making the method particularly useful for meta-analysis. Supporting information includes R code. © 2017 The British Psychological Society.
Significance testing - are we ready yet to abandon its use?

PubMed

The, Bertram

2011-11-01

Understanding of the damaging effects of significance testing has steadily grown. Reporting p values without dichotomizing the result to be significant or not, is not the solution. Confidence intervals are better, but are troubled by a non-intuitive interpretation, and are often misused just to see whether the null value lies within the interval. Bayesian statistics provide an alternative which solves most of these problems. Although criticized for relying on subjective models, the interpretation of a Bayesian posterior probability is more intuitive than the interpretation of a p value, and seems to be closest to intuitive patterns of human decision making. Another alternative could be using confidence interval functions (or p value functions) to display a continuum of intervals at different levels of confidence around a point estimate. Thus, better alternatives to significance testing exist. The reluctance to abandon this practice might be both preference of clinging to old habits as well as the unfamiliarity with better methods. Authors might question if using less commonly exercised, though superior, techniques will be well received by the editors, reviewers and the readership. A joint effort will be needed to abandon significance testing in clinical research in the future.
Effect of Lowering the Dialysate Temperature in Chronic Hemodialysis: A Systematic Review and Meta-Analysis

PubMed Central

Bdair, Fadi; Akl, Elie A.; Garg, Amit X.; Thiessen-Philbrook, Heather; Salameh, Hassan; Kisra, Sood; Nesrallah, Gihad; Al-Jaishi, Ahmad; Patel, Parth; Patel, Payal; Mustafa, Ahmad A.; Schünemann, Holger J.

2016-01-01

Background and objectives Lowering the dialysate temperature may improve outcomes for patients undergoing chronic hemodialysis. We reviewed the reported benefits and harms of lower temperature dialysis. Design, setting, participants, & measurements We searched the Cochrane Central Register, OVID MEDLINE, EMBASE, and Pubmed until April 15, 2015. We reviewed the reference lists of relevant reviews, registered trials, and relevant conference proceedings. We included all randomized, controlled trials that evaluated the effect of reduced temperature dialysis versus standard temperature dialysis in adult patients receiving chronic hemodialysis. We followed the Grading of Recommendations Assessment, Development and Evaluation approach to assess confidence in the estimates of effect (i.e., the quality of evidence). We conducted meta-analyses using random effects models. Results Twenty-six trials were included, consisting of a total of 484 patients. Compared with standard temperature dialysis, reduced temperature dialysis significantly reduced the rate of intradialytic hypotension by 70% (95% confidence interval, 49% to 89%) and significantly increased intradialytic mean arterial pressure by 12 mmHg (95% confidence interval, 8 to 16 mmHg). Symptoms of discomfort occurred 2.95 (95% confidence interval, 0.88 to 9.82) times more often with reduced temperature compared with standard temperature dialysis. The effect on dialysis adequacy was not significantly different, with a Kt/V mean difference of −0.05 (95% confidence interval, −0.09 to 0.01). Small sample sizes, loss to follow-up, and a lack of appropriate blinding in some trials reduced confidence in the estimates of effect. None of the trials reported long-term outcomes. Conclusions In patients receiving chronic hemodialysis, reduced temperature dialysis may reduce the rate of intradialytic hypotension and increase intradialytic mean arterial pressure. High–quality, large, multicenter, randomized trials are needed to determine whether reduced temperature dialysis affects patient mortality and major adverse cardiovascular events. PMID:26712807
Permutation-based inference for the AUC: A unified approach for continuous and discontinuous data.

PubMed

Pauly, Markus; Asendorf, Thomas; Konietschke, Frank

2016-11-01

We investigate rank-based studentized permutation methods for the nonparametric Behrens-Fisher problem, that is, inference methods for the area under the ROC curve. We hereby prove that the studentized permutation distribution of the Brunner-Munzel rank statistic is asymptotically standard normal, even under the alternative. Thus, incidentally providing the hitherto missing theoretical foundation for the Neubert and Brunner studentized permutation test. In particular, we do not only show its consistency, but also that confidence intervals for the underlying treatment effects can be computed by inverting this permutation test. In addition, we derive permutation-based range-preserving confidence intervals. Extensive simulation studies show that the permutation-based confidence intervals appear to maintain the preassigned coverage probability quite accurately (even for rather small sample sizes). For a convenient application of the proposed methods, a freely available software package for the statistical software R has been developed. A real data example illustrates the application. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
A case-control study of influenza vaccine effectiveness among Malaysian pilgrims attending the Haj in Saudi Arabia.

PubMed

Mustafa, Amal Nasir; Gessner, Bradford D; Ismail, Raman; Yusoff, Ahmad Faudzi; Abdullah, Nasuruddin; Ishak, Ilina; Abdullah, Norazmi; Merican, Mohd Ismail

2003-09-01

To determine influenza vaccine effectiveness against clinically defined influenza-like illness among Malaysian pilgrims attending the Haj in Saudi Arabia. During February and March 2000, the authors conducted an unmatched case-control study. Case patients were identified at one of five hotel clinics, while controls were residents of these hotels who had not attended a clinic. Among 820 case patients--84% of whom had received antibiotics--and 600 controls, the adjusted vaccine effectiveness against clinic visits for influenza-like illness was 77% (95% confidence interval: 69, 83), and that against receipt of antibiotics was 66% (95% confidence interval, 54, 75). The vaccine did not prevent clinic visits for non-influenza-like upper respiratory tract illness (adjusted vaccine effectiveness, 20%; 95% confidence interval: -24, 49). Influenza vaccine was effective in preventing clinic visits for influenza-like illness and antibiotic use. Pilgrims traveling to the Haj in Saudi Arabia should consider influenza vaccination use.
Use of Ketorolac Is Associated with Decreased Pneumonia Following Rib Fractures

PubMed Central

Yang, Yifan; Young, Jason B.; Schermer, Carol R.; Utter, Garth H.

2015-01-01

Background The effectiveness of the non-steroidal anti-inflammatory drug ketorolac in reducing pulmonary morbidity following rib fractures remains largely unknown. Methods We conducted a retrospective cohort study spanning January, 2003 to June, 2011, comparing pneumonia within 30 days and potential adverse effects of ketorolac among all patients with rib fractures who received ketorolac within four days post-injury to a random sample of those who did not. Results Among 202 patients who received ketorolac and 417 who did not, ketorolac use was associated with decreased pneumonia [odds ratio 0.14 (95% confidence interval 0.04–0.46)] and increased ventilator- and intensive care unit-free days [1.8 (95% confidence interval 1.1–2.5) and 2.1 (95% confidence interval 1.3–3.0) days, respectively] within 30 days. The rates of acute kidney injury, gastrointestinal hemorrhage, and fracture non-union were not different. Conclusions Early administration of ketorolac to patients with rib fractures is associated with a decreased likelihood of pneumonia, without apparent risks. PMID:24112670
Use of ketorolac is associated with decreased pneumonia following rib fractures.

