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.

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.

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.

Accuracy and precision of as-received implant torque wrenches.

PubMed

Britton-Vidal, Eduardo; Baker, Philip; Mettenburg, Donald; Pannu, Darshanjit S; Looney, Stephen W; Londono, Jimmy; Rueggeberg, Frederick A

2014-10-01

Previous implant torque evaluation did not determine if the target value fell within a confidence interval for the population mean of the test groups, disallowing determination of whether a specific type of wrench met a standardized goal value. The purpose of this study was to measure both the accuracy and precision of 2 different configurations (spring style and peak break) of as-received implant torque wrenches and compare the measured values to manufacturer-stated values. Ten wrenches from 4 manufacturers, representing a variety of torque-limiting mechanisms and specificity of use (with either a specific brand or universally with any brand of implant product). Drivers were placed into the wrench, and tightening torque was applied to reach predetermined values using a NIST-calibrated digital torque wrench. Five replications of measurement were made for each wrench and averaged to provide a single value from that instrument. The target torque value for each wrench brand was compared to the 95% confidence interval for the true population mean of measured values to see if it fell within the measured range. Only 1 wrench brand (Nobel Biocare) demonstrated the target torque value falling within the 95% confidence interval for the true population mean. For others, the targeted torque value fell above the 95% confidence interval (Straumann and Imtec) or below (Salvin Torq). Neither type of torque-limiting mechanism nor designation of a wrench to be used as a dedicated brand-only product or to be used as a universal product on many brands affected the ability of a wrench to deliver torque values where the true population mean included the target torque level. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

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.

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...

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.

Confidence interval or p-value?: part 4 of a series on evaluation of scientific publications.

PubMed

du Prel, Jean-Baptist; Hommel, Gerhard; Röhrig, Bernd; Blettner, Maria

2009-05-01

An understanding of p-values and confidence intervals is necessary for the evaluation of scientific articles. This article will inform the reader of the meaning and interpretation of these two statistical concepts. The uses of these two statistical concepts and the differences between them are discussed on the basis of a selective literature search concerning the methods employed in scientific articles. P-values in scientific studies are used to determine whether a null hypothesis formulated before the performance of the study is to be accepted or rejected. In exploratory studies, p-values enable the recognition of any statistically noteworthy findings. Confidence intervals provide information about a range in which the true value lies with a certain degree of probability, as well as about the direction and strength of the demonstrated effect. This enables conclusions to be drawn about the statistical plausibility and clinical relevance of the study findings. It is often useful for both statistical measures to be reported in scientific articles, because they provide complementary types of information.

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.

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.

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.

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.

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.

Dietary Protein and Potassium, Diet-Dependent Net Acid Load, and Risk of Incident Kidney Stones.

PubMed

Ferraro, Pietro Manuel; Mandel, Ernest I; Curhan, Gary C; Gambaro, Giovanni; Taylor, Eric N

2016-10-07

Protein and potassium intake and the resulting diet-dependent net acid load may affect kidney stone formation. It is not known whether protein type or net acid load is associated with risk of kidney stones. We prospectively examined intakes of protein (dairy, nondairy animal, and vegetable), potassium, and animal protein-to-potassium ratio (an estimate of net acid load) and risk of incident kidney stones in the Health Professionals Follow-Up Study ( n =42,919), the Nurses' Health Study I ( n =60,128), and the Nurses' Health Study II ( n =90,629). Multivariable models were adjusted for age, body mass index, diet, and other factors. We also analyzed cross-sectional associations with 24-hour urine ( n =6129). During 3,108,264 person-years of follow-up, there were 6308 incident kidney stones. Dairy protein was associated with lower risk in the Nurses' Health Study II (hazard ratio for highest versus lowest quintile, 0.84; 95% confidence interval, 0.73 to 0.96; P value for trend <0.01). The hazard ratios for nondairy animal protein were 1.15 (95% confidence interval, 0.97 to 1.36; P value for trend =0.04) in the Health Professionals Follow-Up Study and 1.20 (95% confidence interval, 0.99 to 1.46; P value for trend =0.06) in the Nurses' Health Study I. Potassium intake was associated with lower risk in all three cohorts (hazard ratios from 0.44 [95% confidence interval, 0.36 to 0.53] to 0.67 [95% confidence interval, 0.57 to 0.78]; P values for trend <0.001). Animal protein-to-potassium ratio was associated with higher risk ( P value for trend =0.004), even after adjustment for animal protein and potassium. Higher dietary potassium was associated with higher urine citrate, pH, and volume ( P values for trend <0.002). Kidney stone risk may vary by protein type. Diets high in potassium or with a relative abundance of potassium compared with animal protein could represent a means of stone prevention. Copyright © 2016 by the American Society of Nephrology.

Dietary Protein and Potassium, Diet–Dependent Net Acid Load, and Risk of Incident Kidney Stones

PubMed Central

Mandel, Ernest I.; Curhan, Gary C.; Gambaro, Giovanni; Taylor, Eric N.

2016-01-01

Background and objectives Protein and potassium intake and the resulting diet–dependent net acid load may affect kidney stone formation. It is not known whether protein type or net acid load is associated with risk of kidney stones. Design, setting, participants, & measurements We prospectively examined intakes of protein (dairy, nondairy animal, and vegetable), potassium, and animal protein-to-potassium ratio (an estimate of net acid load) and risk of incident kidney stones in the Health Professionals Follow-Up Study (n=42,919), the Nurses’ Health Study I (n=60,128), and the Nurses’ Health Study II (n=90,629). Multivariable models were adjusted for age, body mass index, diet, and other factors. We also analyzed cross-sectional associations with 24-hour urine (n=6129). Results During 3,108,264 person-years of follow-up, there were 6308 incident kidney stones. Dairy protein was associated with lower risk in the Nurses’ Health Study II (hazard ratio for highest versus lowest quintile, 0.84; 95% confidence interval, 0.73 to 0.96; P value for trend <0.01). The hazard ratios for nondairy animal protein were 1.15 (95% confidence interval, 0.97 to 1.36; P value for trend =0.04) in the Health Professionals Follow-Up Study and 1.20 (95% confidence interval, 0.99 to 1.46; P value for trend =0.06) in the Nurses’ Health Study I. Potassium intake was associated with lower risk in all three cohorts (hazard ratios from 0.44 [95% confidence interval, 0.36 to 0.53] to 0.67 [95% confidence interval, 0.57 to 0.78]; P values for trend <0.001). Animal protein-to-potassium ratio was associated with higher risk (P value for trend =0.004), even after adjustment for animal protein and potassium. Higher dietary potassium was associated with higher urine citrate, pH, and volume (P values for trend <0.002). Conclusions Kidney stone risk may vary by protein type. Diets high in potassium or with a relative abundance of potassium compared with animal protein could represent a means of stone prevention. PMID:27445166

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.

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.

[Confidence interval or p-value--similarities and differences between two important methods of statistical inference of quantitative studies].

PubMed

Harari, Gil

2014-01-01

Statistic significance, also known as p-value, and CI (Confidence Interval) are common statistics measures and are essential for the statistical analysis of studies in medicine and life sciences. These measures provide complementary information about the statistical probability and conclusions regarding the clinical significance of study findings. This article is intended to describe the methodologies, compare between the methods, assert their suitability for the different needs of study results analysis and to explain situations in which each method should be used.

Common pitfalls in statistical analysis: “P” values, statistical significance and confidence intervals

PubMed Central

Ranganathan, Priya; Pramesh, C. S.; Buyse, Marc

2015-01-01

In the second part of a series on pitfalls in statistical analysis, we look at various ways in which a statistically significant study result can be expressed. We debunk some of the myths regarding the ‘P’ value, explain the importance of ‘confidence intervals’ and clarify the importance of including both values in a paper PMID:25878958

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).

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.

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.

The Use of One-Sample Prediction Intervals for Estimating CO2 Scrubber Canister Durations

DTIC Science & Technology

2012-10-01

Grade and 812 D-Grade Sofnolime.3 Definitions According to Devore,4 A CI (confidence interval) refers to a parameter, or population ... characteristic , whose value is fixed but unknown to us. In contrast, a future value of Y is not a parameter but instead a random variable; for this

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.

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...

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…

Mortality and Disability According to Baseline Blood Pressure in Acute Ischemic Stroke Patients Treated by Thrombectomy: A Collaborative Pooled Analysis.

PubMed

Maïer, Benjamin; Gory, Benjamin; Taylor, Guillaume; Labreuche, Julien; Blanc, Raphaël; Obadia, Michael; Abrivard, Marie; Smajda, Stanislas; Desilles, Jean-Philippe; Redjem, Hocine; Ciccio, Gabriele; Lukaszewicz, Anne Claire; Turjman, Francis; Riva, Roberto; Labeyrie, Paul Emile; Duhamel, Alain; Blacher, Jacques; Piotin, Michel; Lapergue, Bertrand; Mazighi, Mikael

2017-10-10

High blood pressure (BP) is associated with worse clinical outcomes in the setting of acute ischemic stroke, but the optimal blood pressure target is still a matter of debate. We aimed to study the association between baseline BP and mortality in acute ischemic stroke patients treated by mechanical thrombectomy. A total of 1332 acute ischemic stroke patients treated by mechanical thrombectomy were enrolled (from January 2012 to June 2016) in the ETIS (Endovascular Treatment in Ischemic Stroke) registry. Linear and polynomial logistic regression models were used to assess the association between BP and mortality and functional outcome at 90 days. Highest mortality was found at lower and higher baseline systolic blood pressure (SBP) values following a J- or U-shaped relationship, with a nadir at 157 mm Hg (95% confidence interval 143-170). When SBP values were categorized in 10-mm Hg increments, the odds ratio for all-cause mortality was 3.78 (95% confidence interval 1.50-9.55) for SBP<110 mm Hg and 1.81 (95% confidence interval 1.01-3.36) for SBP≥180 mm Hg using SBP≥150 to 160 mm Hg as reference. The rate of favorable outcome was the highest at low SBP values and lowest at high SBP values, with a nonlinear relationship; in unplanned exploratory analysis, an optimal threshold SBP≥177 mm Hg was found to predict unfavorable outcome (adjusted odds ratio 0.47; 95% confidence interval 0.31-0.70). In acute ischemic stroke patients treated by mechanical thrombectomy, baseline SBP is associated with all-cause mortality and favorable outcome. In contrast to mortality, favorable outcome rate was the highest at low SBP values and lowest at high SBP values. Further studies are warranted to confirm these findings. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Plasma Klotho and Cognitive Decline in Older Adults: Findings From the InCHIANTI Study

PubMed Central

Semba, Richard D.; Rosano, Caterina; Kalyani, Rita R.; Bandinelli, Stefania; Chia, Chee W.; Ferrucci, Luigi

2016-01-01

Background. The hormone klotho, encoded by the gene klotho, is primarily expressed in the kidney and choroid plexus of the brain. Higher klotho concentrations and certain genetic variants of klotho have been linked to better cognition; however, it is unknown whether klotho relates prospectively to slower cognitive decline in older adults. Methods: Plasma klotho was measured in 833 participants aged 55 or older without dementia enrolled in InCHIANTI, a prospective cohort study comprising Italian adults. Cognition was measured by Mini-Mental State Examination (MMSE) and Trail-Making Tests A and B (Trails A and Trails B) at enrollment and at 3 and 6 years after enrollment. We assessed whether klotho concentrations measured at the 3-year visit related to cognition and cognitive decline. Results: Each additional natural logarithm of klotho (pg/mL) was associated with 35% lower risk of meaningful decline in MMSE, defined as decline exceeding three points (relative risk = 0.65; 95% confidence interval 0.45, 0.95; p value = .02), and 0.75-point smaller average 3-year decline (baseline to 3-year visit) in MMSE (95% confidence interval 0.02, 1.48; p value = .04). No statistically significant associations were found between klotho and declining Trails A (relative risk = 0.99; 95% confidence interval 0.75, 1.32; p value = .97) and B (relative risk = 1.02; 95% confidence interval 0.84, 1.24; p value = .82). Conclusions: Higher plasma klotho concentrations were associated with lower risk of meaningful decline and smaller average decline in MMSE. We did not observe such findings with Trails A and B, perhaps because they test executive function and motor skills, whereas MMSE measures global cognition. Future studies should investigate mechanisms through which klotho may affect domain-specific cognitive changes. PMID:26297657

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.

Influence of fetal birth weight on perinatal outcome in planned vaginal births.

PubMed

Temerinac, Dunja; Chen, Xi; Sütterlin, Marc; Kehl, Sven

2014-02-01

The aim of this study was to provide information for better obstetric counseling by analyzing the impact of fetal birth weight (BW) on fetal and maternal outcome when vaginal birth is planned in a university hospital. In this retrospective study from January 1st 2006 to December 31st 2011, 5,177 singleton, alive deliveries at or >37 gestational weeks were assessed with regard to the fetal BW when vaginal birth was attempted. The normal BW group was defined as ≥2,500 <4,500 g. For comparison, further BW groups were defined as: group 1 <2,500 g, group 2 ≥4,000 <4,250 g, group 3 ≥4,250 <4,500 g and group 4 ≥4,500 g. Outcome criteria were mode of delivery and perineal lacerations as well as the pH and base excess of the umbilical cord artery, the Apgar score after 5 min and occurrence of shoulder dystocia. The set of controlling variables included maternal height, maternal weight, maternal age, gestational age, neonatal sex and parity. Second stage caesarean section is significantly more likely when fetal BW is under 2,500 g (30.7 vs. 15.5 % in the normal BW group, odds ratio 3.01, 95 % confidence interval 2.03-4.46, p value < 0.001). Shoulder dystocia occurred significantly more often when fetal BW was over 4,250 g (group 3: odds ratio 4.95, 95 % confidence interval 1.74-14.10, p value 0.003, group 4: odds ratio 19.96, 95 % confidence interval 7.61-52.38, p value < 0.001). The risk of an Apgar score after 5 min below 7 increased, when fetal BW was below 2,500 g (odds ratio 9.28, 95 % confidence interval 3.15-27.35, p value < 0.001) or above 4,500 g (odds ratio 5.65, 95 % confidence interval 1.22-26.24, p value 0.027). All groups were comparable to the normal group regarding pH and base excess of the umbilical cord artery as well as the risk for severe (third and fourth degree) perineal lacerations. Although a fetal birth weight under 2,500 g and a birth weight over 4,250 g are associated with some risks, there is no general contraindication for an attempt to deliver vaginally in a university hospital with regard to fetal birth weight.

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.

Customized versus population-based birth weight charts for the detection of neonatal growth and perinatal morbidity in a cross-sectional study of term neonates.

PubMed

Carberry, Angela E; Raynes-Greenow, Camille H; Turner, Robin M; Jeffery, Heather E

2013-10-15

Customized birth weight charts that incorporate maternal characteristics are now being adopted into clinical practice. However, there is controversy surrounding the value of these charts in the prediction of growth and perinatal outcomes. The objective of this study was to assess the use of customized charts in predicting growth, defined by body fat percentage, and perinatal morbidity. A total of 581 term (≥37 weeks' gestation) neonates born in Sydney, Australia, in 2010 were included. Body fat percentage measurements were taken by using air displacement plethysmography. Objective composite measurements of perinatal morbidity were used to identify neonates who had poor outcomes; these data were extracted from medical records. The value of customized charts was assessed by calculating positive predictive values, negative predictive values, and odds ratios with 95% confidence intervals. Customized versus population-based charts did not improve the prediction of either low body fat percentage (59% vs. 66% positive predictive value and 87% vs. 89% negative predictive value, respectively) or high body fat percentage (48% vs. 53% positive predictive value and 90% vs. 89% negative predictive value, respectively). Customized charts were not better than population-based charts at predicting perinatal morbidity (for customized charts, odds ratio = 1.02, 95% confidence interval: 1.01, 1.04; for population-based charts, odds ratio = 1.03, 95% confidence interval: 1.01, 1.05) per percentile decrease in birth weight. Customized birth weight charts do not provide significant improvements over population-based charts in predicting neonatal growth and morbidity.

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.

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.

Prediction of the distillation temperatures of crude oils using ¹H NMR and support vector regression with estimated confidence intervals.

PubMed

Filgueiras, Paulo R; Terra, Luciana A; Castro, Eustáquio V R; Oliveira, Lize M S L; Dias, Júlio C M; Poppi, Ronei J

2015-09-01

This paper aims to estimate the temperature equivalent to 10% (T10%), 50% (T50%) and 90% (T90%) of distilled volume in crude oils using (1)H NMR and support vector regression (SVR). Confidence intervals for the predicted values were calculated using a boosting-type ensemble method in a procedure called ensemble support vector regression (eSVR). The estimated confidence intervals obtained by eSVR were compared with previously accepted calculations from partial least squares (PLS) models and a boosting-type ensemble applied in the PLS method (ePLS). By using the proposed boosting strategy, it was possible to identify outliers in the T10% property dataset. The eSVR procedure improved the accuracy of the distillation temperature predictions in relation to standard PLS, ePLS and SVR. For T10%, a root mean square error of prediction (RMSEP) of 11.6°C was obtained in comparison with 15.6°C for PLS, 15.1°C for ePLS and 28.4°C for SVR. The RMSEPs for T50% were 24.2°C, 23.4°C, 22.8°C and 14.4°C for PLS, ePLS, SVR and eSVR, respectively. For T90%, the values of RMSEP were 39.0°C, 39.9°C and 39.9°C for PLS, ePLS, SVR and eSVR, respectively. The confidence intervals calculated by the proposed boosting methodology presented acceptable values for the three properties analyzed; however, they were lower than those calculated by the standard methodology for PLS. Copyright © 2015 Elsevier B.V. All rights reserved.

Computed tomography for occult fractures of the proximal femur, pelvis, and sacrum in clinical practice: single institution, dual-site experience.

PubMed

Mandell, Jacob C; Weaver, Michael J; Khurana, Bharti

2018-06-01

The purpose of this study was to evaluate the diagnostic performance of CT for assessment of occult fractures of the proximal femur, pelvis, and sacrum. A retrospective review was performed on patients who received a CT of the hip or pelvis for suspected occult fracture after negative or equivocal radiographs performed within 24 h. The official radiology report was utilized for the determination of CT findings and calculation of sensitivity and specificity. Surgical reports, MRI reports, and clinical follow-up were used as the standard of reference. Sensitivity and specificity were calculated with 95% confidence intervals. Seventy-four patients received CT of the hip or pelvis for clinical concern for occult fracture after negative or equivocal radiographs. By the reference standard, a total of 40 fractures were present in 25/74 (33.8%) patients, including 35 conservatively treated fractures of the greater trochanter, pelvis, and sacrum, and 5 operatively treated proximal femoral fractures. A total of 14/74 (18.9%) of patients had an MRI within 1 day of CT. MRI identified an operatively treated femoral neck fracture not seen on CT and an operatively treated intertrochanteric fracture, which CT described as a greater trochanteric fracture. There were two false negative conservatively treated pelvic fractures not seen on CT but diagnosed on MRI. On a per-patient basis, CT had an overall sensitivity of 88% (22/25; 95% confidence intervals 69-97%), specificity of 98% (48/49; 95% confidence intervals 89-100%), and negative predictive value of 94%. For the five operative proximal femoral fractures, the sensitivity of CT was 60% (3/5; 95% confidence intervals 15-95%), specificity was 99% (68/69; 95% confidence intervals 92-100%), and negative predictive value was 97%. In the clinical setting of suspected occult fracture, the sensitivity of clinical CT reports for detection of any type of fracture of the proximal femur, pelvis, or sacrum was 88%. For the small number of operatively treated proximal femoral fractures seen in the study, sensitivity of CT was 60% (3/5) and negative predictive value was 97%, although the relatively few patients needing fixation precludes statistical analysis.

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.

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.

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.

Prognostic value of fasting versus nonfasting low-density lipoprotein cholesterol levels on long-term mortality: insight from the National Health and Nutrition Examination Survey III (NHANES-III).

PubMed

Doran, Bethany; Guo, Yu; Xu, Jinfeng; Weintraub, Howard; Mora, Samia; Maron, David J; Bangalore, Sripal

2014-08-12

National and international guidelines recommend fasting lipid panel measurement for risk stratification of patients for prevention of cardiovascular events. However, the prognostic value of fasting versus nonfasting low-density lipoprotein cholesterol (LDL-C) is uncertain. Patients enrolled in the National Health and Nutrition Examination Survey III (NHANES-III), a nationally representative cross-sectional survey performed from 1988 to 1994, were stratified on the basis of fasting status (≥8 or <8 hours) and followed for a mean of 14.0 (±0.22) years. Propensity score matching was used to assemble fasting and nonfasting cohorts with similar baseline characteristics. The risk of outcomes as a function of LDL-C and fasting status was assessed with the use of receiver operating characteristic curves and bootstrapping methods. The interaction between fasting status and LDL-C was assessed with Cox proportional hazards modeling. Primary outcome was all-cause mortality. Secondary outcome was cardiovascular mortality. One-to-one matching based on propensity score yielded 4299 pairs of fasting and nonfasting individuals. For the primary outcome, fasting LDL-C yielded prognostic value similar to that for nonfasting LDL-C (C statistic=0.59 [95% confidence interval, 0.57-0.61] versus 0.58 [95% confidence interval, 0.56-0.60]; P=0.73), and LDL-C by fasting status interaction term in the Cox proportional hazards model was not significant (Pinteraction=0.11). Similar results were seen for the secondary outcome (fasting versus nonfasting C statistic=0.62 [95% confidence interval, 0.60-0.66] versus 0.62 [95% confidence interval, 0.60-0.66]; P=0.96; Pinteraction=0.34). Nonfasting LDL-C has prognostic value similar to that of fasting LDL-C. National and international agencies should consider reevaluating the recommendation that patients fast before obtaining a lipid panel. © 2014 American Heart Association, Inc.

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

Health significance and statistical uncertainty. The value of P-value.

PubMed

Consonni, Dario; Bertazzi, Pier Alberto

2017-10-27

The P-value is widely used as a summary statistics of scientific results. Unfortunately, there is a widespread tendency to dichotomize its value in "P<0.05" (defined as "statistically significant") and "P>0.05" ("statistically not significant"), with the former implying a "positive" result and the latter a "negative" one. To show the unsuitability of such an approach when evaluating the effects of environmental and occupational risk factors. We provide examples of distorted use of P-value and of the negative consequences for science and public health of such a black-and-white vision. The rigid interpretation of P-value as a dichotomy favors the confusion between health relevance and statistical significance, discourages thoughtful thinking, and distorts attention from what really matters, the health significance. A much better way to express and communicate scientific results involves reporting effect estimates (e.g., risks, risks ratios or risk differences) and their confidence intervals (CI), which summarize and convey both health significance and statistical uncertainty. Unfortunately, many researchers do not usually consider the whole interval of CI but only examine if it includes the null-value, therefore degrading this procedure to the same P-value dichotomy (statistical significance or not). In reporting statistical results of scientific research present effects estimates with their confidence intervals and do not qualify the P-value as "significant" or "not significant".

The prognostic value of standardized reference values for speckle-tracking global longitudinal strain in hypertrophic cardiomyopathy.

PubMed

Hartlage, Gregory R; Kim, Jonathan H; Strickland, Patrick T; Cheng, Alan C; Ghasemzadeh, Nima; Pernetz, Maria A; Clements, Stephen D; Williams, B Robinson

2015-03-01

Speckle-tracking left ventricular global longitudinal strain (GLS) assessment may provide substantial prognostic information for hypertrophic cardiomyopathy (HCM) patients. Reference values for GLS have been recently published. We aimed to evaluate the prognostic value of standardized reference values for GLS in HCM patients. An analysis of HCM clinic patients who underwent GLS was performed. GLS was defined as normal (more negative or equal to -16%) and abnormal (less negative than -16%) based on recently published reference values. Patients were followed for a composite of events including heart failure hospitalization, sustained ventricular arrhythmia, and all-cause death. The power of GLS to predict outcomes was assessed relative to traditional clinical and echocardiographic variables present in HCM. 79 HCM patients were followed for a median of 22 months (interquartile range 9-30 months) after imaging. During follow-up, 15 patients (19%) met the primary outcome. Abnormal GLS was the only echocardiographic variable independently predictive of the primary outcome [multivariate Hazard ratio 5.05 (95% confidence interval 1.09-23.4, p = 0.038)]. When combined with traditional clinical variables, abnormal GLS remained independently predictive of the primary outcome [multivariate Hazard ratio 5.31 (95 % confidence interval 1.18-24, p = 0.030)]. In a model including the strongest clinical and echocardiographic predictors of the primary outcome, abnormal GLS demonstrated significant incremental benefit for risk stratification [net reclassification improvement 0.75 (95 % confidence interval 0.21-1.23, p < 0.0001)]. Abnormal GLS is an independent predictor of adverse outcomes in HCM patients. Standardized use of GLS may provide significant incremental value over traditional variables for risk stratification.

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

Statistics Refresher for Molecular Imaging Technologists, Part 2: Accuracy of Interpretation, Significance, and Variance.

PubMed

Farrell, Mary Beth

2018-06-01

This article is the second part of a continuing education series reviewing basic statistics that nuclear medicine and molecular imaging technologists should understand. In this article, the statistics for evaluating interpretation accuracy, significance, and variance are discussed. Throughout the article, actual statistics are pulled from the published literature. We begin by explaining 2 methods for quantifying interpretive accuracy: interreader and intrareader reliability. Agreement among readers can be expressed simply as a percentage. However, the Cohen κ-statistic is a more robust measure of agreement that accounts for chance. The higher the κ-statistic is, the higher is the agreement between readers. When 3 or more readers are being compared, the Fleiss κ-statistic is used. Significance testing determines whether the difference between 2 conditions or interventions is meaningful. Statistical significance is usually expressed using a number called a probability ( P ) value. Calculation of P value is beyond the scope of this review. However, knowing how to interpret P values is important for understanding the scientific literature. Generally, a P value of less than 0.05 is considered significant and indicates that the results of the experiment are due to more than just chance. Variance, standard deviation (SD), confidence interval, and standard error (SE) explain the dispersion of data around a mean of a sample drawn from a population. SD is commonly reported in the literature. A small SD indicates that there is not much variation in the sample data. Many biologic measurements fall into what is referred to as a normal distribution taking the shape of a bell curve. In a normal distribution, 68% of the data will fall within 1 SD, 95% will fall within 2 SDs, and 99.7% will fall within 3 SDs. Confidence interval defines the range of possible values within which the population parameter is likely to lie and gives an idea of the precision of the statistic being measured. A wide confidence interval indicates that if the experiment were repeated multiple times on other samples, the measured statistic would lie within a wide range of possibilities. The confidence interval relies on the SE. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

Measurement of the CKM angle γ from a combination of B±→Dh± analyses

NASA Astrophysics Data System (ADS)

Aaij, R.; Abellan Beteta, C.; Adeva, B.; Adinolfi, M.; Adrover, C.; Affolder, A.; Ajaltouni, Z.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Alvarez Cartelle, P.; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; Anderlini, L.; Anderson, J.; Andreassen, R.; Appleby, R. B.; Aquines Gutierrez, O.; Archilli, F.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Bachmann, S.; Back, J. J.; Baesso, C.; Balagura, V.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Bauer, Th.; Bay, A.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Belogurov, S.; Belous, K.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bettler, M.-O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Bird, T.; Bizzeti, A.; Bjørnstad, P. M.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borgia, A.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Brambach, T.; van den Brand, J.; Bressieux, J.; Brett, D.; Britsch, M.; Britton, T.; Brook, N. H.; Brown, H.; Burducea, I.; Bursche, A.; Busetto, G.; Buytaert, J.; Cadeddu, S.; Callot, O.; Calvi, M.; Calvo Gomez, M.; Camboni, A.; Campana, P.; Campora Perez, D.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carranza-Mejia, H.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Castillo Garcia, L.; Cattaneo, M.; Cauet, Ch.; Charles, M.; Charpentier, Ph.; Chen, P.; Chiapolini, N.; Chrzaszcz, M.; Ciba, K.; Cid Vidal, X.; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coca, C.; Coco, V.; Cogan, J.; Cogneras, E.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; David, P.; David, P. N. Y.; Davis, A.; De Bonis, I.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Silva, W.; De Simone, P.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Déléage, N.; Derkach, D.; Deschamps, O.; Dettori, F.; Di Canto, A.; Dijkstra, H.; Dogaru, M.; Donleavy, S.; Dordei, F.; Dosil Suárez, A.; Dossett, D.; Dovbnya, A.; Dupertuis, F.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; van Eijk, D.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Elsby, D.; Falabella, A.; Färber, C.; Fardell, G.; Farinelli, C.; Farry, S.; Fave, V.; Ferguson, D.; Fernandez Albor, V.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fitzpatrick, C.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Furcas, S.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gandelman, M.; Gandini, P.; Gao, Y.; Garofoli, J.; Garosi, P.; Garra Tico, J.; Garrido, L.; Gaspar, C.; Gauld, R.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gibson, V.; Gligorov, V. V.; Göbel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gordon, H.; Grabalosa Gándara, M.; Graciani Diaz, R.; Granado Cardoso, L. A.; Graugés, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grünberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hampson, T.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; Hartmann, T.; He, J.; Heijne, V.; Hennessy, K.; Henrard, P.; Hernando Morata, J. A.; van Herwijnen, E.; Hicheur, A.; Hicks, E.; Hill, D.; Hoballah, M.; Hombach, C.; Hopchev, P.; Hulsbergen, W.; Hunt, P.; Huse, T.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Iakovenko, V.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jans, E.; Jaton, P.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Kaballo, M.; Kandybei, S.; Karacson, M.; Karbach, T. M.; Kenyon, I. R.; Kerzel, U.; Ketel, T.; Keune, A.; Khanji, B.; Kochebina, O.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Korolev, M.; Kozlinskiy, A.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Kucharczyk, M.; Kudryavtsev, V.; Kvaratskheliya, T.; La Thi, V. N.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lambert, R. W.; Lanciotti, E.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J.-P.; Lefèvre, R.; Leflat, A.; Lefrançois, J.; Leo, S.; Leroy, O.; Lesiak, T.; Leverington, B.; Li, Y.; Li Gioi, L.; Liles, M.; Lindner, R.; Linn, C.; Liu, B.; Liu, G.; Lohn, S.; Longstaff, I.; Lopes, J. H.; Lopez Asamar, E.; Lopez-March, N.; Lu, H.; Lucchesi, D.; Luisier, J.; Luo, H.; Machefert, F.; Machikhiliyan, I. V.; Maciuc, F.; Maev, O.; Malde, S.; Manca, G.; Mancinelli, G.; Marconi, U.; Märki, R.; Marks, J.; Martellotti, G.; Martens, A.; Martín Sánchez, A.; Martinelli, M.; Martinez Santos, D.; Martins Tostes, D.; Massafferri, A.; Matev, R.; Mathe, Z.; Matteuzzi, C.; Maurice, E.; Mazurov, A.; Mc Skelly, B.; McCarthy, J.; McNab, A.; McNulty, R.; Meadows, B.; Meier, F.; Meissner, M.; Merk, M.; Milanes, D. A.; Minard, M.-N.; Molina Rodriguez, J.; Monteil, S.; Moran, D.; Morawski, P.; Morello, M. J.; Mountain, R.; Mous, I.; Muheim, F.; Müller, K.; Muresan, R.; Muryn, B.; Muster, B.; Naik, P.; Nakada, T.; Nandakumar, R.; Nasteva, I.; Needham, M.; Neufeld, N.; Nguyen, A. D.; Nguyen, T. D.; Nguyen-Mau, C.; Nicol, M.; Niess, V.; Niet, R.; Nikitin, N.; Nikodem, T.; Nomerotski, A.; Novoselov, A.; Oblakowska-Mucha, A.; Obraztsov, V.; Oggero, S.; Ogilvy, S.; Okhrimenko, O.; Oldeman, R.; Orlandea, M.; Otalora Goicochea, J. M.; Owen, P.; Oyanguren, A.; Pal, B. K.; Palano, A.; Palutan, M.; Panman, J.; Papanestis, A.; Pappagallo, M.; Parkes, C.; Parkinson, C. J.; Passaleva, G.; Patel, G. D.; Patel, M.; Patrick, G. N.; Patrignani, C.; Pavel-Nicorescu, C.; Pazos Alvarez, A.; Pellegrino, A.; Penso, G.; Pepe Altarelli, M.; Perazzini, S.; Perego, D. L.; Perez Trigo, E.; Pérez-Calero Yzquierdo, A.; Perret, P.; Perrin-Terrin, M.; Pessina, G.; Petridis, K.; Petrolini, A.; Phan, A.; Picatoste Olloqui, E.; Pietrzyk, B.; Pilař, T.; Pinci, D.; Playfer, S.; Plo Casasus, M.; Polci, F.; Polok, G.; Poluektov, A.; Polycarpo, E.; Popov, A.; Popov, D.; Popovici, B.; Potterat, C.; Powell, A.; Prisciandaro, J.; Pritchard, A.; Prouve, C.; Pugatch, V.; Puig Navarro, A.; Punzi, G.; Qian, W.; Rademacker, J. H.; Rakotomiaramanana, B.; Rama, M.; Rangel, M. S.; Raniuk, I.; Rauschmayr, N.; Raven, G.; Redford, S.; Reid, M. M.; dos Reis, A. C.; Ricciardi, S.; Richards, A.; Rinnert, K.; Rives Molina, V.; Roa Romero, D. A.; Robbe, P.; Rodrigues, E.; Rodriguez Perez, P.; Roiser, S.; Romanovsky, V.; Romero Vidal, A.; Rouvinet, J.; Ruf, T.; Ruffini, F.; Ruiz, H.; Ruiz Valls, P.; Sabatino, G.; Saborido Silva, J. J.; Sagidova, N.; Sail, P.; Saitta, B.; Salustino Guimaraes, V.; Salzmann, C.; Sanmartin Sedes, B.; Sannino, M.; Santacesaria, R.; Santamarina Rios, C.; Santovetti, E.; Sapunov, M.; Sarti, A.; Satriano, C.; Satta, A.; Savrie, M.; Savrina, D.; Schaack, P.; Schiller, M.; Schindler, H.; Schlupp, M.; Schmelling, M.; Schmidt, B.; Schneider, O.; Schopper, A.; Schune, M.-H.; Schwemmer, R.; Sciascia, B.; Sciubba, A.; Seco, M.; Semennikov, A.; Senderowska, K.; Sepp, I.; Serra, N.; Serrano, J.; Seyfert, P.; Shapkin, M.; Shapoval, I.; Shatalov, P.; Shcheglov, Y.; Shears, T.; Shekhtman, L.; Shevchenko, O.; Shevchenko, V.; Shires, A.; Silva Coutinho, R.; Skwarnicki, T.; Smith, N. A.; Smith, E.; Smith, M.; Sokoloff, M. D.; Soler, F. J. P.; Soomro, F.; Souza, D.; Souza De Paula, B.; Spaan, B.; Sparkes, A.; Spradlin, P.; Stagni, F.; Stahl, S.; Steinkamp, O.; Stoica, S.; Stone, S.; Storaci, B.; Straticiuc, M.; Straumann, U.; Subbiah, V. K.; Sun, L.; Swientek, S.; Syropoulos, V.; Szczekowski, M.; Szczypka, P.; Szumlak, T.; T'Jampens, S.; Teklishyn, M.; Teodorescu, E.; Teubert, F.; Thomas, C.; Thomas, E.; van Tilburg, J.; Tisserand, V.; Tobin, M.; Tolk, S.; Tonelli, D.; Topp-Joergensen, S.; Torr, N.; Tournefier, E.; Tourneur, S.; Tran, M. T.; Tresch, M.; Tsaregorodtsev, A.; Tsopelas, P.; Tuning, N.; Ubeda Garcia, M.; Ukleja, A.; Urner, D.; Uwer, U.; Vagnoni, V.; Valenti, G.; Vazquez Gomez, R.; Vazquez Regueiro, P.; Vecchi, S.; Velthuis, J. J.; Veltri, M.; Veneziano, G.; Vesterinen, M.; Viaud, B.; Vieira, D.; Vilasis-Cardona, X.; Vollhardt, A.; Volyanskyy, D.; Voong, D.; Vorobyev, A.; Vorobyev, V.; Voß, C.; Voss, H.; Waldi, R.; Wallace, R.; Wandernoth, S.; Wang, J.; Ward, D. R.; Watson, N. K.; Webber, A. D.; Websdale, D.; Whitehead, M.; Wicht, J.; Wiechczynski, J.; Wiedner, D.; Wiggers, L.; Wilkinson, G.; Williams, M. P.; Williams, M.; Wilson, F. F.; Wishahi, J.; Witek, M.; Wotton, S. A.; Wright, S.; Wu, S.; Wyllie, K.; Xie, Y.; Xing, Z.; Yang, Z.; Young, R.; Yuan, X.; Yushchenko, O.; Zangoli, M.; Zavertyaev, M.; Zhang, F.; Zhang, L.; Zhang, W. C.; Zhang, Y.; Zhelezov, A.; Zhokhov, A.; Zhong, L.; Zvyagin, A.