PubMed

Yang, Yifan; Young, Jason B; Schermer, Carol R; Utter, Garth H

2014-04-01

The effectiveness of the nonsteroidal anti-inflammatory drug ketorolac in reducing pulmonary morbidity after rib fractures remains largely unknown. A retrospective cohort study was conducted spanning January 2003 to June 2011 assessing pneumonia within 30 days and potential adverse effects of ketorolac among all patients with rib fractures who received ketorolac <4 days after injury compared with a random sample of those who did not. Among 202 patients who received ketorolac and 417 who did not, ketorolac use was associated with decreased pneumonia (odds ratio, .14; 95% confidence interval, .04 to .46) and increased ventilator-free days (difference, 1.8 days; 95% confidence interval, 1.1 to 2.5) and intensive care unit-free days (difference, 2.1 days; 95% confidence interval, 1.3 to 3.0) within 30 days. The rates of acute kidney injury, gastrointestinal hemorrhage, and fracture nonunion were not different. Early administration of ketorolac to patients with rib fractures is associated with a decreased likelihood of pneumonia, without apparent risks. Copyright © 2014 Elsevier Inc. All rights reserved.
Prescription of Zolpidem and the Risk of Fatal Motor Vehicle Collisions: A Population-Based, Case-Crossover Study from South Korea.

PubMed

Yang, Bo Ram; Kim, Ye-Jee; Kim, Mi-Sook; Jung, Sun-Young; Choi, Nam-Kyong; Hwang, Byungkwan; Park, Byung-Joo; Lee, Joongyub

2018-05-23

Zolpidem is one of the most frequently used hypnotics worldwide, but associations with serious adverse effects such as motor vehicle collisions have been reported. The objective of this study was to evaluate the association of fatal motor vehicle collisions with a prescription for zolpidem, considering the context of the motor vehicle collisions. We conducted a case-crossover study, where each case served as its own control, by linking data about fatal motor vehicle collisions from the Korean Road Traffic Authority between 2010 and 2014 with national health insurance data. The case period was defined as 1 day before the fatal motor vehicle collisions, and was matched to four control periods at 90-day intervals. Conditional logistic regression was performed to calculate the odds ratio for fatal motor vehicle collisions associated with zolpidem exposure, and odds ratios were adjusted for time-varying exposure to confounding medications. A stratified analysis was performed by age group (younger than 65 years or not), the Charlson Comorbidity Index, and whether patients were new zolpidem users. Among the 714 subjects, the adjusted odds ratio for a fatal motor vehicle collision associated with a prescription for zolpidem the previous day was 1.48 (95% confidence interval 1.06-2.07). After stratification, a significantly increased risk was observed in subjects with a high Charlson Comorbidity Index (odds ratio 1.81; 95% confidence interval 1.16-2.84), the younger age group (odds ratio: 1.62; 95% confidence interval 1.03-2.56), and new zolpidem users (odds ratio 2.37; 95% confidence interval 1.40-4.00). A prescription for zolpidem on the previous day was significantly related to an increased risk of fatal motor vehicle collisions in this population-based case-crossover study.
Urinary tract infection-like symptom is associated with worse bladder cancer outcomes in the Medicare population: Implications for sex disparities.

PubMed

Richards, Kyle A; Ham, Sandra; Cohn, Joshua A; Steinberg, Gary D

2016-01-01

To determine the time to bladder cancer diagnosis from initial infection-like symptoms and its impact on cancer outcomes. Using Surveillance, Epidemiology and End Results-Medicare, we designed a retrospective cohort study identifying beneficiaries aged ≥ 66 years diagnosed with bladder cancer from 2007 to 2009. Patients were required to have a hematuria or urinary tract infection claim within 1 year of bladder cancer diagnosis (n = 21 216), and have 2 years of prior Medicare data (n = 18 956) without any precedent hematuria, bladder cancer or urinary tract infection claims (n = 12 195). The number of days to bladder cancer diagnosis was measured, as well as the impact of sex and presenting symptom on time to diagnosis, pathology, and oncological outcomes. The mean time to bladder cancer diagnosis was 72.2 days in women versus 58.9 days in men (P < 0.001). A logistic regression model identified the greatest predictors of ≥ pT2 pathology were both women (odds ratio 2.08, 95% confidence interval 1.70-2.55) and men (odds ratio 1.71, 95% confidence interval 1.49-1.97) presenting with urinary tract infection. Cox proportional hazards analysis identified an increased risk of mortality from bladder cancer and all causes in women presenting with urinary tract infection (hazard ratio 1.37, 95% confidence interval 1.10-1.71, and hazard ratio 1.47, 95% confidence interval 1.28-1.69) compared with women with hematuria. Women have a longer interval from urinary tract infection to diagnosis of bladder cancer. Urinary tract infection presentation can adversely affect time to diagnosis, pathology and survival. Time to diagnosis seems not to be an independent predictor of bladder cancer outcomes. © 2015 The Japanese Urological Association.
Long-term cardiovascular risk of nonsteroidal anti-inflammatory drug use according to time passed after first-time myocardial infarction: a nationwide cohort study.

PubMed

Olsen, Anne-Marie Schjerning; Fosbøl, Emil L; Lindhardsen, Jesper; Folke, Fredrik; Charlot, Mette; Selmer, Christian; Bjerring Olesen, Jonas; Lamberts, Morten; Ruwald, Martin H; Køber, Lars; Hansen, Peter R; Torp-Pedersen, Christian; Gislason, Gunnar H

2012-10-16

The cardiovascular risk after the first myocardial infarction (MI) declines rapidly during the first year. We analyzed whether the cardiovascular risk associated with using nonsteroidal anti-inflammatory drugs (NSAIDs) was associated with the time elapsed following first-time MI. We identified patients aged 30 years or older admitted with first-time MI in 1997 to 2009 and subsequent NSAID use by individual-level linkage of nationwide registries of hospitalization and drug dispensing from pharmacies in Denmark. We calculated the incidence rates of death and a composite end point of coronary death or nonfatal recurrent MIs associated with NSAID use in 1-year time intervals up to 5 years after inclusion and analyzed risk by using multivariable adjusted time-dependent Cox proportional hazards models. Of the 99 187 patients included, 43 608 (44%) were prescribed NSAIDs after the index MI. There were 36 747 deaths and 28 693 coronary deaths or nonfatal recurrent MIs during the 5 years of follow-up. Relative to noncurrent treatment with NSAIDs, the use of any NSAID in the years following MI was persistently associated with an increased risk of death (hazard ratio 1.59 [95% confidence interval, 1.49-1.69]) after 1 year and hazard ratio 1.63 [95% confidence interval, 1.52-1.74] after 5 years) and coronary death or nonfatal recurrent MI (hazard ratio, 1.30 [95% confidence interval,l 1.22-1.39] and hazard ratio, 1.41 [95% confidence interval, 1.28-1.55]). The use of NSAIDs is associated with persistently increased coronary risk regardless of time elapsed after first-time MI. We advise long-term caution in the use of NSAIDs for patients after MI.
A modified Wald interval for the area under the ROC curve (AUC) in diagnostic case-control studies

PubMed Central

2014-01-01

Background The area under the receiver operating characteristic (ROC) curve, referred to as the AUC, is an appropriate measure for describing the overall accuracy of a diagnostic test or a biomarker in early phase trials without having to choose a threshold. There are many approaches for estimating the confidence interval for the AUC. However, all are relatively complicated to implement. Furthermore, many approaches perform poorly for large AUC values or small sample sizes. Methods The AUC is actually a probability. So we propose a modified Wald interval for a single proportion, which can be calculated on a pocket calculator. We performed a simulation study to compare this modified Wald interval (without and with continuity correction) with other intervals regarding coverage probability and statistical power. Results The main result is that the proposed modified Wald intervals maintain and exploit the type I error much better than the intervals of Agresti-Coull, Wilson, and Clopper-Pearson. The interval suggested by Bamber, the Mann-Whitney interval without transformation and also the interval of the binormal AUC are very liberal. For small sample sizes the Wald interval with continuity has a comparable coverage probability as the LT interval and higher power. For large sample sizes the results of the LT interval and of the Wald interval without continuity correction are comparable. Conclusions If individual patient data is not available, but only the estimated AUC and the total sample size, the modified Wald intervals can be recommended as confidence intervals for the AUC. For small sample sizes the continuity correction should be used. PMID:24552686
A modified Wald interval for the area under the ROC curve (AUC) in diagnostic case-control studies.