2013-10-01

A combination of three LHCb measurements of the CKM angle γ is presented. The decays B±→DK± and B±→Dπ± are used, where D denotes an admixture of D0 and D mesons, decaying into K+K-, π+π-, K±π∓, K±π∓π±π∓, KS0π+π-, or KS0K+K- final states. All measurements use a dataset corresponding to 1.0 fb of integrated luminosity. Combining results from B±→DK± decays alone a best-fit value of γ=72.0° is found, and confidence intervals are set γ∈[56.4,86.7]° at 68% CL, γ∈[42.6,99.6]° at 95% CL. The best-fit value of γ found from a combination of results from B±→Dπ± decays alone, is γ=18.9°, and the confidence intervals γ∈[7.4,99.2]°∪[167.9,176.4]° at 68% CL are set, without constraint at 95% CL. The combination of results from B±→DK± and B±→Dπ± decays gives a best-fit value of γ=72.6° and the confidence intervals γ∈[55.4,82.3]° at 68% CL, γ∈[40.2,92.7]° at 95% CL are set. All values are expressed modulo 180°, and are obtained taking into account the effect of D0-D mixing.

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).

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.

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.

Hazard ratio estimation and inference in clinical trials with many tied event times.

PubMed

Mehrotra, Devan V; Zhang, Yiwei

2018-06-13

The medical literature contains numerous examples of randomized clinical trials with time-to-event endpoints in which large numbers of events accrued over relatively short follow-up periods, resulting in many tied event times. A generally common feature across such examples was that the logrank test was used for hypothesis testing and the Cox proportional hazards model was used for hazard ratio estimation. We caution that this common practice is particularly risky in the setting of many tied event times for two reasons. First, the estimator of the hazard ratio can be severely biased if the Breslow tie-handling approximation for the Cox model (the default in SAS and Stata software) is used. Second, the 95% confidence interval for the hazard ratio can include one even when the corresponding logrank test p-value is less than 0.05. To help establish a better practice, with applicability for both superiority and noninferiority trials, we use theory and simulations to contrast Wald and score tests based on well-known tie-handling approximations for the Cox model. Our recommendation is to report the Wald test p-value and corresponding confidence interval based on the Efron approximation. The recommended test is essentially as powerful as the logrank test, the accompanying point and interval estimates of the hazard ratio have excellent statistical properties even in settings with many tied event times, inferential alignment between the p-value and confidence interval is guaranteed, and implementation is straightforward using commonly used software. Copyright © 2018 John Wiley & Sons, Ltd.

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.

Detecting long-duration cloud contamination in hyper-temporal NDVI imagery

NASA Astrophysics Data System (ADS)

Ali, Amjad; de Bie, C. A. J. M.; Skidmore, A. K.

2013-10-01

Cloud contamination impacts on the quality of hyper-temporal NDVI imagery and its subsequent interpretation. Short-duration cloud impacts are easily removed by using quality flags and an upper envelope filter, but long-duration cloud contamination of NDVI imagery remains. In this paper, an approach that goes beyond the use of quality flags and upper envelope filtering is tested to detect when and where long-duration clouds are responsible for unreliable NDVI readings, so that a user can flag those data as missing. The study is based on MODIS Terra and the combined Terra-Aqua 16-day NDVI product for the south of Ghana, where persistent cloud cover occurs throughout the year. The combined product could be assumed to have less cloud contamination, since it is based on two images per day. Short-duration cloud effects were removed from the two products through using the adaptive Savitzky-Golay filter. Then for each 'cleaned' product an unsupervised classified map was prepared using the ISODATA algorithm, and, by class, plots were prepared to depict changes over time of the means and the standard deviations in NDVI values. By comparing plots of similar classes, long-duration cloud contamination appeared to display a decline in mean NDVI below the lower limit 95% confidence interval with a coinciding increase in standard deviation above the upper limit 95% confidence interval. Regression analysis was carried out per NDVI class in two randomly selected groups in order to statistically test standard deviation values related to long-duration cloud contamination. A decline in seasonal NDVI values (growing season) were below the lower limit of 95% confidence interval as well as a concurrent increase in standard deviation values above the upper limit of the 95% confidence interval were noted in 34 NDVI classes. The regression analysis results showed that differences in NDVI class values between the Terra and the Terra-Aqua imagery were significantly correlated (p < 0.05) with the corresponding standard deviation values of the Terra imagery in case of all NDVI classes of two selected NDVI groups. The method successfully detects long-duration cloud contamination that results in unreliable NDVI values. The approach offers scientists interested in time series analysis a method of masking by area (class) the periods when pre-cleaned NDVI values remain affected by clouds. The approach requires no additional data for execution purposes but involves unsupervised classification of the imagery to carry out the evaluation of class-specific mean NDVI and standard deviation values over time.

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.

Validity of self-reported history of Chlamydia trachomatis infection.

PubMed

Frisse, Ann C; Marrazzo, Jeanne M; Tutlam, Nhial T; Schreiber, Courtney A; Teal, Stephanie B; Turok, David K; Peipert, Jeffrey F

2017-04-01

Chlamydia trachomatis infection is common and largely asymptomatic in women. If untreated, it can lead to sequelae such as pelvic inflammatory disease and infertility. It is unknown whether a patient's self-reported history of Chlamydia trachomatis infection is a valid marker of past infection. Our objective was to evaluate the validity of women's self-reported history of Chlamydia trachomatis infection compared with Chlamydia trachomatis serology, a marker for previous infection. We analyzed data from the Fertility After Contraception Termination study. We compared participants' survey responses with the question, "Have you ever been told by a health care provider that you had Chlamydia?" to serological test results indicating the presence or absence of antibodies to Chlamydia trachomatis as assessed by a microimmunofluorescence assay. Prevalence of past infection, sensitivity, specificity, predictive values, and likelihood ratios were calculated. The Cohen's kappa statistic was computed to assess agreement between self-report and serology. Among 409 participants, 108 (26%) reported having a history of Chlamydia trachomatis infection, whereas 146 (36%) had positive serological test results. Relative to positive microimmunofluorescence assay, the sensitivity and specificity of self-reported history of Chlamydia trachomatis infection were 52.1% (95% confidence interval, 43.6-60.4%) and 87.8% (95% confidence interval, 83.3-91.5%), respectively. The positive predictive value of the self-report was 70.4% (95% confidence interval, 60.8-78.8%), and the negative predictive value was 76.7% (95% confidence interval, 71.6-81.4%). The likelihood ratio was found to be 4.28. Agreement between self-report and serology was found to be moderate (kappa = 0.42, P < .001). Self-reported history of Chlamydia trachomatis infection commonly yields false-negative and false-positive results. When definitive status of past Chlamydia trachomatis infection is needed, serology should be obtained. Copyright © 2016 Elsevier Inc. All rights reserved.

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…

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…

SPSS macros to compare any two fitted values from a regression model.

PubMed

Weaver, Bruce; Dubois, Sacha

2012-12-01

In regression models with first-order terms only, the coefficient for a given variable is typically interpreted as the change in the fitted value of Y for a one-unit increase in that variable, with all other variables held constant. Therefore, each regression coefficient represents the difference between two fitted values of Y. But the coefficients represent only a fraction of the possible fitted value comparisons that might be of interest to researchers. For many fitted value comparisons that are not captured by any of the regression coefficients, common statistical software packages do not provide the standard errors needed to compute confidence intervals or carry out statistical tests-particularly in more complex models that include interactions, polynomial terms, or regression splines. We describe two SPSS macros that implement a matrix algebra method for comparing any two fitted values from a regression model. The !OLScomp and !MLEcomp macros are for use with models fitted via ordinary least squares and maximum likelihood estimation, respectively. The output from the macros includes the standard error of the difference between the two fitted values, a 95% confidence interval for the difference, and a corresponding statistical test with its p-value.

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.

Hypothesis Testing, "p" Values, Confidence Intervals, Measures of Effect Size, and Bayesian Methods in Light of Modern Robust Techniques

ERIC Educational Resources Information Center

Wilcox, Rand R.; Serang, Sarfaraz

2017-01-01

The article provides perspectives on p values, null hypothesis testing, and alternative techniques in light of modern robust statistical methods. Null hypothesis testing and "p" values can provide useful information provided they are interpreted in a sound manner, which includes taking into account insights and advances that have…

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.

Tennis Rackets and the Parallel Axis Theorem

ERIC Educational Resources Information Center

Christie, Derek

2014-01-01

This simple experiment uses an unusual graph straightening exercise to confirm the parallel axis theorem for an irregular object. Along the way, it estimates experimental values for g and the moment of inertia of a tennis racket. We use Excel to find a 95% confidence interval for the true values.

Uncertainty analysis for absorbed dose from a brain receptor imaging agent

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

Aydogan, B.; Miller, L.F.; Sparks, R.B.

Absorbed dose estimates are known to contain uncertainties. A recent literature search indicates that prior to this study no rigorous investigation of uncertainty associated with absorbed dose has been undertaken. A method of uncertainty analysis for absorbed dose calculations has been developed and implemented for the brain receptor imaging agent {sup 123}I-IPT. The two major sources of uncertainty considered were the uncertainty associated with the determination of residence time and that associated with the determination of the S values. There are many sources of uncertainty in the determination of the S values, but only the inter-patient organ mass variation wasmore » considered in this work. The absorbed dose uncertainties were determined for lung, liver, heart and brain. Ninety-five percent confidence intervals of the organ absorbed dose distributions for each patient and for a seven-patient population group were determined by the ``Latin Hypercube Sampling`` method. For an individual patient, the upper bound of the 95% confidence interval of the absorbed dose was found to be about 2.5 times larger than the estimated mean absorbed dose. For the seven-patient population the upper bound of the 95% confidence interval of the absorbed dose distribution was around 45% more than the estimated population mean. For example, the 95% confidence interval of the population liver dose distribution was found to be between 1.49E+0.7 Gy/MBq and 4.65E+07 Gy/MBq with a mean of 2.52E+07 Gy/MBq. This study concluded that patients in a population receiving {sup 123}I-IPT could receive absorbed doses as much as twice as large as the standard estimated absorbed dose due to these uncertainties.« less

Accuracy of Cameriere's cut-off value for third molar in assessing 18 years of age.

PubMed

De Luca, S; Biagi, R; Begnoni, G; Farronato, G; Cingolani, M; Merelli, V; Ferrante, L; Cameriere, R

2014-02-01

Due to increasingly numerous international migrations, estimating the age of unaccompanied minors is becoming of enormous significance for forensic professionals who are required to deliver expert opinions. The third molar tooth is one of the few anatomical sites available for estimating the age of individuals in late adolescence. This study verifies the accuracy of Cameriere's cut-off value of the third molar index (I3M) in assessing 18 years of age. For this purpose, a sample of orthopantomographs (OPTs) of 397 living subjects aged between 13 and 22 years (192 female and 205 male) was analyzed. Age distribution gradually decreases as I3M increases in both males and females. The results show that the sensitivity of the test was 86.6%, with a 95% confidence interval of (80.8%, 91.1%), and its specificity was 95.7%, with a 95% confidence interval of (92.1%, 98%). The proportion of correctly classified individuals was 91.4%. Estimated post-test probability, p was 95.6%, with a 95% confidence interval of (92%, 98%). Hence, the probability that a subject positive on the test (i.e., I3M<0.08) was 18 years of age or older was 95.6%. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

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.

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 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.

Reflexion on linear regression trip production modelling method for ensuring good model quality

NASA Astrophysics Data System (ADS)

Suprayitno, Hitapriya; Ratnasari, Vita

2017-11-01

Transport Modelling is important. For certain cases, the conventional model still has to be used, in which having a good trip production model is capital. A good model can only be obtained from a good sample. Two of the basic principles of a good sampling is having a sample capable to represent the population characteristics and capable to produce an acceptable error at a certain confidence level. It seems that this principle is not yet quite understood and used in trip production modeling. Therefore, investigating the Trip Production Modelling practice in Indonesia and try to formulate a better modeling method for ensuring the Model Quality is necessary. This research result is presented as follows. Statistics knows a method to calculate span of prediction value at a certain confidence level for linear regression, which is called Confidence Interval of Predicted Value. The common modeling practice uses R2 as the principal quality measure, the sampling practice varies and not always conform to the sampling principles. An experiment indicates that small sample is already capable to give excellent R2 value and sample composition can significantly change the model. Hence, good R2 value, in fact, does not always mean good model quality. These lead to three basic ideas for ensuring good model quality, i.e. reformulating quality measure, calculation procedure, and sampling method. A quality measure is defined as having a good R2 value and a good Confidence Interval of Predicted Value. Calculation procedure must incorporate statistical calculation method and appropriate statistical tests needed. A good sampling method must incorporate random well distributed stratified sampling with a certain minimum number of samples. These three ideas need to be more developed and tested.

Tablet potency of Tianeptine in coated tablets by near infrared spectroscopy: model optimisation, calibration transfer and confidence intervals.

PubMed

Boiret, Mathieu; Meunier, Loïc; Ginot, Yves-Michel

2011-02-20

A near infrared (NIR) method was developed for determination of tablet potency of active pharmaceutical ingredient (API) in a complex coated tablet matrix. The calibration set contained samples from laboratory and production scale batches. The reference values were obtained by high performance liquid chromatography (HPLC) and partial least squares (PLS) regression was used to establish a model. The model was challenged by calculating tablet potency of two external test sets. Root mean square errors of prediction were respectively equal to 2.0% and 2.7%. To use this model with a second spectrometer from the production field, a calibration transfer method called piecewise direct standardisation (PDS) was used. After the transfer, the root mean square error of prediction of the first test set was 2.4% compared to 4.0% without transferring the spectra. A statistical technique using bootstrap of PLS residuals was used to estimate confidence intervals of tablet potency calculations. This method requires an optimised PLS model, selection of the bootstrap number and determination of the risk. In the case of a chemical analysis, the tablet potency value will be included within the confidence interval calculated by the bootstrap method. An easy to use graphical interface was developed to easily determine if the predictions, surrounded by minimum and maximum values, are within the specifications defined by the regulatory organisation. Copyright © 2010 Elsevier B.V. All rights reserved.

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.

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

Is the P-Value Really Dead? Assessing Inference Learning Outcomes for Social Science Students in an Introductory Statistics Course

ERIC Educational Resources Information Center

Lane-Getaz, Sharon

2017-01-01

In reaction to misuses and misinterpretations of p-values and confidence intervals, a social science journal editor banned p-values from its pages. This study aimed to show that education could address misuse and abuse. This study examines inference-related learning outcomes for social science students in an introductory course supplemented with…

Efficient bootstrap estimates for tail statistics

NASA Astrophysics Data System (ADS)

Breivik, Øyvind; Aarnes, Ole Johan

2017-03-01

Bootstrap resamples can be used to investigate the tail of empirical distributions as well as return value estimates from the extremal behaviour of the sample. Specifically, the confidence intervals on return value estimates or bounds on in-sample tail statistics can be obtained using bootstrap techniques. However, non-parametric bootstrapping from the entire sample is expensive. It is shown here that it suffices to bootstrap from a small subset consisting of the highest entries in the sequence to make estimates that are essentially identical to bootstraps from the entire sample. Similarly, bootstrap estimates of confidence intervals of threshold return estimates are found to be well approximated by using a subset consisting of the highest entries. This has practical consequences in fields such as meteorology, oceanography and hydrology where return values are calculated from very large gridded model integrations spanning decades at high temporal resolution or from large ensembles of independent and identically distributed model fields. In such cases the computational savings are substantial.

ESTABLISHMENT OF A FIBRINOGEN REFERENCE INTERVAL IN ORNATE BOX TURTLES (TERRAPENE ORNATA ORNATA).

PubMed

Parkinson, Lily; Olea-Popelka, Francisco; Klaphake, Eric; Dadone, Liza; Johnston, Matthew

2016-09-01

This study sought to establish a reference interval for fibrinogen in healthy ornate box turtles ( Terrapene ornata ornata). A total of 48 turtles were enrolled, with 42 turtles deemed to be noninflammatory and thus fitting the inclusion criteria and utilized to estimate a fibrinogen reference interval. Turtles were excluded based upon physical examination and blood work abnormalities. A Shapiro-Wilk normality test indicated that the noninflammatory turtle fibrinogen values were normally distributed (Gaussian distribution) with an average of 108 mg/dl and a 95% confidence interval of the mean of 97.9-117 mg/dl. Those turtles excluded from the reference interval because of abnormalities affecting their health had significantly different fibrinogen values (P = 0.313). A reference interval for healthy ornate box turtles was calculated. Further investigation into the utility of fibrinogen measurement for clinical usage in ornate box turtles is warranted.

Interlaboratory Reproducibility and Proficiency Testing within the Human Papillomavirus Cervical Cancer Screening Program in Catalonia, Spain

PubMed Central

Ibáñez, R.; Félez-Sánchez, M.; Godínez, J. M.; Guardià, C.; Caballero, E.; Juve, R.; Combalia, N.; Bellosillo, B.; Cuevas, D.; Moreno-Crespi, J.; Pons, L.; Autonell, J.; Gutierrez, C.; Ordi, J.; de Sanjosé, S.

2014-01-01

In Catalonia, a screening protocol for cervical cancer, including human papillomavirus (HPV) DNA testing using the Digene Hybrid Capture 2 (HC2) assay, was implemented in 2006. In order to monitor interlaboratory reproducibility, a proficiency testing (PT) survey of the HPV samples was launched in 2008. The aim of this study was to explore the repeatability of the HC2 assay's performance. Participating laboratories provided 20 samples annually, 5 randomly chosen samples from each of the following relative light unit (RLU) intervals: <0.5, 0.5 to 0.99, 1 to 9.99, and ≥10. Kappa statistics were used to determine the agreement levels between the original and the PT readings. The nature and origin of the discrepant results were calculated by bootstrapping. A total of 946 specimens were retested. The kappa values were 0.91 for positive/negative categorical classification and 0.79 for the four RLU intervals studied. Sample retesting yielded systematically lower RLU values than the original test (P < 0.005), independently of the time elapsed between the two determinations (median, 53 days), possibly due to freeze-thaw cycles. The probability for a sample to show clinically discrepant results upon retesting was a function of the RLU value; samples with RLU values in the 0.5 to 5 interval showed 10.80% probability to yield discrepant results (95% confidence interval [CI], 7.86 to 14.33) compared to 0.85% probability for samples outside this interval (95% CI, 0.17 to 1.69). Globally, the HC2 assay shows high interlaboratory concordance. We have identified differential confidence thresholds and suggested the guidelines for interlaboratory PT in the future, as analytical quality assessment of HPV DNA detection remains a central component of the screening program for cervical cancer prevention. PMID:24574284

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.

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.

Descriptive Statistics: Reporting the Answers to the 5 Basic Questions of Who, What, Why, When, Where, and a Sixth, So What?

PubMed

Vetter, Thomas R

2017-11-01

Descriptive statistics are specific methods basically used to calculate, describe, and summarize collected research data in a logical, meaningful, and efficient way. Descriptive statistics are reported numerically in the manuscript text and/or in its tables, or graphically in its figures. This basic statistical tutorial discusses a series of fundamental concepts about descriptive statistics and their reporting. The mean, median, and mode are 3 measures of the center or central tendency of a set of data. In addition to a measure of its central tendency (mean, median, or mode), another important characteristic of a research data set is its variability or dispersion (ie, spread). In simplest terms, variability is how much the individual recorded scores or observed values differ from one another. The range, standard deviation, and interquartile range are 3 measures of variability or dispersion. The standard deviation is typically reported for a mean, and the interquartile range for a median. Testing for statistical significance, along with calculating the observed treatment effect (or the strength of the association between an exposure and an outcome), and generating a corresponding confidence interval are 3 tools commonly used by researchers (and their collaborating biostatistician or epidemiologist) to validly make inferences and more generalized conclusions from their collected data and descriptive statistics. A number of journals, including Anesthesia & Analgesia, strongly encourage or require the reporting of pertinent confidence intervals. A confidence interval can be calculated for virtually any variable or outcome measure in an experimental, quasi-experimental, or observational research study design. Generally speaking, in a clinical trial, the confidence interval is the range of values within which the true treatment effect in the population likely resides. In an observational study, the confidence interval is the range of values within which the true strength of the association between the exposure and the outcome (eg, the risk ratio or odds ratio) in the population likely resides. There are many possible ways to graphically display or illustrate different types of data. While there is often latitude as to the choice of format, ultimately, the simplest and most comprehensible format is preferred. Common examples include a histogram, bar chart, line chart or line graph, pie chart, scatterplot, and box-and-whisker plot. Valid and reliable descriptive statistics can answer basic yet important questions about a research data set, namely: "Who, What, Why, When, Where, How, How Much?"

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).

Using Replicates in Information Retrieval Evaluation.

PubMed

Voorhees, Ellen M; Samarov, Daniel; Soboroff, Ian

2017-09-01

This article explores a method for more accurately estimating the main effect of the system in a typical test-collection-based evaluation of information retrieval systems, thus increasing the sensitivity of system comparisons. Randomly partitioning the test document collection allows for multiple tests of a given system and topic (replicates). Bootstrap ANOVA can use these replicates to extract system-topic interactions-something not possible without replicates-yielding a more precise value for the system effect and a narrower confidence interval around that value. Experiments using multiple TREC collections demonstrate that removing the topic-system interactions substantially reduces the confidence intervals around the system effect as well as increases the number of significant pairwise differences found. Further, the method is robust against small changes in the number of partitions used, against variability in the documents that constitute the partitions, and the measure of effectiveness used to quantify system effectiveness.

Accounting for dropout bias using mixed-effects models.

PubMed

Mallinckrodt, C H; Clark, W S; David, S R

2001-01-01

Treatment effects are often evaluated by comparing change over time in outcome measures. However, valid analyses of longitudinal data can be problematic when subjects discontinue (dropout) prior to completing the study. This study assessed the merits of likelihood-based repeated measures analyses (MMRM) compared with fixed-effects analysis of variance where missing values were imputed using the last observation carried forward approach (LOCF) in accounting for dropout bias. Comparisons were made in simulated data and in data from a randomized clinical trial. Subject dropout was introduced in the simulated data to generate ignorable and nonignorable missingness. Estimates of treatment group differences in mean change from baseline to endpoint from MMRM were, on average, markedly closer to the true value than estimates from LOCF in every scenario simulated. Standard errors and confidence intervals from MMRM accurately reflected the uncertainty of the estimates, whereas standard errors and confidence intervals from LOCF underestimated uncertainty.

Using Replicates in Information Retrieval Evaluation

PubMed Central

VOORHEES, ELLEN M.; SAMAROV, DANIEL; SOBOROFF, IAN

2018-01-01

This article explores a method for more accurately estimating the main effect of the system in a typical test-collection-based evaluation of information retrieval systems, thus increasing the sensitivity of system comparisons. Randomly partitioning the test document collection allows for multiple tests of a given system and topic (replicates). Bootstrap ANOVA can use these replicates to extract system-topic interactions—something not possible without replicates—yielding a more precise value for the system effect and a narrower confidence interval around that value. Experiments using multiple TREC collections demonstrate that removing the topic-system interactions substantially reduces the confidence intervals around the system effect as well as increases the number of significant pairwise differences found. Further, the method is robust against small changes in the number of partitions used, against variability in the documents that constitute the partitions, and the measure of effectiveness used to quantify system effectiveness. PMID:29905334

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

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.…

A simple approach to detect and correct signal faults of Hall position sensors for brushless DC motors at steady speed

NASA Astrophysics Data System (ADS)

Shi, Yongli; Wu, Zhong; Zhi, Kangyi; Xiong, Jun

2018-03-01

In order to realize reliable commutation of brushless DC motors (BLDCMs), a simple approach is proposed to detect and correct signal faults of Hall position sensors in this paper. First, the time instant of the next jumping edge for Hall signals is predicted by using prior information of pulse intervals in the last electrical period. Considering the possible errors between the predicted instant and the real one, a confidence interval is set by using the predicted value and a suitable tolerance for the next pulse edge. According to the relationship between the real pulse edge and the confidence interval, Hall signals can be judged and the signal faults can be corrected. Experimental results of a BLDCM at steady speed demonstrate the effectiveness of the approach.

Normative values for the unipedal stance test with eyes open and closed.

PubMed

Springer, Barbara A; Marin, Raul; Cyhan, Tamara; Roberts, Holly; Gill, Norman W

2007-01-01

Limited normative data are available for the unipedal stance test (UPST), making it difficult for clinicians to use it confidently to detect subtle balance impairments. The purpose of this study was to generate normative values for repeated trials of the UPST with eyes opened and eyes closed across age groups and gender. This prospective, mixed-model design was set in a tertiary care medical center. Healthy subjects (n= 549), 18 years or older, performed the UPST with eyes open and closed. Mean and best of 3 UPST times for males and females of 6 age groups (18-39, 40-49, 50-59, 60-69, 70-79, and 80+) were documented and inter-rater reliability was tested. There was a significant age dependent decrease in UPST time during both conditions. Inter-rater reliability for the best of 3 trials was determined to be excellent with an intra-class correlation coefficient of 0.994 (95% confidence interval 0.989-0.996) for eyes open and 0.998 (95% confidence interval 0.996-0.999) for eyes closed. This study adds to the understanding of typical performance on the UPST. Performance is age-specific and not related to gender. Clinicians now have more extensive normative values to which individuals can be compared.

A multi-directional in vitro investigation into friction, damage and wear of innovative chondroplasty materials against articular cartilage.

PubMed

Northwood, Ewen; Fisher, John

2007-08-01

The wear of the biomaterial/cartilage interface is vital for the development of innovative chondroplasty therapies. The aim of this study was to investigate potential chondroplasty biomaterials when sliding against natural articular cartilage under uniaxial reciprocating and multi-directional rotation/reciprocating motions. Three biphasic hydrogels were compared to articular cartilage (negative control) and stainless steel (positive control). Friction was measured by means of a simple geometry friction and wear simulator. All tests were completed in 25% bovine serum at 20 degrees C. Mechanical alterations to the surface structure were quantified using surface topography. Articular cartilage produced a constant friction value of 0.05 (confidence interval=0.015) with and without rotation. Stainless steel against articular cartilage produced an increase in friction over time resulting in a peak value of 0.7 (confidence interval=0.02) without rotation, increasing to 0.88 (confidence interval=0.03) with rotation. All biphasic hydrogels produced peak friction values lower than the positive control and demonstrated no difference between uni- and multi-directional motion. Degradation of the opposing cartilage surface showed a significant difference between the positive and negative controls, with the greater cartilage damage when sliding against stainless steel under uni-directional motion. The lower friction and reduction of opposing cartilage surface degradation with the potential chondroplasty biomaterials can be attributed to their biphasic properties. This study illustrated the importance of biphasic properties within the tribology of cartilage substitution materials and future work will focus on the optimisation of biphasic properties such that materials more closely mimic natural cartilage.

Crash Lethality Model

DTIC Science & Technology

2012-06-06

Statistical Data ........................................................................................... 45 31 Parametric Model for Rotor Wing Debris...Area .............................................................. 46 32 Skid Distance Statistical Data...results. The curve that related the BC value to the probability of skull fracture resulted in a tight confidence interval and a two tailed statistical p

Number of positive nodes is superior to the lymph node ratio and American Joint Committee on Cancer N staging for the prognosis of surgically treated head and neck squamous cell carcinomas.

PubMed

Roberts, Thomas J; Colevas, A Dimitrios; Hara, Wendy; Holsinger, F Christopher; Oakley-Girvan, Ingrid; Divi, Vasu

2016-05-01

Recent changes in head and neck cancer epidemiology have created a need for improved lymph node prognostics. This article compares the prognostic value of the number of positive nodes (pN) with the value of the lymph node ratio (LNR) and American Joint Committee on Cancer (AJCC) N staging in surgical patients. The Surveillance, Epidemiology, and End Results database was used to identify cases of head and neck squamous cell carcinomas from 2004 to 2012. The sample was grouped by the AJCC N stage, LNR, and pN and was analyzed with Kaplan-Meier and multivariate Cox proportional hazards models. The sample was also analyzed by the site of the primary tumor. This study identified 12,437 patients. Kaplan-Meier survival curves showed superior prognostic ability for LNR and pN staging in comparison with AJCC staging. Patients with a pN value > 5 had the worst overall survival (5-year survival rate, 16%). Patients with oropharyngeal tumors had better outcomes for all groupings, and a pN value > 5 for oropharyngeal cancers was associated with decreased survival. Multivariate regressions demonstrated larger hazard ratios (HRs) and a lower Akaike information criterion for the pN model versus the AJCC stage and LNR models. The HRs were 1.78 (95% confidence interval, 1.62-1.95) for a pN value of 1, 2.53 (95% confidence interval, 2.32-2.75) for a pN value of 2 to 5, and 4.64 (95% confidence interval, 4.18-5.14) for a pN value > 5. The pN models demonstrated superior prognostic value in comparison with the LNR and AJCC N staging. Future modifications of the nodal staging system should be based on the pN with a separate system for oropharyngeal cancers. Future trials should consider examining adjuvant treatment escalation in patients with >5 lymph nodes. Cancer 2016;122:1388-1397. © 2016 American Cancer Society. © 2015 American Cancer Society.

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"…

Contraction induced h reflexes in the diagnosis of cervical radiculopathy.

PubMed

Bodofsky, Elliot B; Campellone, Joseph V; Cohen, Stephen J; Caten, Holly N; Schindelheim, Adam M

2015-06-01

To determine whether Contraction Induced H Reflexes (CIHR) can accurately detect cervical radiculopathy. Comparison of CIHR results with Needle Electromyography at academic outpatient Electromyography/Nerve Conduction laboratories. Participants were all patients over 18 with a needle electromyography diagnosis of cervical radiculopathy. Patients were tested for CIHR in at least two upper extremity muscles in electromyographically proven myotomes bilaterally. Patients were requested to perform a moderate contraction while stimulus was applied proximally (elbow or Erb's point). Outcome measures included H Reflex onset latency and side-to-side latency differences. These were compared against previously established normal values. Overall, 10 of 15 patients who met criteria for cervical radiculopathy showed CIHR abnormalities (sensitivity = 67%; 95% confidence interval, 43-91). Counting each side and level separately, CIHR identified 16/27 radiculopathies (sensitivity = 59.2%; 95% confidence interval, 40.6-77.8). Contraction Induced H Reflexes identified 1 possible radiculopathy not seen on electromyography (specificity = 98%; 95% confidence interval, 95-100). Contraction induced H Reflexes have a sensitivity and specificity for cervical radiculopathy similar to the resting Gastroc-Soleus H Reflex.

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.

Nonparametric evaluation of quantitative traits in population-based association studies when the genetic model is unknown.

PubMed

Konietschke, Frank; Libiger, Ondrej; Hothorn, Ludwig A

2012-01-01

Statistical association between a single nucleotide polymorphism (SNP) genotype and a quantitative trait in genome-wide association studies is usually assessed using a linear regression model, or, in the case of non-normally distributed trait values, using the Kruskal-Wallis test. While linear regression models assume an additive mode of inheritance via equi-distant genotype scores, Kruskal-Wallis test merely tests global differences in trait values associated with the three genotype groups. Both approaches thus exhibit suboptimal power when the underlying inheritance mode is dominant or recessive. Furthermore, these tests do not perform well in the common situations when only a few trait values are available in a rare genotype category (disbalance), or when the values associated with the three genotype categories exhibit unequal variance (variance heterogeneity). We propose a maximum test based on Marcus-type multiple contrast test for relative effect sizes. This test allows model-specific testing of either dominant, additive or recessive mode of inheritance, and it is robust against variance heterogeneity. We show how to obtain mode-specific simultaneous confidence intervals for the relative effect sizes to aid in interpreting the biological relevance of the results. Further, we discuss the use of a related all-pairwise comparisons contrast test with range preserving confidence intervals as an alternative to Kruskal-Wallis heterogeneity test. We applied the proposed maximum test to the Bogalusa Heart Study dataset, and gained a remarkable increase in the power to detect association, particularly for rare genotypes. Our simulation study also demonstrated that the proposed non-parametric tests control family-wise error rate in the presence of non-normality and variance heterogeneity contrary to the standard parametric approaches. We provide a publicly available R library nparcomp that can be used to estimate simultaneous confidence intervals or compatible multiplicity-adjusted p-values associated with the proposed maximum test.

Temporal Variability in the Deglutition Literature

PubMed Central

Molfenter, Sonja M.; Steele, Catriona M.

2013-01-01

A literature review was conducted on temporal measures of swallowing in healthy individuals with the purpose of determining the degree of variability present in such measures within the literature. A total of 46 studies that met inclusion criteria were reviewed. The definitions and descriptive statistics for all reported temporal parameters were compiled for meta-analysis. In total, 119 different temporal parameters were found in the literature. The three most-frequently occurring durational measures were: UES opening, laryngeal closure and hyoid movement. The three most-frequently occurring interval measures were: stage transition duration, pharyngeal transit time and duration from laryngeal closure to UES opening. Subtle variations in operational definitions across studies were noted, making the comparison of data challenging. Analysis of forest plots compiling descriptive statistical data (means and 95% confidence intervals) across studies revealed differing degrees of variability across durations and intervals. Two parameters (UES opening duration and the laryngeal-closure-to-UES-opening interval) demonstrated the least variability, reflected by small ranges for mean values and tight confidence intervals. Trends emerged for factors of bolus size and participant age for some variables. Other potential sources of variability are discussed. PMID:22366761

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.

Prognostic Value of Residual Urine Volume, GFR by 24-hour Urine Collection, and eGFR in Patients Receiving Dialysis.

PubMed

Lee, Mi Jung; Park, Jung Tak; Park, Kyoung Sook; Kwon, Young Eun; Oh, Hyung Jung; Yoo, Tae-Hyun; Kim, Yong-Lim; Kim, Yon Su; Yang, Chul Woo; Kim, Nam-Ho; Kang, Shin-Wook; Han, Seung Hyeok

2017-03-07

Residual kidney function can be assessed by simply measuring urine volume, calculating GFR using 24-hour urine collection, or estimating GFR using the proposed equation (eGFR). We aimed to investigate the relative prognostic value of these residual kidney function parameters in patients on dialysis. Using the database from a nationwide prospective cohort study, we compared differential implications of the residual kidney function indices in 1946 patients on dialysis at 36 dialysis centers in Korea between August 1, 2008 and December 31, 2014. Residual GFR calculated using 24-hour urine collection was determined by an average of renal urea and creatinine clearance on the basis of 24-hour urine collection. eGFR-urea, creatinine and eGFR β 2 -microglobulin were calculated from the equations using serum urea and creatinine and β 2 -microglobulin, respectively. The primary outcome was all-cause death. During a mean follow-up of 42 months, 385 (19.8%) patients died. In multivariable Cox analyses, residual urine volume (hazard ratio, 0.96 per 0.1-L/d higher volume; 95% confidence interval, 0.94 to 0.98) and GFR calculated using 24-hour urine collection (hazard ratio, 0.98; 95% confidence interval, 0.95 to 0.99) were independently associated with all-cause mortality. In 1640 patients who had eGFR β 2 -microglobulin data, eGFR β 2 -microglobulin (hazard ratio, 0.98; 95% confidence interval, 0.96 to 0.99) was also significantly associated with all-cause mortality as well as residual urine volume (hazard ratio, 0.96 per 0.1-L/d higher volume; 95% confidence interval, 0.94 to 0.98) and GFR calculated using 24-hour urine collection (hazard ratio, 0.97; 95% confidence interval, 0.95 to 0.99). When each residual kidney function index was added to the base model, only urine volume improved the predictability for all-cause mortality (net reclassification index =0.11, P =0.01; integrated discrimination improvement =0.01, P =0.01). Higher residual urine volume was significantly associated with a lower risk of death and exhibited a stronger association with mortality than GFR calculated using 24-hour urine collection and eGFR-urea, creatinine. These results suggest that determining residual urine volume may be beneficial to predict patient survival in patients on dialysis. Copyright © 2017 by the American Society of Nephrology.

Length of occlusion predicts recanalization and outcome after intravenous thrombolysis in middle cerebral artery stroke.

PubMed

Rohan, Vladimir; Baxa, Jan; Tupy, Radek; Cerna, Lenka; Sevcik, Petr; Friesl, Michal; Polivka, Jiri; Polivka, Jiri; Ferda, Jiri

2014-07-01

The length of large vessel occlusion is considered a major factor for therapy in patients with ischemic stroke. We used 4D-CT angiography evaluation of middle cerebral artery occlusion in prediction of recanalization and favorable clinical outcome and after intravenous thrombolysis (IV-tPA). In 80 patients treated with IV-tPA for acute complete middle cerebral artery/M1 occlusion determined using CT angiography and temporal maximum intensity projection, calculated from 4D-CT angiography, the length of middle cerebral artery proximal stump, occlusion in M1 or M1 and M2 segment were measured. Univariate and multivariate analyses were performed to define independent predictors of successful recanalization after 24 hours and favorable outcome after 3 months. The length of occlusion was measureable in all patients using temporal maximum intensity projection. Recanalization thrombolysis in myocardial infarction 2 to 3 was achieved in 37 individuals (46%). The extension to M2 segment as a category (odds ratio, 4.58; 95% confidence interval, 1.39-15.05; P=0.012) and the length of M1 segment occlusion (odds ratio, 0.82; 95% confidence interval, 0.73-0.92; P=0.0007) with an optimal cutoff value of 12 mm (sensitivity 0.67; specificity 0.71) were significant independent predictors of recanalization. Favorable outcome (modified Rankin scale 0-2) was achieved in 25 patients (31%), baseline National Institutes of Health Stroke Scale (odds ratio, 0.82; 95% confidence interval, 0.72-0.93; P=0.003) and the length of occlusion M1 in segment (odds ratio, 0.79; 95% confidence interval, 0.69-0.91; P=0.0008) with an optimal cutoff value of 11 mm (sensitivity 0.74; specificity 0.76) were significant independent predictors of favorable outcome. The length of middle cerebral artery occlusion is an independent predictor of successful IV-tPA treatment. © 2014 American Heart Association, Inc.