PubMed

Kottas, Martina; Kuss, Oliver; Zapf, Antonia

2014-02-19

The area under the receiver operating characteristic (ROC) curve, referred to as the AUC, is an appropriate measure for describing the overall accuracy of a diagnostic test or a biomarker in early phase trials without having to choose a threshold. There are many approaches for estimating the confidence interval for the AUC. However, all are relatively complicated to implement. Furthermore, many approaches perform poorly for large AUC values or small sample sizes. The AUC is actually a probability. So we propose a modified Wald interval for a single proportion, which can be calculated on a pocket calculator. We performed a simulation study to compare this modified Wald interval (without and with continuity correction) with other intervals regarding coverage probability and statistical power. The main result is that the proposed modified Wald intervals maintain and exploit the type I error much better than the intervals of Agresti-Coull, Wilson, and Clopper-Pearson. The interval suggested by Bamber, the Mann-Whitney interval without transformation and also the interval of the binormal AUC are very liberal. For small sample sizes the Wald interval with continuity has a comparable coverage probability as the LT interval and higher power. For large sample sizes the results of the LT interval and of the Wald interval without continuity correction are comparable. If individual patient data is not available, but only the estimated AUC and the total sample size, the modified Wald intervals can be recommended as confidence intervals for the AUC. For small sample sizes the continuity correction should be used.
Mining a clinical data warehouse to discover disease-finding associations using co-occurrence statistics.

PubMed

Cao, Hui; Markatou, Marianthi; Melton, Genevieve B; Chiang, Michael F; Hripcsak, George

2005-01-01

This paper applies co-occurrence statistics to discover disease-finding associations in a clinical data warehouse. We used two methods, chi2 statistics and the proportion confidence interval (PCI) method, to measure the dependence of pairs of diseases and findings, and then used heuristic cutoff values for association selection. An intrinsic evaluation showed that 94 percent of disease-finding associations obtained by chi2 statistics and 76.8 percent obtained by the PCI method were true associations. The selected associations were used to construct knowledge bases of disease-finding relations (KB-chi2, KB-PCI). An extrinsic evaluation showed that both KB-chi2 and KB-PCI could assist in eliminating clinically non-informative and redundant findings from problem lists generated by our automated problem list summarization system.
Terrestrial laser scanning used to detect asymmetries in boat hulls

NASA Astrophysics Data System (ADS)

Roca-Pardiñas, Javier; López-Alvarez, Francisco; Ordóñez, Celestino; Menéndez, Agustín; Bernardo-Sánchez, Antonio

2012-01-01

We describe a methodology for identifying asymmetries in boat hull sections reconstructed from point clouds captured using a terrestrial laser scanner (TLS). A surface was first fit to the point cloud using a nonparametric regression method that permitted the construction of a continuous smooth surface. Asymmetries in cross-sections of the surface were identified using a bootstrap resampling technique that took into account uncertainty in the coordinates of the scanned points. Each reconstructed section was analyzed to check, for a given level of significance, that it was within the confidence interval for the theoretical symmetrical section. The method was applied to the study of asymmetries in a medium-sized yacht. Identified were differences of up to 5 cm between the real and theoretical sections in some parts of the hull.
Association between smoking and p53 mutation in lung cancer: a meta-analysis.

PubMed

Liu, X; Lin, X J; Wang, C P; Yan, K K; Zhao, L Y; An, W X; Liu, X D

2014-01-01

To carry out a meta-analysis on the relationship between smoking and p53 gene mutation in lung cancer patients. PubMed, Web of Science, ProQest and Medline were searched by using the key words: 'lung cancer or lung neoplasm or lung carcinoma', 'p53 mutation' and 'smoking'. According to the selection criteria, 15 articles were identified and methodologically analysed by stata 12.0 software package. Crude odds ratios with 95% confidence intervals calculated using the fixed-effects model were used to assess the strength of association between smoking and p53 mutation in lung cancer. In total, 15 articles with 1770 lung cancer patients were identified; 69.6% of the patients were smokers, 30.4% were non-smokers. Overall, smokers with lung cancer had a 2.70-fold (95% confidence interval 2.04-3.59) higher risk for mutation than the non-smokers with lung cancer. In subgroup analyses, the increased risk of p53 mutation in smokers than in non-smokers was found in the non-small cell lung cancer (NSCLC) group (odds ratio = 2.38, 95% confidence interval = 1.71-3.32) and in the NSCLC and SCLC group (odds ratio = 3.82, 95% confidence interval = 2.19-6.69). This meta-analysis strongly suggests that p53 mutation is associated with smoking-induced lung cancer. Smokers with lung cancer had a higher risk for p53 mutation than non-smokers. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Meta-Analysis and Systematic Review to Assess the Role of Soluble FMS-Like Tyrosine Kinase-1 and Placenta Growth Factor Ratio in Prediction of Preeclampsia: The SaPPPhirE Study.

PubMed

Agrawal, Swati; Cerdeira, Ana Sofia; Redman, Christopher; Vatish, Manu

2018-02-01

Preeclampsia is a major cause of morbidity and mortality worldwide. Numerous candidate biomarkers have been proposed for diagnosis and prediction of preeclampsia. Measurement of maternal circulating angiogenesis biomarker as the ratio of sFlt-1 (soluble FMS-like tyrosine kinase-1; an antiangiogenic factor)/PlGF (placental growth factor; an angiogenic factor) reflects the antiangiogenic balance that characterizes incipient or overt preeclampsia. The ratio increases before the onset of the disease and thus may help in predicting preeclampsia. We conducted a meta-analysis to explore the predictive accuracy of sFlt-1/PlGF ratio in preeclampsia. We included 15 studies with 534 cases with preeclampsia and 19 587 controls. The ratio has a pooled sensitivity of 80% (95% confidence interval, 0.68-0.88), specificity of 92% (95% confidence interval, 0.87-0.96), positive likelihood ratio of 10.5 (95% confidence interval, 6.2-18.0), and a negative likelihood ratio of 0.22 (95% confidence interval, 0.13-0.35) in predicting preeclampsia in both high- and low-risk patients. Most of the studies have not made a distinction between early- and late-onset disease, and therefore, the analysis for it could not be done. It can prove to be a valuable screening tool for preeclampsia and may also help in decision-making, treatment stratification, and better resource allocation. © 2017 American Heart Association, Inc.
Transient Elastography vs. Aspartate Aminotransferase to Platelet Ratio Index in Hepatitis C: A Meta-Analysis.