Validation of an International Statistical Classification of Diseases and Related Health Problems 10th Revision Coding Algorithm for Hospital Encounters with Hypoglycemia.

PubMed

Hodge, Meryl C; Dixon, Stephanie; Garg, Amit X; Clemens, Kristin K

2017-06-01

To determine the positive predictive value and sensitivity of an International Statistical Classification of Diseases and Related Health Problems, 10th Revision, coding algorithm for hospital encounters concerning hypoglycemia. We carried out 2 retrospective studies in Ontario, Canada. We examined medical records from 2002 through 2014, in which older adults (mean age, 76) were assigned at least 1 code for hypoglycemia (E15, E160, E161, E162, E1063, E1163, E1363, E1463). The positive predictive value of the algorithm was calculated using a gold-standard definition (blood glucose value <4 mmol/L or physician diagnosis of hypoglycemia). To determine the algorithm's sensitivity, we used linked healthcare databases to identify older adults (mean age, 77) with laboratory plasma glucose values <4 mmol/L during a hospital encounter that took place between 2003 and 2011. We assessed how frequently a code for hypoglycemia was present. We also examined the algorithm's performance in differing clinical settings (e.g. inpatient vs. emergency department, by hypoglycemia severity). The positive predictive value of the algorithm was 94.0% (95% confidence interval 89.3% to 97.0%), and its sensitivity was 12.7% (95% confidence interval 11.9% to 13.5%). It performed better in the emergency department and in cases of more severe hypoglycemia (plasma glucose values <3.5 mmol/L compared with ≥3.5 mmol/L). Our hypoglycemia algorithm has a high positive predictive value but is limited in sensitivity. Although we can be confident that older adults who are assigned 1 of these codes truly had a hypoglycemia event, many episodes will not be captured by studies using administrative databases. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

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

Shaffer, Richard, E-mail: rickyshaffer@yahoo.co.u; Department of Clinical Oncology, Imperial College London National Health Service Trust, London; Pickles, Tom

Purpose: Prior studies have derived low values of alpha-beta ratio (a/ss) for prostate cancer of approximately 1-2 Gy. These studies used poorly matched groups, differing definitions of biochemical failure, and insufficient follow-up. Methods and Materials: National Comprehensive Cancer Network low- or low-intermediate risk prostate cancer patients, treated with external beam radiotherapy or permanent prostate brachytherapy, were matched for prostate-specific antigen, Gleason score, T-stage, percentage of positive cores, androgen deprivation therapy, and era, yielding 118 patient pairs. The Phoenix definition of biochemical failure was used. The best-fitting value for a/ss was found for up to 90-month follow-up using maximum likelihood analysis,more » and the 95% confidence interval using the profile likelihood method. Linear quadratic formalism was applied with the radiobiological parameters of relative biological effectiveness = 1.0, potential doubling time = 45 days, and repair half-time = 1 hour. Bootstrap analysis was performed to estimate uncertainties in outcomes, and hence in a/ss. Sensitivity analysis was performed by varying the values of the radiobiological parameters to extreme values. Results: The value of a/ss best fitting the outcomes data was >30 Gy, with lower 95% confidence limit of 5.2 Gy. This was confirmed on bootstrap analysis. Varying parameters to extreme values still yielded best-fit a/ss of >30 Gy, although the lower 95% confidence interval limit was reduced to 0.6 Gy. Conclusions: Using carefully matched groups, long follow-up, the Phoenix definition of biochemical failure, and well-established statistical methods, the best estimate of a/ss for low and low-tier intermediate-risk prostate cancer is likely to be higher than that of normal tissues, although a low value cannot be excluded.« less

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.

Criterion validity study of the cervical range of motion (CROM) device for rotational range of motion on healthy adults.

PubMed

Tousignant, Michel; Smeesters, Cécil; Breton, Anne-Marie; Breton, Emilie; Corriveau, Hélène

2006-04-01

This study compared range of motion (ROM) measurements using a cervical range of motion device (CROM) and an optoelectronic system (OPTOTRAK). To examine the criterion validity of the CROM for the measurement of cervical ROM on healthy adults. Whereas measurements of cervical ROM are recognized as part of the assessment of patients with neck pain, few devices are available in clinical settings. Two papers published previously showed excellent criterion validity for measurements of cervical flexion/extension and lateral flexion using the CROM. Subjects performed neck rotation, flexion/extension, and lateral flexion while sitting on a wooden chair. The ROM values were measured by the CROM as well as the OPTOTRAK. The cervical rotational ROM values using the CROM demonstrated a good to excellent linear relationship with those using the OPTOTRAK: right rotation, r = 0.89 (95% confidence interval, 0.81-0.94), and left rotation, r = 0.94 (95% confidence interval, 0.90-0.97). Similar results were also obtained for flexion/extension and lateral flexion ROM values. The CROM showed excellent criterion validity for measurements of cervical rotation. We propose using ROM values measured by the CROM as outcome measures for patients with neck pain.

Sensitivity and Specificity of Histoplasma Antigen Detection by Enzyme Immunoassay.

PubMed

Cunningham, Lauren; Cook, Audrey; Hanzlicek, Andrew; Harkin, Kenneth; Wheat, Joseph; Goad, Carla; Kirsch, Emily

2015-01-01

The objective of this study was to evaluate the sensitivity and specificity of an antigen enzyme immunoassay (EIA) on urine samples for the diagnosis of histoplasmosis in dogs. This retrospective medical records review included canine cases with urine samples submitted for Histoplasma EIA antigen assay between 2007 and 2011 from three veterinary institutions. Cases for which urine samples were submitted for Histoplasma antigen testing were reviewed and compared to the gold standard of finding Histoplasma organisms or an alternative diagnosis on cytology or histopathology. Sensitivity, specificity, negative predictive value, positive predictive value, and the kappa coefficient and associated confidence interval were calculated for the EIA-based Histoplasma antigen assay. Sixty cases met the inclusion criteria. Seventeen cases were considered true positives based on identification of the organism, and 41 cases were considered true negatives with an alternative definitive diagnosis. Two cases were considered false negatives, and there were no false positives. Sensitivity was 89.47% and the negative predictive value was 95.35%. Specificity and the positive predictive value were both 100%. The kappa coefficient was 0.9207 (95% confidence interval, 0.8131-1). The Histoplasma antigen EIA test demonstrated high specificity and sensitivity for the diagnosis of histoplasmosis in dogs.

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

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.

Oral and intraperitoneal LD50 of thymoquinone, an active principle of Nigella sativa, in mice and rats.

PubMed

Al-Ali, Amein; Alkhawajah, Abdul Aziz; Randhawa, Mohammad Akram; Shaikh, Nisar Ahmed

2008-01-01

Thymoquinone is the major active principle of Nigella sativa (N. sativa) and constitutes about 30% of its volatile oil or ether extract. N. sativa oil and seed are commonly used as a natural remedy for many ailments. Using modern scientific techniques, a number of pharmacological actions of N. sativa have been investigated including immunostimulant, anti-inflammatory, anticancer, antioxidant, antihistaminic, antiasthmatic, hypoglycemic, antimicrobial and antiparasitic. There are only few reports regarding the toxicity of thymoquinone. The present study was carried out to determine LD50 of thymoquinone both in mice and rats, orally as well as intraperitoneall, by the method of Miller and Tainter. Autopsy and histopathology of liver, kidney, heart and lungs were also determined. The LD50 in mice after intraperitoneal injection was determined to be 104.7 mg/kg (89.7-119.7, 95% confidence interval) and after oral ingestion was 870.9 mg/kg (647.1-1094.8, 95% confidence interval). Whereas, LD50 in rats after intraperitoneal injection was determined to be 57.5 mg/kg (45.6-69.4, 95% confidence intervals) and after oral ingestion was 794.3 mg/kg (469.8-1118.8, 95% confidence intervals). The LD50 values presented here after intraperitoneal injection and oral gavages are 10-15 times and 100-150 times greater than doses of thymoquinone reported for its anti-inflammatory, anti-oxidant and anti-cancer effects. Thymoquinone is a relatively safe compound, particularly when given orally to experimental animals.

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.

Continuous Amplitude-Integrated Electroencephalographic Monitoring Is a Useful Prognostic Tool for Hypothermia-Treated Cardiac Arrest Patients.

PubMed

Oh, Sang Hoon; Park, Kyu Nam; Shon, Young-Min; Kim, Young-Min; Kim, Han Joon; Youn, Chun Song; Kim, Soo Hyun; Choi, Seung Pill; Kim, Seok Chan

2015-09-22

Modern treatments have improved the survival rate following cardiac arrest, but prognostication remains a challenge. We examined the prognostic value of continuous electroencephalography according to time by performing amplitude-integrated electroencephalography on patients with cardiac arrest receiving therapeutic hypothermia. We prospectively studied 130 comatose patients treated with hypothermia from September 2010 to April 2013. We evaluated the time to normal trace (TTNT) as a neurological outcome predictor and determined the prognostic value of burst suppression and status epilepticus, with a particular focus on their time of occurrence. Fifty-five patients exhibited a cerebral performance category score of 1 to 2. The area under the curve for TTNT was 0.97 (95% confidence interval, 0.92-0.99), and the sensitivity and specificity of TTNT<24 hours after resuscitation as a threshold for predicting good neurological outcome were 94.6% (95% confidence interval, 84.9%-98.9%) and 90.7% (95% confidence interval, 81.7%-96.2%), respectively. The threshold displaying 100% specificity for predicting poor neurological outcome was TTNT>36 hours. Burst suppression and status epilepticus predicted poor neurological outcome (positive predictive value of 98.3% and 96.4%, respectively). The combination of these factors predicted a negative outcome at a median of 6.2 hours after resuscitation (sensitivity and specificity of 92.0% and 96.4%, respectively). A TTNT<24 hours was associated with good neurological outcome. The lack of normal trace development within 36 hours, status epilepticus, and burst suppression were predictors of poor outcome. The combination of these negative predictors may improve their prognostic performance at an earlier stage. © 2015 The Authors.

Diagnostic capability of spectral-domain optical coherence tomography for glaucoma.

PubMed

Wu, Huijuan; de Boer, Johannes F; Chen, Teresa C

2012-05-01

To determine the diagnostic capability of spectral-domain optical coherence tomography in glaucoma patients with visual field defects. Prospective, cross-sectional study. Participants were recruited from a university hospital clinic. One eye of 85 normal subjects and 61 glaucoma patients with average visual field mean deviation of -9.61 ± 8.76 dB was selected randomly for the study. A subgroup of the glaucoma patients with early visual field defects was calculated separately. Spectralis optical coherence tomography (Heidelberg Engineering, Inc) circular scans were performed to obtain peripapillary retinal nerve fiber layer (RNFL) thicknesses. The RNFL diagnostic parameters based on the normative database were used alone or in combination for identifying glaucomatous RNFL thinning. To evaluate diagnostic performance, calculations included areas under the receiver operating characteristic curve, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio. Overall RNFL thickness had the highest area under the receiver operating characteristic curve values: 0.952 for all patients and 0.895 for the early glaucoma subgroup. For all patients, the highest sensitivity (98.4%; 95% confidence interval, 96.3% to 100%) was achieved by using 2 criteria: ≥ 1 RNFL sectors being abnormal at the < 5% level and overall classification of borderline or outside normal limits, with specificities of 88.9% (95% confidence interval, 84.0% to 94.0%) and 87.1% (95% confidence interval, 81.6% to 92.5%), respectively, for these 2 criteria. Statistical parameters for evaluating the diagnostic performance of the Spectralis spectral-domain optical coherence tomography were good for early perimetric glaucoma and were excellent for moderately advanced perimetric glaucoma. Copyright © 2012 Elsevier Inc. All rights reserved.

Is it possible to identify a risk factor condition of hypocalcemia in patients candidates to thyroidectomy for benign disease?

PubMed

Del Rio, Paolo; Iapichino, Gioacchino; De Simone, Belinda; Bezer, Lamia; Arcuri, MariaFrancesca; Sianesi, Mario

2010-01-01

Hypocalcaemia is the most frequent complication after total thyroidectomy. The incidence of postoperative hypocalcaemia is reported with different percentages in literature. We report 227 patients undergoing surgery for benign thyroid disease. After obtaining patient's informed consent, we collected and analyzed prospectively the following data: calcium serum levels pre and postoperative in the first 24 hours after surgery according to sex, age, duration of surgery, number of parathyroids identified by the surgeon, surgical technique (open and minimally invasive video-assisted thyroidectomy, i.e., MIVAT). We have considered cases treated consecutively from the same two experienced endocrine surgeons. Hypocalcaemia is assumed when the value of serum calcium is below 7.5 mg/dL. Pre-and post-operative mean serum calcium, with confidence intervals at 99% divided by sex, revealed a statistically significant difference in the ANOVA test (p < 0.01) in terms of incidence. Female sex has higher incidence of hypocalcemia. The evaluation of the mean serum calcium in pre-and post-operative period, with confidence intervals at 95%, depending on the number of identified parathyroid glands by surgeon, showed that the result is not correlated with values of postoperative serum calcium. Age and pre-and postoperative serum calcium values with confidence intervals at 99% based on sex of patients, didn't show statistically significant differences. We haven't highlighted a significant difference in postoperative hypocalcemia in patients treated with conventional thyroidectomy versus MIVAT. A difference in pre- and postoperative mean serum calcium occurs in all patients surgically treated. The only statistical meaningful risk factor for hypocalcemia has been the female sex.

Exploring students’ perceived and actual ability in solving statistical problems based on Rasch measurement tools

NASA Astrophysics Data System (ADS)

Azila Che Musa, Nor; Mahmud, Zamalia; Baharun, Norhayati

2017-09-01

One of the important skills that is required from any student who are learning statistics is knowing how to solve statistical problems correctly using appropriate statistical methods. This will enable them to arrive at a conclusion and make a significant contribution and decision for the society. In this study, a group of 22 students majoring in statistics at UiTM Shah Alam were given problems relating to topics on testing of hypothesis which require them to solve the problems using confidence interval, traditional and p-value approach. Hypothesis testing is one of the techniques used in solving real problems and it is listed as one of the difficult concepts for students to grasp. The objectives of this study is to explore students’ perceived and actual ability in solving statistical problems and to determine which item in statistical problem solving that students find difficult to grasp. Students’ perceived and actual ability were measured based on the instruments developed from the respective topics. Rasch measurement tools such as Wright map and item measures for fit statistics were used to accomplish the objectives. Data were collected and analysed using Winsteps 3.90 software which is developed based on the Rasch measurement model. The results showed that students’ perceived themselves as moderately competent in solving the statistical problems using confidence interval and p-value approach even though their actual performance showed otherwise. Item measures for fit statistics also showed that the maximum estimated measures were found on two problems. These measures indicate that none of the students have attempted these problems correctly due to reasons which include their lack of understanding in confidence interval and probability values.

A NEW METHOD OF SWEAT TESTING: THE CF QUANTUM® SWEAT TEST

PubMed Central

Rock, Michael J.; Makholm, Linda; Eickhoff, Jens

2015-01-01

Background Conventional methods of sweat testing are time consuming and have many steps that can and do lead to errors. This study compares conventional sweat testing to a new quantitative method, the CF Quantum® (CFQT) sweat test. This study tests the diagnostic accuracy and analytic validity of the CFQT. Methods Previously diagnosed CF patients and patients who required a sweat test for clinical indications were invited to have the CFQT test performed. Both conventional sweat testing and the CFQT were performed bilaterally on the same day. Pairs of data from each test are plotted as a correlation graph and Bland Altman plot. Sensitivity and specificity were calculated as well as the means and coefficient of variation by test and by extremity. After completing the study, subjects or their parents were asked for their preference of the CFQT and conventional sweat testing. Results The correlation coefficient between the CFQT and conventional sweat testing was 0.98 (95% confidence interval: 0.97–0.99). The sensitivity and specificity of the CFQT in diagnosing CF was 100% (95% confidence interval: 94–100%) and 96% (95% confidence interval: 89–99%), respectively. In one center in this three center multicenter study, there were higher sweat chloride values in patients with CF and also more tests that were invalid due to discrepant values between the two extremities. The percentage of invalid tests was higher in the CFQT method (16.5%) compared to conventional sweat testing (3.8%)(p < 0.001). In the post-test questionnaire, 88% of subjects/parents preferred the CFQT test. Conclusions The CFQT is a fast and simple method of quantitative sweat chloride determination. This technology requires further refinement to improve the analytic accuracy at higher sweat chloride values and to decrease the number of invalid tests. PMID:24862724

Pharmacological identification of β-adrenoceptor subtypes mediating isoprenaline-induced relaxation of guinea pig colonic longitudinal smooth muscle.

PubMed

Chino, Daisuke; Sone, Tomoyo; Yamazaki, Kumi; Tsuruoka, Yuri; Yamagishi, Risa; Shiina, Shunsuke; Obara, Keisuke; Yamaki, Fumiko; Higai, Koji; Tanaka, Yoshio

2018-01-01

Object We aimed to identify the β-adrenoceptor (β-AR) subtypes involved in isoprenaline-induced relaxation of guinea pig colonic longitudinal smooth muscle using pharmacological and biochemical approaches. Methods Longitudinal smooth muscle was prepared from the male guinea pig ascending colon and contracted with histamine prior to comparing the relaxant responses to three catecholamines (isoprenaline, adrenaline, and noradrenaline). The inhibitory effects of subtype-selective β-AR antagonists on isoprenaline-induced relaxation were then investigated. Results The relaxant potencies of the catecholamines were ranked as: isoprenaline > noradrenaline ≈ adrenaline, whereas the rank order was isoprenaline > noradrenaline > adrenaline in the presence of propranolol (a non-selective β-AR antagonist; 3 × 10 -7 M). Atenolol (a selective β 1 -AR antagonist; 3 × 10 -7 -10 -6  M) acted as a competitive antagonist of isoprenaline-induced relaxation, and the pA 2 value was calculated to be 6.49 (95% confidence interval: 6.34-6.83). The relaxation to isoprenaline was not affected by ICI-118,551 (a selective β 2 -AR antagonist) at 10 -9 -10 -8  M, but was competitively antagonized by 10 -7 -3 × 10 -7  M, with a pA 2 value of 7.41 (95% confidence interval: 7.18-8.02). In the presence of propranolol (3 × 10 -7 M), the relaxant effect of isoprenaline was competitively antagonized by bupranolol (a non-selective β-AR antagonist), with a pA 2 value of 5.90 (95% confidence interval: 5.73-6.35). Conclusion These findings indicated that the β-AR subtypes involved in isoprenaline-induced relaxation of colonic longitudinal guinea pig muscles are β 1 -AR and β 3 -AR.

The probability of being identified as an outlier with commonly used funnel plot control limits for the standardised mortality ratio.

PubMed

Seaton, Sarah E; Manktelow, Bradley N

2012-07-16

Emphasis is increasingly being placed on the monitoring of clinical outcomes for health care providers. Funnel plots have become an increasingly popular graphical methodology used to identify potential outliers. It is assumed that a provider only displaying expected random variation (i.e. 'in-control') will fall outside a control limit with a known probability. In reality, the discrete count nature of these data, and the differing methods, can lead to true probabilities quite different from the nominal value. This paper investigates the true probability of an 'in control' provider falling outside control limits for the Standardised Mortality Ratio (SMR). The true probabilities of an 'in control' provider falling outside control limits for the SMR were calculated and compared for three commonly used limits: Wald confidence interval; 'exact' confidence interval; probability-based prediction interval. The probability of falling above the upper limit, or below the lower limit, often varied greatly from the nominal value. This was particularly apparent when there were a small number of expected events: for expected events ≤ 50 the median probability of an 'in-control' provider falling above the upper 95% limit was 0.0301 (Wald), 0.0121 ('exact'), 0.0201 (prediction). It is important to understand the properties and probability of being identified as an outlier by each of these different methods to aid the correct identification of poorly performing health care providers. The limits obtained using probability-based prediction limits have the most intuitive interpretation and their properties can be defined a priori. Funnel plot control limits for the SMR should not be based on confidence intervals.

Stability of INFIT and OUTFIT Compared to Simulated Estimates in Applied Setting.

PubMed

Hodge, Kari J; Morgan, Grant B

Residual-based fit statistics are commonly used as an indication of the extent to which the item response data fit the Rash model. Fit statistic estimates are influenced by sample size and rules-of thumb estimates may result in incorrect conclusions about the extent to which the model fits the data. Estimates obtained in this analysis were compared to 250 simulated data sets to examine the stability of the estimates. All INFIT estimates were within the rule-of-thumb range of 0.7 to 1.3. However, only 82% of the INFIT estimates fell within the 2.5th and 97.5th percentile of the simulated item's INFIT distributions using this 95% confidence-like interval. This is a 18 percentage point difference in items that were classified as acceptable. Fourty-eight percent of OUTFIT estimates fell within the 0.7 to 1.3 rule- of-thumb range. Whereas 34% of OUTFIT estimates fell within the 2.5th and 97.5th percentile of the simulated item's OUTFIT distributions. This is a 13 percentage point difference in items that were classified as acceptable. When using the rule-of- thumb ranges for fit estimates the magnitude of misfit was smaller than with the 95% confidence interval of the simulated distribution. The findings indicate that the use of confidence intervals as critical values for fit statistics leads to different model data fit conclusions than traditional rule of thumb critical values.

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…

Digital Games, Design, and Learning: A Systematic Review and Meta-Analysis.

PubMed

Clark, Douglas B; Tanner-Smith, Emily E; Killingsworth, Stephen S

2016-03-01

In this meta-analysis, we systematically reviewed research on digital games and learning for K-16 students. We synthesized comparisons of game versus nongame conditions (i.e., media comparisons) and comparisons of augmented games versus standard game designs (i.e., value-added comparisons). We used random-effects meta-regression models with robust variance estimates to summarize overall effects and explore potential moderator effects. Results from media comparisons indicated that digital games significantly enhanced student learning relative to nongame conditions ([Formula: see text] = 0.33, 95% confidence interval [0.19, 0.48], k = 57, n = 209). Results from value-added comparisons indicated significant learning benefits associated with augmented game designs ([Formula: see text] = 0.34, 95% confidence interval [0.17, 0.51], k = 20, n = 40). Moderator analyses demonstrated that effects varied across various game mechanics characteristics, visual and narrative characteristics, and research quality characteristics. Taken together, the results highlight the affordances of games for learning as well as the key role of design beyond medium.

Digital Games, Design, and Learning

PubMed Central

Clark, Douglas B.; Tanner-Smith, Emily E.; Killingsworth, Stephen S.

2016-01-01

In this meta-analysis, we systematically reviewed research on digital games and learning for K–16 students. We synthesized comparisons of game versus nongame conditions (i.e., media comparisons) and comparisons of augmented games versus standard game designs (i.e., value-added comparisons). We used random-effects meta-regression models with robust variance estimates to summarize overall effects and explore potential moderator effects. Results from media comparisons indicated that digital games significantly enhanced student learning relative to nongame conditions (g¯ = 0.33, 95% confidence interval [0.19, 0.48], k = 57, n = 209). Results from value-added comparisons indicated significant learning benefits associated with augmented game designs (g¯ = 0.34, 95% confidence interval [0.17, 0.51], k = 20, n = 40). Moderator analyses demonstrated that effects varied across various game mechanics characteristics, visual and narrative characteristics, and research quality characteristics. Taken together, the results highlight the affordances of games for learning as well as the key role of design beyond medium. PMID:26937054

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

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.

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.

New Approaches to Robust Confidence Intervals for Location: A Simulation Study.

DTIC Science & Technology

1984-06-01

obtain a denominator for the test statistic. Those statistics based on location estimates derived from Hampel’s redescending influence function or v...defined an influence function for a test in terms of the behavior of its P-values when the data are sampled from a model distribution modified by point...proposal could be used for interval estimation as well as hypothesis testing, the extension is immediate. Once an influence function has been defined

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.

Quantifying Safety Margin Using the Risk-Informed Safety Margin Characterization (RISMC)

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

Grabaskas, David; Bucknor, Matthew; Brunett, Acacia

2015-04-26

The Risk-Informed Safety Margin Characterization (RISMC), developed by Idaho National Laboratory as part of the Light-Water Reactor Sustainability Project, utilizes a probabilistic safety margin comparison between a load and capacity distribution, rather than a deterministic comparison between two values, as is usually done in best-estimate plus uncertainty analyses. The goal is to determine the failure probability, or in other words, the probability of the system load equaling or exceeding the system capacity. While this method has been used in pilot studies, there has been little work conducted investigating the statistical significance of the resulting failure probability. In particular, it ismore » difficult to determine how many simulations are necessary to properly characterize the failure probability. This work uses classical (frequentist) statistics and confidence intervals to examine the impact in statistical accuracy when the number of simulations is varied. Two methods are proposed to establish confidence intervals related to the failure probability established using a RISMC analysis. The confidence interval provides information about the statistical accuracy of the method utilized to explore the uncertainty space, and offers a quantitative method to gauge the increase in statistical accuracy due to performing additional simulations.« less

Practical Advice on Calculating Confidence Intervals for Radioprotection Effects and Reducing Animal Numbers in Radiation Countermeasure Experiments

PubMed Central

Landes, Reid D.; Lensing, Shelly Y.; Kodell, Ralph L.; Hauer-Jensen, Martin

2014-01-01

The dose of a substance that causes death in P% of a population is called an LDP, where LD stands for lethal dose. In radiation research, a common LDP of interest is the radiation dose that kills 50% of the population by a specified time, i.e., lethal dose 50 or LD50. When comparing LD50 between two populations, relative potency is the parameter of interest. In radiation research, this is commonly known as the dose reduction factor (DRF). Unfortunately, statistical inference on dose reduction factor is seldom reported. We illustrate how to calculate confidence intervals for dose reduction factor, which may then be used for statistical inference. Further, most dose reduction factor experiments use hundreds, rather than tens of animals. Through better dosing strategies and the use of a recently available sample size formula, we also show how animal numbers may be reduced while maintaining high statistical power. The illustrations center on realistic examples comparing LD50 values between a radiation countermeasure group and a radiation-only control. We also provide easy-to-use spreadsheets for sample size calculations and confidence interval calculations, as well as SAS® and R code for the latter. PMID:24164553

The health impacts and economic value of wildland fire ...

EPA Pesticide Factsheets

Introduction: Wildland fires degrade regional air quality and adversely affect human health. A growing body of epidemiology literature report increased rates of emergency department, hospital admission and premature deaths from wildfire smoke exposure. Objective: Our research aimed to characterized excess mortality and morbidity events, and the economic value of these impacts, from wildland fire smoke exposure in the U.S over a multi-year period; to date no other burden assessment has done this. Methods: We first completed a systematic review of the epidemiologic literature and then performed photochemical air quality modeling for the years 2008 to 2012 in the Continental U.S. Finally, we estimated the morbidity, mortality, and economic burden of wildland fires. Results: Our models suggest that areas including northern California, Oregon and Idaho in the West, and Florida, Louisiana and Georgia in the East were most affected by wildland fire events in the form of additional premature deaths and respiratory hospital admissions. We estimated the economic value of these cases due to short term exposures as being between $11 and $20B (2010$) per year, with a net present value of $63B (95% confidence intervals $6-$170); we estimate the value of long- term exposures as being between $76 and $130B (2010$) per year, with a net present value of $450B (95% confidence intervals $42-$1,200). Conclusion: The public health burden of wildland fires-in terms of the number and

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.

Exact intervals and tests for median when one sample value possibly an outliner

NASA Technical Reports Server (NTRS)

Keller, G. J.; Walsh, J. E.

1973-01-01

Available are independent observations (continuous data) that are believed to be a random sample. Desired are distribution-free confidence intervals and significance tests for the population median. However, there is the possibility that either the smallest or the largest observation is an outlier. Then, use of a procedure for rejection of an outlying observation might seem appropriate. Such a procedure would consider that two alternative situations are possible and would select one of them. Either (1) the n observations are truly a random sample, or (2) an outlier exists and its removal leaves a random sample of size n-1. For either situation, confidence intervals and tests are desired for the median of the population yielding the random sample. Unfortunately, satisfactory rejection procedures of a distribution-free nature do not seem to be available. Moreover, all rejection procedures impose undesirable conditional effects on the observations, and also, can select the wrong one of the two above situations. It is found that two-sided intervals and tests based on two symmetrically located order statistics (not the largest and smallest) of the n observations have this property.

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.

A spreadsheet template compatible with Microsoft Excel and iWork Numbers that returns the simultaneous confidence intervals for all pairwise differences between multiple sample means.

PubMed

Brown, Angus M

2010-04-01

The objective of the method described in this paper is to develop a spreadsheet template for the purpose of comparing multiple sample means. An initial analysis of variance (ANOVA) test on the data returns F--the test statistic. If F is larger than the critical F value drawn from the F distribution at the appropriate degrees of freedom, convention dictates rejection of the null hypothesis and allows subsequent multiple comparison testing to determine where the inequalities between the sample means lie. A variety of multiple comparison methods are described that return the 95% confidence intervals for differences between means using an inclusive pairwise comparison of the sample means. 2009 Elsevier Ireland Ltd. All rights reserved.

ON THE SUBJECT OF HYPOTHESIS TESTING

PubMed Central

Ugoni, Antony

1993-01-01

In this paper, the definition of a statistical hypothesis is discussed, and the considerations which need to be addressed when testing a hypothesis. In particular, the p-value, significance level, and power of a test are reviewed. Finally, the often quoted confidence interval is given a brief introduction. PMID:17989768

Detection of human papillomavirus DNA in patients referred to a family practice colposcopy clinic.

PubMed

Holman, J R

1996-01-01

Human papillomavirus (HPV) is strongly implicated in the pathogenesis of cervical neoplasia. The ability of a commercially available kit (Virapap/Viratype) to detect evidence of HPV is compared with cervical cytology, colposcopy, and directed biopsies. During a period of 16 months, cervical samples from 241 consecutive new patients referred for a colposcopy examination were obtained for HPV-DNA hybridization typing according to the kit instructions. Samples were sent to a reference laboratory for testing. The results were compared with results of the colposcopy examination, cervical cytology, and directed cervical biopsy samples processed and evaluated by our hospital laboratory. HPV DNA was detected in 27 of 107 patients who had abnormal colposcopy findings for a sensitivity of 25 +/- 7.5 percent at the 90 percent confidence interval. One of 134 patients with normal findings was positive for a specificity of 99 +/- 5 percent at the 95 percent confidence interval. Based on a 75 percent probability of HPV in the population, the positive predictive value was 99 percent and the negative predictive value 30 percent. With the low negative predictive value and sensitivity, HPV-DNA testing by this commercial kit is not an adequate tool for screening HPV in this population.

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.

Cardiopulmonary resuscitation duration and survival in out-of-hospital cardiac arrest patients.

PubMed

Adnet, Frederic; Triba, Mohamed N; Borron, Stephen W; Lapostolle, Frederic; Hubert, Hervé; Gueugniaud, Pierre-Yves; Escutnaire, Josephine; Guenin, Aurelien; Hoogvorst, Astrid; Marbeuf-Gueye, Carol; Reuter, Paul-Georges; Javaud, Nicolas; Vicaut, Eric; Chevret, Sylvie

2017-02-01

Relationship between cardiopulmonary arrest and resuscitation (CPR) durations and survival after out-of-hospital cardiac arrest (OHCA) remain unclear. Our primary aim was to determine the association between survival without neurologic sequelae and cardiac arrest intervals in the setting of witnessed OHCA. We analyzed 27,301 non-traumatic, witnessed OHCA patients in France included in the national registry from June 1, 2011 through December 1, 2015. We analyzed cardiac arrest intervals, designated as no-flow (NF; from collapse to start of CPR) and low-flow (LF; from start of CPR to cessation of resuscitation) in relation to 30-day survival without sequelae. We determined the influence of recognized prognostic factors (age, gender, initial rhythm, location of cardiac arrest) on this relation. For the entire cohort, the area delimited by a value of NF greater than 12min (95% confidence interval: 11-13min) and LF greater than 33min (95% confidence interval: 29-45min), yielded a probability of 30-day survival of less than 1%. These sets of values were greatly influenced by initial cardiac arrest rhythm, age, sex and location of cardiac arrest. Extended CPR duration (greater than 40min) in the setting of initial shockable cardiac rhythm is associated with greater than 1% survival with NF less than 18min. The NF interval was highly influential on the LF interval regardless of outcome, whether return of spontaneous circulation (p<0.001) or death (p<0.001). NF duration must be considered in determining CPR duration in OHCA patients. The knowledge of (NF, LF) curves as function of age, initial rhythm, location of cardiac arrest or gender may aid in decision-making vis-à-vis the termination of CPR or employment of advanced techniques. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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…

The health impacts and economic value of wildland fire episodes in the U.S.: 2008-2012.

PubMed

Fann, Neal; Alman, Breanna; Broome, Richard A; Morgan, Geoffrey G; Johnston, Fay H; Pouliot, George; Rappold, Ana G

2018-01-01

Wildland fires degrade air quality and adversely affect human health. A growing body of epidemiology literature reports increased rates of emergency departments, hospital admissions and premature deaths from wildfire smoke exposure. Our research aimed to characterize excess mortality and morbidity events, and the economic value of these impacts, from wildland fire smoke exposure in the U.S. over a multi-year period; to date no other burden assessment has done this. We first completed a systematic review of the epidemiologic literature and then performed photochemical air quality modeling for the years 2008 to 2012 in the continental U.S. Finally, we estimated the morbidity, mortality, and economic burden of wildland fires. Our models suggest that areas including northern California, Oregon and Idaho in the West, and Florida, Louisiana and Georgia in the East were most affected by wildland fire events in the form of additional premature deaths and respiratory hospital admissions. We estimated the economic value of these cases due to short term exposures as being between $11 and $20B (2010$) per year, with a net present value of $63B (95% confidence intervals $6-$170); we estimate the value of long-term exposures as being between $76 and $130B (2010$) per year, with a net present value of $450B (95% confidence intervals $42-$1200). The public health burden of wildland fires-in terms of the number and economic value of deaths and illnesses-is considerable. Published by Elsevier B.V.

The effect of migration of instantaneous centre of knee orthosis rotation during gait - in vivo displacement measurements in two experimental variants.

PubMed

Bogucki, Artur J

2014-01-01

The knee joint is a bicondylar hinge two-level joint with six degrees of freedom. The location of the functional axis of flexion-extension motion is still a subject of research and discussions. During the swing phase, the femoral condyles do not have direct contact with the tibial articular surfaces and the intra-articular space narrows with increasing weight bearing. The geometry of knee movements is determined by the shape of articular surfaces. A digital recording of the gait of a healthy volunteer was analysed. In the first experimental variant, the subject was wearing a knee orthosis controlling flexion and extension with a hinge-type single-axis joint. In the second variant, the examination involved a hinge-type double-axis orthosis. Statistical analysis involved mathematically calculated values of displacement P. Scatter graphs with a fourth-order polynomial trend line with a confidence interval of 0.95 due to noise were prepared for each experimental variant. In Variant 1, the average displacement was 15.1 mm, the number of tests was 43, standard deviation was 8.761, and the confidence interval was 2.2. The maximum value of displacement was 30.9 mm and the minimum value was 0.7 mm. In Variant 2, the average displacement was 13.4 mm, the number of tests was 44, standard deviation was 7.275, and the confidence interval was 1.8. The maximum value of displacement was 30.2 mm and the minimum value was 3.4 mm. An analysis of moving averages for both experimental variants revealed that displacement trends for both types of orthosis were compatible from the mid-stance to the mid-swing phase. 1. The method employed in the experiment allows for determining the alignment between the axis of the knee joint and that of shin and thigh orthoses. 2. Migration of the single and double-axis orthoses during the gait cycle exceeded 3 cm. 3. During weight bearing, the double-axis orthosis was positioned more correctly. 4. The study results may be helpful in designing new hinge-type knee joints.

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.

Lipid-Lowering Agents and High HDL (High-Density Lipoprotein) Are Inversely Associated With Intracranial Aneurysm Rupture.

PubMed

Can, Anil; Castro, Victor M; Dligach, Dmitriy; Finan, Sean; Yu, Sheng; Gainer, Vivian; Shadick, Nancy A; Savova, Guergana; Murphy, Shawn; Cai, Tianxi; Weiss, Scott T; Du, Rose

2018-05-01

Growing evidence from experimental animal models and clinical studies suggests the protective effect of statin use against rupture of intracranial aneurysms; however, results from large studies detailing the relationship between intracranial aneurysm rupture and total cholesterol, HDL (high-density lipoprotein), LDL (low-density lipoprotein), and lipid-lowering agent use are lacking. The medical records of 4701 patients with 6411 intracranial aneurysms diagnosed at the Massachusetts General Hospital and the Brigham and Women's Hospital between 1990 and 2016 were reviewed and analyzed. Patients were separated into ruptured and nonruptured groups. Univariable and multivariable logistic regression analyses were performed to determine the effects of lipids (total cholesterol, LDL, and HDL) and lipid-lowering medications on intracranial aneurysm rupture risk. Propensity score weighting was used to account for differences in baseline characteristics of the cohorts. Lipid-lowering agent use was significantly inversely associated with rupture status (odds ratio, 0.58; 95% confidence interval, 0.47-0.71). In a subgroup analysis of complete cases that includes both lipid-lowering agent use and lipid values, higher HDL levels (odds ratio, 0.95; 95% confidence interval, 0.93-0.98) and lipid-lowering agent use (odds ratio, 0.41; 95% confidence interval, 0.23-0.73) were both significantly and inversely associated with rupture status, whereas total cholesterol and LDL levels were not significant. A monotonic exposure-response curve between HDL levels and risk of aneurysmal rupture was obtained. Higher HDL values and the use of lipid-lowering agents are significantly inversely associated with ruptured intracranial aneurysms. © 2018 American Heart Association, Inc.

Making physiology learning memorable: a mobile phone-assisted case-based instructional strategy.

PubMed

Kukolja Taradi, S; Taradi, M

2016-09-01

The goal of the present study was to determine whether an active learning/teaching strategy facilitated with mobile technologies can improve students' levels of memory retention of key physiological concepts. We used a quasiexperimental pretest/posttest nonequivalent group design to compare the test performances of second-year medical students (n = 311) taught by conventional didactic methods (traditional group) with those involved in a case-based problem-solving learning approach facilitated with mobile phones as web-based "clickers" (experimental group). Using their cell phones, students answered the same questions about the key physiological concepts three times. A pretest to determine their baseline knowledge was followed by two followup tests after 1 wk and 2 mo, respectively. The experimental group scored a mean of 93.2% correct items after 1 wk and 84.8% correct items after 2 mo [95% confidence intervals: (89.4, 97.0) and (79.4, 90.3), respectively]. Compared with their colleagues in the traditional group who scored 33.3% [95% confidence interval: (18.9, 47.8)] and 38.5% [95% confidence interval: (23.6, 53.4)] correct items, respectively, this was a significant increase of ∼50% (P < 0.0001). Furthermore, for the experimental group, Cohen's effect size (d) values of d = 1.67 (1-wk posttest) and d = 1.38 (2-mo posttest) suggested a very high practical significance. In contrast, in the traditional group, Cohen's d values of d = 0.04 (1-wk posttest) and d = 0.15 (2-mo posttest) assumed a very low practical significance. Copyright © 2016 The American Physiological Society.

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…

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…

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.

Predictors and Prognostic Value of Worsening Renal Function During Admission in HFpEF Versus HFrEF: Data From the KorAHF (Korean Acute Heart Failure) Registry.

PubMed

Kang, Jeehoon; Park, Jin Joo; Cho, Young-Jin; Oh, Il-Young; Park, Hyun-Ah; Lee, Sang Eun; Kim, Min-Seok; Cho, Hyun-Jai; Lee, Hae-Young; Choi, Jin Oh; Hwang, Kyung-Kuk; Kim, Kye Hun; Yoo, Byung-Su; Kang, Seok-Min; Baek, Sang Hong; Jeon, Eun-Seok; Kim, Jae-Joong; Cho, Myeong-Chan; Chae, Shung Chull; Oh, Byung-Hee; Choi, Dong-Ju

2018-03-13

Worsening renal function (WRF) is associated with adverse outcomes in patients with heart failure. We investigated the predictors and prognostic value of WRF during admission, in patients with preserved ejection fraction (HFpEF) versus those with reduced ejection fraction (HFrEF). A total of 5625 patients were enrolled in the KorAHF (Korean Acute Heart Failure) registry. WRF was defined as an absolute increase in creatinine of ≥0.3 mg/dL. Transient WRF was defined as recovery of creatinine at discharge, whereas persistent WRF was indicated by a nonrecovered creatinine level. HFpEF and HFrEF were defined as a left ventricle ejection fraction ≥50% and ≤40%, respectively. Among the total population, WRF occurred in 3101 patients (55.1%). By heart failure subgroup, WRF occurred more frequently in HFrEF (57.0% versus 51.3%; P <0.001 in HFrEF and HFpEF). Prevalence of WRF increased as creatinine clearance decreased in both heart failure subgroups. Among various predictors of WRF, chronic renal failure was the strongest predictor. WRF was an independent predictor of adverse in-hospital outcomes (HFrEF: odds ratio; 2.75; 95% confidence interval, 1.50-5.02; P =0.001; HFpEF: odds ratio, 9.48; 95% confidence interval, 1.19-75.89; P =0.034) and 1-year mortality (HFrEF: hazard ratio, 1.41; 95% confidence interval, 1.12-1.78; P =0.004 versus HFpEF: hazard ratio, 1.72; 95% confidence interval, 1.23-2.42; P =0.002). Transient WRF was a risk factor for 1-year mortality, whereas persistent WRF had no additive risk compared to transient WRF. In patients with acute heart failure patients, WRF is an independent predictor of adverse in-hospital and follow-up outcomes in both HFrEF and HFpEF, though with a different effect size. URL: https://www.clinicaltrials.gov. Unique identifier: NCT01389843. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Asymptomatic peripheral artery disease can limit maximal exercise capacity in chronic obstructive pulmonary disease patients regardless of airflow obstruction and lung hyperinflation.

PubMed

Crisafulli, Ernesto; Scelfo, Chiara; Tzani, Panagiota; Aiello, Marina; Bertorelli, Giuseppina; Chetta, Alfredo

2017-06-01

Background Silent/asymptomatic peripheral artery disease may occur in patients with chronic obstructive pulmonary disease, but it is poorly investigated. The primary aim of this study was to evaluate in chronic obstructive pulmonary disease patients the impact of asymptomatic/silent peripheral artery disease on maximal exercise capacity; the secondary aim was to search for predictors of peripheral artery disease. Methods We prospectively enrolled chronic obstructive pulmonary disease outpatients. Data on anthropometric characteristics, lung function, cardiopulmonary exercise test and ankle-brachial index were recorded. The cut-off of ankle-brachial index used to define patients with peripheral artery disease was ≤0.90. Results We studied 47 patients and found 24 patients (51%) who showed peripheral artery disease. As compared to patients without peripheral artery disease, patients with peripheral artery disease had lower values of peak oxygen uptake, peak workload, energy expenditure (metabolic equivalents) and heart rate recovery, but showed the same degree of airflow obstruction and static and dynamic hyperinflation. In a multivariate linear regression model performed to identify variables predicting metabolic equivalents, ankle-brachial index (β 2.59; 95% confidence interval 0.51-4.67; p = 0.016) was an independent variable. In the search for predictors of peripheral artery disease, heart rate recovery (odds ratio 8.80; 95% confidence interval 1.30-59.35; p = 0.026) increased the risk of peripheral artery disease, whereas metabolic equivalents (odds ratio 0.50; 95% confidence interval 0.26-0.94, p = 0.033) and inhaled corticosteroids+long-acting β 2 agonists (odds ratio 0.13; 95% confidence interval 0.02-0.83; p = 0.030) reduced this risk. Conclusions In chronic obstructive pulmonary disease outpatients, asymptomatic/silent peripheral artery disease affects the maximal exercise capacity regardless of airflow obstruction and lung hyperinflation. A delay of heart rate recovery increase the risk of peripheral artery disease, whereas high values of metabolic equivalents and the use of inhaled corticosteroids+long-acting β 2 agonists reduces this risk.

Average grip strength: a meta-analysis of data obtained with a Jamar dynamometer from individuals 75 years or more of age.

PubMed

Bohannon, Richard W; Bear-Lehman, Jane; Desrosiers, Johanne; Massy-Westropp, Nicola; Mathiowetz, Virgil

2007-01-01

Although strength diminishes with age, average values for grip strength have not been available heretofore for discrete strata after 75 years. The purpose of this meta-analysis was to provide average values for the left and right hands of men and women 75-79, 80-84, 85-89, and 90-99 years. Contributing to the analysis were 7 studies and 739 subjects with whom the Jamar dynamometer and standard procedures were employed. Based on the analysis, average values for the left and right hands of men and women in each age stratum were derived. The derived values can serve as a standard of comparison for individual patients. An individual whose grip strength is below the lower limit of the confidence intervals of each stratum can be confidently considered to have less than average grip strength.

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

Performance analysis of newly developed point-of-care hemoglobinometer (TrueHb) against an automated hematology analyzer (Sysmex XT 1800i) in terms of precision in hemoglobin measurement.

PubMed

Srivastava, A; Koul, V; Dwivedi, S N; Upadhyaya, A D; Ahuja, A; Saxena, R

2015-08-01

The aim of this study was to evaluate the performance of the newly developed handheld hemoglobinmeter (TrueHb) by comparing its performance against and an automated five-part hematology analyzer, Sysmex counter XT 1800i (Sysmex). Two hundred venous blood samples were subjected through their total hemoglobin evaluation on each device three times. The average of the three readings on each device was considered as their respective device values, that is, TrueHb values and Sysmex values. The two set of values were comparatively analyzed. The repeatability of the performance of TrueHb was also evaluated against Sysmex values. The scatter plot of TrueHb values and Sysmex values showed linear distribution with positive correlations (r = 0.99). The intraclass correlation (ICC) values between the two set of values was found to be 0.995. Regression coefficients through origin, β, was found to be 0.995, with 95% confidence intervals (CI) ranging between 0.9900 and 1.0000. The mean difference in Bland-Altman plots of TrueHb values against the Sysmex values was found to be -0.02, with limits of agreement between -0.777 and 0.732 g/dL. Statistical analysis suggested good repeatability in results of TrueHb, having a low mean CV of 2.22, against 4.44, that of Sysmex values, and 95% confidence interval of 1.99-2.44, against 3.85-5.03, that of Sysmex values. These results suggested a strong positive correlation between the two measurements devices. It is thus concluded that TrueHb is a good point-of-care testing tool for estimating hemoglobin. © 2014 John Wiley & Sons Ltd.

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.

Hematology and biochemistry reference intervals for Ontario commercial nursing pigs close to the time of weaning

PubMed Central

Perri, Amanda M.; O’Sullivan, Terri L.; Harding, John C.S.; Wood, R. Darren; Friendship, Robert M.

2017-01-01

The evaluation of pig hematology and biochemistry parameters is rarely done largely due to the costs associated with laboratory testing and labor, and the limited availability of reference intervals needed for interpretation. Within-herd and between-herd biological variation of these values also make it difficult to establish reference intervals. Regardless, baseline reference intervals are important to aid veterinarians in the interpretation of blood parameters for the diagnosis and treatment of diseased swine. The objective of this research was to provide reference intervals for hematology and biochemistry parameters of 3-week-old commercial nursing piglets in Ontario. A total of 1032 pigs lacking clinical signs of disease from 20 swine farms were sampled for hematology and iron panel evaluation, with biochemistry analysis performed on a subset of 189 randomly selected pigs. The 95% reference interval, mean, median, range, and 90% confidence intervals were calculated for each parameter. PMID:28373729

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.

Probability density function of non-reactive solute concentration in heterogeneous porous formations

Treesearch

Alberto Bellin; Daniele Tonina

2007-01-01

Available models of solute transport in heterogeneous formations lack in providing complete characterization of the predicted concentration. This is a serious drawback especially in risk analysis where confidence intervals and probability of exceeding threshold values are required. Our contribution to fill this gap of knowledge is a probability distribution model for...

Ideal Cardiovascular Health and Subclinical Markers of Carotid Structure and Function: The Paris Prospective Study III.

PubMed

Gaye, Bamba; Mustafic, Hazrije; Laurent, Stéphane; Perier, Marie-Cécile; Thomas, Frédérique; Guibout, Catherine; Tafflet, Muriel; Pannier, Bruno; Boutouyrie, Pierre; Jouven, Xavier; Empana, Jean-Philippe

2016-10-01

We hypothesized that subclinical markers of vascular structure and function, which are independent predictors of cardiovascular disease, would be less frequent in subjects with ideal than poor cardiovascular health (CVH) as defined by the American Heart Association (AHA). Carotid parameters were measured using high-precision echotracking device in 9155 nonreferred participants attending a health checkup in a large health center in Paris (France) between 2008 and 2012. According to the AHA, participants with 0 to 2, 3 to 4, and 5 to 7 metrics (smoking, physical activity, body mass index, diet, blood glucose and total cholesterol, blood pressure) at the ideal level were categorized as having poor, intermediate, and ideal CVH. Carotid parameters were dichotomized according to their median value, and multivariable logistic regression analysis was performed. Mean age was 59.5 (SD 6.3) years; 39% were females, and ideal CVH was present in 10.11% of the study participants. After adjustment for age, sex, education, and living alone and compared with a poor CVH, an ideal CVH was associated with lower common carotid artery intima-media thickness (odds ratio=1.64; 95% confidence interval 1.40, 1.93), absence of carotid plaques (odds ratio=2.14; 95% confidence interval 1.60, 2.87), lower Young's elastic modulus (odds ratio=2.43; 95% confidence interval 2.07, 2.84), and higher carotid distensibility coefficient (odds ratio=2.90; 95% confidence interval 2.47, 3.41). In community subjects aged 50 to 75 years, ideal CVH was associated with substantially less arterial stiffness and thickness. These associations might contribute to the lower risk of cardiovascular diseases in subjects with ideal CVH. © 2016 American Heart Association, Inc.

An assessment of DDT and other chlorinated compounds and the reproductive success of American robins (Turdus migratonrius) breeding in fruit orchards.

PubMed

Gill, Harpreet; Wilson, Laurie K; Cheng, Kimberly M; Elliott, John E

2003-01-01

Although DDT was banned in the 1970s, American robins (Turdus migratorius) breeding in fruit orchards of the Okanagan Valley, British Columbia, continue to be contaminated with DDT and its metabolites. The objectives of our study were (1) to assess organochlorine (OC) contamination in robins breeding in Okanagan orchards (1993-1995, 1997-1998) and (2) to determine if exposure affected reproductive success when compared to robins from non-orchard habitat (lower mainland, British Columbia). Robins in orchards had total DDT egg residues of 48.64 mg/kg (geometric mean; n = 92) while those in non-orchard habitat had 1.10 mg/kg (geometric mean; n = 26), wet weight. The probability of nest survival during the incubation period was 96.7% (confidence interval: 95.7-97.5%; n = 165) in orchard habitat and 96.7% (confidence interval: 94.6-98.1%; n = 28) in non-orchard habitat. During the nestling period the probability of nest survival was 98.2% (confidence interval: 97.2-98.9%; n = 123) in orchard habitat and 96.2% (confidence interval: 92.8-98.0%; n = 34) in non-orchard habitat. Clutch (p < 0.0001) and brood size (p = 0.0133) were larger in orchards (n = 150 and n = 93, respectively) compared to non-orchard nests (n = 42 and n = 23, respectively) with no difference in fledge rate. DDE (r2 = 0.11, p = 0.0030, n = 68) and dieldrin (r2 = 0.29, p < 0.0001, n = 68) were negatively correlated with fledge rate in robin eggs collected from orchard habitat, however, low r2 values signify minimal biological significance. Although American robins nesting in Okanagan orchards are exposed to high OC levels, reproductive success does not appear to be negatively impacted.

Association Between Endometriosis and Hypercholesterolemia or Hypertension.

PubMed

Mu, Fan; Rich-Edwards, Janet; Rimm, Eric B; Spiegelman, Donna; Forman, John P; Missmer, Stacey A

2017-07-01

An altered hormonal or chronic systemic inflammatory milieu characterizing endometriosis may result in a higher risk of hypercholesterolemia and hypertension. Conversely, elevated low-density lipoprotein in hypercholesterolemia and chronic systemic inflammation resulting from hypertension may increase the risk of endometriosis. We assessed the association of laparoscopically confirmed endometriosis with hypercholesterolemia and hypertension in a large prospective cohort study. In 1989, 116 430 registered female nurses aged 25 to 42 completed the baseline questionnaire and were followed for 20 years. Multivariable Cox proportional hazards models were applied. In 1989, there were 4244 women with laparoscopically confirmed endometriosis and 91 554 women without. After adjusting for demographic, anthropometric, family history, reproductive, dietary, and lifestyle risk factors prospectively, comparing women with laparoscopically confirmed endometriosis to women without, the relative risks were 1.25 (95% confidence interval, 1.21-1.30) for development of hypercholesterolemia and 1.14 (95% confidence interval, 1.09-1.18) for hypertension. Conversely, the relative risks of developing laparoscopically confirmed endometriosis were 1.22 (95% confidence interval, 1.15-1.31) comparing women with hypercholesterolemia to women without and 1.29 (95% confidence interval, 1.18-1.41) comparing women with hypertension to women without. The strength of associations of laparoscopically confirmed endometriosis with hypercholesterolemia or hypertension was strongest among women aged ≤40 and weakened as age increased ( P values for interaction <0.001). We observed that ≈45% of the associations between endometriosis and hypercholesterolemia and hypertension could be accounted for by treatment factors after endometriosis diagnosis, including greater frequency of hysterectomy/oophorectomy and earlier age for this surgery. In this large cohort study, laparoscopically confirmed endometriosis was prospectively associated with increased risk of hypercholesterolemia and hypertension. Conversely, hypercholesterolemia and hypertension were prospectively associated with higher risk of laparoscopically confirmed endometriosis. © 2017 American Heart Association, Inc.

Association of Parental Hypertension With Arterial Stiffness in Nonhypertensive Offspring: The Framingham Heart Study.

PubMed

Andersson, Charlotte; Quiroz, Rene; Enserro, Danielle; Larson, Martin G; Hamburg, Naomi M; Vita, Joseph A; Levy, Daniel; Benjamin, Emelia J; Mitchell, Gary F; Vasan, Ramachandran S

2016-09-01

High arterial stiffness seems to be causally involved in the pathogenesis of hypertension. We tested the hypothesis that offspring of parents with hypertension may display higher arterial stiffness before clinically manifest hypertension, given that hypertension is a heritable condition. We compared arterial tonometry measures in a sample of 1564 nonhypertensive Framingham Heart Study third-generation cohort participants (mean age: 38 years; 55% women) whose parents were enrolled in the Framingham Offspring Study. A total of 468, 715, and 381 participants had 0 (referent), 1, and 2 parents with hypertension. Parental hypertension was associated with greater offspring mean arterial pressure (multivariable-adjusted estimate=2.9 mm Hg; 95% confidence interval, 1.9-3.9, and 4.2 mm Hg; 95% confidence interval, 2.9-5.5, for 1 and 2 parents with hypertension, respectively; P<0.001 for both) and with greater forward pressure wave amplitude (1.6 mm Hg; 95% confidence interval, 0.6-2.7, and 1.9 mm Hg; 95% confidence interval, 0.6-3.2, for 1 and 2 parents with hypertension, respectively; P=0.003 for both). Carotid-femoral pulse wave velocity and augmentation index displayed similar dose-dependent relations with parental hypertension in sex-, age-, and height-adjusted models, but associations were attenuated on further adjustment. Offspring with at least 1 parent in the upper quartile of augmentation index and carotid-femoral pulse wave velocity had significantly higher values themselves (P≤0.02). In conclusion, in this community-based sample of young, nonhypertensive adults, we observed greater arterial stiffness in offspring of parents with hypertension. These observations are consistent with higher vascular stiffness at an early stage in the pathogenesis of hypertension. © 2016 American Heart Association, Inc.

Abnormal P-Wave Axis and Ischemic Stroke: The ARIC Study (Atherosclerosis Risk In Communities).

PubMed

Maheshwari, Ankit; Norby, Faye L; Soliman, Elsayed Z; Koene, Ryan J; Rooney, Mary R; O'Neal, Wesley T; Alonso, Alvaro; Chen, Lin Y

2017-08-01

Abnormal P-wave axis (aPWA) has been linked to incident atrial fibrillation and mortality; however, the relationship between aPWA and stroke has not been reported. We hypothesized that aPWA is associated with ischemic stroke independent of atrial fibrillation and other stroke risk factors and tested our hypothesis in the ARIC study (Atherosclerosis Risk In Communities), a community-based prospective cohort study. We included 15 102 participants (aged 54.2±5.7 years; 55.2% women; 26.5% blacks) who attended the baseline examination (1987-1989) and without prevalent stroke. We defined aPWA as any value outside 0 to 75° using 12-lead ECGs obtained during study visits. Each case of incident ischemic stroke was classified in accordance with criteria from the National Survey of Stroke by a computer algorithm and adjudicated by physician review. Multivariable Cox regression was used to estimate hazard ratios and 95% confidence intervals for the association of aPWA with stroke. During a mean follow-up of 20.2 years, there were 657 incident ischemic stroke cases. aPWA was independently associated with a 1.50-fold (95% confidence interval, 1.22-1.85) increased risk of ischemic stroke in the multivariable model that included atrial fibrillation. When subtyped, aPWA was associated with a 2.04-fold (95% confidence interval, 1.42-2.95) increased risk of cardioembolic stroke and a 1.32-fold (95% confidence interval, 1.03-1.71) increased risk of thrombotic stroke. aPWA is independently associated with ischemic stroke. This association seems to be stronger for cardioembolic strokes. Collectively, our findings suggest that alterations in atrial electric activation may predispose to cardiac thromboembolism independent of atrial fibrillation. © 2017 American Heart Association, Inc.

Prognostic value of long noncoding RNA MALAT1 in digestive system malignancies.

PubMed

Zhai, Hui; Li, Xiao-Mei; Maimaiti, Ailifeire; Chen, Qing-Jie; Liao, Wu; Lai, Hong-Mei; Liu, Fen; Yang, Yi-Ning

2015-01-01

MALAT1, a newly discovered long noncoding RNA (lncRNA), has been reported to be highly expressed in many types of cancers. This meta-analysis summarizes its potential prognostic value in digestive system malignancies. A quantitative meta-analysis was performed through a systematic search in PubMed, Cochrane Library, Web of Science and Chinese National Knowledge Infrastructure (CNKI) for eligible papers on the prognostic impact of MALAT1 in digestive system malignancies from inception to Apr. 25, 2015. Pooled hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated to summarize the effect. Five studies were included in the study, with a total of 527 patients. A significant association was observed between MALAT1 abundance and poor overall survival (OS) of patients with digestive system malignancies, with pooled hazard ratio (HR) of 7.68 (95% confidence interval [CI]: 4.32-13.66, P<0.001). Meta sensitivity analysis suggested the reliability of our findings. No publication bias was observed. MALAT1 abundance may serve as a novel predictive factor for poor prognosis in patients with digestive system malignancies.

Branchial cleft anomalies: accuracy of pre-operative diagnosis, clinical presentation and management.

PubMed

Guldfred, L-A; Philipsen, B B; Siim, C

2012-06-01

To examine the accuracy of the pre-operative diagnosis of branchial cleft anomalies, and also to describe their occurrence, clinical presentation and management. Retrospective review of the records of patients diagnosed with a branchial cleft anomaly between 1997 and 2006. One hundred and twenty-six patients were included. Pre-operative diagnosis had a positive predictive value of 0.856 (95 per cent confidence interval, 0.771-0.918) and a sensitivity of 0.944 (95 per cent confidence interval, 0.869-0.979). These patients' demographic data, investigations, findings and management are presented, along with a possible strategy for dealing with solitary cystic masses in the neck. As pre-operative diagnosis has a positive predictive value of 86 per cent, cystic lesions in the neck should be presumed to be carcinomatous until proven otherwise. Branchial fistulae and sinuses seem to be a disease of childhood, while branchial cysts occur mainly in adults. Branchial cleft anomalies are equally frequent in men and women, and equally distributed on the left and right side of the neck.

Robust misinterpretation of confidence intervals.

PubMed

Hoekstra, Rink; Morey, Richard D; Rouder, Jeffrey N; Wagenmakers, Eric-Jan

2014-10-01

Null hypothesis significance testing (NHST) is undoubtedly the most common inferential technique used to justify claims in the social sciences. However, even staunch defenders of NHST agree that its outcomes are often misinterpreted. Confidence intervals (CIs) have frequently been proposed as a more useful alternative to NHST, and their use is strongly encouraged in the APA Manual. Nevertheless, little is known about how researchers interpret CIs. In this study, 120 researchers and 442 students-all in the field of psychology-were asked to assess the truth value of six particular statements involving different interpretations of a CI. Although all six statements were false, both researchers and students endorsed, on average, more than three statements, indicating a gross misunderstanding of CIs. Self-declared experience with statistics was not related to researchers' performance, and, even more surprisingly, researchers hardly outperformed the students, even though the students had not received any education on statistical inference whatsoever. Our findings suggest that many researchers do not know the correct interpretation of a CI. The misunderstandings surrounding p-values and CIs are particularly unfortunate because they constitute the main tools by which psychologists draw conclusions from data.

Prognostic value of long noncoding RNA MALAT1 in digestive system malignancies

PubMed Central

Zhai, Hui; Li, Xiao-Mei; Maimaiti, Ailifeire; Chen, Qing-Jie; Liao, Wu; Lai, Hong-Mei; Liu, Fen; Yang, Yi-Ning

2015-01-01

Background: MALAT1, a newly discovered long noncoding RNA (lncRNA), has been reported to be highly expressed in many types of cancers. This meta-analysis summarizes its potential prognostic value in digestive system malignancies. Methods: A quantitative meta-analysis was performed through a systematic search in PubMed, Cochrane Library, Web of Science and Chinese National Knowledge Infrastructure (CNKI) for eligible papers on the prognostic impact of MALAT1 in digestive system malignancies from inception to Apr. 25, 2015. Pooled hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated to summarize the effect. Results: Five studies were included in the study, with a total of 527 patients. A significant association was observed between MALAT1 abundance and poor overall survival (OS) of patients with digestive system malignancies, with pooled hazard ratio (HR) of 7.68 (95% confidence interval [CI]: 4.32-13.66, P<0.001). Meta sensitivity analysis suggested the reliability of our findings. No publication bias was observed. Conclusions: MALAT1 abundance may serve as a novel predictive factor for poor prognosis in patients with digestive system malignancies. PMID:26770406

Biomass Thermogravimetric Analysis: Uncertainty Determination Methodology and Sampling Maps Generation

PubMed Central

Pazó, Jose A.; Granada, Enrique; Saavedra, Ángeles; Eguía, Pablo; Collazo, Joaquín

2010-01-01

The objective of this study was to develop a methodology for the determination of the maximum sampling error and confidence intervals of thermal properties obtained from thermogravimetric analysis (TG), including moisture, volatile matter, fixed carbon and ash content. The sampling procedure of the TG analysis was of particular interest and was conducted with care. The results of the present study were compared to those of a prompt analysis, and a correlation between the mean values and maximum sampling errors of the methods were not observed. In general, low and acceptable levels of uncertainty and error were obtained, demonstrating that the properties evaluated by TG analysis were representative of the overall fuel composition. The accurate determination of the thermal properties of biomass with precise confidence intervals is of particular interest in energetic biomass applications. PMID:20717532

Fetal sex determination in twin pregnancies using cell free fetal DNA analysis.

PubMed

Milan, Miguel; Mateu, Emilia; Blesa, David; Clemente-Ciscar, Monica; Simon, Carlos

2018-04-23

We sought to develop an accurate sex classification method in twin pregnancies using data obtained from a standard commercial non-invasive prenatal test. A total of 706 twin pregnancies were included in this retrospective analytical data study. Normalized chromosome values for chromosomes X and Y were used and adapted into a sex-score to predict fetal sex in each fetus, and results were compared with the clinical outcome at birth. Outcome information at birth for sex chromosomes was available for 232 twin pregnancies. From these, a total of 173 twin pregnancies with a Y chromosome identified in non-invasive pregnancy testing were used for the development of a predictive model. Global accuracy for sex classification in the testing set with 51 samples was 0.98 (95% confidence interval [0.90,0.99]), with a specificity and sensitivity of 1 (95% confidence interval [0.82,1.00]) and 0.97 (95% confidence interval [0.84,0.99]), respectively. While non-invasive prenatal testing is a screening method and confirmatory results must be obtained by ultrasound or genetic diagnosis, the sex-score determination presented herein offers an accurate and useful approach to characterizing fetus sex in twin pregnancies in a non-invasive manner early on in pregnancy. © 2018 John Wiley & Sons, Ltd.

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.

A method for meta-analysis of epidemiological studies.

PubMed

Einarson, T R; Leeder, J S; Koren, G

1988-10-01

This article presents a stepwise approach for conducting a meta-analysis of epidemiological studies based on proposed guidelines. This systematic method is recommended for practitioners evaluating epidemiological studies in the literature to arrive at an overall quantitative estimate of the impact of a treatment. Bendectin is used as an illustrative example. Meta-analysts should establish a priori the purpose of the analysis and a complete protocol. This protocol should be adhered to, and all steps performed should be recorded in detail. To aid in developing such a protocol, we present methods the researcher can use to perform each of 22 steps in six major areas. The illustrative meta-analysis confirmed previous traditional narrative literature reviews that Bendectin is not related to teratogenic outcomes in humans. The overall summary odds ratio was 1.01 (chi 2 = 0.05, p = 0.815) with a 95 percent confidence interval of 0.66-1.55. When the studies were separated according to study type, the summary odds ratio for cohort studies was 0.95 with a 95 percent confidence interval of 0.62-1.45. For case-control studies, the summary odds ratio was 1.27 with a 95 percent confidence interval of 0.83-1.94. The corresponding chi-square values were not statistically significant at the p = 0.05 level.

A cross-country Exchange Market Pressure (EMP) dataset.

PubMed

Desai, Mohit; Patnaik, Ila; Felman, Joshua; Shah, Ajay

2017-06-01

The data presented in this article are related to the research article titled - "An exchange market pressure measure for cross country analysis" (Patnaik et al. [1]). In this article, we present the dataset for Exchange Market Pressure values (EMP) for 139 countries along with their conversion factors, ρ (rho). Exchange Market Pressure, expressed in percentage change in exchange rate, measures the change in exchange rate that would have taken place had the central bank not intervened. The conversion factor ρ can interpreted as the change in exchange rate associated with $1 billion of intervention. Estimates of conversion factor ρ allow us to calculate a monthly time series of EMP for 139 countries. Additionally, the dataset contains the 68% confidence interval (high and low values) for the point estimates of ρ 's. Using the standard errors of estimates of ρ 's, we obtain one sigma intervals around mean estimates of EMP values. These values are also reported in the dataset.

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…

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...

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 new method of sweat testing: the CF Quantum®sweat test.

PubMed

Rock, Michael J; Makholm, Linda; Eickhoff, Jens

2014-09-01

Conventional methods of sweat testing are time consuming and have many steps that can and do lead to errors. This study compares conventional sweat testing to a new quantitative method, the CF Quantum® (CFQT) sweat test. This study tests the diagnostic accuracy and analytic validity of the CFQT. Previously diagnosed CF patients and patients who required a sweat test for clinical indications were invited to have the CFQT test performed. Both conventional sweat testing and the CFQT were performed bilaterally on the same day. Pairs of data from each test are plotted as a correlation graph and Bland-Altman plot. Sensitivity and specificity were calculated as well as the means and coefficient of variation by test and by extremity. After completing the study, subjects or their parents were asked for their preference of the CFQT and conventional sweat testing. The correlation coefficient between the CFQT and conventional sweat testing was 0.98 (95% confidence interval: 0.97-0.99). The sensitivity and specificity of the CFQT in diagnosing CF was 100% (95% confidence interval: 94-100%) and 96% (95% confidence interval: 89-99%), respectively. In one center in this three center multicenter study, there were higher sweat chloride values in patients with CF and also more tests that were invalid due to discrepant values between the two extremities. The percentage of invalid tests was higher in the CFQT method (16.5%) compared to conventional sweat testing (3.8%) (p < 0.001). In the post-test questionnaire, 88% of subjects/parents preferred the CFQT test. The CFQT is a fast and simple method of quantitative sweat chloride determination. This technology requires further refinement to improve the analytic accuracy at higher sweat chloride values and to decrease the number of invalid tests. Copyright © 2014 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

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.

Iodine concentration: a new, important characteristic of the spot sign that predicts haematoma expansion.

PubMed

Fu, Fan; Sun, Shengjun; Liu, Liping; Li, Jianying; Su, Yaping; Li, Yingying

2018-04-19

The computed tomography angiography (CTA) spot sign is a validated predictor of haematoma expansion (HE) in spontaneous intracerebral haemorrhage (SICH). We investigated whether defining the iodine concentration (IC) inside the spot sign and the haematoma on Gemstone spectral imaging (GSI) would improve its sensitivity and specificity for predicting HE. From 2014 to 2016, we prospectively enrolled 65 SICH patients who underwent single-phase spectral CTA within 6 h. Logistic regression was performed to assess the risk factors for HE. The predictive performance of individual spot sign characteristics was examined via receiver operating characteristic (ROC) analysis. The spot sign was detected in 46.1% (30/65) of patients. ROC analysis indicated that IC inside the spot sign had the greatest area under the ROC curve for HE (0.858; 95% confidence interval, 0.727-0.989; p = 0.003). Multivariate analysis found that spot sign with higher IC (i.e. IC > 7.82 100 μg/ml) was an independent predictor of HE (odds ratio = 34.27; 95% confidence interval, 5.608-209.41; p < 0.001) with sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 0.81, 0.75, 0.90 and 0.60, respectively; while the spot sign showed sensitivity, specificity, PPV and NPV of 0.81, 0.79, 0.73 and 0.86. Logistic regression analysis indicated that the IC in haematomas was independently associated with HE (odds ratio = 1.525; 95% confidence interval, 1.041-2.235; p = 0.030). ICs in haematoma and in spot sign were all independently associated with HE. IC analysis in spectral imaging may help to identify SICH patients for targeted haemostatic therapy. • Iodine concentration in spot sign and haematoma can predict haematoma expansion • Spectral imaging could measure the IC inside the spot sign and haematoma • IC in spot sign improved the positive predictive value (PPV) cf. CTA.

Effect of rosuvastatin on the echolucency of the common carotid intima-media in low-risk individuals: the METEOR trial.

PubMed

Lind, Lars; Peters, Sanne A E; den Ruijter, Hester M; Palmer, Mike K; Grobbee, Diederick E; Crouse, John R; O'Leary, Daniel H; Evans, Gregory W; Raichlen, Joel S; Bots, Michiel L

2012-10-01

The echolucency of the carotid intima-media is related to increased cardiovascular risk factor levels, morbidity, and mortality. The aim of this study was to assess the effect of statins on the echolucency of the common carotid intima-media in a low-risk population. Data from the Measuring Effects on Intima-Media Thickness: An Evaluation of Rosuvastatin study were used. Ultrasound images from the far walls of the left and right common carotid arteries were used for evaluation of the echolucency of the carotid intima-media, measured by grayscale median (GSM). Low GSM values reflect echolucent structures, whereas high values reflect echogenic structures. The primary end point was the difference in the annual rate of change in GSM between rosuvastatin and placebo. Two-year change in GSM did not significantly differ between rosuvastatin and placebo in the total population, with a mean difference in the rate of change in GSM of 1.13 (95% confidence interval, -1.00 to 3.25). The effect of rosuvastatin differed across quintiles of baseline GSM values (P for interaction = .01). In the lowest quintile (n = 175) (i.e., in those with the most echolucent intima-media), the difference in the rate of change in GSM between rosuvastatin and placebo was 4.18 (95% confidence interval, -0.23 to 8.58). Increases in GSM were significantly related to decreasing low-density lipoprotein cholesterol levels in the lowest quintile (β = 0.76; 95% confidence interval, 0.26 to 1.25). Treatment with rosuvastatin did not affect the echolucency of the arterial wall in all low-risk individuals. However, a potential effect of rosuvastatin on the echolucency of the common carotid intima-media is most likely to be found in individuals with echolucent arterial walls at baseline. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

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.

Environmental assessment of three egg production systems--Part I: Monitoring system and indoor air quality.

PubMed

Zhao, Y; Shepherd, T A; Li, H; Xin, H

2015-03-01

To comprehensively assess conventional vs. some alternative laying-hen housing systems under U.S. production conditions, a multi-institute and multi-disciplinary project, known as the Coalition for Sustainable Egg Supply (CSES) study, was carried out at a commercial egg production farm in the Midwestern United States over two single-cycle production flocks. The housing systems studied include a conventional cage house (200,000 hen capacity), an aviary house (50,000 hen capacity), and an enriched colony house (50,000 hen capacity). As an integral part of the CSES project, continual environmental monitoring over a 27-month period described in this paper quantifies indoor gaseous and particulate matter concentrations, thermal environment, and building ventilation rate of each house. Results showed that similar indoor thermal environments in all three houses were maintained through ventilation management and environmental control. Gaseous and particulate matter concentrations of the enriched colony house were comparable with those of the conventional cage house. In comparison, the aviary house had poorer indoor air quality, especially in wintertime, resulting from the presence of floor litter (higher ammonia levels) and hens' activities (higher particulate matter levels) in it. Specifically, daily mean indoor ammonia concentrations had the 95% confidence interval values of 3.8 to 4.2 (overall mean of 4.0) ppm for the conventional cage house; 6.2 to 7.2 (overall mean of 6.7) ppm for the aviary house; and 2.7 to 3.0 (overall mean of 2.8) ppm for the enriched colony house. The 95% confidence interval (overall mean) values of daily mean indoor carbon dioxide concentrations were 1997 to 2170 (2083) ppm for the conventional cage house, 2367 to 2582 (2475) ppm for the aviary house, and 2124 to 2309 (2216) ppm for the enriched colony house. Daily mean indoor methane concentrations were similar for all three houses, with 95% confidence interval values of 11.1 to 11.9 (overall mean of 11.5) ppm. The 95% confidence interval values (overall mean) of daily mean PM10 and PM2.5 concentrations, in mg/m3, were, respectively, 0.57 to 0.61 (0.59) and 0.033 to 0.037 (0.035) for the conventional cage house, 3.61 to 4.29 (3.95) and 0.374 to 0.446 (0.410) for the aviary house, and 0.42 to 0.46 (0.44) and 0.054 to 0.059 (0.056) for the enriched colony house. Investigation of mitigation practices to improve indoor air quality of the litter-floor aviary housing system is warranted. © The Author 2015. Published by Oxford University Press on behalf of Poultry Science Association.