PubMed

Mattos, A Z; Mattos, A A

Many different non-invasive methods have been studied with the purpose of staging liver fibrosis. The objective of this study was verifying if transient elastography is superior to aspartate aminotransferase to platelet ratio index for staging fibrosis in patients with chronic hepatitis C. A systematic review with meta-analysis of studies which evaluated both non-invasive tests and used biopsy as the reference standard was performed. A random-effects model was used, anticipating heterogeneity among studies. Diagnostic odds ratio was the main effect measure, and summary receiver operating characteristic curves were created. A sensitivity analysis was planned, in which the meta-analysis would be repeated excluding each study at a time. Eight studies were included in the meta-analysis. Regarding the prediction of significant fibrosis, transient elastography and aspartate aminotransferase to platelet ratio index had diagnostic odds ratios of 11.70 (95% confidence interval = 7.13-19.21) and 8.56 (95% confidence interval = 4.90-14.94) respectively. Concerning the prediction of cirrhosis, transient elastography and aspartate aminotransferase to platelet ratio index had diagnostic odds ratios of 66.49 (95% confidence interval = 23.71-186.48) and 7.47 (95% confidence interval = 4.88-11.43) respectively. In conclusion, there was no evidence of significant superiority of transient elastography over aspartate aminotransferase to platelet ratio index regarding the prediction of significant fibrosis, but the former proved to be better than the latter concerning prediction of cirrhosis.
Comparative Diagnostic Performance of Ultrasonography and 99mTc-Sestamibi Scintigraphy for Parathyroid Adenoma in Primary Hyperparathyroidism; Systematic Review and Meta- Analysis

PubMed

Nafisi Moghadam, Reza; Amlelshahbaz, Amir Pasha; Namiranian, Nasim; Sobhan-Ardekani, Mohammad; Emami-Meybodi, Mahmood; Dehghan, Ali; Rahmanian, Masoud; Razavi-Ratki, Seid Kazem

2017-12-28

Objective: Ultrasonography (US) and parathyroid scintigraphy (PS) with 99mTc-MIBI are common methods for preoperative localization of parathyroid adenomas but there discrepancies exist with regard to diagnostic accuracy. The aim of the study was to compare PS and US for localization of parathyroid adenoma with a systematic review and meta-analysis of the literature. Methods: Pub Med, Scopus (EMbase), Web of Science and the reference lists of all included studies were searched up to 1st January 2016. The search strategy was according PICO characteristics. Heterogeneity between the studies was accounted by P < 0.1. Point estimates were pooled estimate of sensitivity, specificity and positive predictive value of SPECT and ultrasonography with 99% confidence intervals (CIs) by pooling available data. Data analysis was performed using Meta-DiSc software (version 1.4). Results: Among 188 studies and after deletion of duplicated studies (75), a total of 113 titles and abstracts were studied. From these, 12 studies were selected. The meta-analysis determined a pooled sensitivity for scintigraphy of 83% [99% confidence interval (CI) 96.358 -97.412] and for ultra-sonography of 80% [99% confidence interval (CI) 76-83]. Similar results for specificity were also obtained for both approache. Conclusion: According this meta- analysis, there were no significant differences between the two methods in terms of sensitivity and specificity. There were overlaps in 99% confidence intervals. Also features of the two methods are similar. Creative Commons Attribution License

Incidence, reasons, and risk factors for readmission after surgery for benign distal esophageal disease.

PubMed

Poupore, Amy K; Stem, Miloslawa; Molena, Daniela; Lidor, Anne O

2016-09-01

Our aim was to ascertain the incidence of, reasons for, and risk factors associated with hospital readmission after an operation for benign distal esophageal disease. Using the American College of Surgeons National Surgical Quality Improvement Program database (2012-2014), patients with a primary diagnosis of gastroesophageal reflux disease, paraesophageal hiatal hernia, or achalasia who underwent fundoplication, paraesophageal hernia repair, or Heller myotomy were identified. The primary outcome was hospital readmission. Multivariable logistic regression analysis was used to identify risk factors associated with hospital readmission. Of the 14,478 patients included in this study, 801 (5.5%) were readmitted at a median of 11 days (interquartile range 6-17) postprocedure. Intolerance of oral intake (21.8%), respiratory complications (11.6%), abdominal pain (6.0%), and venous thromboembolic events (4.7%) were some of the most common reasons for readmission. Open operative approach (odds ratio 1.34, 95% confidence interval 1.05-1.71), chronic steroid use (odds ratio 1.48, 95% confidence interval 1.10-2.00), emergency admission (odds ratio 1.50, 95% confidence interval 1.01-2.21), and predischarge complication (odds ratio 1.91, 95% confidence interval 1.42-2.59) were associated most strongly with hospital readmission. Implementing standardized perioperative strategies, such as nutritional counseling, early ambulation, intensive pulmonary toilet, and deep vein thrombosis prophylaxis, may help decrease the number of preventable readmissions and enhance the overall quality of care in this patient population. Copyright © 2016 Elsevier Inc. All rights reserved.
Are Household Firearms Stored Less Safely in Homes With Adolescents?

PubMed Central

Johnson, Renee M.; Miller, Matthew; Vriniotis, Mary; Azrael, Deborah; Hemenway, David

2011-01-01

Objective To examine whether firearms are more frequently stored loaded, unlocked, or both in households with adolescents only (aged 13-17 years) compared with households with younger children only (aged 0-12 years). Design Random-digit-dial survey on firearms (n=2770). We computed bivariate associations between the presence of adolescents and firearm storage practices. Statistical significance was assessed using prevalence ratios with 95% confidence intervals. Setting United States. Participants Survey respondents with children (aged <18 years) who reported the presence of a household firearm. Main Outcome Measures Prevalence of firearms in the home stored loaded and/or unlocked. Results Of the 392 respondents, 22% had a loaded firearm, 32% had an unlocked firearm, and 8% had a firearm stored loaded and unlocked. Compared with households with younger children, households with adolescents only were somewhat more likely to store a firearm unlocked (42% vs 29%; prevalence ratio, 1.48; 95% confidence interval, 1.04-2.02), loaded (26% vs 20%; prevalence ratio, 1.25; 95% confidence interval, 0.82-1.91), or both (10% vs 8%; prevalence ratio, 1.43; 95% confidence interval, 0.64-3.19). Conclusions Parents of adolescents appear to be more likely to keep household firearms stored unsafely, especially with regard to keeping firearms unlocked. This is of concern because most youth firearm injuries happen to adolescents. Firearm injury prevention programs should directly target parents of adolescents to promote safe firearm storage. PMID:16894076
The relationship between body mass index and uric acid: a study on Japanese adult twins.

PubMed

Tanaka, Kentaro; Ogata, Soshiro; Tanaka, Haruka; Omura, Kayoko; Honda, Chika; Hayakawa, Kazuo

2015-09-01

The present study aimed to investigate the association between body mass index (BMI) and uric acid (UA) using the twin study methodology to adjust for genetic factors. The association between BMI and UA was investigated in a cross-sectional study using data from both monozygotic and dizygotic twins registered at the Osaka University Center for Twin Research and the Osaka University Graduate School of Medicine. From January 2011 to March 2014, 422 individuals participated in the health examination. We measured height, weight, age, BMI, lifestyle habits (Breslow's Health Practice Index), serum UA, and serum creatinine. To investigate the association between UA and BMI with adjustment for the clustering of a twin within a pair, individual-level analyses were performed using generalized linear mixed models (GLMMs). To investigate an association with adjustment for genetic and family environmental factors, twin-pair difference values analyses were performed. In all analysis, BMI was associated with UA in men and women. Using the GLMMs, standardized regression coefficients were 0.194 (95 % confidence interval: 0.016-0.373) in men and 0.186 (95 % confidence interval: 0.071-0.302) in women. Considering twin-pair difference value analyses, standardized regression coefficients were 0.333 (95 % confidence interval: 0.072-0.594) in men and 0.314 (95 % confidence interval: 0.151-0.477) in women. The present study shows that BMI was significantly associated with UA, after adjusting for both genetic and familial environment factors in both men and women.
Use of mobile phones in Norway and risk of intracranial tumours.