Environmental assessment of three egg production systems–Part I: Monitoring system and indoor air quality

PubMed Central

Zhao, Y.; Shepherd, T. A.; Li, H.; Xin, H.

2015-01-01

To comprehensively assess conventional vs. some alternative laying-hen housing systems under U.S. production conditions, a multi-institute and multi-disciplinary project, known as the Coalition for Sustainable Egg Supply (CSES) study, was carried out at a commercial egg production farm in the Midwestern United States over two single-cycle production flocks. The housing systems studied include a conventional cage house (200,000 hen capacity), an aviary house (50,000 hen capacity), and an enriched colony house (50,000 hen capacity). As an integral part of the CSES project, continual environmental monitoring over a 27-month period described in this paper quantifies indoor gaseous and particulate matter concentrations, thermal environment, and building ventilation rate of each house. Results showed that similar indoor thermal environments in all three houses were maintained through ventilation management and environmental control. Gaseous and particulate matter concentrations of the enriched colony house were comparable with those of the conventional cage house. In comparison, the aviary house had poorer indoor air quality, especially in wintertime, resulting from the presence of floor litter (higher ammonia levels) and hens’ activities (higher particulate matter levels) in it. Specifically, daily mean indoor ammonia concentrations had the 95% confidence interval values of 3.8 to 4.2 (overall mean of 4.0) ppm for the conventional cage house; 6.2 to 7.2 (overall mean of 6.7) ppm for the aviary house; and 2.7 to 3.0 (overall mean of 2.8) ppm for the enriched colony house. The 95% confidence interval (overall mean) values of daily mean indoor carbon dioxide concentrations were 1997 to 2170 (2083) ppm for the conventional cage house, 2367 to 2582 (2475) ppm for the aviary house, and 2124 to 2309 (2216) ppm for the enriched colony house. Daily mean indoor methane concentrations were similar for all three houses, with 95% confidence interval values of 11.1 to 11.9 (overall mean of 11.5) ppm. The 95% confidence interval values (overall mean) of daily mean PM10 and PM2.5 concentrations, in mg/m3, were, respectively, 0.57 to 0.61 (0.59) and 0.033 to 0.037 (0.035) for the conventional cage house, 3.61 to 4.29 (3.95) and 0.374 to 0.446 (0.410) for the aviary house, and 0.42 to 0.46 (0.44) and 0.054 to 0.059 (0.056) for the enriched colony house. Investigation of mitigation practices to improve indoor air quality of the litter-floor aviary housing system is warranted. PMID:25737567

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.

Description and Evaluation of an Educational Intervention on Health Care Costs and Value.

PubMed

Jonas, Jennifer A; Ronan, Jeanine C; Petrie, Ian; Fieldston, Evan S

2016-02-01

There is growing consensus that to ensure that health care dollars are spent efficiently, physicians need more training in how to provide high-value, cost-conscious care. Thus, in fiscal year 2014, The Children's Hospital of Philadelphia piloted a 9-part curriculum on health care costs and value for faculty in the Division of General Pediatrics. This study uses baseline and postintervention surveys to gauge knowledge, perceptions, and views on these issues and to assess the efficacy of the pilot curriculum. Faculty completed surveys about their knowledge and perceptions about health care costs and value and their views on the role physicians should play in containing costs and promoting value. Baseline and postintervention responses were compared and analyzed on the basis of how many of the sessions respondents attended. Sixty-two faculty members completed the baseline survey (71% response rate), and 45 faculty members completed the postintervention survey (63% response rate). Reported knowledge of health care costs and value increased significantly in the postintervention survey (P=.04 and P<.001). Odds of being knowledgeable about costs and value were 2.42 (confidence interval: 1.05-5.58) and 6.22 times greater (confidence interval: 2.29-16.90), respectively, postintervention. Reported knowledge of health care costs and value increased with number of sessions attended (P=.01 and P<.001). The pilot curriculum appeared to successfully introduce physicians to concepts around health care costs and value and initiated important discussions about the role physicians can play in containing costs and promoting value. Additional education, increased cost transparency, and more decision support tools are needed to help physicians translate knowledge into practice. Copyright © 2016 by the American Academy of Pediatrics.

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...

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…

Prediction of parenteral nutrition osmolarity by digital refractometry.

PubMed

Chang, Wei-Kuo; Yeh, Ming-Kung

2011-05-01

Infusion of high-osmolarity parenteral nutrition (PN) formulations into a peripheral vein will damage the vessel. In this study, the authors developed a refractometric method to predict PN formulation osmolarity for patients receiving PN. Nutrients in PN formulations were prepared for Brix value and osmolality measurement. Brix value and osmolality measurement of the dextrose, amino acids, and electrolytes were used to evaluate the limiting factor of PN osmolarity prediction. A best-fit equation was generated to predict PN osmolarity (mOsm/L): 81.05 × Brix value--116.33 (R(2) > 0.99). To validate the PN osmolarity prediction by these 4 equations, a total of 500 PN admixtures were tested. The authors found strong linear relationships between the Brix values and the osmolality measurement of dextrose (R(2) = 0.97), amino acids (R(2) = 0.99), and electrolytes (R(2) > 0.96). When PN-measured osmolality was between 600 and 900 mOsm/kg, approximately 43%, 29%, 43%, and 0% of the predicted osmolarity obtained by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively. When measured osmolality was between 900 and 1,500 mOsm/kg, 31%, 100%, 85%, and 15% of the predicted osmolarity by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively. The refractive method permits accurate PN osmolarity prediction and reasonable quality assurance before PN formulation administration.

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.

Common y-intercept and single compound regressions of gas-particle partitioning data vs 1/T

NASA Astrophysics Data System (ADS)

Pankow, James F.

Confidence intervals are placed around the log Kp vs 1/ T correlation equations obtained using simple linear regressions (SLR) with the gas-particle partitioning data set of Yamasaki et al. [(1982) Env. Sci. Technol.16, 189-194]. The compounds and groups of compounds studied include the polycylic aromatic hydrocarbons phenanthrene + anthracene, me-phenanthrene + me-anthracene, fluoranthene, pyrene, benzo[ a]fluorene + benzo[ b]fluorene, chrysene + benz[ a]anthracene + triphenylene, benzo[ b]fluoranthene + benzo[ k]fluoranthene, and benzo[ a]pyrene + benzo[ e]pyrene (note: me = methyl). For any given compound, at equilibrium, the partition coefficient Kp equals ( F/ TSP)/ A where F is the particulate-matter associated concentration (ng m -3), A is the gas-phase concentration (ng m -3), and TSP is the concentration of particulate matter (μg m -3). At temperatures more than 10°C from the mean sampling temperature of 17°C, the confidence intervals are quite wide. Since theory predicts that similar compounds sorbing on the same particulate matter should possess very similar y-intercepts, the data set was also fitted using a special common y-intercept regression (CYIR). For most of the compounds, the CYIR equations fell inside of the SLR 95% confidence intervals. The CYIR y-intercept value is -18.48, and is reasonably close to the type of value that can be predicted for PAH compounds. The set of CYIR regression equations is probably more reliable than the set of SLR equations. For example, the CYIR-derived desorption enthalpies are much more highly correlated with vaporization enthalpies than are the SLR-derived desorption enthalpies. It is recommended that the CYIR approach be considered whenever analysing temperature-dependent gas-particle partitioning data.

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.

Effect of Turbulent-Flow Pasteurization on Survival of Mycobacterium avium subsp. paratuberculosis Added to Raw Milk

PubMed Central

Pearce, Lindsay E.; Truong, H. Tuan; Crawford, Robert A.; Yates, Gary F.; Cavaignac, Sonia; de Lisle, Geoffrey W.

2001-01-01

A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity of Mycobacterium avium subsp. paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated in raw whole milk for 15 s at 63, 66, 69, and 72°C in duplicate trials. No strains survived at 72°C for 15 s; and only one strain survived at 69°C. Means of pooled D values (decimal reduction times) at 63 and 66°C were 15.0 ± 2.8 s (95% confidence interval) and 5.9 ± 0.7 s (95% confidence interval), respectively. The mean extrapolated D72°C was <2.03 s. This was equivalent to a >7 log10 kill at 72°C for 15 s (95% confidence interval). The mean Z value (degrees required for the decimal reduction time to traverse one log cycle) was 8.6°C. These five strains showed similar survival whether recovery was on Herrold's egg yolk medium containing mycobactin or by a radiometric culture method (BACTEC). Milk was inoculated with fresh fecal material from a high-level fecal shedder with clinical Johne's disease. After heating at 72°C for 15 s, the minimum M. avium subsp. paratuberculosis kill was >4 log10. Properly maintained and operated equipment should ensure the absence of viable M. avium subsp. paratuberculosis in retail milk and other pasteurized dairy products. An additional safeguard is the widespread commercial practice of pasteurizing 1.5 to 2° above 72°C. PMID:11525992

Prognostic value of changes in galectin-3 levels over time in patients with heart failure: data from CORONA and COACH.

PubMed

van der Velde, A Rogier; Gullestad, Lars; Ueland, Thor; Aukrust, Pål; Guo, Yu; Adourian, Aram; Muntendam, Pieter; van Veldhuisen, Dirk J; de Boer, Rudolf A

2013-03-01

In several cross-sectional analyses, circulating baseline levels of galectin-3, a protein involved in myocardial fibrosis and remodeling, have been associated with increased risk for morbidity and mortality in patients with heart failure (HF). The importance and clinical use of repeated measurements of galectin-3 have not yet been reported. Plasma galectin-3 was measured at baseline and at 3 months in patients enrolled in the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA) trial (n=1329), and at baseline and at 6 months in patients enrolled in the Coordinating Study Evaluating Outcomes of Advising and Counseling Failure (COACH) trial (n=324). Patient results were analyzed by categorical and percentage changes in galectin-3 level. A threshold value of 17.8 ng/mL or 15% change from baseline was used to categorize patients. Increasing galectin-3 levels over time, from a low to high galectin-3 category, were associated with significantly more HF hospitalization and mortality compared with stable or decreasing galectin-3 levels (hazard ratio in CORONA, 1.60; 95% confidence interval, 1.13-2.25; P=0.007; hazard ratio in COACH, 2.38; 95% confidence interval, 1.02-5.55; P=0.046). In addition, patients whose galectin-3 increased by >15% between measurements had a 50% higher relative hazard of adverse event than those whose galectin-3 stayed within ±15% of the baseline value, independent of age, sex, diabetes mellitus, left ventricular ejection fraction, renal function, medication (β-blocker, angiotensin converting enzyme inhibitor, and angiotensin receptor blocker), and N-terminal probrain natriuretic peptide (hazard ratio in CORONA, 1.50; 95% confidence interval, 1.17-1.92; P=0.001). The impact of changing galectin-3 levels on other secondary end points was comparable. In 2 large cohorts of patients with chronic and acute decompensated HF, repeated measurements of galectin-3 level provided important and significant prognostic value in identifying patients with HF at elevated risk for subsequent HF morbidity and mortality.

Using spatially explicit surveillance models to provide confidence in the eradication of an invasive ant

PubMed Central

Ward, Darren F.; Anderson, Dean P.; Barron, Mandy C.

2016-01-01

Effective detection plays an important role in the surveillance and management of invasive species. Invasive ants are very difficult to eradicate and are prone to imperfect detection because of their small size and cryptic nature. Here we demonstrate the use of spatially explicit surveillance models to estimate the probability that Argentine ants (Linepithema humile) have been eradicated from an offshore island site, given their absence across four surveys and three surveillance methods, conducted since ant control was applied. The probability of eradication increased sharply as each survey was conducted. Using all surveys and surveillance methods combined, the overall median probability of eradication of Argentine ants was 0.96. There was a high level of confidence in this result, with a high Credible Interval Value of 0.87. Our results demonstrate the value of spatially explicit surveillance models for the likelihood of eradication of Argentine ants. We argue that such models are vital to give confidence in eradication programs, especially from highly valued conservation areas such as offshore islands. PMID:27721491

Trends in P Value, Confidence Interval, and Power Analysis Reporting in Health Professions Education Research Reports: A Systematic Appraisal.

PubMed

Abbott, Eduardo F; Serrano, Valentina P; Rethlefsen, Melissa L; Pandian, T K; Naik, Nimesh D; West, Colin P; Pankratz, V Shane; Cook, David A

2018-02-01

To characterize reporting of P values, confidence intervals (CIs), and statistical power in health professions education research (HPER) through manual and computerized analysis of published research reports. The authors searched PubMed, Embase, and CINAHL in May 2016, for comparative research studies. For manual analysis of abstracts and main texts, they randomly sampled 250 HPER reports published in 1985, 1995, 2005, and 2015, and 100 biomedical research reports published in 1985 and 2015. Automated computerized analysis of abstracts included all HPER reports published 1970-2015. In the 2015 HPER sample, P values were reported in 69/100 abstracts and 94 main texts. CIs were reported in 6 abstracts and 22 main texts. Most P values (≥77%) were ≤.05. Across all years, 60/164 two-group HPER studies had ≥80% power to detect a between-group difference of 0.5 standard deviations. From 1985 to 2015, the proportion of HPER abstracts reporting a CI did not change significantly (odds ratio [OR] 2.87; 95% CI 1.04, 7.88) whereas that of main texts reporting a CI increased (OR 1.96; 95% CI 1.39, 2.78). Comparison with biomedical studies revealed similar reporting of P values, but more frequent use of CIs in biomedicine. Automated analysis of 56,440 HPER abstracts found 14,867 (26.3%) reporting a P value, 3,024 (5.4%) reporting a CI, and increased reporting of P values and CIs from 1970 to 2015. P values are ubiquitous in HPER, CIs are rarely reported, and most studies are underpowered. Most reported P values would be considered statistically significant.

Assessing Live Fuel Moisture For Fire Management Applications

Treesearch

David R. Weise; Roberta A. Hartford; Larry Mahaffey

1998-01-01

The variation associated with sampling live fuel moisture was examined for several shrub and canopy fuels in southern California, Arizona, and Colorado. Ninety-five % confidence intervals ranged from 5 to % . Estimated sample sizes varied greatly. The value of knowing the live fuel moisture content in fire decision making is unknown. If the fuel moisture is highly...

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.

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.

Estimated preejection period (PEP) based on the detection of the R-wave and dZ/dt-min peaks in ECG and ICG

NASA Astrophysics Data System (ADS)

van Lien, René; Schutte, Nienke M.; Meijer, Jan H.; de Geus, Eco J. C.

2013-04-01

The validity of estimating the PEP from a fixed value for the Q-wave onset to the R-wave peak (QR) interval and from the R-wave peak to the dZ/dt-min peak (ISTI) interval is evaluated. Ninety-one subjects participated in a laboratory experiment in which a variety of physical and mental stressors were presented and 31 further subjects participated in a sequence of structured ambulatory activities in which large variation in posture and physical activity was induced. PEP, QR interval, and ISTI were scored. Across the diverse laboratory and ambulatory conditions the QR interval could be approximated by a fixed interval of 40 ms but 95% confidence intervals were large (25 to 54 ms). Multilevel analysis showed that 79% to 81% of the within and between-subject variation in the RB interval could be predicted by the ISTI. However, the optimal intercept and slope values varied significantly across subjects and study setting. Bland-Altman plots revealed a large discrepancy between the estimated PEP and the actual PEP based on the Q-wave onset and B-point. It is concluded that the estimated PEP can be a useful tool but cannot replace the actual PEP to index cardiac sympathetic control.

SLDAssay: A software package and web tool for analyzing limiting dilution assays.

PubMed

Trumble, Ilana M; Allmon, Andrew G; Archin, Nancie M; Rigdon, Joseph; Francis, Owen; Baldoni, Pedro L; Hudgens, Michael G

2017-11-01

Serial limiting dilution (SLD) assays are used in many areas of infectious disease related research. This paper presents SLDAssay, a free and publicly available R software package and web tool for analyzing data from SLD assays. SLDAssay computes the maximum likelihood estimate (MLE) for the concentration of target cells, with corresponding exact and asymptotic confidence intervals. Exact and asymptotic goodness of fit p-values, and a bias-corrected (BC) MLE are also provided. No other publicly available software currently implements the BC MLE or the exact methods. For validation of SLDAssay, results from Myers et al. (1994) are replicated. Simulations demonstrate the BC MLE is less biased than the MLE. Additionally, simulations demonstrate that exact methods tend to give better confidence interval coverage and goodness-of-fit tests with lower type I error than the asymptotic methods. Additional advantages of using exact methods are also discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of a smoking ban on respiratory health in nonsmoking hospitality workers: a prospective cohort study.

PubMed

Rajkumar, Sarah; Stolz, Daiana; Hammer, Jürg; Moeller, Alexander; Bauer, Georg F; Huynh, Cong Khanh; Röösli, Martin

2014-10-01

The aim of this study was to examine the effect of a smoking ban on lung function, fractional exhaled nitric oxide, and respiratory symptoms in nonsmoking hospitality workers. Secondhand smoke exposure at the workplace, spirometry, and fractional exhaled nitric oxide were measured in 92 nonsmoking hospitality workers before as well as twice after a smoking ban. At baseline, secondhand smoke-exposed hospitality workers had lung function values significantly below the population average. After the smoking ban, the covariate-adjusted odds ratio for cough was 0.59 (95% confidence interval, 0.36 to 0.93) and for chronic bronchitis 0.75 (95% confidence interval, 0.55 to 1.02) compared with the preban period. The below-average lung function before the smoking ban indicates chronic damages from long-term exposure. Respiratory symptoms such as cough decreased within 12 months after the ban.

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.

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.

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

Fuzzy time series forecasting model with natural partitioning length approach for predicting the unemployment rate under different degree of confidence

NASA Astrophysics Data System (ADS)

Ramli, Nazirah; Mutalib, Siti Musleha Ab; Mohamad, Daud

2017-08-01

Fuzzy time series forecasting model has been proposed since 1993 to cater for data in linguistic values. Many improvement and modification have been made to the model such as enhancement on the length of interval and types of fuzzy logical relation. However, most of the improvement models represent the linguistic term in the form of discrete fuzzy sets. In this paper, fuzzy time series model with data in the form of trapezoidal fuzzy numbers and natural partitioning length approach is introduced for predicting the unemployment rate. Two types of fuzzy relations are used in this study which are first order and second order fuzzy relation. This proposed model can produce the forecasted values under different degree of confidence.

Conformal Regression for Quantitative Structure-Activity Relationship Modeling-Quantifying Prediction Uncertainty.

PubMed

Svensson, Fredrik; Aniceto, Natalia; Norinder, Ulf; Cortes-Ciriano, Isidro; Spjuth, Ola; Carlsson, Lars; Bender, Andreas

2018-05-29

Making predictions with an associated confidence is highly desirable as it facilitates decision making and resource prioritization. Conformal regression is a machine learning framework that allows the user to define the required confidence and delivers predictions that are guaranteed to be correct to the selected extent. In this study, we apply conformal regression to model molecular properties and bioactivity values and investigate different ways to scale the resultant prediction intervals to create as efficient (i.e., narrow) regressors as possible. Different algorithms to estimate the prediction uncertainty were used to normalize the prediction ranges, and the different approaches were evaluated on 29 publicly available data sets. Our results show that the most efficient conformal regressors are obtained when using the natural exponential of the ensemble standard deviation from the underlying random forest to scale the prediction intervals, but other approaches were almost as efficient. This approach afforded an average prediction range of 1.65 pIC50 units at the 80% confidence level when applied to bioactivity modeling. The choice of nonconformity function has a pronounced impact on the average prediction range with a difference of close to one log unit in bioactivity between the tightest and widest prediction range. Overall, conformal regression is a robust approach to generate bioactivity predictions with associated confidence.

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

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.

Reference values for 34 frequently used laboratory tests in 80-year-old men and women.

PubMed

Helmersson-Karlqvist, Johanna; Ridefelt, Peter; Lind, Lars; Larsson, Anders

2016-10-01

Reference values are usually based on blood samples from healthy individuals in the age range 20-50 years. Most patients seeking health care are older than this reference population. Many reference intervals are age dependent and there is thus a need to have appropriate reference intervals also for elderly individuals. We analyzed a group of frequently used laboratory tests in an 80-year-old population (n=531, 266 females and 265 males). The 2.5th and 97.5th percentiles for these markers were calculated according to the International Federation of Clinical Chemistry guidelines on the statistical treatment of reference values. Reference values are reported for serum alanine transaminase (ALT), albumin, alkaline phosphatase, pancreatic amylase, apolipoprotein A1, apolipoprotein B, apolipoprotein B/apolipoprotein A1 ratio, aspartate aminotransferase (AST), AST/ALT ratio, bilirubin, calcium, calprotectin, cholesterol, HDL-cholesterol, creatinine kinase (CK), creatinine, creatinine estimated GFR, C-reactive protein, cystatin C, cystatin C estimated GFR, gamma-glutamyltransferase (GGT), iron, iron saturation, lactate dehydrogenase (LDH), magnesium, phosphate, transferrin, triglycerides, urate, urea, zinc, hemoglobin, platelet count and white blood cell count. The upper reference limit for creatinine and urea was significantly increased while the lower limit for iron and albumin was decreased in this elderly population in comparison with the population in the Nordic Reference Interval Project (NORIP). Reference values calculated from the whole population and a subpopulation without cardiovascular disease showed strong concordance. Several of the reference interval limits were outside the 90% confidence interval of NORIP. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Selecting Sensitive Parameter Subsets in Dynamical Models With Application to Biomechanical System Identification.

PubMed

Ramadan, Ahmed; Boss, Connor; Choi, Jongeun; Peter Reeves, N; Cholewicki, Jacek; Popovich, John M; Radcliffe, Clark J

2018-07-01

Estimating many parameters of biomechanical systems with limited data may achieve good fit but may also increase 95% confidence intervals in parameter estimates. This results in poor identifiability in the estimation problem. Therefore, we propose a novel method to select sensitive biomechanical model parameters that should be estimated, while fixing the remaining parameters to values obtained from preliminary estimation. Our method relies on identifying the parameters to which the measurement output is most sensitive. The proposed method is based on the Fisher information matrix (FIM). It was compared against the nonlinear least absolute shrinkage and selection operator (LASSO) method to guide modelers on the pros and cons of our FIM method. We present an application identifying a biomechanical parametric model of a head position-tracking task for ten human subjects. Using measured data, our method (1) reduced model complexity by only requiring five out of twelve parameters to be estimated, (2) significantly reduced parameter 95% confidence intervals by up to 89% of the original confidence interval, (3) maintained goodness of fit measured by variance accounted for (VAF) at 82%, (4) reduced computation time, where our FIM method was 164 times faster than the LASSO method, and (5) selected similar sensitive parameters to the LASSO method, where three out of five selected sensitive parameters were shared by FIM and LASSO methods.

Impact of influent data frequency and model structure on the quality of WWTP model calibration and uncertainty.

PubMed

Cierkens, Katrijn; Plano, Salvatore; Benedetti, Lorenzo; Weijers, Stefan; de Jonge, Jarno; Nopens, Ingmar

2012-01-01

Application of activated sludge models (ASMs) to full-scale wastewater treatment plants (WWTPs) is still hampered by the problem of model calibration of these over-parameterised models. This either requires expert knowledge or global methods that explore a large parameter space. However, a better balance in structure between the submodels (ASM, hydraulic, aeration, etc.) and improved quality of influent data result in much smaller calibration efforts. In this contribution, a methodology is proposed that links data frequency and model structure to calibration quality and output uncertainty. It is composed of defining the model structure, the input data, an automated calibration, confidence interval computation and uncertainty propagation to the model output. Apart from the last step, the methodology is applied to an existing WWTP using three models differing only in the aeration submodel. A sensitivity analysis was performed on all models, allowing the ranking of the most important parameters to select in the subsequent calibration step. The aeration submodel proved very important to get good NH(4) predictions. Finally, the impact of data frequency was explored. Lowering the frequency resulted in larger deviations of parameter estimates from their default values and larger confidence intervals. Autocorrelation due to high frequency calibration data has an opposite effect on the confidence intervals. The proposed methodology opens doors to facilitate and improve calibration efforts and to design measurement campaigns.

Complementary Roles for Biomarkers of Biomechanical Strain ST2 and N-Terminal Prohormone B-Type Natriuretic Peptide in Patients With ST-Elevation Myocardial Infarction

PubMed Central

Sabatine, Marc S.; Morrow, David A.; Higgins, Luke J.; MacGillivray, Catherine; Guo, Wei; Bode, Christophe; Rifai, Nader; Cannon, Christopher P.; Gerszten, Robert E.; Lee, Richard T.

2014-01-01

Background ST2 is a member of the interleukin-1 receptor family with a soluble form that is markedly upregulated on application of biomechanical strain to cardiac myocytes. Circulating ST2 levels are elevated in the setting of acute myocardial infarction, but the predictive value of ST2 independent of traditional clinical factors and of an established biomarker of biomechanical strain, N-terminal prohormone B-type natriuretic peptide (NT-proBNP), has not been established. Methods and Results We measured ST2 at baseline in 1239 patients with ST-elevation myocardial infarction from the CLopidogrel as Adjunctive ReperfusIon TherapY–Thrombolysis in Myocardial Infarction 28 (CLARITY-TIMI 28) trial. Per trial protocol, patients were to undergo coronary angiography after 2 to 8 days and were followed up for 30 days for clinical events. In contrast to NT-proBNP, ST2 levels were independent of clinical factors potentially related to chronic increased left ventricular wall stress, including age, hypertension, prior myocardial infarction, and prior heart failure; levels also were only modestly correlated with NT-proBNP (r=0.14). After adjustment for baseline characteristics and NT-proBNP levels, an ST2 level above the median was associated with a significantly greater risk of cardiovascular death or heart failure (third quartile: adjusted odds ratio, 1.42; 95% confidence interval, 0.68 to 3.57; fourth quartile: adjusted odds ratio, 3.57; 95% confidence interval, 1.87 to 6.81; P<0.0001 for trend). When both ST2 and NT-proBNP were added to a model containing traditional clinical predictors, the c statistic significantly improved from 0.82 (95% confidence interval, 0.77 to 0.87) to 0.86 (95% confidence interval, 0.81 to 0.90) (P=0.017). Conclusions In ST-elevation myocardial infarction, high baseline ST2 levels are a significant predictor of cardiovascular death and heart failure independently of baseline characteristics and NT-proBNP, and the combination of ST2 and NT-proBNP significantly improves risk stratification. These data highlight the prognostic value of multiple, complementary biomarkers of biomechanical strain in ST-elevation myocardial infarction. PMID:18378613

The association between preoperative spinal cord rotation and postoperative C5 nerve palsy.

PubMed

Eskander, Mark S; Balsis, Steve M; Balinger, Chris; Howard, Caitlin M; Lewing, Nicholas W; Eskander, Jonathan P; Aubin, Michelle E; Lange, Jeffrey; Eck, Jason; Connolly, Patrick J; Jenis, Louis G

2012-09-05

C5 nerve palsy is a known complication of cervical spine surgery. The development and etiology of this complication are not completely understood. The purpose of the present study was to determine whether rotation of the cervical spinal cord predicts the development of a C5 palsy. We performed a retrospective review of prospectively collected spine registry data as well as magnetic resonance images. We reviewed the records for 176 patients with degenerative disorders of the cervical spine who underwent anterior cervical decompression or corpectomy within the C4 to C6 levels. Our measurements included area for the spinal cord, space available for the cord, and rotation of the cord with respect to the vertebral body. There was a 6.8% prevalence of postoperative C5 nerve palsy as defined by deltoid motor strength of ≤ 3 of 5. The average rotation of the spinal cord (and standard deviation) was 2.8° ± 3.0°. A significant association was detected between the degree of rotation (0° to 5° versus 6° to 10° versus ≥ 11°) and palsy (point-biserial correlation = 0.94; p < 0.001). A diagnostic criterion of 6° of rotation could identify patients who had a C5 palsy (sensitivity = 1.00 [95% confidence interval, 0.70 to 1.00], specificity = 0.97 [95% confidence interval, 0.93 to 0.99], positive predictive value = 0.71 [95% confidence interval, 0.44 to 0.89], negative predictive value = 1.00 [95% confidence interval, 0.97 to 1.00]). Our evidence suggests that spinal cord rotation is a strong and significant predictor of C5 palsy postoperatively. Patients can be classified into three types, with Type 1 representing mild rotation (0° to 5°), Type 2 representing moderate rotation (6° to 10°), and Type 3 representing severe rotation (≥ 11°). The rate of C5 palsy was zero of 159 in the Type-1 group, eight of thirteen in the Type-2 group, and four of four in the Type-3 group. This information may be valuable for surgeons and patients considering anterior surgery in the C4 to C6 levels.

Influence of air quality model resolution on uncertainty associated with health impacts

NASA Astrophysics Data System (ADS)

Thompson, T. M.; Selin, N. E.

2012-06-01

We use regional air quality modeling to evaluate the impact of model resolution on uncertainty associated with the human health benefits resulting from proposed air quality regulations. Using a regional photochemical model (CAMx), we ran a modeling episode with meteorological inputs representing conditions as they occurred during August through September 2006, and two emissions inventories (a 2006 base case and a 2018 proposed control scenario, both for Houston, Texas) at 36, 12, 4 and 2 km resolution. The base case model performance was evaluated for each resolution against daily maximum 8-h averaged ozone measured at monitoring stations. Results from each resolution were more similar to each other than they were to measured values. Population-weighted ozone concentrations were calculated for each resolution and applied to concentration response functions (with 95% confidence intervals) to estimate the health impacts of modeled ozone reduction from the base case to the control scenario. We found that estimated avoided mortalities were not significantly different between 2, 4 and 12 km resolution runs, but 36 km resolution may over-predict some potential health impacts. Given the cost/benefit analysis requirements of the Clean Air Act, the uncertainty associated with human health impacts and therefore the results reported in this study, we conclude that health impacts calculated from population weighted ozone concentrations obtained using regional photochemical models at 36 km resolution fall within the range of values obtained using fine (12 km or finer) resolution modeling. However, in some cases, 36 km resolution may not be fine enough to statistically replicate the results achieved using 2 and 4 km resolution. On average, when modeling at 36 km resolution, 7 deaths per ozone month were avoided because of ozone reductions resulting from the proposed emissions reductions (95% confidence interval was 2-9). When modeling at 2, 4 or 12 km finer scale resolution, on average 5 deaths were avoided due to the same reductions (95% confidence interval was 2-7). Initial results for this specific region show that modeling at a resolution finer than 12 km is unlikely to improve uncertainty in benefits analysis. We suggest that 12 km resolution may be appropriate for uncertainty analyses in areas with similar chemistry, but that resolution requirements should be assessed on a case-by-case basis and revised as confidence intervals for concentration-response functions are updated.

Sublobar resection is equivalent to lobectomy for clinical stage 1A lung cancer in solid nodules.

PubMed

Altorki, Nasser K; Yip, Rowena; Hanaoka, Takaomi; Bauer, Thomas; Aye, Ralph; Kohman, Leslie; Sheppard, Barry; Thurer, Richard; Andaz, Shahriyour; Smith, Michael; Mayfield, William; Grannis, Fred; Korst, Robert; Pass, Harvey; Straznicka, Michaela; Flores, Raja; Henschke, Claudia I

2014-02-01

A single randomized trial established lobectomy as the standard of care for the surgical treatment of early-stage non-small cell lung cancer. Recent advances in imaging/staging modalities and detection of smaller tumors have once again rekindled interest in sublobar resection for early-stage disease. The objective of this study was to compare lung cancer survival in patients with non-small cell lung cancer with a diameter of 30 mm or less with clinical stage 1 disease who underwent lobectomy or sublobar resection. We identified 347 patients diagnosed with lung cancer who underwent lobectomy (n = 294) or sublobar resection (n = 53) for non-small cell lung cancer manifesting as a solid nodule in the International Early Lung Cancer Action Program from 1993 to 2011. Differences in the distribution of the presurgical covariates between sublobar resection and lobectomy were assessed using unadjusted P values determined by logistic regression analysis. Propensity scoring was performed using the same covariates. Differences in the distribution of the same covariates between sublobar resection and lobectomy were assessed using adjusted P values determined by logistic regression analysis with adjustment for the propensity scores. Lung cancer-specific survival was determined by the Kaplan-Meier method. Cox survival regression analysis was used to compare sublobar resection with lobectomy, adjusted for the propensity scores, surgical, and pathology findings, when adjusted and stratified by propensity quintiles. Among 347 patients, 10-year Kaplan-Meier for 53 patients treated by sublobar resection compared with 294 patients treated by lobectomy was 85% (95% confidence interval, 80-91) versus 86% (confidence interval, 75-96) (P = .86). Cox survival analysis showed no significant difference between sublobar resection and lobectomy when adjusted for propensity scores or when using propensity quintiles (P = .62 and P = .79, respectively). For those with cancers 20 mm or less in diameter, the 10-year rates were 88% (95% confidence interval, 82-93) versus 84% (95% confidence interval, 73-96) (P = .45), and Cox survival analysis showed no significant difference between sublobar resection and lobectomy using either approach (P = .42 and P = .52, respectively). Sublobar resection and lobectomy have equivalent survival for patients with clinical stage IA non-small cell lung cancer in the context of computed tomography screening for lung cancer. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Statistical procedures for determination and verification of minimum reporting levels for drinking water methods.

PubMed

Winslow, Stephen D; Pepich, Barry V; Martin, John J; Hallberg, George R; Munch, David J; Frebis, Christopher P; Hedrick, Elizabeth J; Krop, Richard A

2006-01-01

The United States Environmental Protection Agency's Office of Ground Water and Drinking Water has developed a single-laboratory quantitation procedure: the lowest concentration minimum reporting level (LCMRL). The LCMRL is the lowest true concentration for which future recovery is predicted to fall, with high confidence (99%), between 50% and 150%. The procedure takes into account precision and accuracy. Multiple concentration replicates are processed through the entire analytical method and the data are plotted as measured sample concentration (y-axis) versus true concentration (x-axis). If the data support an assumption of constant variance over the concentration range, an ordinary least-squares regression line is drawn; otherwise, a variance-weighted least-squares regression is used. Prediction interval lines of 99% confidence are drawn about the regression. At the points where the prediction interval lines intersect with data quality objective lines of 50% and 150% recovery, lines are dropped to the x-axis. The higher of the two values is the LCMRL. The LCMRL procedure is flexible because the data quality objectives (50-150%) and the prediction interval confidence (99%) can be varied to suit program needs. The LCMRL determination is performed during method development only. A simpler procedure for verification of data quality objectives at a given minimum reporting level (MRL) is also presented. The verification procedure requires a single set of seven samples taken through the entire method procedure. If the calculated prediction interval is contained within data quality recovery limits (50-150%), the laboratory performance at the MRL is verified.

Confidence intervals for predicting lumber strength properties based on ratios of percentiles from two Weibull populations.

Treesearch

Richard A. Johnson; James W. Evans; David W. Green

2003-01-01

Ratios of strength properties of lumber are commonly used to calculate property values for standards. Although originally proposed in terms of means, ratios are being applied without regard to position in the distribution. It is now known that lumber strength properties are generally not normally distributed. Therefore, nonparametric methods are often used to derive...

Methodical aspects of rearing decapod larvae, Pagurus bernhardus (Paguridae) and Carcinus maenas (Portunidae)

NASA Astrophysics Data System (ADS)

Dawirs, R. R.

1982-12-01

Improved methods for experimental rearing of Pagurus bernhardus and Carcinus maenas larvae are presented. Isolated maintenance was found essential for reliable statistical evaluation of results obtained from stages older than zoea-1. Only by isolated rearing is it possible to calculate mean values ±95% confidence intervals of stage duration. Mean values (without confidence intervals) can only be given for group-reared larvae if mortality is zero. Compared to group rearing, isolated rearing led to better survival, shorter periods of development and stimulated growth. Due to different swimming behavior P. bernhardus zoeae needed larger water volumes than Carcinus maenas larvae. P. bernhardus zoeae were reared with best results when isolated in Petri dishes (ca. 50 ml). They fed on newly hatched brine shrimp nauplii ( Artemia spp.). P. bernhardus megalopa did not require any gastropod shell or substratum; it developed best in glass vials without any food. C. maenas larvae could be reared most sucessfully in glass vials (ca 20 ml) under a simulated day-night regime (LD 16:8); constant darkness had a detrimental effect on development, leading to prolonged stage-duration times. C. maenas larvae were fed a mixture of newly hatched brine shrimp naupli and rotifers ( Brachionus plicatilis).

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.

After p Values: The New Statistics for Undergraduate Neuroscience Education.

PubMed

Calin-Jageman, Robert J

2017-01-01

Statistical inference is a methodological cornerstone for neuroscience education. For many years this has meant inculcating neuroscience majors into null hypothesis significance testing with p values. There is increasing concern, however, about the pervasive misuse of p values. It is time to start planning statistics curricula for neuroscience majors that replaces or de-emphasizes p values. One promising alternative approach is what Cumming has dubbed the "New Statistics", an approach that emphasizes effect sizes, confidence intervals, meta-analysis, and open science. I give an example of the New Statistics in action and describe some of the key benefits of adopting this approach in neuroscience education.

Analysis of routine histological evaluation of tissues removed during primary hip and knee arthroplasty.

PubMed

Lawrence, T; Moskal, J T; Diduch, D R

1999-07-01

It has often been hospital policy to send all resected specimens obtained during a total hip or knee arthroplasty for histological evaluation. This practice is expensive and may be unnecessary. We sought to determine the ability of surgeons to diagnose primary joint conditions correctly, and we attempted to identify any possible risks to the patient resulting from the omission of routine histological evaluation of specimens at the surgeon's discretion. Our objective was to ascertain whether routine histological evaluation could be safely omitted from the protocol for primary hip and knee arthroplasty without compromising the care of the patient. A total of 1388 consecutive arthroplasties in 1136 patients were identified from a database of primary total hip and knee arthroplasties that was prospectively maintained by the senior one of us. Follow-up data obtained at a mean of 5.5 years (range, two to ten years) were available after 92 percent (1273) of the 1388 arthroplasties. The preoperative diagnosis was determined from the history, findings on clinical examination, and radiographs. The intraoperative diagnosis was determined by gross inspection of joint fluid, articular cartilage, synovial tissue, and the cut surfaces of resected specimens. The combination of the preoperative and intraoperative diagnoses was considered to be the surgeon's clinical diagnosis. All resected specimens were sent for routine histological evaluation, and a pathological diagnosis was made. Attention was given to whether a discrepancy between the surgeon's clinical diagnosis and the pathological diagnosis altered the management of the patient. The original diagnoses were updated with use of annual radiographs and clinical assessments. The cost of histological examination of specimens obtained at arthroplasty was determined by consultation with hospital administration, accounting, and pathology department personnel. A pathological fracture or an impending fracture was diagnosed preoperatively and confirmed intraoperatively during twelve of the 1388 arthroplasties. Histological analysis demonstrated malignancy in specimens obtained during eleven of these arthroplasties and evidence of a benign rheumatoid geode in the specimen obtained during the twelfth arthroplasty. The preoperative and intraoperative diagnoses made before and during the remaining 1376 arthroplasties were benign conditions, which were confirmed histologically in all patients. No diagnosis changed during the follow-up period. As demonstrated by a comparison with the histological diagnosis, the surgeon's clinical diagnosis of malignancy had a sensitivity of 100 percent (95 percent confidence interval, 74.0 to 100 percent), a specificity of 99.9 percent (95 percent confidence interval, 99.6 to 100 percent), a positive predictive value of 91.7 percent (95 percent confidence interval, 64.6 to 98.5 percent), and a negative predictive value of 100 percent (95 percent confidence interval, 99.7 to 100 percent). There was a discrepancy between the preoperative and intraoperative diagnoses associated with eleven arthroplasties. All eleven intraoperative diagnoses were correct, as confirmed histologically. Excluding the patients who had a pathological or impending fracture, the accuracy of the surgeon's preoperative diagnosis was 99.2 percent (95 percent confidence interval, 98.6 to 99.5 percent). When the intraoperative and preoperative diagnoses were combined, the accuracy was 100 percent (95 percent confidence interval, 99.7 to 100 percent). Histological evaluation at our hospital resulted in total charges, including hospital costs and professional fees, of $196.27 and a mean total reimbursement of $102.59 per evaluation. In our series of 1136 patients with 1388 arthroplasties, these costs could have been eliminated for all but the twelve patients who had a suspected malignant lesion and the one patient in whom pigmented villonodular synovitis was found. (ABSTRACT

Aspirin for Evidence-Based Preeclampsia Prevention trial: effect of aspirin in prevention of preterm preeclampsia in subgroups of women according to their characteristics and medical and obstetrical history.

PubMed

Poon, Liona C; Wright, David; Rolnik, Daniel L; Syngelaki, Argyro; Delgado, Juan Luis; Tsokaki, Theodora; Leipold, Gergo; Akolekar, Ranjit; Shearing, Siobhan; De Stefani, Luciana; Jani, Jacques C; Plasencia, Walter; Evangelinakis, Nikolaos; Gonzalez-Vanegas, Otilia; Persico, Nicola; Nicolaides, Kypros H

2017-11-01

The Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Preeclampsia Prevention trial demonstrated that in women who were at high risk for preterm preeclampsia with delivery at <37 weeks' gestation identified by screening by means of an algorithm that combines maternal factors and biomarkers at 11-13 weeks' gestation, aspirin administration from 11 to 14 until 36 weeks' gestation was associated with a significant reduction in the incidence of preterm preeclampsia (odds ratio 0.38; 95% confidence interval, 0.20 to 0.74; P=0.004). We sought to examine whether there are differences in the effect of aspirin on the incidence of preterm preeclampsia in the Aspirin for Evidence-Based Preeclampsia Prevention trial in subgroups defined according to maternal characteristics and medical and obstetrical history. This was a secondary analysis of data from the Aspirin for Evidence-Based Preeclampsia Prevention trial. Subgroup analysis was performed to assess evidence of differences in the effect of aspirin on incidence of preterm preeclampsia in subgroups defined by maternal age (<30 and ≥30 years), body mass index (<25 and ≥25 kg/m 2 ), racial origin (Afro-Caribbean, Caucasian and other), method of conception (natural and assisted), cigarette smoking (smoker and non-smoker), family history of preterm preeclampsia (present and absent), obstetrical history (nulliparous, multiparous with previous preterm preeclampsia and multiparous without previous preterm preeclampsia), history of chronic hypertension (present and absent). Interaction tests were performed on the full data set of patients in the intention to treat population and on the data set of patients who took ≥ 90% of the prescribed medication. Results are presented as forest plot with P values for the interaction effects, group sizes, event counts and estimated odds ratios. We examined whether the test of interaction was significant at the 5% level with a Bonferroni adjustment for multiple comparisons. There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history. In participants with chronic hypertension preterm preeclampsia occurred in 10.2% (5/49) in the aspirin group and 8.2% (5/61) in the placebo group (adjusted odds ratio, 1.29; 95% confidence interval, 0.33-5.12). The respective values in those without chronic hypertension were 1.1% (8/749) in the aspirin group and 3.9% (30/761) in the placebo group (adjusted odds ratio, 0.27; 95% confidence interval, 0.12-0.60). In all participants with adherence of ≥90% the adjusted odds ratio in the aspirin group was 0.24 (95% confidence interval, 0.09-0.65); in the subgroup with chronic hypertension it was 2.06 (95% confidence interval, 0.40-10.71); and in those without chronic hypertension it was 0.05 (95% confidence interval, 0.01-0.41). For the complete data set the test of interaction was not significant at the 5% level (P = .055), but in those with adherence ≥90%, after adjustment for multiple comparisons, the interaction was significant at the 5% level (P = .0019). The beneficial effect of aspirin in the prevention of preterm preeclampsia may not apply in pregnancies with chronic hypertension. There was no evidence of heterogeneity in the aspirin effect in subgroups defined according to maternal characteristics and obstetrical history. Copyright © 2017 Elsevier Inc. All rights reserved.

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.

Lower Leg Injury Reference Values and Risk Curves from Survival Analysis for Male and Female Dummies: Meta-analysis of Postmortem Human Subject Tests.

PubMed

Yoganandan, Narayan; Arun, Mike W J; Pintar, Frank A; Banerjee, Anjishnu

2015-01-01

Derive lower leg injury risk functions using survival analysis and determine injury reference values (IRV) applicable to human mid-size male and small-size female anthropometries by conducting a meta-analysis of experimental data from different studies under axial impact loading to the foot-ankle-leg complex. Specimen-specific dynamic peak force, age, total body mass, and injury data were obtained from tests conducted by applying the external load to the dorsal surface of the foot of postmortem human subject (PMHS) foot-ankle-leg preparations. Calcaneus and/or tibia injuries, alone or in combination and with/without involvement of adjacent articular complexes, were included in the injury group. Injury and noninjury tests were included. Maximum axial loads recorded by a load cell attached to the proximal end of the preparation were used. Data were analyzed by treating force as the primary variable. Age was considered as the covariate. Data were censored based on the number of tests conducted on each specimen and whether it remained intact or sustained injury; that is, right, left, and interval censoring. The best fits from different distributions were based on the Akaike information criterion; mean and plus and minus 95% confidence intervals were obtained; and normalized confidence interval sizes (quality indices) were determined at 5, 10, 25, and 50% risk levels. The normalization was based on the mean curve. Using human-equivalent age as 45 years, data were normalized and risk curves were developed for the 50th and 5th percentile human size of the dummies. Out of the available 114 tests (76 fracture and 38 no injury) from 5 groups of experiments, survival analysis was carried out using 3 groups consisting of 62 tests (35 fracture and 27 no injury). Peak forces associated with 4 specific risk levels at 25, 45, and 65 years of age are given along with probability curves (mean and plus and minus 95% confidence intervals) for PMHS and normalized data applicable to male and female dummies. Quality indices increased (less tightness-of-fit) with decreasing age and risk level for all age groups and these data are given for all chosen risk levels. These PMHS-based probability distributions at different ages using information from different groups of researchers constituting the largest body of data can be used as human tolerances to lower leg injury from axial loading. Decreasing quality indices (increasing index value) at lower probabilities suggest the need for additional tests. The anthropometry-specific mid-size male and small-size female mean human risk curves along with plus and minus 95% confidence intervals from survival analysis and associated IRV data can be used as a first step in studies aimed at advancing occupant safety in automotive and other environments.

CI2 for creating and comparing confidence-intervals for time-series bivariate plots.

PubMed

Mullineaux, David R

2017-02-01

Currently no method exists for calculating and comparing the confidence-intervals (CI) for the time-series of a bivariate plot. The study's aim was to develop 'CI2' as a method to calculate the CI on time-series bivariate plots, and to identify if the CI between two bivariate time-series overlap. The test data were the knee and ankle angles from 10 healthy participants running on a motorised standard-treadmill and non-motorised curved-treadmill. For a recommended 10+ trials, CI2 involved calculating 95% confidence-ellipses at each time-point, then taking as the CI the points on the ellipses that were perpendicular to the direction vector between the means of two adjacent time-points. Consecutive pairs of CI created convex quadrilaterals, and any overlap of these quadrilaterals at the same time or ±1 frame as a time-lag calculated using cross-correlations, indicated where the two time-series differed. CI2 showed no group differences between left and right legs on both treadmills, but the same legs between treadmills for all participants showed differences of less knee extension on the curved-treadmill before heel-strike. To improve and standardise the use of CI2 it is recommended to remove outlier time-series, use 95% confidence-ellipses, and scale the ellipse by the fixed Chi-square value as opposed to the sample-size dependent F-value. For practical use, and to aid in standardisation or future development of CI2, Matlab code is provided. CI2 provides an effective method to quantify the CI of bivariate plots, and to explore the differences in CI between two bivariate time-series. Copyright © 2016 Elsevier B.V. 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.

Imputation for multisource data with comparison and assessment techniques

DOE PAGES

Casleton, Emily Michele; Osthus, David Allen; Van Buren, Kendra Lu

2017-12-27

Missing data are prevalent issue in analyses involving data collection. The problem of missing data is exacerbated for multisource analysis, where data from multiple sensors are combined to arrive at a single conclusion. In this scenario, it is more likely to occur and can lead to discarding a large amount of data collected; however, the information from observed sensors can be leveraged to estimate those values not observed. We propose two methods for imputation of multisource data, both of which take advantage of potential correlation between data from different sensors, through ridge regression and a state-space model. These methods, asmore » well as the common median imputation, are applied to data collected from a variety of sensors monitoring an experimental facility. Performance of imputation methods is compared with the mean absolute deviation; however, rather than using this metric to solely rank themethods,we also propose an approach to identify significant differences. Imputation techniqueswill also be assessed by their ability to produce appropriate confidence intervals, through coverage and length, around the imputed values. Finally, performance of imputed datasets is compared with a marginalized dataset through a weighted k-means clustering. In general, we found that imputation through a dynamic linearmodel tended to be the most accurate and to produce the most precise confidence intervals, and that imputing the missing values and down weighting them with respect to observed values in the analysis led to the most accurate performance.« less

Imputation for multisource data with comparison and assessment techniques

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

Casleton, Emily Michele; Osthus, David Allen; Van Buren, Kendra Lu

Missing data are prevalent issue in analyses involving data collection. The problem of missing data is exacerbated for multisource analysis, where data from multiple sensors are combined to arrive at a single conclusion. In this scenario, it is more likely to occur and can lead to discarding a large amount of data collected; however, the information from observed sensors can be leveraged to estimate those values not observed. We propose two methods for imputation of multisource data, both of which take advantage of potential correlation between data from different sensors, through ridge regression and a state-space model. These methods, asmore » well as the common median imputation, are applied to data collected from a variety of sensors monitoring an experimental facility. Performance of imputation methods is compared with the mean absolute deviation; however, rather than using this metric to solely rank themethods,we also propose an approach to identify significant differences. Imputation techniqueswill also be assessed by their ability to produce appropriate confidence intervals, through coverage and length, around the imputed values. Finally, performance of imputed datasets is compared with a marginalized dataset through a weighted k-means clustering. In general, we found that imputation through a dynamic linearmodel tended to be the most accurate and to produce the most precise confidence intervals, and that imputing the missing values and down weighting them with respect to observed values in the analysis led to the most accurate performance.« less

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

Lack of effect of oral cabotegravir on the pharmacokinetics of a levonorgestrel/ethinyl oestradiol‐containing oral contraceptive in healthy adult women

PubMed Central

Trezza, Christine; Ford, Susan L.; Gould, Elizabeth; Lou, Yu; Huang, Chuyun; Ritter, James M.; Buchanan, Ann M.; Spreen, William

2017-01-01

Aims This study aimed to investigate whether cabotegravir (CAB), an integrase inhibitor in development for treatment and prevention of human immunodeficiency virus‐1, influences the pharmacokinetics (PK) of a levonorgestrel (LNG) and ethinyl oestradiol (EO)–containing oral contraceptive (OC) in healthy women. Methods In this open‐label, fixed‐sequence crossover study, healthy female subjects received LNG 0.15 mg/EO 0.03 mg tablet once daily Days 1–10 alone and with oral CAB 30 mg once daily Days 11–21. At the end of each treatment period, subjects underwent predose sampling for concentrations of follicle‐stimulating hormone, luteinizing hormone, and progesterone and serial PK sampling for plasma LNG, EO, and CAB concentrations. Results Twenty women were enrolled, and 19 completed the study. One subject was withdrawn due to an adverse event unrelated to study medications. Geometric least squares mean ratios (90% confidence interval) of LNG + CAB vs. LNG alone for LNG area under the plasma concentration–time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.12 (1.07–1.18) and 1.05 (0.96–1.15), respectively. Geometric least squares mean ratio (90% confidence interval) of EO + CAB vs. EO alone for EO area under the plasma concentration–time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.02 (0.97–1.08) and 0.92 (0.83–1.03), respectively. Steady‐state CAB PK parameters were comparable to historical values. There was no apparent difference in mean luteinizing hormone, follicle‐stimulating hormone, and progesterone concentrations between periods. No clinically significant trends in laboratory values, vital signs, or electrocardiography values were observed. Conclusions Repeat doses of oral CAB had no significant effect on LNG/EO PK or pharmacodynamics, which supports CAB coadministration with LNG/EO OCs in clinical practice. PMID:28087972

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.

BRIDGING GAPS BETWEEN ZOO AND WILDLIFE MEDICINE: ESTABLISHING REFERENCE INTERVALS FOR FREE-RANGING AFRICAN LIONS (PANTHERA LEO).

PubMed

Broughton, Heather M; Govender, Danny; Shikwambana, Purvance; Chappell, Patrick; Jolles, Anna

2017-06-01

The International Species Information System has set forth an extensive database of reference intervals for zoologic species, allowing veterinarians and game park officials to distinguish normal health parameters from underlying disease processes in captive wildlife. However, several recent studies comparing reference values from captive and free-ranging animals have found significant variation between populations, necessitating the development of separate reference intervals in free-ranging wildlife to aid in the interpretation of health data. Thus, this study characterizes reference intervals for six biochemical analytes, eleven hematologic or immune parameters, and three hormones using samples from 219 free-ranging African lions ( Panthera leo ) captured in Kruger National Park, South Africa. Using the original sample population, exclusion criteria based on physical examination were applied to yield a final reference population of 52 clinically normal lions. Reference intervals were then generated via 90% confidence intervals on log-transformed data using parametric bootstrapping techniques. In addition to the generation of reference intervals, linear mixed-effect models and generalized linear mixed-effect models were used to model associations of each focal parameter with the following independent variables: age, sex, and body condition score. Age and sex were statistically significant drivers for changes in hepatic enzymes, renal values, hematologic parameters, and leptin, a hormone related to body fat stores. Body condition was positively correlated with changes in monocyte counts. Given the large variation in reference values taken from captive versus free-ranging lions, it is our hope that this study will serve as a baseline for future clinical evaluations and biomedical research targeting free-ranging African lions.

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.

Right ventricular function in heart failure with preserved ejection fraction: a community-based study.

PubMed

Mohammed, Selma F; Hussain, Imad; AbouEzzeddine, Omar F; Abou Ezzeddine, Omar F; Takahama, Hiroyuki; Kwon, Susan H; Forfia, Paul; Roger, Véronique L; Redfield, Margaret M

2014-12-23

The prevalence and clinical significance of right ventricular (RV) systolic dysfunction (RVD) in patients with heart failure and preserved ejection fraction (HFpEF) are not well characterized. Consecutive, prospectively identified HFpEF (Framingham HF criteria, ejection fraction ≥50%) patients (n=562) from Olmsted County, Minnesota, underwent echocardiography at HF diagnosis and follow-up for cause-specific mortality and HF hospitalization. RV function was categorized by tertiles of tricuspid annular plane systolic excursion and by semiquantitative (normal, mild RVD, or moderate to severe RVD) 2-dimensional assessment. Whether RVD was defined by semiquantitative assessment or tricuspid annular plane systolic excursion ≤15 mm, HFpEF patients with RVD were more likely to have atrial fibrillation, pacemakers, and chronic diuretic therapy. At echocardiography, patients with RVD had slightly lower left ventricular ejection fraction, worse diastolic dysfunction, lower blood pressure and cardiac output, higher pulmonary artery systolic pressure, and more severe RV enlargement and tricuspid valve regurgitation. After adjustment for age, sex, pulmonary artery systolic pressure, and comorbidities, the presence of any RVD by semiquantitative assessment was associated with higher all-cause (hazard ratio=1.35; 95% confidence interval, 1.03-1.77; P=0.03) and cardiovascular (hazard ratio=1.85; 95% confidence interval, 1.20-2.80; P=0.006) mortality and higher first (hazard ratio=1.99; 95% confidence interval, 1.35-2.90; P=0.0006) and multiple (hazard ratio=1.81; 95% confidence interval, 1.18-2.78; P=0.007) HF hospitalization rates. RVD defined by tricuspid annular plane systolic excursion values showed similar but weaker associations with mortality and HF hospitalizations. In the community, RVD is common in HFpEF patients, is associated with clinical and echocardiographic evidence of more advanced HF, and is predictive of poorer outcomes. © 2014 American Heart Association, Inc.

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

PubMed

Cochrane, Shannon K; Chen, Shyh-Huei; Fitzgerald, Jodi D; Dodson, John A; Fielding, Roger A; King, Abby C; McDermott, Mary M; Manini, Todd M; Marsh, Anthony P; Newman, Anne B; Pahor, Marco; Tudor-Locke, Catrine; Ambrosius, Walter T; Buford, Thomas W

2017-12-02

Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P =0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [ P =0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [ P =0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [ P =0.002]) were significantly associated with lower cardiovascular event rates. Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Circulating endothelial progenitor cells and cardiovascular outcomes.

PubMed

Werner, Nikos; Kosiol, Sonja; Schiegl, Tobias; Ahlers, Patrick; Walenta, Katrin; Link, Andreas; Böhm, Michael; Nickenig, Georg

2005-09-08

Endothelial progenitor cells derived from bone marrow are believed to support the integrity of the vascular endothelium. The number and function of endothelial progenitor cells correlate inversely with cardiovascular risk factors, but the prognostic value associated with circulating endothelial progenitor cells has not been defined. The number of endothelial progenitor cells positive for CD34 and kinase insert domain receptor (KDR) was determined with the use of flow cytometry in 519 patients with coronary artery disease as confirmed on angiography. After 12 months, we evaluated the association between baseline levels of endothelial progenitor cells and death from cardiovascular causes, the occurrence of a first major cardiovascular event (myocardial infarction, hospitalization, revascularization, or death from cardiovascular causes), revascularization, hospitalization, and death from all causes. A total of 43 participants died, 23 from cardiovascular causes. A first major cardiovascular event occurred in 214 patients. The cumulative event-free survival rate increased stepwise across three increasing baseline levels of endothelial progenitor cells in an analysis of death from cardiovascular causes, a first major cardiovascular event, revascularization, and hospitalization. After adjustment for age, sex, vascular risk factors, and other relevant variables, increased levels of endothelial progenitor cells were associated with a reduced risk of death from cardiovascular causes (hazard ratio, 0.31; 95 percent confidence interval, 0.16 to 0.63; P=0.001), a first major cardiovascular event (hazard ratio, 0.74; 95 percent confidence interval, 0.62 to 0.89; P=0.002), revascularization (hazard ratio, 0.77; 95 percent confidence interval, 0.62 to 0.95; P=0.02), and hospitalization (hazard ratio, 0.76; 95 percent confidence interval, 0.63 to 0.94; P=0.01). Endothelial progenitor-cell levels were not predictive of myocardial infarction or of death from all causes. The level of circulating CD34+KDR+ endothelial progenitor cells predicts the occurrence of cardiovascular events and death from cardiovascular causes and may help to identify patients at increased cardiovascular risk. Copyright 2005 Massachusetts Medical Society.

Study of FibroTest and hyaluronic acid biological variation in healthy volunteers and comparison of serum hyaluronic acid biological variation between chronic liver diseases of different etiology and fibrotic stage using confidence intervals.

PubMed

Istaces, Nicolas; Gulbis, Béatrice

2015-07-01

Personalized ranges of liver fibrosis serum biomarkers such as FibroTest or hyaluronic acid could be used for early detection of fibrotic changes in patients with progressive chronic liver disease. Our aim was to generate reliable biological variation estimates for these two biomarkers with confidence intervals for within-subject biological variation and reference change value. Nine fasting healthy volunteers and 66 chronic liver disease patients were included. Biological variation estimates were calculated for FibroTest in healthy volunteers, and for hyaluronic acid in healthy volunteers and chronic liver disease patients stratified by etiology and liver fibrosis stage. In healthy volunteers, within-subject biological coefficient of variation (with 95% confidence intervals) and index of individuality were 20% (16%-28%) and 0.6 for FibroTest and 34% (27%-47%) and 0.79 for hyaluronic acid, respectively. Overall hyaluronic acid within-subject biological coefficient of variation was similar among non-alcoholic fatty liver disease and chronic hepatitis C with 41% (34%-52%) and 45% (39%-55%), respectively, in contrast to chronic hepatitis B with 170% (140%-215%). Hyaluronic acid within-subject biological coefficients of variation were similar between F0-F1, F2 and F3 liver fibrosis stages in non-alcoholic fatty liver disease with 34% (25%-49%), 41% (31%-59%) and 34% (23%-62%), respectively, and in chronic hepatitis C with 34% (27%-47%), 33% (26%-45%) and 38% (27%-65%), respectively. However, corresponding hyaluronic acid indexes of individuality were lower in the higher fibrosis stages. Non-overlapping confidence intervals of biological variation estimates allowed us to detect significant differences regarding hyaluronic acid biological variation between chronic liver disease subgroups. Copyright © 2015 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Risk score to predict hospital-acquired pneumonia after spontaneous intracerebral hemorrhage.

PubMed

Ji, Ruijun; Shen, Haipeng; Pan, Yuesong; Du, Wanliang; Wang, Penglian; Liu, Gaifen; Wang, Yilong; Li, Hao; Zhao, Xingquan; Wang, Yongjun

2014-09-01

We aimed to develop a risk score (intracerebral hemorrhage-associated pneumonia score, ICH-APS) for predicting hospital-acquired stroke-associated pneumonia (SAP) after ICH. The ICH-APS was developed based on the China National Stroke Registry (CNSR), in which eligible patients were randomly divided into derivation (60%) and validation (40%) cohorts. Variables routinely collected at presentation were used for predicting SAP after ICH. For testing the added value of hematoma volume measure, we separately developed 2 models with (ICH-APS-B) and without (ICH-APS-A) hematoma volume included. Multivariable logistic regression was performed to identify independent predictors. The area under the receiver operating characteristic curve (AUROC), Hosmer-Lemeshow goodness-of-fit test, and integrated discrimination index were used to assess model discrimination, calibration, and reclassification, respectively. The SAP was 16.4% and 17.7% in the overall derivation (n=2998) and validation (n=2000) cohorts, respectively. A 23-point ICH-APS-A was developed based on a set of predictors and showed good discrimination in the overall derivation (AUROC, 0.75; 95% confidence interval, 0.72-0.77) and validation (AUROC, 0.76; 95% confidence interval, 0.71-0.79) cohorts. The ICH-APS-A was more sensitive for patients with length of stay >48 hours (AUROC, 0.78; 95% confidence interval, 0.75-0.81) than those with length of stay <48 hours (AUROC, 0.64; 95% confidence interval, 0.55-0.73). The ICH-APS-A was well calibrated (Hosmer-Lemeshow test) in the derivation (P=0.20) and validation (P=0.66) cohorts. Similarly, a 26-point ICH-APS-B was established. The ICH-APS-A and ICH-APS-B were not significantly different in discrimination and reclassification for SAP after ICH. The ICH-APSs are valid risk scores for predicting SAP after ICH, especially for patients with length of stay >48 hours. © 2014 American Heart Association, Inc.

Is use of homeopathy associated with poor prescribing in English primary care? A cross-sectional study.

PubMed

Walker, Alex J; Croker, Richard; Bacon, Seb; Ernst, Edzard; Curtis, Helen J; Goldacre, Ben

2018-05-01

Objectives Prescribing of homeopathy still occurs in a small minority of English general practices. We hypothesised that practices that prescribe any homeopathic preparations might differ in their prescribing of other drugs. Design Cross-sectional analysis. Setting English primary care. Participants English general practices. Main outcome measures We identified practices that made any homeopathy prescriptions over six months of data. We measured associations with four prescribing and two practice quality indicators using multivariable logistic regression. Results Only 8.5% of practices (644) prescribed homeopathy between December 2016 and May 2017. Practices in the worst-scoring quartile for a composite measure of prescribing quality (>51.4 mean percentile) were 2.1 times more likely to prescribe homeopathy than those in the best category (<40.3) (95% confidence interval: 1.6-2.8). Aggregate savings from the subset of these measures where a cost saving could be calculated were also strongly associated (highest vs. lowest quartile multivariable odds ratio: 2.9, confidence interval: 2.1-4.1). Of practices spending the most on medicines identified as 'low value' by NHS England, 12.8% prescribed homeopathy, compared to 3.9% for lowest spenders (multivariable odds ratio: 2.6, confidence interval: 1.9-3.6). Of practices in the worst category for aggregated price-per-unit cost savings, 12.7% prescribed homeopathy, compared to 3.5% in the best category (multivariable odds ratio: 2.7, confidence interval: 1.9-3.9). Practice quality outcomes framework scores and patient recommendation rates were not associated with prescribing homeopathy (odds ratio range: 0.9-1.2). Conclusions Even infrequent homeopathy prescribing is strongly associated with poor performance on a range of prescribing quality measures, but not with overall patient recommendation or quality outcomes framework score. The association is unlikely to be a direct causal relationship, but may reflect underlying practice features, such as the extent of respect for evidence-based practice, or poorer stewardship of the prescribing budget.

Presence of Late Gadolinium Enhancement by Cardiac Magnetic Resonance Among Patients With Suspected Cardiac Sarcoidosis Is Associated With Adverse Cardiovascular Prognosis: A Systematic Review and Meta-Analysis.

PubMed

Hulten, Edward; Agarwal, Vikram; Cahill, Michael; Cole, Geoff; Vita, Tomas; Parrish, Scott; Bittencourt, Marcio Sommer; Murthy, Venkatesh L; Kwong, Raymond; Di Carli, Marcelo F; Blankstein, Ron

2016-09-01

Individuals with cardiac sarcoidosis have an increased risk of ventricular arrhythmia and death. Several small cohort studies have evaluated the ability of late gadolinium enhancement (LGE) by cardiac magnetic resonance imaging (MRI) to predict adverse cardiovascular events. However, studies have yielded inconsistent results, and some analyses were underpowered. Therefore, we sought to systematically review and perform meta-analysis of the prognostic value of cardiac MRI for patients with known or suspected cardiac sarcoidosis. We systematically searched for cohort studies of patients with known sarcoidosis with suspected cardiac involvement who underwent cardiac MRI with LGE with at least 12 months of either prospective or retrospective follow-up data regarding post-MRI adverse cardiovascular outcomes. We identified 7 studies of 694 subjects (mean age 53; 42% men).One hundred and ninety-nine patients (29%) were LGE positive. All-cause mortality occurred in 19 LGE-positive versus 17 LGE-negative subjects (annualized incidence, 3.1% versus 0.6%). The pooled relative risk was 3.38 (95% confidence interval, 1.07-10.7; P=0.04). Cardiovascular mortality occurred in 10 LGE-positive versus 2 LGE-negative subjects (annualized incidence, 1.9% versus 0.3%; relative risk 10.7 [95% confidence interval, 1.34-86.3]; P=0.03). Ventricular arrhythmia occurred in 41 LGE-positive versus 0 LGE-negative subjects (annualized incidence, 5.9% versus 0%; relative risk 19.5 [95% confidence interval, 2.68-143]; P=0.003). A combined end point of death or ventricular arrhythmia occurred in 64 LGE-positive versus 18 LGE-negative subjects (annualized incidence, 8.8% versus 0.6%; relative risk 6.20 [95% confidence interval, 2.47-15.6]; P<0.001). There was no significant heterogeneity for any outcomes. LGE is associated with future cardiovascular death and ventricular arrhythmia among patients referred to MRI for known or suspected cardiac sarcoidosis. © 2016 American Heart Association, Inc.

Contact-Free Screening of Atrial Fibrillation by a Smartphone Using Facial Pulsatile Photoplethysmographic Signals.

PubMed

Yan, Bryan P; Lai, William H S; Chan, Christy K Y; Chan, Stephen Chun-Hin; Chan, Lok-Hei; Lam, Ka-Ming; Lau, Ho-Wang; Ng, Chak-Ming; Tai, Lok-Yin; Yip, Kin-Wai; To, Olivia T L; Freedman, Ben; Poh, Yukkee C; Poh, Ming-Zher

2018-04-05

We aimed to evaluate a novel method of atrial fibrillation (AF) screening using an iPhone camera to detect and analyze photoplethysmographic signals from the face without physical contact by extracting subtle beat-to-beat variations of skin color that reflect the cardiac pulsatile signal. Patients admitted to the cardiology ward of the hospital for clinical reasons were recruited. Simultaneous facial and fingertip photoplethysmographic measurements were obtained from 217 hospital inpatients (mean age, 70.3±13.9 years; 71.4% men) facing the front camera and with an index finger covering the back camera of 2 independent iPhones before a 12-lead ECG was recorded. Backdrop and background light intensity was monitored during signal acquisition. Three successive 20-second (total, 60 seconds) recordings were acquired per patient and analyzed for heart rate regularity by Cardiio Rhythm (Cardiio Inc, Cambridge, MA) smartphone application. Pulse irregularity in ≥1 photoplethysmographic readings or 3 uninterpretable photoplethysmographic readings were considered a positive AF screening result. AF was present on 12-lead ECG in 34.6% (n=75/217) patients. The Cardiio Rhythm facial photoplethysmographic application demonstrated high sensitivity (95%; 95% confidence interval, 87%-98%) and specificity (96%; 95% confidence interval, 91%-98%) in discriminating AF from sinus rhythm compared with 12-lead ECG. The positive and negative predictive values were 92% (95% confidence interval, 84%-96%) and 97% (95% confidence interval, 93%-99%), respectively. Detection of a facial photoplethysmographic signal to determine pulse irregularity attributable to AF is feasible. The Cardiio Rhythm smartphone application showed high sensitivity and specificity, with low negative likelihood ratio for AF from facial photoplethysmographic signals. The convenience of a contact-free approach is attractive for community screening and has the potential to be useful for distant AF screening. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Higher insulin sensitivity in vegans is not associated with higher mitochondrial density.

PubMed

Gojda, J; Patková, J; Jaček, M; Potočková, J; Trnka, J; Kraml, P; Anděl, M

2013-12-01

Vegans have a lower incidence of insulin resistance (IR)-associated diseases and a higher insulin sensitivity (IS) compared with omnivores. The aim of this study was to examine whether the higher IS in vegans relates to markers of mitochondrial biogenesis and to intramyocellular lipid (IMCL) content. Eleven vegans and 10 matched (race, age, sex, body mass index, physical activity and energy intake) omnivorous controls were enrolled in a case-control study. Anthropometry, bioimpedance (BIA), ultrasound measurement of visceral and subcutaneous fat layer, parameters of glucose and lipid homeostasis, hyperinsulinemic euglycemic clamp and muscle biopsies were performed. Citrate synthase (CS) activity, mitochondrial DNA (mtDNA) and IMCL content were assessed in skeletal muscle samples. Both groups were comparable in anthropometric and BIA parameters, physical activity and protein-energy intake. Vegans had significantly higher glucose disposal (M-value, vegans 8.11±1.51 vs controls 6.31±1.57 mg/kg/min, 95% confidence interval: 0.402 to 3.212, P=0.014), slightly lower IMCL content (vegans 13.91 (7.8 to 44.0) vs controls 17.36 (12.4 to 78.5) mg/g of muscle, 95% confidence interval: -7.594 to 24.550, P=0.193) and slightly higher relative muscle mtDNA amount (vegans 1.36±0.31 vs controls 1.13±0.36, 95% confidence interval:-0.078 to 0.537, P=0.135). No significant differences were found in CS activity (vegans 18.43±5.05 vs controls 18.16±5.41 μmol/g/min, 95% confidence interval: -4.503 to 5.050, P=0.906). Vegans have a higher IS, but comparable mitochondrial density and IMCL content with omnivores. This suggests that a decrease in whole-body glucose disposal may precede muscle lipid accumulation and mitochondrial dysfunction in IR development.

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.

Real-Time Optical Biopsy of Colon Polyps With Narrow Band Imaging in Community Practice Does Not Yet Meet Key Thresholds for Clinical Decisions

PubMed Central

LADABAUM, URI; FIORITTO, ANN; MITANI, AYA; DESAI, MANISHA; KIM, JANE P.; REX, DOUGLAS K.; IMPERIALE, THOMAS; GUNARATNAM, NARESH

2017-01-01

BACKGROUND & AIMS Accurate optical analysis of colorectal polyps (optical biopsy) could prevent unnecessary polypectomies or allow a “resect and discard” strategy with surveillance intervals determined based on the results of the optical biopsy; this could be less expensive than histopathologic analysis of polyps. We prospectively evaluated real-time optical biopsy analysis of polyps with narrow band imaging (NBI) by community-based gastroenterologists. METHODS We first analyzed a computerized module to train gastroenterologists (N = 13) in optical biopsy skills using photographs of polyps. Then we evaluated a practice-based learning program for these gastroenterologists (n = 12) that included real-time optical analysis of polyps in vivo, comparison of optical biopsy predictions to histopathologic analysis, and ongoing feedback on performance. RESULTS Twelve of 13 subjects identified adenomas with >90% accuracy at the end of the computer study, and 3 of 12 subjects did so with accuracy ≥90% in the in vivo study. Learning curves showed considerable variation among batches of polyps. For diminutive rectosigmoid polyps assessed with high confidence at the end of the study, adenomas were identified with mean (95% confidence interval [CI]) accuracy, sensitivity, specificity, and negative predictive values of 81% (73%–89%), 85% (74%–96%), 78% (66%–92%), and 91% (86%–97%), respectively. The adjusted odds ratio for high confidence as a predictor of accuracy was 1.8 (95% CI, 1.3–2.5). The agreement between surveillance recommendations informed by high-confidence NBI analysis of diminutive polyps and results from histopathologic analysis of all polyps was 80% (95% CI, 77%–82%). CONCLUSIONS In an evaluation of real-time optical biopsy analysis of polyps with NBI, only 25% of gastroenterologists assessed polyps with ≥90% accuracy. The negative predictive value for identification of adenomas, but not the surveillance interval agreement, met the American Society for Gastrointestinal Endoscopy–recommended thresholds for optical biopsy. Better results in community practice must be achieved before NBI-based optical biopsy methods can be used routinely to evaluate polyps; ClinicalTrials.gov number, NCT01638091. PMID:23041328

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

A thorough QT study to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine and escitalopram, in healthy volunteers.

PubMed

Kim, Anhye; Lim, Kyoung Soo; Lee, Howard; Chung, Hyewon; Yoon, Seo Hyun; Yu, Kyung-Sang; Cho, Joo-Youn; Jang, In-Jin; Chung, Jae-Yong

2016-07-01

Prolongation of the QT interval on an ECG is a surrogate marker for predicting the proarrhythmic potential of a drug under development. The aim of this study was to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine immediate release (IR) and escitalopram, in healthy individuals. This was a randomized, open-label, 4×4 Williams crossover study, with four single-dose treatments [placebo, 400 mg moxifloxacin (positive control), 20 mg escitalopram, and 100 mg quetiapine IR], conducted in 40 healthy volunteers. Serial blood samples for pharmacokinetics and ECG were collected. Individually, RR-corrected QTc intervals (QTcI) and placebo-adjusted changes from baseline values of QTcI (ΔΔQTcI) were evaluated. Lower-bound values of the one-sided 95% confidence interval for ΔΔQTcI of moxifloxacin with more than 5 ms confirmed the sensitivity of the assay. The maximum upper bound 95% confidence interval for the ΔΔQTcI of quetiapine IR and escitalopram was 13.7 and 10.5 ms, with mean estimates of 10.2 and 6.9 ms, respectively. Peak effects of moxifloxacin and quetiapine IR on ΔΔQTcI were observed at approximately time to maximum concentration (Tmax), whereas that of escitalopram was observed 3 h after Tmax. The concentration-ΔΔQTcI relationships of quetiapine IR and escitalopram were relatively flat, as compared with that of moxifloxacin. The results demonstrated the validity of trial methodology and that quetiapine IR and escitalopram caused QT prolongation in healthy individuals. In addition, hysteresis of escitalopram-induced QTc prolongation. These results indicate that higher doses of these drugs could lead to greater QT prolongation in a dose-response manner.