PubMed

Klaeboe, Lars; Blaasaas, Karl Gerhard; Tynes, Tore

2007-04-01

To test the hypothesis that exposure to radio-frequency electromagnetic fields from mobile phones increases the incidence of gliomas, meningiomas and acoustic neuromas in adults. The incident cases were of patients aged 19-69 years who were diagnosed during 2001-2002 in Southern Norway. Population controls were selected and frequency-matched for age, sex, and residential area. Detailed information about mobile phone use was collected from 289 glioma (response rate 77%), 207 meningioma patients (71%), and 45 acoustic neuroma patients (68%) and from 358 (69%) controls. For regular mobile phone use, defined as use on average at least once a week or more for at least 6 months, the odds ratio was 0.6 (95% confidence interval 0.4-0.9) for gliomas, 0.8 (95% confidence interval 0.5-1.1) for meningiomas and 0.5 (95% confidence interval 0.2-1.0) for acoustic neuromas. Similar results were found with mobile phone use for 6 years or more for gliomas and acoustic neuromas. An exception was meningiomas, where the odds ratio was 1.2 (95% confidence interval 0.6-2.2). Furthermore, no increasing trend was observed for gliomas or acoustic neuromas by increasing duration of regular use, the time since first regular use or cumulative use of mobile phones. The results from the present study indicate that use of mobile phones is not associated with an increased risk of gliomas, meningiomas or acoustic neuromas.
Quality of Vitamin K Antagonist Anticoagulation in Spain: Prevalence of Poor Control and Associated Factors.

PubMed

Anguita Sánchez, Manuel; Bertomeu Martínez, Vicente; Cequier Fillat, Ángel

2015-09-01

To study the prevalence of poorly controlled vitamin K antagonist anticoagulation in Spain in patients with nonvalvular atrial fibrillation, and to identify associated factors. We studied 1056 consecutive patients seen at 120 cardiology clinics in Spain between November 2013 and March 2014. We analyzed the international normalized ratio from the 6 months prior to the patient's visit, calculating the prevalence of poorly controlled anticoagulation, defined as < 65% time in therapeutic range using the Rosendaal method. Mean age was 73.6 years (standard deviation, 9.8 years); women accounted for 42% of patients. The prevalence of poorly controlled anticoagulation was 47.3%. Mean time in therapeutic range was 63.8% (25.9%). The following factors were independently associated with poorly controlled anticoagulation: kidney disease (odds ratio = 1.53; 95% confidence interval, 1.08-2.18; P = .018), routine nonsteroidal anti-inflammatory drugs (odds ratio = 1.79; 95% confidence interval, 1.20-2.79; P = .004), antiplatelet therapy (odds ratio = 2.16; 95% confidence interval, 1.49-3.12; P < .0001) and absence of angiotensin receptor blockers (odds ratio = 1.39; 95% confidence interval, 1.08-1.79; P = .011). There is a high prevalence of poorly controlled vitamin K antagonist anticoagulation in Spain. Factors associated with poor control are kidney disease, routine nonsteroidal anti-inflammatory drugs, antiplatelet use, and absence of angiotensin receptor blockers. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.
Missing doses in the life span study of Japanese atomic bomb survivors.

PubMed

Richardson, David B; Wing, Steve; Cole, Stephen R

2013-03-15

The Life Span Study of atomic bomb survivors is an important source of risk estimates used to inform radiation protection and compensation. Interviews with survivors in the 1950s and 1960s provided information needed to estimate radiation doses for survivors proximal to ground zero. Because of a lack of interview or the complexity of shielding, doses are missing for 7,058 of the 68,119 proximal survivors. Recent analyses excluded people with missing doses, and despite the protracted collection of interview information necessary to estimate some survivors' doses, defined start of follow-up as October 1, 1950, for everyone. We describe the prevalence of missing doses and its association with mortality, distance from hypocenter, city, age, and sex. Missing doses were more common among Nagasaki residents than among Hiroshima residents (prevalence ratio = 2.05; 95% confidence interval: 1.96, 2.14), among people who were closer to ground zero than among those who were far from it, among people who were younger at enrollment than among those who were older, and among males than among females (prevalence ratio = 1.22; 95% confidence interval: 1.17, 1.28). Missing dose was associated with all-cancer and leukemia mortality, particularly during the first years of follow-up (all-cancer rate ratio = 2.16, 95% confidence interval: 1.51, 3.08; and leukemia rate ratio = 4.28, 95% confidence interval: 1.72, 10.67). Accounting for missing dose and late entry should reduce bias in estimated dose-mortality associations.
Identifying types of domestic violence and its associated risk factors in a pregnant population in Kerman hospitals, Iran Republic.

PubMed

Salari, Zohreh; Nakhaee, Nouzar

2008-01-01

The objective of this study was to estimate the prevalence of different kinds of physical and emotional violence in an Iranian pregnant population and to examine its associated risk factors. This cross-sectional study was done from March through July 2005 in the 4 main hospitals of Kerman, Iran, which had maternity units. In total, 416 out of 460 women who were asked to participate agreed to be interviewed, a 90.4% response rate. All respondents were interviewed privately during the first 48 hours after delivery. The mean age (+/- SD) was 28.0 +/- 5.6, and all were married. Most of the women were urban residents (89.2%), and the majority of them were multiparous (78.8%). Nearly 16% of mothers said the pregnancies were unintended. In total, 35% (95% confidence interval: 30%-40%) of women had experienced 1 or more episodes of emotional violence during the pregnancy inflicted by their husbands, and 106 women (25%; 95% confidence interval: 21%-30%) had experienced at least 1 episode of physical violence. The highest odds of domestic violence during pregnancy was associated with unintended pregnancies (odds ratio: 7.66; 95% confidence interval: 3.45-16.99) and multiparous pregnancies (odds ratio: 6.88; 95% confidence interval: 3.46-13.68). Considering the high prevalence of different types of domestic violence during pregnancy, it should be regarded as a priority for health policy experts in Kerman and possibly Iran.
Job strain as a risk factor for leisure-time physical inactivity: an individual-participant meta-analysis of up to 170,000 men and women: the IPD-Work Consortium.