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 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...

Percentage of Positive Biopsy Cores: A Better Risk Stratification Model for Prostate Cancer?

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

Huang Jiayi; Vicini, Frank A.; Williams, Scott G.

2012-07-15

Purpose: To assess the prognostic value of the percentage of positive biopsy cores (PPC) and perineural invasion in predicting the clinical outcomes after radiotherapy (RT) for prostate cancer and to explore the possibilities to improve on existing risk-stratification models. Methods and Materials: Between 1993 and 2004, 1,056 patients with clinical Stage T1c-T3N0M0 prostate cancer, who had four or more biopsy cores sampled and complete biopsy core data available, were treated with external beam RT, with or without a high-dose-rate brachytherapy boost at William Beaumont Hospital. The median follow-up was 7.6 years. Multivariate Cox regression analysis was performed with PPC, Gleasonmore » score, pretreatment prostate-specific antigen, T stage, PNI, radiation dose, androgen deprivation, age, prostate-specific antigen frequency, and follow-up duration. A new risk stratification (PPC classification) was empirically devised to incorporate PPC and replace the T stage. Results: On multivariate Cox regression analysis, the PPC was an independent predictor of distant metastasis, cause-specific survival, and overall survival (all p < .05). A PPC >50% was associated with significantly greater distant metastasis (hazard ratio, 4.01; 95% confidence interval, 1.86-8.61), and its independent predictive value remained significant with or without androgen deprivation therapy (all p < .05). In contrast, PNI and T stage were only predictive for locoregional recurrence. Combining the PPC ({<=}50% vs. >50%) with National Comprehensive Cancer Network risk stratification demonstrated added prognostic value of distant metastasis for the intermediate-risk (hazard ratio, 5.44; 95% confidence interval, 1.78-16.6) and high-risk (hazard ratio, 4.39; 95% confidence interval, 1.70-11.3) groups, regardless of the use of androgen deprivation and high-dose RT (all p < .05). The proposed PPC classification appears to provide improved stratification of the clinical outcomes relative to the National Comprehensive Cancer Network classification. Conclusions: The PPC is an independent and powerful predictor of clinical outcomes of prostate cancer after RT. A risk model replacing T stage with the PPC to reduce subjectivity demonstrated potentially improved stratification.« less

PGS-FISH in reproductive medicine and perspective directions for improvement: a systematic review.

PubMed

Zamora, Sandra; Clavero, Ana; Gonzalvo, M Carmen; de Dios Luna Del Castillo, Juan; Roldán-Nofuentes, Jose Antonio; Mozas, Juan; Castilla, Jose Antonio

2011-08-01

Embryo selection can be carried out via morphological criteria or by using genetic studies based on Preimplantation Genetic Screening. In the present study, we evaluate the clinical validity of Preimplantation Genetic Screening with fluorescence in situ hybridization (PGS-FISH) compared with morphological embryo criteria. A systematic review was made of the bibliography, with the following goals: firstly, to determine the prevalence of embryo chromosome alteration in clinical situations in which the PGS-FISH technique has been used; secondly, to calculate the statistics of diagnostic efficiency (negative Likelihood Ratio), using 2 × 2 tables, derived from PGS-FISH. The results obtained were compared with those obtained from embryo morphology. We calculated the probability of transferring at least one chromosome-normal embryo when it was selected using either morphological criteria or PGS-FISH, and considered what diagnostic performance should be expected of an embryo selection test with respect to achieving greater clinical validity than that obtained from embryo morphology. After an embryo morphology selection that produced a negative result (normal morphology), the likelihood of embryo aneuploidies was found to range from a pre-test value of 65% (prevalence of embryo chromosome alteration registered in all the study groups) to a post-test value of 55% (Confidence interval: 50-61), while after PGS-FISH with a negative result (euploid), the post-test probability was 42% (Confidence interval: 35-49) (p < 0.05). The probability of transferring at least one euploid embryo was the same whether 3 embryos were selected according to morphological criteria or whether 2, selected by PGS-FISH, were transferred. Any embryo selection test, if it is to provide greater clinical validity than embryo morphology, must present a LR-value of 0.40 (Confidence interval: 0.32-0.51) in single embryo transfer, and 0.06 (CI: 0.05-0.07) in double embryo transfer. With currently available technology, and taking into account the number of embryos to be transferred, the clinical validity of PGS-FISH, although superior to that of morphological criteria, does not appear to be clinically relevant.

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…

A Test by Any Other Name: P Values, Bayes Factors, and Statistical Inference.

PubMed

Stern, Hal S

2016-01-01

Procedures used for statistical inference are receiving increased scrutiny as the scientific community studies the factors associated with insuring reproducible research. This note addresses recent negative attention directed at p values, the relationship of confidence intervals and tests, and the role of Bayesian inference and Bayes factors, with an eye toward better understanding these different strategies for statistical inference. We argue that researchers and data analysts too often resort to binary decisions (e.g., whether to reject or accept the null hypothesis) in settings where this may not be required.

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.

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.

Assessing Mediational Models: Testing and Interval Estimation for Indirect Effects.

PubMed

Biesanz, Jeremy C; Falk, Carl F; Savalei, Victoria

2010-08-06

Theoretical models specifying indirect or mediated effects are common in the social sciences. An indirect effect exists when an independent variable's influence on the dependent variable is mediated through an intervening variable. Classic approaches to assessing such mediational hypotheses ( Baron & Kenny, 1986 ; Sobel, 1982 ) have in recent years been supplemented by computationally intensive methods such as bootstrapping, the distribution of the product methods, and hierarchical Bayesian Markov chain Monte Carlo (MCMC) methods. These different approaches for assessing mediation are illustrated using data from Dunn, Biesanz, Human, and Finn (2007). However, little is known about how these methods perform relative to each other, particularly in more challenging situations, such as with data that are incomplete and/or nonnormal. This article presents an extensive Monte Carlo simulation evaluating a host of approaches for assessing mediation. We examine Type I error rates, power, and coverage. We study normal and nonnormal data as well as complete and incomplete data. In addition, we adapt a method, recently proposed in statistical literature, that does not rely on confidence intervals (CIs) to test the null hypothesis of no indirect effect. The results suggest that the new inferential method-the partial posterior p value-slightly outperforms existing ones in terms of maintaining Type I error rates while maximizing power, especially with incomplete data. Among confidence interval approaches, the bias-corrected accelerated (BC a ) bootstrapping approach often has inflated Type I error rates and inconsistent coverage and is not recommended; In contrast, the bootstrapped percentile confidence interval and the hierarchical Bayesian MCMC method perform best overall, maintaining Type I error rates, exhibiting reasonable power, and producing stable and accurate coverage rates.

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.

Predictors of neonatal outcome in women with severe preeclampsia or eclampsia between 24 and 33 weeks' gestation.

PubMed

Witlin, A G; Saade, G R; Mattar, F; Sibai, B M

2000-03-01

We sought to characterize predictors of neonatal outcome in women with severe preeclampsia or eclampsia who were delivered of their infants preterm. We performed a retrospective analysis of 195 pregnancies delivered between 24 and 33 weeks' gestation because of severe preeclampsia or eclampsia. Multiple logistic regression and univariate chi(2) analysis were performed for the dependent outcome variables of survival and respiratory distress syndrome by use of independent fetal and maternal variables. A P value of <.05 was considered significant. In the multivariate analysis, respiratory distress syndrome was inversely related to gestational age at delivery (P =.0018) and directly related to cesarean delivery (P =.02), whereas survival was directly related to birth weight (P =.00025). There was no correlation in the multivariate analysis between respiratory distress syndrome or survival and corticosteroid use, composite neonatal morbidity, mean arterial pressure, eclampsia, or abruptio placentae. In the univariate analysis respiratory distress syndrome was associated with cesarean delivery (odds ratio, 7.19; 95% confidence interval, 2. 91-18.32). The incidence of intrauterine growth restriction increased as gestational age advanced. Furthermore, intrauterine growth restriction decreased survival in both the multivariate (P =. 038; odds ratio, 13.2; 95% confidence interval, 1.16-151.8) and univariate (P =.001; odds ratio, 5.88; 95% confidence interval, 1. 81-19.26) analyses. The presence of intrauterine growth restriction adversely affected survival independently of other variables. Presumed intrauterine stress, as reflected by the severity of maternal disease, did not improve neonatal outcome.

Relationship between chewing ability and sarcopenia in Japanese community-dwelling older adults.

PubMed

Murakami, Masaharu; Hirano, Hirohiko; Watanabe, Yutaka; Sakai, Katsuhiko; Kim, Hunkyoung; Katakura, Akira

2015-08-01

It has been reported that if nutrient intake is unbalanced, muscle mass, muscle strength and physical performance declines, and therefore it is important to maintain chewing ability to keep a balanced nutrient intake. However, the relationship between chewing ability and sarcopenia has not been previously reported. Therefore, the present study investigated the relationship between chewing ability and sarcopenia in addition to known sarcopenia-related factors. We examined 761 participants (average age 73.0 ± 5.1 years), who lived in the Itabashi city of Tokyo. Our research was designed to examine the relationship between chewing ability and sarcopenia. We carried out regression analysis to analyze the relationship with sarcopenia-related factors with consideration of the age of the participants. The 761 participants were divided into two groups in terms of the stage of sarcopenia according to whether there was a deterioration of muscle strength or physical performance. Furthermore, we carried out logistic regression analyses on the value as a dependent variable, including known sarcopenia-related factors. There were significant correlations of sarcopenia with age (odds ratio 2.37, 95% confidence interval 1.52-3.70), body mass index (odds ratio 0.75, 95% confidence interval 0.69-0.81) and chewing ability (odds ratio 2.18, 95% confidence interval 1.21-3.93). The present study shows that chewing ability is related to sarcopenia, which is equal to the relationship with the known factor of age by odds ratio. © 2014 Japan Geriatrics Society.

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.

Characterization and Uncertainty Analysis of a Reference Pressure Measurement System for Wind Tunnels

NASA Technical Reports Server (NTRS)

Amer, Tahani; Tripp, John; Tcheng, Ping; Burkett, Cecil; Sealey, Bradley

2004-01-01

This paper presents the calibration results and uncertainty analysis of a high-precision reference pressure measurement system currently used in wind tunnels at the NASA Langley Research Center (LaRC). Sensors, calibration standards, and measurement instruments are subject to errors due to aging, drift with time, environment effects, transportation, the mathematical model, the calibration experimental design, and other factors. Errors occur at every link in the chain of measurements and data reduction from the sensor to the final computed results. At each link of the chain, bias and precision uncertainties must be separately estimated for facility use, and are combined to produce overall calibration and prediction confidence intervals for the instrument, typically at a 95% confidence level. The uncertainty analysis and calibration experimental designs used herein, based on techniques developed at LaRC, employ replicated experimental designs for efficiency, separate estimation of bias and precision uncertainties, and detection of significant parameter drift with time. Final results, including calibration confidence intervals and prediction intervals given as functions of the applied inputs, not as a fixed percentage of the full-scale value are presented. System uncertainties are propagated beginning with the initial reference pressure standard, to the calibrated instrument as a working standard in the facility. Among the several parameters that can affect the overall results are operating temperature, atmospheric pressure, humidity, and facility vibration. Effects of factors such as initial zeroing and temperature are investigated. The effects of the identified parameters on system performance and accuracy are discussed.

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.

Modified Dempster-Shafer approach using an expected utility interval decision rule

NASA Astrophysics Data System (ADS)

Cheaito, Ali; Lecours, Michael; Bosse, Eloi

1999-03-01

The combination operation of the conventional Dempster- Shafer algorithm has a tendency to increase exponentially the number of propositions involved in bodies of evidence by creating new ones. The aim of this paper is to explore a 'modified Dempster-Shafer' approach of fusing identity declarations emanating form different sources which include a number of radars, IFF and ESM systems in order to limit the explosion of the number of propositions. We use a non-ad hoc decision rule based on the expected utility interval to select the most probable object in a comprehensive Platform Data Base containing all the possible identity values that a potential target may take. We study the effect of the redistribution of the confidence levels of the eliminated propositions which otherwise overload the real-time data fusion system; these eliminated confidence levels can in particular be assigned to ignorance, or uniformly added to the remaining propositions and to ignorance. A scenario has been selected to demonstrate the performance of our modified Dempster-Shafer method of evidential reasoning.

Can insertion length for a double-lumen endobronchial tube be predicted?

PubMed

Dyer, R A; Heijke, S A; Russell, W J; Bloch, M B; James, M F

2000-12-01

It has been suggested that the appropriate length of insertion for double-lumen tubes can be estimated by external measurement. This study examined the accuracy of external measurement in estimating the actual length of insertion required in 130 patients. It also examined the relationship between the length inserted and the patient's height in 126 patients and their weight in 125 patients. Although there was a fair correlation between the measured external length and the final inserted length (r = 0.61), the 95% confidence intervals of slope and intercept allowed a large variation and the prediction was too wide to be clinically useful. Height was reasonably well correlated with the final length (r = 0.51) but an equally wide 95% confidence interval rendered it of little clinical value. There was no correlation between weight and final tube length. It is concluded that external measurement alone is not adequate to predict a clinically acceptable position of the double-lumen tube.

Comparing interval estimates for small sample ordinal CFA models

PubMed Central

Natesan, Prathiba

2015-01-01

Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading. Therefore, editors and policymakers should continue to emphasize the inclusion of interval estimates in research. PMID:26579002

Comparing interval estimates for small sample ordinal CFA models.

PubMed

Natesan, Prathiba

2015-01-01

Robust maximum likelihood (RML) and asymptotically generalized least squares (AGLS) methods have been recommended for fitting ordinal structural equation models. Studies show that some of these methods underestimate standard errors. However, these studies have not investigated the coverage and bias of interval estimates. An estimate with a reasonable standard error could still be severely biased. This can only be known by systematically investigating the interval estimates. The present study compares Bayesian, RML, and AGLS interval estimates of factor correlations in ordinal confirmatory factor analysis models (CFA) for small sample data. Six sample sizes, 3 factor correlations, and 2 factor score distributions (multivariate normal and multivariate mildly skewed) were studied. Two Bayesian prior specifications, informative and relatively less informative were studied. Undercoverage of confidence intervals and underestimation of standard errors was common in non-Bayesian methods. Underestimated standard errors may lead to inflated Type-I error rates. Non-Bayesian intervals were more positive biased than negatively biased, that is, most intervals that did not contain the true value were greater than the true value. Some non-Bayesian methods had non-converging and inadmissible solutions for small samples and non-normal data. Bayesian empirical standard error estimates for informative and relatively less informative priors were closer to the average standard errors of the estimates. The coverage of Bayesian credibility intervals was closer to what was expected with overcoverage in a few cases. Although some Bayesian credibility intervals were wider, they reflected the nature of statistical uncertainty that comes with the data (e.g., small sample). Bayesian point estimates were also more accurate than non-Bayesian estimates. The results illustrate the importance of analyzing coverage and bias of interval estimates, and how ignoring interval estimates can be misleading. Therefore, editors and policymakers should continue to emphasize the inclusion of interval estimates in research.

Illness Identity: A Novel Predictor for Healthcare Use in Adults With Congenital Heart Disease.

PubMed

Van Bulck, Liesbet; Goossens, Eva; Luyckx, Koen; Oris, Leen; Apers, Silke; Moons, Philip

2018-05-22

To optimize healthcare use of adults with congenital heart disease, all important predictors of healthcare utilization should be identified. Clinical and psychological characteristics (eg, age and depression) have been found to be associated with healthcare use. However, the concept of illness identity, which assesses the degree to which congenital heart disease is integrated into one's identity, has not yet been investigated in association with healthcare use. Hence, the purpose of the study is to examine the predictive value of illness identity for healthcare use. In this ambispective analytical observational cohort study, 216 adults with congenital heart disease were included. The self-reported Illness Identity Questionnaire was used to assess illness identity states: engulfment, rejection, acceptance, and enrichment. After 1 year, self-reported healthcare use for congenital heart disease or other reasons over the past 6 months was assessed including hospitalizations; visits to general practitioner; visits to medical specialists; and emergency room visits. Binary logistic and negative binomial regression analyses were conducted, adjusting for age, sex, disease complexity, and depressive and anxious symptoms. The more profoundly the heart defect dominated one's identity (ie, engulfment), the more likely this person was to be hospitalized (odds ratio=3.76; 95% confidence interval=1.43-9.86), to visit a medical specialist (odds ratio=2.32; 95% confidence interval=1.35-4.00) or a general practitioner (odds ratio=1.78; 95% confidence interval=1.01-3.17), because of their heart defect. Illness identity, more specifically engulfment, has a unique predictive value for the occurrence of healthcare encounters. This association deserves further investigation, in which the directionality of effects and the contribution of illness identity in terms of preventing inappropriate healthcare use should be determined. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Blood Pressure Reduction and Secondary Stroke Prevention: A Systematic Review and Metaregression Analysis of Randomized Clinical Trials.

PubMed

Katsanos, Aristeidis H; Filippatou, Angeliki; Manios, Efstathios; Deftereos, Spyridon; Parissis, John; Frogoudaki, Alexandra; Vrettou, Agathi-Rosa; Ikonomidis, Ignatios; Pikilidou, Maria; Kargiotis, Odysseas; Voumvourakis, Konstantinos; Alexandrov, Anne W; Alexandrov, Andrei V; Tsivgoulis, Georgios

2017-01-01

Current recommendations do not specifically address the optimal blood pressure (BP) reduction for secondary stroke prevention in patients with previous cerebrovascular events. We conducted a systematic review and metaregression analysis on the association of BP reduction with recurrent stroke and cardiovascular events using data from randomized controlled clinical trials of secondary stroke prevention. For all reported events during each eligible study period, we calculated the corresponding risk ratios to express the comparison of event occurrence risk between patients randomized to antihypertensive treatment and those randomized to placebo. On the basis of the reported BP values, we performed univariate metaregression analyses according to the achieved BP values under the random-effects model (Method of Moments) for those adverse events reported in ≥10 total subgroups of included randomized controlled clinical trials. In pairwise meta-analyses, antihypertensive treatment lowered the risk for recurrent stroke (risk ratio, 0.73; 95% confidence interval, 0.62-0.87; P<0.001), disabling or fatal stroke (risk ratio, 0.71; 95% confidence interval, 0.59-0.85; P<0.001), and cardiovascular death (risk ratio, 0.85; 95% confidence interval, 0.75-0.96; P=0.01). In metaregression analyses, systolic BP reduction was linearly related to the lower risk of recurrent stroke (P=0.049), myocardial infarction (P=0.024), death from any cause (P=0.001), and cardiovascular death (P<0.001). Similarly, diastolic BP reduction was linearly related to a lower risk of recurrent stroke (P=0.026) and all-cause mortality (P=0.009). Funnel plot inspection and Egger statistical test revealed no evidence of publication bias. The extent of BP reduction is linearly associated with the magnitude of risk reduction in recurrent cerebrovascular and cardiovascular events. Strict and aggressive BP control seems to be essential for effective secondary stroke prevention. © 2016 American Heart Association, Inc.

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...

Prognostic Importance of Low Admission Serum Creatinine Concentration for Mortality in Hospitalized Patients.

PubMed

Thongprayoon, Charat; Cheungpasitporn, Wisit; Kittanamongkolchai, Wonngarm; Harrison, Andrew M; Kashani, Kianoush

2017-05-01

The study objective was to assess the association between low serum creatinine value at admission and in-hospital mortality in hospitalized patients. This was a retrospective single-center cohort study conducted at a tertiary referral hospital. All hospitalized adult patients between 2011 and 2013 who had an admission creatinine value available were identified for inclusion in this study. Admission creatinine value was categorized into 7 groups: ≤0.4, 0.5 to 0.6, 0.7 to 0.8, 0.9 to 1.0, 1.1 to 1.2, 1.3 to 1.4, and ≥1.5 mg/dL. The primary outcome was in-hospital mortality. Logistic regression analysis was performed to obtain the odds ratio of in-hospital mortality for the various admission creatinine levels, using a creatinine value of 0.7 to 0.8 mg/dL as the reference group in the analysis of all patients and female patients and of 0.9 to 1.0 mg/dL in the analysis of male patients because it was associated with the lowest in-hospital mortality. Of 73,994 included patients, 973 (1.3%) died in the hospital. The association between different categories of admission creatinine value and in-hospital mortality assumed a U-shaped distribution, with both low and high creatinine values associated with higher in-hospital mortality. After adjustment for age, sex, ethnicity, principal diagnosis, and comorbid conditions, very low creatinine value (≤0.4 mg/dL) was significantly associated with increased mortality (odds ratio, 3.29; 95% confidence interval, 2.08-5.00), exceeding the risk related to a markedly increased creatinine value of ≥1.5 mg/dL (odds ratio, 2.56; 95% confidence interval, 2.07-3.17). The association remained significant in the subgroup analysis of male and female patients. Low creatinine value at admission is independently associated with increased in-hospital mortality in hospitalized patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Laharz_py: GIS tools for automated mapping of lahar inundation hazard zones

USGS Publications Warehouse

Schilling, Steve P.

2014-01-01

Laharz_py is written in the Python programming language as a suite of tools for use in ArcMap Geographic Information System (GIS). Primarily, Laharz_py is a computational model that uses statistical descriptions of areas inundated by past mass-flow events to forecast areas likely to be inundated by hypothetical future events. The forecasts use physically motivated and statistically calibrated power-law equations that each has a form A = cV2/3, relating mass-flow volume (V) to planimetric or cross-sectional areas (A) inundated by an average flow as it descends a given drainage. Calibration of the equations utilizes logarithmic transformation and linear regression to determine the best-fit values of c. The software uses values of V, an algorithm for idenitifying mass-flow source locations, and digital elevation models of topography to portray forecast hazard zones for lahars, debris flows, or rock avalanches on maps. Laharz_py offers two methods to construct areas of potential inundation for lahars: (1) Selection of a range of plausible V values results in a set of nested hazard zones showing areas likely to be inundated by a range of hypothetical flows; and (2) The user selects a single volume and a confidence interval for the prediction. In either case, Laharz_py calculates the mean expected A and B value from each user-selected value of V. However, for the second case, a single value of V yields two additional results representing the upper and lower values of the confidence interval of prediction. Calculation of these two bounding predictions require the statistically calibrated prediction equations, a user-specified level of confidence, and t-distribution statistics to calculate the standard error of regression, standard error of the mean, and standard error of prediction. The portrayal of results from these two methods on maps compares the range of inundation areas due to prediction uncertainties with uncertainties in selection of V values. The Open-File Report document contains an explanation of how to install and use the software. The Laharz_py software includes an example data set for Mount Rainier, Washington. The second part of the documentation describes how to use all of the Laharz_py tools in an example dataset at Mount Rainier, Washington.

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

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.

Employee age and tenure within organizations: relationship to workplace satisfaction and workplace climate perceptions.

PubMed

Teclaw, Robert; Osatuke, Katerine; Fishman, Jonathan; Moore, Scott C; Dyrenforth, Sue

2014-01-01

This study estimated the relative influence of age/generation and tenure on job satisfaction and workplace climate perceptions. Data from the 2004, 2008, and 2012 Veterans Health Administration All Employee Survey (sample sizes >100 000) were examined in general linear models, with demographic characteristics simultaneously included as independent variables. Ten dependent variables represented a broad range of employee attitudes. Age/generation and tenure effects were compared through partial η(2) (95% confidence interval), P value of F statistic, and overall model R(2). Demographic variables taken together were only weakly related to employee attitudes, accounting for less than 10% of the variance. Consistently across survey years, for all dependent variables, age and age-squared had very weak to no effects, whereas tenure and tenure-squared had meaningfully greater partial η(2) values. Except for 1 independent variable in 1 year, none of the partial η(2) confidence intervals for age and age-squared overlapped those of tenure and tenure-squared. Much has been made in the popular and professional press of the importance of generational differences in workplace attitudes. Empirical studies have been contradictory and therefore inconclusive. The findings reported here suggest that age/generational differences might not influence employee perceptions to the extent that human resource and management practitioners have been led to believe.

Estimation of parameters of dose volume models and their confidence limits

NASA Astrophysics Data System (ADS)

van Luijk, P.; Delvigne, T. C.; Schilstra, C.; Schippers, J. M.

2003-07-01

Predictions of the normal-tissue complication probability (NTCP) for the ranking of treatment plans are based on fits of dose-volume models to clinical and/or experimental data. In the literature several different fit methods are used. In this work frequently used methods and techniques to fit NTCP models to dose response data for establishing dose-volume effects, are discussed. The techniques are tested for their usability with dose-volume data and NTCP models. Different methods to estimate the confidence intervals of the model parameters are part of this study. From a critical-volume (CV) model with biologically realistic parameters a primary dataset was generated, serving as the reference for this study and describable by the NTCP model. The CV model was fitted to this dataset. From the resulting parameters and the CV model, 1000 secondary datasets were generated by Monte Carlo simulation. All secondary datasets were fitted to obtain 1000 parameter sets of the CV model. Thus the 'real' spread in fit results due to statistical spreading in the data is obtained and has been compared with estimates of the confidence intervals obtained by different methods applied to the primary dataset. The confidence limits of the parameters of one dataset were estimated using the methods, employing the covariance matrix, the jackknife method and directly from the likelihood landscape. These results were compared with the spread of the parameters, obtained from the secondary parameter sets. For the estimation of confidence intervals on NTCP predictions, three methods were tested. Firstly, propagation of errors using the covariance matrix was used. Secondly, the meaning of the width of a bundle of curves that resulted from parameters that were within the one standard deviation region in the likelihood space was investigated. Thirdly, many parameter sets and their likelihood were used to create a likelihood-weighted probability distribution of the NTCP. It is concluded that for the type of dose response data used here, only a full likelihood analysis will produce reliable results. The often-used approximations, such as the usage of the covariance matrix, produce inconsistent confidence limits on both the parameter sets and the resulting NTCP values.

Reliability growth modeling analysis of the space shuttle main engines based upon the Weibull process

NASA Technical Reports Server (NTRS)

Wheeler, J. T.

1990-01-01

The Weibull process, identified as the inhomogeneous Poisson process with the Weibull intensity function, is used to model the reliability growth assessment of the space shuttle main engine test and flight failure data. Additional tables of percentage-point probabilities for several different values of the confidence coefficient have been generated for setting (1-alpha)100-percent two sided confidence interval estimates on the mean time between failures. The tabled data pertain to two cases: (1) time-terminated testing, and (2) failure-terminated testing. The critical values of the three test statistics, namely Cramer-von Mises, Kolmogorov-Smirnov, and chi-square, were calculated and tabled for use in the goodness of fit tests for the engine reliability data. Numerical results are presented for five different groupings of the engine data that reflect the actual response to the failures.

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.

A Direct Imaging Survey of Spitzer-detected Debris Disks: Occurrence of Giant Planets in Dusty Systems

NASA Astrophysics Data System (ADS)

Meshkat, Tiffany; Mawet, Dimitri; Bryan, Marta L.; Hinkley, Sasha; Bowler, Brendan P.; Stapelfeldt, Karl R.; Batygin, Konstantin; Padgett, Deborah; Morales, Farisa Y.; Serabyn, Eugene; Christiaens, Valentin; Brandt, Timothy D.; Wahhaj, Zahed

2017-12-01

We describe a joint high-contrast imaging survey for planets at the Keck and Very Large Telescope of the last large sample of debris disks identified by the Spitzer Space Telescope. No new substellar companions were discovered in our survey of 30 Spitzer-selected targets. We combine our observations with data from four published surveys to place constraints on the frequency of planets around 130 debris disk single stars, the largest sample to date. For a control sample, we assembled contrast curves from several published surveys targeting 277 stars that do not show infrared excesses. We assumed a double power-law distribution in mass and semimajor axis (SMA) of the form f(m,a)={{Cm}}α {a}β , where we adopted power-law values and logarithmically flat values for the mass and SMA of planets. We find that the frequency of giant planets with masses 5-20 M Jup and separations 10-1000 au around stars with debris disks is 6.27% (68% confidence interval 3.68%-9.76%), compared to 0.73% (68% confidence interval 0.20%-1.80%) for the control sample of stars without disks. These distributions differ at the 88% confidence level, tentatively suggesting distinctness of these samples. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

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.

Reference Value Advisor: a new freeware set of macroinstructions to calculate reference intervals with Microsoft Excel.

PubMed

Geffré, Anne; Concordet, Didier; Braun, Jean-Pierre; Trumel, Catherine

2011-03-01

International recommendations for determination of reference intervals have been recently updated, especially for small reference sample groups, and use of the robust method and Box-Cox transformation is now recommended. Unfortunately, these methods are not included in most software programs used for data analysis by clinical laboratories. We have created a set of macroinstructions, named Reference Value Advisor, for use in Microsoft Excel to calculate reference limits applying different methods. For any series of data, Reference Value Advisor calculates reference limits (with 90% confidence intervals [CI]) using a nonparametric method when n≥40 and by parametric and robust methods from native and Box-Cox transformed values; tests normality of distributions using the Anderson-Darling test and outliers using Tukey and Dixon-Reed tests; displays the distribution of values in dot plots and histograms and constructs Q-Q plots for visual inspection of normality; and provides minimal guidelines in the form of comments based on international recommendations. The critical steps in determination of reference intervals are correct selection of as many reference individuals as possible and analysis of specimens in controlled preanalytical and analytical conditions. Computing tools cannot compensate for flaws in selection and size of the reference sample group and handling and analysis of samples. However, if those steps are performed properly, Reference Value Advisor, available as freeware at http://www.biostat.envt.fr/spip/spip.php?article63, permits rapid assessment and comparison of results calculated using different methods, including currently unavailable methods. This allows for selection of the most appropriate method, especially as the program provides the CI of limits. It should be useful in veterinary clinical pathology when only small reference sample groups are available. ©2011 American Society for Veterinary Clinical Pathology.

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.

Disease duration and Medsger's severity score are associated with significant liver fibrosis in patients with systemic sclerosis.

PubMed

Lee, Sang-Won; Kim, Beom Kyung; Park, Jun Yong; Kim, Do Young; Ahn, Sang Hoon; Song, Jason Jungsik; Park, Yong-Beom; Lee, Soo-Kon; Han, Kwang-Hyub; Kim, Seung Up

2015-01-01

We investigated the prevalence and predictors of significant liver fibrosis in patients with systemic sclerosis (SSc) who had no evidences of liver diseases due to viral infection, drug, and heavy alcohol consumption. A total of 44 SSc patients were recruited. In addition to the clinical and laboratory data, the 2013 College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria score, modified Rodnan skin score (mRSS), and Medsger's severity score (MSS) were analysed. Liver stiffness (LS) was measured using transient elastography to assess the degree of liver fibrosis and 7.4 kPa was adopted as the cut-off value for significant liver fibrosis. The median age of patients (38 women) was 54 years and the median disease duration was 41.0 months. The median LS value was 4.6 kPa. The median mRSS and MSS were 7.0 and 5.0, respectively. Six (13.6%) patients had significant liver fibrosis. Disease duration (standardised β=0.375, p=0.018) and MSS (standardised β=0.398, p=0.047) significantly correlated with LS values. In multivariate analysis, disease duration≥63 months (odds ratio (OR) 19.166, 95% confidence interval 1.090, 336.962, p=0.043) and MSS≥7 (OR 19.796, 95% confidence interval 1.439, 272.252, p=0.026) independently predicted the presence of significant liver fibrosis. The prevalence of significant liver fibrosis was relatively high (13.6%) and its independent predictors were disease duration and MSS.

Statistical inference for extended or shortened phase II studies based on Simon's two-stage designs.

PubMed

Zhao, Junjun; Yu, Menggang; Feng, Xi-Ping

2015-06-07

Simon's two-stage designs are popular choices for conducting phase II clinical trials, especially in the oncology trials to reduce the number of patients placed on ineffective experimental therapies. Recently Koyama and Chen (2008) discussed how to conduct proper inference for such studies because they found that inference procedures used with Simon's designs almost always ignore the actual sampling plan used. In particular, they proposed an inference method for studies when the actual second stage sample sizes differ from planned ones. We consider an alternative inference method based on likelihood ratio. In particular, we order permissible sample paths under Simon's two-stage designs using their corresponding conditional likelihood. In this way, we can calculate p-values using the common definition: the probability of obtaining a test statistic value at least as extreme as that observed under the null hypothesis. In addition to providing inference for a couple of scenarios where Koyama and Chen's method can be difficult to apply, the resulting estimate based on our method appears to have certain advantage in terms of inference properties in many numerical simulations. It generally led to smaller biases and narrower confidence intervals while maintaining similar coverages. We also illustrated the two methods in a real data setting. Inference procedures used with Simon's designs almost always ignore the actual sampling plan. Reported P-values, point estimates and confidence intervals for the response rate are not usually adjusted for the design's adaptiveness. Proper statistical inference procedures should be used.

The meaning of diagnostic test results: a spreadsheet for swift data analysis.

PubMed

Maceneaney, P M; Malone, D E

2000-03-01

To design a spreadsheet program to: (a) analyse rapidly diagnostic test result data produced in local research or reported in the literature; (b) correct reported predictive values for disease prevalence in any population; (c) estimate the post-test probability of disease in individual patients. Microsoft Excel(TM)was used. Section A: a contingency (2 x 2) table was incorporated into the spreadsheet. Formulae for standard calculations [sample size, disease prevalence, sensitivity and specificity with 95% confidence intervals, predictive values and likelihood ratios (LRs)] were linked to this table. The results change automatically when the data in the true or false negative and positive cells are changed. Section B: this estimates predictive values in any population, compensating for altered disease prevalence. Sections C-F: Bayes' theorem was incorporated to generate individual post-test probabilities. The spreadsheet generates 95% confidence intervals, LRs and a table and graph of conditional probabilities once the sensitivity and specificity of the test are entered. The latter shows the expected post-test probability of disease for any pre-test probability when a test of known sensitivity and specificity is positive or negative. This spreadsheet can be used on desktop and palmtop computers. The MS Excel(TM)version can be downloaded via the Internet from the URL ftp://radiography.com/pub/Rad-data99.xls A spreadsheet is useful for contingency table data analysis and assessment of the clinical meaning of diagnostic test results. Copyright 2000 The Royal College of Radiologists.

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.

Substitution of (R,S)-methadone by (R)-methadone: Impact on QTc interval.

PubMed

Ansermot, Nicolas; Albayrak, Ozgür; Schläpfer, Jürg; Crettol, Séverine; Croquette-Krokar, Marina; Bourquin, Michel; Déglon, Jean-Jacques; Faouzi, Mohamed; Scherbaum, Norbert; Eap, Chin B

2010-03-22

Methadone is administered as a chiral mixture of (R,S)-methadone. The opioid effect is mainly mediated by (R)-methadone, whereas (S)-methadone blocks the human ether-à-go-go-related gene (hERG) voltage-gated potassium channel more potently, which can cause drug-induced long QT syndrome, leading to potentially lethal ventricular tachyarrhythmias. To investigate whether substitution of (R,S)-methadone by (R)-methadone could reduce the corrected QT (QTc) interval, (R,S)-methadone was replaced by (R)-methadone (half-dose) in 39 opioid-dependent patients receiving maintenance treatment for 14 days. (R)-methadone was then replaced by the initial dose of (R,S)-methadone for 14 days (n = 29). Trough (R)-methadone and (S)-methadone plasma levels and electrocardiogram measurements were taken. The Fridericia-corrected QT (QTcF) interval decreased when (R,S)-methadone was replaced by a half-dose of (R)-methadone; the median (interquartile range [IQR]) values were 423 (398-440) milliseconds (ms) and 412 (395-431) ms (P = .06) at days 0 and 14, respectively. Using a univariate mixed-effect linear model, the QTcF value decreased by a mean of -3.9 ms (95% confidence interval [CI], -7.7 to -0.2) per week (P = .04). The QTcF value increased when (R)-methadone was replaced by the initial dose of (R,S)-methadone for 14 days; median (IQR) values were 424 (398-436) ms and 424 (412-443) ms (P = .01) at days 14 and 28, respectively. The univariate model showed that the QTcF value increased by a mean of 4.7 ms (95% CI, 1.3-8.1) per week (P = .006). Substitution of (R,S)-methadone by (R)-methadone reduces the QTc interval value. A safer cardiac profile of (R)-methadone is in agreement with previous in vitro and pharmacogenetic studies. If the present results are confirmed by larger studies, (R)-methadone should be prescribed instead of (R,S)-methadone to reduce the risk of cardiac toxic effects and sudden death.

Dimensions of human ejaculated spermatozoa in Papanicolaou-stained seminal and swim-up smears obtained from the Integrated Semen Analysis System (ISAS®)

PubMed Central

Bellastella, Giuseppe; Cooper, Trevor G.; Battaglia, Marina; Ströse, Anda; Torres, Inma; Hellenkemper, Barbara; Soler, Carles; Sinisi, Antonio A.