PubMed

Fransson, Eleonor I; Heikkilä, Katriina; Nyberg, Solja T; Zins, Marie; Westerlund, Hugo; Westerholm, Peter; Väänänen, Ari; Virtanen, Marianna; Vahtera, Jussi; Theorell, Töres; Suominen, Sakari; Singh-Manoux, Archana; Siegrist, Johannes; Sabia, Séverine; Rugulies, Reiner; Pentti, Jaana; Oksanen, Tuula; Nordin, Maria; Nielsen, Martin L; Marmot, Michael G; Magnusson Hanson, Linda L; Madsen, Ida E H; Lunau, Thorsten; Leineweber, Constanze; Kumari, Meena; Kouvonen, Anne; Koskinen, Aki; Koskenvuo, Markku; Knutsson, Anders; Kittel, France; Jöckel, Karl-Heinz; Joensuu, Matti; Houtman, Irene L; Hooftman, Wendela E; Goldberg, Marcel; Geuskens, Goedele A; Ferrie, Jane E; Erbel, Raimund; Dragano, Nico; De Bacquer, Dirk; Clays, Els; Casini, Annalisa; Burr, Hermann; Borritz, Marianne; Bonenfant, Sébastien; Bjorner, Jakob B; Alfredsson, Lars; Hamer, Mark; Batty, G David; Kivimäki, Mika

2012-12-15

Unfavorable work characteristics, such as low job control and too high or too low job demands, have been suggested to increase the likelihood of physical inactivity during leisure time, but this has not been verified in large-scale studies. The authors combined individual-level data from 14 European cohort studies (baseline years from 1985-1988 to 2006-2008) to examine the association between unfavorable work characteristics and leisure-time physical inactivity in a total of 170,162 employees (50% women; mean age, 43.5 years). Of these employees, 56,735 were reexamined after 2-9 years. In cross-sectional analyses, the odds for physical inactivity were 26% higher (odds ratio = 1.26, 95% confidence interval: 1.15, 1.38) for employees with high-strain jobs (low control/high demands) and 21% higher (odds ratio = 1.21, 95% confidence interval: 1.11, 1.31) for those with passive jobs (low control/low demands) compared with employees in low-strain jobs (high control/low demands). In prospective analyses restricted to physically active participants, the odds of becoming physically inactive during follow-up were 21% and 20% higher for those with high-strain (odds ratio = 1.21, 95% confidence interval: 1.11, 1.32) and passive (odds ratio = 1.20, 95% confidence interval: 1.11, 1.30) jobs at baseline. These data suggest that unfavorable work characteristics may have a spillover effect on leisure-time physical activity.
Determinants of Quality of Interview and Impact on Risk Estimates in a Case-Control Study of Bladder Cancer

PubMed Central

Silverman, Debra T.; Malats, Núria; Tardon, Adonina; Garcia-Closas, Reina; Serra, Consol; Carrato, Alfredo; Fortuny, Joan; Rothman, Nathaniel; Dosemeci, Mustafa; Kogevinas, Manolis

2009-01-01

The authors evaluated potential determinants of the quality of the interview in a case-control study of bladder cancer and assessed the effect of the interview quality on the risk estimates. The analysis included 1,219 incident bladder cancer cases and 1,271 controls recruited in Spain in 1998–2001. Information on etiologic factors for bladder cancer was collected through personal interviews, which were scored as unsatisfactory, questionable, reliable, or high quality by the interviewers. Eight percent of the interviews were unsatisfactory or questionable. Increasing age, lower socioeconomic status, and poorer self-perceived health led to higher proportions of questionable or unreliable interviews. The odds ratio for cigarette smoking, the main risk factor for bladder cancer, was 6.18 (95% confidence interval: 4.56, 8.39) overall, 3.20 (95% confidence interval: 1.13, 9.04) among unsatisfactory or questionable interviews, 6.86 (95% confidence interval: 4.80, 9.82) among reliable interviews, and 7.70 (95% confidence interval: 3.64, 16.30) among high-quality interviews. Similar trends were observed for employment in high-risk occupations, drinking water containing elevated levels of trihalomethanes, and use of analgesics. Higher quality interviews led to stronger associations compared with risk estimation that did not take the quality of interview into account. The collection of quality of interview scores and the exclusion of unreliable interviews probably reduce misclassification of exposure in observational studies. PMID:19478234
Discharge Disposition After Stroke in Patients With Liver Disease.

PubMed

Parikh, Neal S; Merkler, Alexander E; Schneider, Yecheskel; Navi, Babak B; Kamel, Hooman

2017-02-01

Liver disease is associated with both hemorrhagic and thrombotic processes, including an elevated risk of intracranial hemorrhage. We sought to assess the relationship between liver disease and outcomes after stroke, as measured by discharge disposition. Using administrative claims data, we identified a cohort of patients hospitalized with stroke in California, Florida, and New York from 2005 to 2013. The predictor variable was liver disease. All diagnoses were defined using validated diagnosis codes. Ordinal logistic regression was used to analyze the association between liver disease and worsening discharge disposition: home, nursing/rehabilitation facility, or death. Secondarily, multiple logistic regression was used to analyze the association between liver disease and in-hospital mortality. Models were adjusted for demographics, vascular risk factors, and comorbidities. We identified 121 428 patients with intracerebral hemorrhage and 703 918 with ischemic stroke. Liver disease was documented in 13 584 patients (1.7%). Liver disease was associated with worse discharge disposition after both intracerebral hemorrhage (global odds ratio, 1.28; 95% confidence interval, 1.19-1.38) and ischemic stroke (odds ratio, 1.23; 95% confidence interval, 1.17-1.29). Similarly, liver disease was associated with in-hospital death after both intracerebral hemorrhage (odds ratio, 1.33; 95% confidence interval, 1.23-1.44) and ischemic stroke (odds ratio, 1.60; 95% confidence interval, 1.51-1.71). Liver disease was associated with worse hospital discharge disposition and in-hospital mortality after stroke, suggesting worse functional outcomes. © 2016 American Heart Association, Inc.
Assessment of the Thematic Accuracy of Land Cover Maps

NASA Astrophysics Data System (ADS)

Höhle, J.

2015-08-01

Several land cover maps are generated from aerial imagery and assessed by different approaches. The test site is an urban area in Europe for which six classes (`building', `hedge and bush', `grass', `road and parking lot', `tree', `wall and car port') had to be derived. Two classification methods were applied (`Decision Tree' and `Support Vector Machine') using only two attributes (height above ground and normalized difference vegetation index) which both are derived from the images. The assessment of the thematic accuracy applied a stratified design and was based on accuracy measures such as user's and producer's accuracy, and kappa coefficient. In addition, confidence intervals were computed for several accuracy measures. The achieved accuracies and confidence intervals are thoroughly analysed and recommendations are derived from the gained experiences. Reliable reference values are obtained using stereovision, false-colour image pairs, and positioning to the checkpoints with 3D coordinates. The influence of the training areas on the results is studied. Cross validation has been tested with a few reference points in order to derive approximate accuracy measures. The two classification methods perform equally for five classes. Trees are classified with a much better accuracy and a smaller confidence interval by means of the decision tree method. Buildings are classified by both methods with an accuracy of 99% (95% CI: 95%-100%) using independent 3D checkpoints. The average width of the confidence interval of six classes was 14% of the user's accuracy.
LONG-TERM INTRAOCULAR PRESSURE AFTER UNCOMPLICATED PARS PLANA VITRECTOMY FOR IDIOPATHIC EPIRETINAL MEMBRANE.

PubMed

Tognetto, Daniele; Pastore, Marco R; Cirigliano, Gabriella; DʼAloisio, Rossella; Borelli, Massimo; De Giacinto, Chiara

2017-11-16

To investigate long-term intraocular pressure trends after uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane. Three hundred and sixty-eight eyes of 368 consecutive patients were enrolled. Changes in intraocular pressure 1, 3, 6, and 12 months after surgery and during the final follow-up visit were evaluated in vitrectomized eyes and nonvitrectomized fellow eyes. The median follow-up period was 36 months (range 12-92 months). Longitudinal data analysis evidenced a 2.5-mmHg (2.2 mmHg; 2.7 mmHg, 95% confidence interval) statistically significant difference in intraocular pressure 30 days after surgery between treated and fellow untreated eyes, gradually recovering to a not significant 0.2-mmHg (-0.1 mmHg; 0.4 mmHg, 95% confidence interval) difference within 26 months. The incidence of late-onset ocular hypertension was 5.7% (21 over 347, 2%; 12%, 95% confidence interval) without difference between the treated eyes and the group control. No significant difference in the incidence of late-onset ocular hypertension and sex, lens status, or gauge of vitrectomy instruments was detected. Only patient's age was significantly higher (mean difference 4.2 years; 0.1-8.0 years, Monte Carlo, 95% confidence interval) in those who developed late-onset ocular hypertension in the vitrectomized eye. Uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane seems not to increase the risk of late-onset ocular hypertension or open-angle glaucoma development.
Each procedure matters: threshold for surgeon volume to minimize complications and decrease cost associated with adrenalectomy.

PubMed

Anderson, Kevin L; Thomas, Samantha M; Adam, Mohamed A; Pontius, Lauren N; Stang, Michael T; Scheri, Randall P; Roman, Sanziana A; Sosa, Julie A

2018-01-01

An association has been suggested between increasing surgeon volume and improved patient outcomes, but a threshold has not been defined for what constitutes a "high-volume" adrenal surgeon. Adult patients who underwent adrenalectomy by an identifiable surgeon between 1998-2009 were selected from the Healthcare Cost and Utilization Project National Inpatient Sample. Logistic regression modeling with restricted cubic splines was utilized to estimate the association between annual surgeon volume and complication rates in order to identify a volume threshold. A total of 3,496 surgeons performed adrenalectomies on 6,712 patients; median annual surgeon volume was 1 case. After adjustment, the likelihood of experiencing a complication decreased with increasing annual surgeon volume up to 5.6 cases (95% confidence interval, 3.27-5.96). After adjustment, patients undergoing resection by low-volume surgeons (<6 cases/year) were more likely to experience complications (odds ratio 1.71, 95% confidence interval, 1.27-2.31, P = .005), have a greater hospital stay (relative risk 1.46, 95% confidence interval, 1.25-1.70, P = .003), and at increased cost (+26.2%, 95% confidence interval, 12.6-39.9, P = .02). This study suggests that an annual threshold of surgeon volume (≥6 cases/year) that is associated with improved patient outcomes and decreased hospital cost. This volume threshold has implications for quality improvement, surgical referral and reimbursement, and surgical training. Copyright © 2017 Elsevier Inc. All rights reserved.
Job Strain as a Risk Factor for Leisure-Time Physical Inactivity: An Individual-Participant Meta-Analysis of Up to 170,000 Men and Women

PubMed Central

Fransson, Eleonor I.; Heikkilä, Katriina; Nyberg, Solja T.; Zins, Marie; Westerlund, Hugo; Westerholm, Peter; Väänänen, Ari; Virtanen, Marianna; Vahtera, Jussi; Theorell, Töres; Suominen, Sakari; Singh-Manoux, Archana; Siegrist, Johannes; Sabia, Séverine; Rugulies, Reiner; Pentti, Jaana; Oksanen, Tuula; Nordin, Maria; Nielsen, Martin L.; Marmot, Michael G.; Magnusson Hanson, Linda L.; Madsen, Ida E. H.; Lunau, Thorsten; Leineweber, Constanze; Kumari, Meena; Kouvonen, Anne; Koskinen, Aki; Koskenvuo, Markku; Knutsson, Anders; Kittel, France; Jöckel, Karl-Heinz; Joensuu, Matti; Houtman, Irene L.; Hooftman, Wendela E.; Goldberg, Marcel; Geuskens, Goedele A.; Ferrie, Jane E.; Erbel, Raimund; Dragano, Nico; De Bacquer, Dirk; Clays, Els; Casini, Annalisa; Burr, Hermann; Borritz, Marianne; Bonenfant, Sébastien; Bjorner, Jakob B.; Alfredsson, Lars; Hamer, Mark; Batty, G. David; Kivimäki, Mika

2012-01-01

Unfavorable work characteristics, such as low job control and too high or too low job demands, have been suggested to increase the likelihood of physical inactivity during leisure time, but this has not been verified in large-scale studies. The authors combined individual-level data from 14 European cohort studies (baseline years from 1985–1988 to 2006–2008) to examine the association between unfavorable work characteristics and leisure-time physical inactivity in a total of 170,162 employees (50% women; mean age, 43.5 years). Of these employees, 56,735 were reexamined after 2–9 years. In cross-sectional analyses, the odds for physical inactivity were 26% higher (odds ratio = 1.26, 95% confidence interval: 1.15, 1.38) for employees with high-strain jobs (low control/high demands) and 21% higher (odds ratio = 1.21, 95% confidence interval: 1.11, 1.31) for those with passive jobs (low control/low demands) compared with employees in low-strain jobs (high control/low demands). In prospective analyses restricted to physically active participants, the odds of becoming physically inactive during follow-up were 21% and 20% higher for those with high-strain (odds ratio = 1.21, 95% confidence interval: 1.11, 1.32) and passive (odds ratio = 1.20, 95% confidence interval: 1.11, 1.30) jobs at baseline. These data suggest that unfavorable work characteristics may have a spillover effect on leisure-time physical activity. PMID:23144364
Association between chronic azotemic kidney disease and the severity of periodontal disease in dogs.

PubMed

Glickman, Lawrence T; Glickman, Nita W; Moore, George E; Lund, Elizabeth M; Lantz, Gary C; Pressler, Barrak M

2011-05-01

Naturally occurring periodontal disease affects >75% of dogs and has been associated with cardiac lesions and presumptive endocarditis. However, the relationships between periodontal disease and chronic kidney disease (CKD) in dogs have not been studied. In a retrospective longitudinal study the incidence of azotemic CKD was compared between a cohort of 164,706 dogs with periodontal disease and a cohort of age-matched dogs with no periodontal disease from a national primary care practice. These dogs contributed 415,971 dog-years of follow-up from 2002 to 2008. Hazard ratios and 95% confidence intervals from Cox regression were used to compare the incidence of azotemic CKD in dogs with stage 1, 2, or 3/4 periodontal disease to dogs with no periodontal disease. The hazard ratio for azotemic CKD increased with increasing severity of periodontal disease (stage 1 hazard ratio=1.8, 95% confidence interval: 1.6, 2.1; stage 2 hazard ratio=2.0, 95% confidence interval: 1.7, 2.3; stage 3/4 hazard ratio=2.7, 95% confidence interval: 2.3, 3.0; P(trend)=<0.0001) after adjustment for age, gender, neuter status, breed, body weight, number of hospital visits, and dental procedures. Increasing severity of periodontal disease was also associated with serum creatinine >1.4 mg/dl and blood urea nitrogen >36 mg/dl, independent of a veterinarian's clinical diagnosis of CKD. Copyright © 2011 Elsevier B.V. All rights reserved.
Prognostic factors of premature closure of the ductus arteriosus in utero: a systematic literature review.

PubMed

Ishida, Hidekazu; Kawazu, Yukiko; Kayatani, Futoshi; Inamura, Noboru

2017-05-01

A number of case reports show various outcomes of premature closure of the ductus arteriosus in utero, including persistent pulmonary hypertension of the newborn and fetal or neonatal death; however, no study clarifies the clinical observations that are related to their prognoses. We aimed to clarify the prognostic factors of intrauterine ductal closure by a systematic literature review. Data sources We searched PubMed database (1975-2014) to identify case reports and studies on intrauterine closure of the ductus arteriosus, including maternal, fetal, and neonatal clinical information and their prognoses. We analysed the data of 116 patients from 39 articles. Of these, 12 (10.3%) died after birth or in utero. Fetal or neonatal death was significantly correlated with fetal hydrops (odds ratio=39.6, 95% confidence interval=4.6-47.8) and complete closure of the ductus arteriosus (odds ratio=5.5, 95% confidence interval=1.2-15.1). Persistent pulmonary hypertension was observed in 33 cases (28.4%), and was also correlated with fetal hydrops (odds ratio=4.2, 95% confidence interval=1.3-4.6) and complete closure of the ductus arteriosus (odds ratio=5.5, 95% confidence interval=1.6-6.0). Interestingly, maternal drug administration was not correlated with the risk of death and persistent pulmonary hypertension. Fetal hydrops and complete ductal closure are significant risk factors for both death and persistent pulmonary hypertension. Cardiac or neurological prognoses could be favourable if the patients overcome right heart failure during the perinatal period.
Missing Doses in the Life Span Study of Japanese Atomic Bomb Survivors

PubMed Central

Richardson, David B.; Wing, Steve; Cole, Stephen R.

2013-01-01

The Life Span Study of atomic bomb survivors is an important source of risk estimates used to inform radiation protection and compensation. Interviews with survivors in the 1950s and 1960s provided information needed to estimate radiation doses for survivors proximal to ground zero. Because of a lack of interview or the complexity of shielding, doses are missing for 7,058 of the 68,119 proximal survivors. Recent analyses excluded people with missing doses, and despite the protracted collection of interview information necessary to estimate some survivors' doses, defined start of follow-up as October 1, 1950, for everyone. We describe the prevalence of missing doses and its association with mortality, distance from hypocenter, city, age, and sex. Missing doses were more common among Nagasaki residents than among Hiroshima residents (prevalence ratio = 2.05; 95% confidence interval: 1.96, 2.14), among people who were closer to ground zero than among those who were far from it, among people who were younger at enrollment than among those who were older, and among males than among females (prevalence ratio = 1.22; 95% confidence interval: 1.17, 1.28). Missing dose was associated with all-cancer and leukemia mortality, particularly during the first years of follow-up (all-cancer rate ratio = 2.16, 95% confidence interval: 1.51, 3.08; and leukemia rate ratio = 4.28, 95% confidence interval: 1.72, 10.67). Accounting for missing dose and late entry should reduce bias in estimated dose-mortality associations. PMID:23429722
Gestational diabetes mellitus and pregnancy outcomes among Chinese and South Asian women in Canada.

PubMed

Mukerji, Geetha; Chiu, Maria; Shah, Baiju R

2013-02-01

To determine the association between Chinese or South Asian ethnicity and adverse neonatal and maternal outcomes for women with gestational diabetes compared to the general population. A cohort study was conducted using population-based health care databases in Ontario, Canada. All 35,577 women aged 15-49 with gestational diabetes who had live births between April 2002 and March 2011 were identified. Their delivery hospitalization records and the birth records of their neonates were examined to identify adverse neonatal outcomes and adverse maternal outcomes. Compared to infants of mothers from the general population (55.5%), infants of Chinese mothers had a lower risk of an adverse outcome at delivery (42.9%, adjusted odds ratio 0.63, 95% confidence interval 0.58-0.68), whereas infants of South Asian mothers had a higher risk (58.9%, adjusted odds ratio 1.15, 95% confidence interval 1.07-1.23). Chinese women also had a lower risk of adverse maternal outcomes (32.4%, adjusted odds ratio 0.58, 95% confidence interval 0.54-0.63) compared to general population women (41.2%), whereas the risk for South Asian women was not different (39.4%, adjusted odds ratio 0.94, 95% confidence interval 0.88-1.02) from that of general population women. The risk of complications of gestational diabetes differs significantly between Chinese and South Asian patients and the general population in Ontario. Tailored interventions for gestational diabetes management may be required to improve pregnancy outcomes in high-risk ethnic groups.
Patching vs Atropine to Treat Amblyopia in Children Aged 7 to 12 Years: A Randomized Trial

PubMed Central

2008-01-01

Objective To compare patching with atropine eye drops in the treatment of moderate amblyopia (20/40 -20/100) in children age 7 to 12 years. Methods In a randomized multi-center clinical trial, 193 children with amblyopia were randomized to weekend atropine or patching 2 hours per day of the sound eye. Main Outcome Measure Masked assessment of amblyopic eye visual acuity using the EETDRS testing protocol at 17 weeks. Results At 17 weeks, visual acuity had improved from baseline by an average of 7.6 letters in the atropine group and 8.6 letters in the patching group. The mean difference (patching minus atropine) between groups adjusted for baseline acuity was 1.2 letters (ends of complementary 1-sided 95% confidence intervals for noninferiority = -0.7 and +3.1 letters). Based on the confidence intervals this difference met the pre-specified definition for equivalence (ends of confidence intervals <5 letters). Amblyopic eye visual acuity was 20/25 or better in 15 subjects (17%) in the atropine group and 20 subjects (24%) in the patching group (difference = 7%, 95% confidence interval = -3% to 17%). Conclusions Treatment with atropine or patching leads to similar degrees of improvement in 7 to 12 year old children with moderate amblyopia. About 1 in 5 achieves 20/25 or better visual acuity in the amblyopic eye. Application to Clinical Practice Treatment of older children with unilateral amblyopia. PMID:19064841
Pigmentation Traits, Sun Exposure, and Risk of Incident Vitiligo in Women.

PubMed

Dunlap, Rachel; Wu, Shaowei; Wilmer, Erin; Cho, Eunyoung; Li, Wen-Qing; Lajevardi, Newsha; Qureshi, Abrar

2017-06-01

Vitiligo is the most common cutaneous depigmentation disorder worldwide, yet little is known about specific risk factors for disease development. Using data from the Nurses' Health Study, a prospective cohort study of 51,337 white women, we examined the associations between (i) pigmentary traits and (ii) reactions to sun exposure and risk of incident vitiligo. Nurses' Health Study participants responded to a question about clinician-diagnosed vitiligo and year of diagnosis (2001 or before, 2002-2005, 2006-2009, 2010-2011, or 2012+). We used Cox proportional hazards regression models to estimate the multivariate-adjusted hazard ratios and 95% confidence intervals of incident vitiligo associated with exposures variables, adjusting for potential confounders. We documented 271 cases of incident vitiligo over 835,594 person-years. Vitiligo risk was higher in women who had at least one mole larger than 3 mm in diameter on their left arms (hazard ratio = 1.37, 95% confidence interval = 1.02-1.83). Additionally, vitiligo risk was higher among women with better tanning ability (hazard ratio = 2.59, 95% confidence interval = 1.21-5.54) and in women who experienced at least one blistering sunburn (hazard ratio = 2.17, 95% confidence interval = 1.15-4.10). In this study, upper extremity moles, a higher ability to achieve a tan, and history of a blistering sunburn were associated with a higher risk of developing vitiligo in a population of white women. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

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