2010-01-01

Objective measurements are required for computer-aided sperm morphometric analysis (CASMA) machines to distinguish normal from abnormal sperm heads. The morphometric characteristics of spermatozoa in 72 samples of semen and of spermatozoa from 72 other semen samples after swim-up were quantified by the semi-automated Integrated Sperm Analysis System (ISAS) computer-aided system, which measured the sperm head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. For each man a homogeneous population of distributions characterized seminal spermatozoa (7 942 cells: median values L 4.4 μm, W 2.8 μm, A 9.8 μm2, P 12.5 μm, Ac 47.5%, L/W 1.57, P/A 1.27), and there was no significant difference in within- and among-individual variation. Different men could have spermatozoa of significantly different dimensions. Head dimensions for swim-up spermatozoa from different men (4 812 cells) were similar to those in semen, differing only by 2%–5%. The values of L, W and L/W fell within the limits given by the World Health Organization (WHO). Although these samples were not biologically matched, linear mixed-effects statistical analyses permitted valid comparison of the groups. A subpopulation of 404 spermatozoa considered to fit the stringent criteria of WHO 'normal' seminal spermatozoa from both semen and swim-up were characterized by median values (and 95% confidence intervals) of L, 4.3 μm (3.8–4.9), W, 2.9 μm (2.6–3.3), A, 10.2 μm2 (8.5–12.2), P, 12.4 μm (11.3–13.9), Ac, 49% (36–60), L/W, 1.49 (1.32–1.67) and P/A, 1.22 (1.11–1.35). These median values fall within the 95th centile confidence limits given by WHO, but the confidence intervals for L and W were larger. Although these differences in head dimensions among men and after swim-up could be detected by CASMA, the small differences make it unlikely that technicians would be able to distinguish them. The values could be used as default sperm head values for the CASMA machine used here. PMID:20852650

Dimensions of human ejaculated spermatozoa in Papanicolaou-stained seminal and swim-up smears obtained from the Integrated Semen Analysis System (ISAS(®)).

PubMed

Bellastella, Giuseppe; Cooper, Trevor G; Battaglia, Marina; Ströse, Anda; Torres, Inma; Hellenkemper, Barbara; Soler, Carles; Sinisi, Antonio A

2010-11-01

Objective measurements are required for computer-aided sperm morphometric analysis (CASMA) machines to distinguish normal from abnormal sperm heads. The morphometric characteristics of spermatozoa in 72 samples of semen and of spermatozoa from 72 other semen samples after swim-up were quantified by the semi-automated Integrated Sperm Analysis System (ISAS) computer-aided system, which measured the sperm head parameters length (L), width (W), area (A), perimeter (P), acrosomal area (Ac), and the derived values L/W and P/A. For each man a homogeneous population of distributions characterized seminal spermatozoa (7 942 cells: median values L 4.4 μm, W 2.8 μm, A 9.8 μm(2), P 12.5 μm, Ac 47.5%, L/W 1.57, P/A 1.27), and there was no significant difference in within- and among-individual variation. Different men could have spermatozoa of significantly different dimensions. Head dimensions for swim-up spermatozoa from different men (4 812 cells) were similar to those in semen, differing only by 2%-5%. The values of L, W and L/W fell within the limits given by the World Health Organization (WHO). Although these samples were not biologically matched, linear mixed-effects statistical analyses permitted valid comparison of the groups. A subpopulation of 404 spermatozoa considered to fit the stringent criteria of WHO 'normal' seminal spermatozoa from both semen and swim-up were characterized by median values (and 95% confidence intervals) of L, 4.3 μm (3.8-4.9), W, 2.9 μm (2.6-3.3), A, 10.2 μm(2) (8.5-12.2), P, 12.4 μm (11.3-13.9), Ac, 49% (36-60), L/W, 1.49 (1.32-1.67) and P/A, 1.22 (1.11-1.35). These median values fall within the 95th centile confidence limits given by WHO, but the confidence intervals for L and W were larger. Although these differences in head dimensions among men and after swim-up could be detected by CASMA, the small differences make it unlikely that technicians would be able to distinguish them. The values could be used as default sperm head values for the CASMA machine used here.

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.

Identifying the bad guy in a lineup using confidence judgments under deadline pressure.

PubMed

Brewer, Neil; Weber, Nathan; Wootton, David; Lindsay, D Stephen

2012-10-01

Eyewitness-identification tests often culminate in witnesses not picking the culprit or identifying innocent suspects. We tested a radical alternative to the traditional lineup procedure used in such tests. Rather than making a positive identification, witnesses made confidence judgments under a short deadline about whether each lineup member was the culprit. We compared this deadline procedure with the traditional sequential-lineup procedure in three experiments with retention intervals ranging from 5 min to 1 week. A classification algorithm that identified confidence criteria that optimally discriminated accurate from inaccurate decisions revealed that decision accuracy was 24% to 66% higher under the deadline procedure than under the traditional procedure. Confidence profiles across lineup stimuli were more informative than were identification decisions about the likelihood that an individual witness recognized the culprit or correctly recognized that the culprit was not present. Large differences between the maximum and the next-highest confidence value signaled very high accuracy. Future support for this procedure across varied conditions would highlight a viable alternative to the problematic lineup procedures that have traditionally been used by law enforcement.

[Reference values for lead in blood in urban population in southern Brazil].

PubMed

Paoliello, M M; Gutierrez, P R; Turini, C A; Matsuo, T; Mezzaroba, L; Barbosa, D S; Carvalho, S R; Alvarenga, A L; Rezende, M I; Figueiroa, G A; Leite, V G; Gutierrez, A C; Lobo, B C; Cascales, R A

2001-05-01

To describe the reference values for lead in blood in an urban population in the city of Londrina, in the state of Paraná, Brazil. The reference population was composed of 520 adult volunteers who were assessed from November 1994 to December 1996. Exclusion criteria were: occupational exposure to lead, exposure through personal habits or practices, smoking more than 10 cigarettes per day, and living near industrial plants or other places that use lead in their production processes. Also excluded were individuals with abnormal clinical or laboratory results or with chronic diseases or cardiovascular disorders. Lead blood levels were determined using air-acetylene flame atomic absorption spectrophotometry. The detectable limit was 1.23 micrograms/dL. After the analyses of lead in blood, the following values were determined: minimum value, first quartile, median, third quartile, and maximum value; geometric mean; 95% confidence interval; experimental interval; and reference value. The reference values for lead in blood ranged from 1.20 micrograms/dL to 13.72 micrograms/dL. The geometric mean was 5.5 micrograms/dL. In general, the values found in this study are lower than those that have been reported for other countries. Additional data should be gathered from Brazilian populations living in more-industrialized areas.

Forecasting overhaul or replacement intervals based on estimated system failure intensity

NASA Astrophysics Data System (ADS)

Gannon, James M.

1994-12-01

System reliability can be expressed in terms of the pattern of failure events over time. Assuming a nonhomogeneous Poisson process and Weibull intensity function for complex repairable system failures, the degree of system deterioration can be approximated. Maximum likelihood estimators (MLE's) for the system Rate of Occurrence of Failure (ROCOF) function are presented. Evaluating the integral of the ROCOF over annual usage intervals yields the expected number of annual system failures. By associating a cost of failure with the expected number of failures, budget and program policy decisions can be made based on expected future maintenance costs. Monte Carlo simulation is used to estimate the range and the distribution of the net present value and internal rate of return of alternative cash flows based on the distributions of the cost inputs and confidence intervals of the MLE's.

Cell-free DNA screening in clinical practice: abnormal autosomal aneuploidy and microdeletion results.

PubMed

Valderramos, Stephanie G; Rao, Rashmi R; Scibetta, Emily W; Silverman, Neil S; Han, Christina S; Platt, Lawrence D

2016-11-01

Since its commercial release in 2011 cell-free DNA screening has been rapidly adopted as a routine prenatal genetic test. However, little is known about its performance in actual clinical practice. We sought to investigate factors associated with the accuracy of abnormal autosomal cell-free DNA results. We conducted a retrospective cohort study of 121 patients with abnormal cell-free DNA results from a referral maternal-fetal medicine practice from March 2013 through July 2015. Patients were included if cell-free DNA results for trisomy 21, trisomy 18, trisomy 13, or microdeletions (if reported by the laboratory) were positive or nonreportable. The primary outcome was confirmed aneuploidy or microarray abnormality on either prenatal or postnatal karyotype or microarray. Secondary outcomes were identifiable associations with in vitro fertilization, twins, ultrasound findings, testing platform, and testing laboratory. Kruskal-Wallis or Fisher exact tests were used as appropriate. A total of 121 patients had abnormal cell-free DNA results for trisomy 21, trisomy 18, trisomy 13, and/or microdeletions. In all, 105 patients had abnormal cell-free DNA results for trisomy 21, trisomy 18, and trisomy 13. Of these, 92 (87.6%) were positive and 13 (12.4%) were nonreportable. The results of the 92 positive cell-free DNA were for trisomy 21 (48, 52.2%), trisomy 18 (22, 23.9%), trisomy 13 (17, 18.5%), triploidy (2, 2.2%), and positive for >1 parameter (3, 3.3%). Overall, the positive predictive value of cell-free DNA was 73.5% (61/83; 95% confidence interval, 63-82%) for all trisomies (by chromosome: trisomy 21, 83.0% [39/47; 95% confidence interval, 69-92%], trisomy 18, 65.0% [13/20; 95% confidence interval, 41-84%], and trisomy 13, 43.8% [7/16; 95% confidence interval, 21-70%]). Abnormal cell-free DNA results were associated with positive serum screening (by group: trisomy 21 [17/48, 70.8%]; trisomy 18 [7/22, 77.8%]; trisomy 13 [3/17, 37.5%]; nonreportable [2/13, 16.7%]; P = .004), and abnormal first-trimester ultrasound (trisomy 21 [25/45, 55.6%]; trisomy 18 [13/20, 65%]; trisomy 13 [6/14, 42.9%]; nonreportable [1/13, 7.7%]; P = .003). There was no association between false-positive rates and testing platform, but there was a difference between the 4 laboratories (P = .018). In all, 26 patients had positive (n = 9) or nonreportable (n = 17) microdeletion results. Seven of 9 screens positive for microdeletions underwent confirmatory testing; all were false positives. The positive predictive value of 73.5% for cell-free DNA screening for autosomal aneuploidy is lower than reported. The positive predictive value for microdeletion testing was 0%. Diagnostic testing is needed to confirm abnormal cell-free DNA results for aneuploidy and microdeletions. Copyright © 2016 Elsevier Inc. All rights reserved.

Life in Meridiani Planum. Mars. (Italian Title: Vita in Meridiani Planum, Marte)

NASA Astrophysics Data System (ADS)

Bianciardi, G.; Rizzo, V.; Cantasano, V.

2015-05-01

We performed a quantitative image analysis to compare microstructures of microbialites with the images photographed by the Rover Opportunity. Terrestrial and Martian textures present a multifractal aspect. Mean values and confidence intervals from the Martian images overlapped perfectly with those from the terrestrial samples (p<0.004). Our work shows the presumptive evidence of microbialites in the Martian outcroppings: the presence of unicellular life widespread on the ancient Mars.

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.

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.

Predictive value of N-terminal pro-brain natriuretic peptide in severe sepsis and septic shock.

PubMed

Varpula, Marjut; Pulkki, Kari; Karlsson, Sari; Ruokonen, Esko; Pettilä, Ville

2007-05-01

The aim of this study was to evaluate the predictive value of N-terminal pro-brain natriuretic peptide (NT-proBNP) on mortality in a large, unselected patient population with severe sepsis and septic shock. Prospective observational cohort study about incidence and prognosis of sepsis in 24 intensive care units in Finland (the FINNSEPSIS study). A total of 254 patients with severe sepsis or septic shock. After informed consent, the blood tests for NT-proBNP analyses were drawn on the day of admission and 72 hrs thereafter. Patients' demographic data were collected, and intensive care unit and hospital mortality and basic hemodynamic and laboratory data were recorded daily. NT-proBNP levels at admission were significantly higher in hospital nonsurvivors (median, 7908 pg/mL) compared with survivors (median, 3479 pg/mL; p = .002), and the difference remained after 72 hrs (p = .002). The receiver operating characteristic curves of admission and 72-hr NT-proBNP levels for hospital mortality resulted in area under the curve values of 0.631 (95% confidence interval, 0.549-0.712; p = .002) and 0.648 (95% confidence interval, 0.554-0.741; p = .002), respectively. In logistic regression analyses, NT-proBNP values at 72 hrs after inclusion and Simplified Acute Physiology Score for the first 24 hrs were independent predictors of hospital mortality. Pulmonary artery occlusion pressure (p < .001), plasma creatinine clearance (p = .001), platelet count (p = .03), and positive blood culture (p = .04) had an independent effect on first-day NT-proBNP values, whereas after 72 hrs, only plasma creatinine clearance (p < .001) was significant in linear regression analysis. NT-proBNP values are frequently increased in severe sepsis and septic shock. Values are significantly higher in nonsurvivors than survivors. NT-proBNP on day 3 in the intensive care unit is an independent prognostic marker of mortality in severe sepsis.

Measuring coverage in MNCH: total survey error and the interpretation of intervention coverage estimates from household surveys.

PubMed

Eisele, Thomas P; Rhoda, Dale A; Cutts, Felicity T; Keating, Joseph; Ren, Ruilin; Barros, Aluisio J D; Arnold, Fred

2013-01-01

Nationally representative household surveys are increasingly relied upon to measure maternal, newborn, and child health (MNCH) intervention coverage at the population level in low- and middle-income countries. Surveys are the best tool we have for this purpose and are central to national and global decision making. However, all survey point estimates have a certain level of error (total survey error) comprising sampling and non-sampling error, both of which must be considered when interpreting survey results for decision making. In this review, we discuss the importance of considering these errors when interpreting MNCH intervention coverage estimates derived from household surveys, using relevant examples from national surveys to provide context. Sampling error is usually thought of as the precision of a point estimate and is represented by 95% confidence intervals, which are measurable. Confidence intervals can inform judgments about whether estimated parameters are likely to be different from the real value of a parameter. We recommend, therefore, that confidence intervals for key coverage indicators should always be provided in survey reports. By contrast, the direction and magnitude of non-sampling error is almost always unmeasurable, and therefore unknown. Information error and bias are the most common sources of non-sampling error in household survey estimates and we recommend that they should always be carefully considered when interpreting MNCH intervention coverage based on survey data. Overall, we recommend that future research on measuring MNCH intervention coverage should focus on refining and improving survey-based coverage estimates to develop a better understanding of how results should be interpreted and used.

Measuring Coverage in MNCH: Total Survey Error and the Interpretation of Intervention Coverage Estimates from Household Surveys

PubMed Central

Eisele, Thomas P.; Rhoda, Dale A.; Cutts, Felicity T.; Keating, Joseph; Ren, Ruilin; Barros, Aluisio J. D.; Arnold, Fred

2013-01-01

Nationally representative household surveys are increasingly relied upon to measure maternal, newborn, and child health (MNCH) intervention coverage at the population level in low- and middle-income countries. Surveys are the best tool we have for this purpose and are central to national and global decision making. However, all survey point estimates have a certain level of error (total survey error) comprising sampling and non-sampling error, both of which must be considered when interpreting survey results for decision making. In this review, we discuss the importance of considering these errors when interpreting MNCH intervention coverage estimates derived from household surveys, using relevant examples from national surveys to provide context. Sampling error is usually thought of as the precision of a point estimate and is represented by 95% confidence intervals, which are measurable. Confidence intervals can inform judgments about whether estimated parameters are likely to be different from the real value of a parameter. We recommend, therefore, that confidence intervals for key coverage indicators should always be provided in survey reports. By contrast, the direction and magnitude of non-sampling error is almost always unmeasurable, and therefore unknown. Information error and bias are the most common sources of non-sampling error in household survey estimates and we recommend that they should always be carefully considered when interpreting MNCH intervention coverage based on survey data. Overall, we recommend that future research on measuring MNCH intervention coverage should focus on refining and improving survey-based coverage estimates to develop a better understanding of how results should be interpreted and used. PMID:23667331

The Skin Cancer Objective Structured Clinical Examination (SCOSCE): A multi-institutional collaboration to develop and validate a clinical skills assessment for melanoma.

PubMed

Garg, Amit; Biello, Katie; Hoot, Joyce W; Reddy, Shalini B; Wilson, Lindsay; George, Paul; Robinson-Bostom, Leslie; Belazarian, Leah; Domingues, Erik; Powers, Jennifer; Jacob, Reza; Powers, Michael; Besen, Justin; Geller, Alan C

2015-12-01

Assessing medical students on core skills related to melanoma detection is challenging in the absence of a well-developed instrument. We sought to develop an objective structured clinical examination for the detection and evaluation of melanoma among medical students. This was a prospective cohort analysis of student and objective rater agreement on performance of clinical skills and assessment of differences in performance across 3 schools. Kappa coefficients indicated excellent agreement for 3 of 5 core skills including commenting on the presence of the moulage (k = 0.87, 95% confidence interval 0.77-0.96), obtaining a history for the moulage (k = 0.84, 95% confidence interval 0.74-0.94), and making a clinical impression (k = 0.80, 95% confidence interval 0.68-0.92). There were no differences in performance across schools with respect to 3 of 5 core skills: commenting on the presence of the moulage (P = .15), initiating a history (P = .53), and managing the suspicious lesion (P value range .07-.17). Overall, 54.2% and 44.7% of students commented on the presence of the moulage and achieved maximum performance of core skills, respectively, with no difference in performance across schools. Limitations include overall sample size of students and schools. The Skin Cancer Objective Structured Clinical Examination represents a potentially important instrument to measure students' performance on the optimal step-by-step evaluation of a melanoma. Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

A case control study of nutritional factors and cervical dysplasia.

PubMed

Liu, T; Soong, S J; Wilson, N P; Craig, C B; Cole, P; Macaluso, M; Butterworth, C E

1993-01-01

The association of nutritional factors with cervical dysplasia was examined through a case-control study. Analysis was conducted in 257 cases and 133 controls confirmed both by cytological examination and colposcopic findings. A 24-h dietary recall questionnaire was used to assess nutritional intake. Various risk factors (including age at first intercourse, number of sexual partners, parity, cigarette smoking, oral contraceptive use, human papillomavirus type 16 infection, and age and race) were adjusted for their potential confounding effects. While analyses were also performed to adjust for total calories, results were not changed significantly. Among the nutrients examined, vitamin A intake showed a significantly increased risk at the lowest quartile compared to the highest quartile, with an odds ratio of 2.2 (95% confidence interval, 1.2-4.2). A significant trend of increasing risk was also observed with lower intake of vitamin A (P = 0.05). Riboflavin showed increased risk at the two lower quartiles of intake with a trend test P value of 0.04. Increased risk was also found for lower intakes of vitamin C compared to the highest intake level. For folate, increased risk was found in the second highest quartile compared with the highest quartile with an odds ratio of 2.0 (95% confidence interval, 1.0-3.8). The calcium:phosphorus ratio showed an increased risk at the lowest level (odds ratio, 2.0; 95% confidence interval, 1.0-4.3). Insufficient intake of vitamin A, riboflavin, ascorbate, and folate is associated with an increased risk of cervical dysplasia.

Spot sign on 90-second delayed computed tomography angiography improves sensitivity for hematoma expansion and mortality: prospective study.

PubMed

Ciura, Viesha A; Brouwers, H Bart; Pizzolato, Raffaella; Ortiz, Claudia J; Rosand, Jonathan; Goldstein, Joshua N; Greenberg, Steven M; Pomerantz, Stuart R; Gonzalez, R Gilberto; Romero, Javier M

2014-11-01

The computed tomography angiography (CTA) spot sign is a validated biomarker for poor outcome and hematoma expansion in intracerebral hemorrhage. The spot sign has proven to be a dynamic entity, with multimodal imaging proving to be of additional value. We investigated whether the addition of a 90-second delayed CTA acquisition would capture additional intracerebral hemorrhage patients with the spot sign and increase the sensitivity of the spot sign. We prospectively enrolled consecutive intracerebral hemorrhage patients undergoing first pass and 90-second delayed CTA for 18 months at a single academic center. Univariate and multivariate logistic regression were performed to assess clinical and neuroimaging covariates for relationship with hematoma expansion and mortality. Sensitivity of the spot sign for hematoma expansion on first pass CTA was 55%, which increased to 64% if the spot sign was present on either CTA acquisition. In multivariate analysis the spot sign presence was associated with significant hematoma expansion: odds ratio, 17.7 (95% confidence interval, 3.7-84.2; P=0.0004), 8.3 (95% confidence interval, 2.0-33.4; P=0.004), and 12.0 (95% confidence interval, 2.9-50.5; P=0.0008) if present on first pass, delayed, or either CTA acquisition, respectively. Spot sign presence on either acquisitions was also significant for mortality. We demonstrate improved sensitivity for predicting hematoma expansion and poor outcome by adding a 90-second delayed CTA, which may enhance selection of patients who may benefit from hemostatic therapy. © 2014 American Heart Association, Inc.

The association between depressive symptoms and mortality among Chinese elderly: a Hong Kong cohort study.

PubMed

Sun, Wenjie; Schooling, C Mary; Chan, Wai Man; Ho, Kin Sang; Lam, Tai Hing

2011-04-01

Increasingly, researchers have begun to explore the association between depression and mortality. The current study examined the association between depressive symptoms and all-cause and cause-specific mortality in Chinese older people. Further to examine whether any associations were similar by sex and health status. We used the Chinese version of the 15-item Geriatric Depression Scale to measure depressive symptoms (Geriatric Depression Scale score ≥ 8) and Cox regression to examine the association with all-cause and cause-specific mortality in a population-based cohort study of all 56,088 enrollees, aged 65 years or older, from July 1998 to December 2000 at all 18 Elderly Health Centers of Department of Health of Hong Kong. The cohort was followed up for mortality till December 31, 2005. Depressive symptoms were associated with all-cause mortality (hazard ratio 1.21, 95% confidence interval: 1.08-1.37) in men only (p value for sex interaction <.05) and with suicide mortality in men (hazard ratio 2.81, 95% confidence interval: 1.13-7.01) and women (hazard ratio 2.40, 95% confidence interval: 1.18-4.82) but not with other major causes of death after adjusting for age, education, monthly expenditure, smoking, alcohol drinking, physical activity, body mass index, health status, and self-rated health. The associations did not vary with health status. Depressive symptoms were associated with all-cause mortality in men and with suicide in both sexes. Randomized controlled trials concerning the effects of treatment of depression on mortality are needed to clarify the causal pathways.

Recolonization of group B Streptococcus (GBS) in women with prior GBS genital colonization in pregnancy.

PubMed

Tam, Teresa; Bilinski, Ewa; Lombard, Emily

2012-10-01

The purpose of the study is to evaluate the incidence of women with prior GBS genital colonization who have recolonization in subsequent pregnancies. This is a retrospective, cohort study of patients with a prior GBS genital colonization in pregnancy and a subsequent pregnancy with a recorded GBS culture result, from January 2000 through June 2007. Documentation of GBS status was through GBS culture performed between 35 to 37 weeks gestation. Exclusion criteria included pregnancies with unknown GBS status, patients with GBS bacteriuria, women with a previous neonate with GBS disease and GBS finding prior to 35 weeks. Data was analyzed using SPSS 15.0. The sample proportion of subjects with GBS genital colonization and its confidence interval were computed to estimate the incidence rate. Logistic regression was performed to assess potential determinants of GBS colonization. Regression coefficients, odds ratios and associated confidence intervals, and p-values were reported, with significant results reported. There were 371 pregnancies that met the test criteria. There were 151 subsequent pregnancies with GBS genital colonization and 220 without GBS recolonization. The incidence of GBS recolonization on patients with prior GBS genital colonization was 40.7% (95% confidence interval 35.7-45.69%). The incidence rate for the sample was significantly larger than 30% (p < .001), which is the estimated incidence rate for all pregnant women who are GBS carriers regardless of prior history. These results suggest that patients with a history of GBS are at a significantly higher risk of GBS recolonization in subsequent pregnancies.

The Quality of Reporting of Measures of Precision in Animal Experiments in Implant Dentistry: A Methodological Study.

PubMed

Faggion, Clovis Mariano; Aranda, Luisiana; Diaz, Karla Tatiana; Shih, Ming-Chieh; Tu, Yu-Kang; Alarcón, Marco Antonio

2016-01-01

Information on precision of treatment-effect estimates is pivotal for understanding research findings. In animal experiments, which provide important information for supporting clinical trials in implant dentistry, inaccurate information may lead to biased clinical trials. The aim of this methodological study was to determine whether sample size calculation, standard errors, and confidence intervals for treatment-effect estimates are reported accurately in publications describing animal experiments in implant dentistry. MEDLINE (via PubMed), Scopus, and SciELO databases were searched to identify reports involving animal experiments with dental implants published from September 2010 to March 2015. Data from publications were extracted into a standardized form with nine items related to precision of treatment estimates and experiment characteristics. Data selection and extraction were performed independently and in duplicate, with disagreements resolved by discussion-based consensus. The chi-square and Fisher exact tests were used to assess differences in reporting according to study sponsorship type and impact factor of the journal of publication. The sample comprised reports of 161 animal experiments. Sample size calculation was reported in five (2%) publications. P values and confidence intervals were reported in 152 (94%) and 13 (8%) of these publications, respectively. Standard errors were reported in 19 (12%) publications. Confidence intervals were better reported in publications describing industry-supported animal experiments (P = .03) and with a higher impact factor (P = .02). Information on precision of estimates is rarely reported in publications describing animal experiments in implant dentistry. This lack of information makes it difficult to evaluate whether the translation of animal research findings to clinical trials is adequate.

Lack of effect of oral cabotegravir on the pharmacokinetics of a levonorgestrel/ethinyl oestradiol-containing oral contraceptive in healthy adult women.

PubMed

Trezza, Christine; Ford, Susan L; Gould, Elizabeth; Lou, Yu; Huang, Chuyun; Ritter, James M; Buchanan, Ann M; Spreen, William; Patel, Parul

2017-07-01

This study aimed to investigate whether cabotegravir (CAB), an integrase inhibitor in development for treatment and prevention of human immunodeficiency virus-1, influences the pharmacokinetics (PK) of a levonorgestrel (LNG) and ethinyl oestradiol (EO)-containing oral contraceptive (OC) in healthy women. In this open-label, fixed-sequence crossover study, healthy female subjects received LNG 0.15 mg/EO 0.03 mg tablet once daily Days 1-10 alone and with oral CAB 30 mg once daily Days 11-21. At the end of each treatment period, subjects underwent predose sampling for concentrations of follicle-stimulating hormone, luteinizing hormone, and progesterone and serial PK sampling for plasma LNG, EO, and CAB concentrations. Twenty women were enrolled, and 19 completed the study. One subject was withdrawn due to an adverse event unrelated to study medications. Geometric least squares mean ratios (90% confidence interval) of LNG + CAB vs. LNG alone for LNG area under the plasma concentration-time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.12 (1.07-1.18) and 1.05 (0.96-1.15), respectively. Geometric least squares mean ratio (90% confidence interval) of EO + CAB vs. EO alone for EO area under the plasma concentration-time curve over the dosing interval of duration τ and maximum observed plasma concentration were 1.02 (0.97-1.08) and 0.92 (0.83-1.03), respectively. Steady-state CAB PK parameters were comparable to historical values. There was no apparent difference in mean luteinizing hormone, follicle-stimulating hormone, and progesterone concentrations between periods. No clinically significant trends in laboratory values, vital signs, or electrocardiography values were observed. Repeat doses of oral CAB had no significant effect on LNG/EO PK or pharmacodynamics, which supports CAB coadministration with LNG/EO OCs in clinical practice. © 2017 ViiV Healthcare. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

Childhood Abuse and Suicidal Ideation in a Cohort of Pregnant Peruvian Women

PubMed Central

ZHONG, Qiu-Yue; WELLS, Anne; RONDON, Marta B.; WILLIAMS, Michelle A.; BARRIOS, Yasmin V.; SANCHEZ, Sixto E.; GELAYE, Bizu

2016-01-01

Background Childhood abuse is a major global and public health problem associated with a myriad of adverse outcomes across the life course. Suicide is one of the leading causes of mortality during the perinatal period. However, few studies have assessed the relationship between experiences of childhood abuse and suicidal ideation in pregnancy. Objective To examine the association between exposure to childhood abuse and suicidal ideation among pregnant women. Study Design A cross-sectional study was conducted among 2,964 pregnant women attending prenatal clinics, in Lima, Peru. Childhood abuse was assessed using the Childhood Physical and Sexual Abuse Questionnaire. Depression and suicidal ideation were assessed using the Patient Health Questionnaire-9 scale. Logistic regression procedures were performed to estimate adjusted odds ratios and 95% confidence intervals adjusted for potential confounders. Results Overall, the prevalence of childhood abuse in this cohort was 71.8% and antepartum suicidal ideation was 15.8%. The prevalence of antepartum suicidal ideation was higher among women who reported experiencing any childhood abuse compared to those reporting none (89.3% vs. 10.7%, P<0.0001). After adjusting for potential confounders, including antepartum depression and lifetime intimate partner violence, those with history of any childhood abuse had a 2.9-fold (adjusted odds ratios; 95% confidence intervals: 2.12-3.97) increased odds of reporting suicidal ideation. Women who experienced both physical and sexual childhood abuse had much higher odds of suicidal ideation (adjusted odds ratios =4.04; 95% confidence intervals: 2.88-5.68). Women who experienced any childhood abuse and reported depression had 3.44-fold (adjusted odds ratios; 95% confidence intervals: 1.84-6.43) increased odds of suicidal ideation compared with depressed women with no history of childhood abuse. Finally, the odds of suicidal ideation increased with increased number of childhood abuse events experienced (P-value for trend<0.001). Conclusion Maternal history of childhood abuse was associated with increased odds of antepartum suicidal ideation. It is important for clinicians to be aware of the potential increased risk of suicidal behaviors among pregnant women with a history of childhood physical and sexual abuse. PMID:27173085

Right ventricular dysfunction affects survival after surgical left ventricular restoration.

PubMed

Couperus, Lotte E; Delgado, Victoria; Palmen, Meindert; van Vessem, Marieke E; Braun, Jerry; Fiocco, Marta; Tops, Laurens F; Verwey, Harriëtte F; Klautz, Robert J M; Schalij, Martin J; Beeres, Saskia L M A

2017-04-01

Several clinical and left ventricular parameters have been associated with prognosis after surgical left ventricular restoration in patients with ischemic heart failure. The aim of this study was to determine the prognostic value of right ventricular function. A total of 139 patients with ischemic heart failure (62 ± 10 years; 79% were male; left ventricular ejection fraction 27% ± 7%) underwent surgical left ventricular restoration. Biventricular function was assessed with echocardiography before surgery. The independent association between all-cause mortality and right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain was assessed. The additive effect of multiple impaired right ventricular parameters on mortality also was assessed. Baseline right ventricular fractional area change was 42% ± 9%, tricuspid annular plane systolic excursion was 18 ± 3 mm, and right ventricular longitudinal peak systolic strain was -24% ± 7%. Within 30 days after surgery, 15 patients died. Right ventricular fractional area change (hazard ratio, 0.93; 95% confidence interval, 0.88-0.98; P < .01), tricuspid annular plane systolic excursion (hazard ratio, 0.80; 95% confidence interval, 0.66-0.96; P = .02), and right ventricular longitudinal peak systolic strain (hazard ratio, 1.15; 95% confidence interval, 1.05-1.26; P < .01) were independently associated with 30-day mortality, after adjusting for left ventricular ejection fraction and aortic crossclamping time. Right ventricular function was impaired in 21%, 20%, and 27% of patients on the basis of right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain, respectively. Any echocardiographic parameter of right ventricular dysfunction was present in 39% of patients. The coexistence of several impaired right ventricular parameters per patient was independently associated with increased 30-day mortality (hazard ratio, 2.83; 95% confidence interval, 1.64-4.87, P < .01 per additional impaired parameter). Baseline right ventricular systolic dysfunction is independently associated with increased mortality in patients with ischemic heart failure undergoing surgical left ventricular restoration. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Is the placebo powerless? An analysis of clinical trials comparing placebo with no treatment.

PubMed

Hróbjartsson, A; Gøtzsche, P C

2001-05-24

Placebo treatments have been reported to help patients with many diseases, but the quality of the evidence supporting this finding has not been rigorously evaluated. We conducted a systematic review of clinical trials in which patients were randomly assigned to either placebo or no treatment. A placebo could be pharmacologic (e.g., a tablet), physical (e.g., a manipulation), or psychological (e.g., a conversation). We identified 130 trials that met our inclusion criteria. After the exclusion of 16 trials without relevant data on outcomes, there were 32 with binary outcomes (involving 3795 patients, with a median of 51 patients per trial) and 82 with continuous outcomes (involving 4730 patients, with a median of 27 patients per trial). As compared with no treatment, placebo had no significant effect on binary outcomes (pooled relative risk of an unwanted outcome with placebo, 0.95; 95 percent confidence interval, 0.88 to 1.02), regardless of whether these outcomes were subjective or objective. For the trials with continuous outcomes, placebo had a beneficial effect (pooled standardized mean difference in the value for an unwanted outcome between the placebo and untreated groups, -0.28; 95 percent confidence interval, -0.38 to -0.19), but the effect decreased with increasing sample size, indicating a possible bias related to the effects of small trials. The pooled standardized mean difference was significant for the trials with subjective outcomes (-0.36; 95 percent confidence interval, -0.47 to -0.25) but not for those with objective outcomes. In 27 trials involving the treatment of pain, placebo had a beneficial effect (-0.27; 95 percent confidence interval, -0.40 to -0.15). This corresponded to a reduction in the intensity of pain of 6.5 mm on a 100-mm visual-analogue scale. We found little evidence in general that placebos had powerful clinical effects. Although placebos had no significant effects on objective or binary outcomes, they had possible small benefits in studies with continuous subjective outcomes and for the treatment of pain. Outside the setting of clinical trials, there is no justification for the use of placebos.

Childhood abuse and suicidal ideation in a cohort of pregnant Peruvian women.

PubMed

Zhong, Qiu-Yue; Wells, Anne; Rondon, Marta B; Williams, Michelle A; Barrios, Yasmin V; Sanchez, Sixto E; Gelaye, Bizu

2016-10-01

Childhood abuse is a major global and public health problem associated with a myriad of adverse outcomes across the life course. Suicide is one of the leading causes of mortality during the perinatal period. However, few studies have assessed the relationship between experiences of childhood abuse and suicidal ideation in pregnancy. We sought to examine the association between exposure to childhood abuse and suicidal ideation among pregnant women. A cross-sectional study was conducted among 2964 pregnant women attending prenatal clinics in Lima, Peru. Childhood abuse was assessed using the Childhood Physical and Sexual Abuse Questionnaire. Depression and suicidal ideation were assessed using the Patient Health Questionnaire-9 scale. Logistic regression procedures were performed to estimate adjusted odds ratios and 95% confidence intervals adjusted for potential confounders. Overall, the prevalence of childhood abuse in this cohort was 71.8% and antepartum suicidal ideation was 15.8%. The prevalence of antepartum suicidal ideation was higher among women who reported experiencing any childhood abuse compared to those reporting none (89.3% vs 10.7%, P < .0001). After adjusting for potential confounders, including antepartum depression and lifetime intimate partner violence, those with history of any childhood abuse had a 2.9-fold (2.90, adjusted odds ratio; 95% confidence interval, 2.12-3.97) increased odds of reporting suicidal ideation. Women who experienced both physical and sexual childhood abuse had much higher odds of suicidal ideation (adjusted odds ratio, 4.04; 95% confidence interval, 2.88-5.68). Women who experienced any childhood abuse and reported depression had 3.44-fold (3.44, adjusted odds ratio; 95% confidence interval, 1.84-6.43) increased odds of suicidal ideation compared with depressed women with no history of childhood abuse. Finally, the odds of suicidal ideation increased with increased number of childhood abuse events experienced (P value for linear trend < .001). Maternal history of childhood abuse was associated with increased odds of antepartum suicidal ideation. It is important for clinicians to be aware of the potential increased risk of suicidal behaviors among pregnant women with a history of childhood physical and sexual abuse. Copyright © 2016 Elsevier Inc. All rights reserved.

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…

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)

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.

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.

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

Cardiovascular performance of adult breeding sows fails to obey allometric scaling laws.

PubMed

van Essen, G J; Vernooij, J C M; Heesterbeek, J A P; Anjema, D; Merkus, D; Duncker, D J

2011-02-01

In view of the remarkable decrease of the relative heart weight (HW) and the relative blood volume in growing pigs, we investigated whether HW, cardiac output (CO), and stroke volume (SV) of modern growing pigs are proportional to BW, as predicted by allometric scaling laws: HW (or CO or SV) = a·BW(b), in which a and b are constants, and constant b is a multiple of 0.25 (quarter-power scaling law). Specifically, we tested the hypothesis that both HW and CO scale with BW to the power of 0.75 (HW or CO = a·BW(0.75)) and SV scales with BW to the power of 1.00 (SV = a·BW(1.0)). For this purpose, 2 groups of pigs (group 1, consisting of 157 pigs of 50 ± 1 kg; group 2, consisting of 45 pigs of 268 ± 18 kg) were surgically instrumented with a flow probe or a thermodilution dilution catheter, under open-chest anesthetized conditions to measure CO and SV, after which HW was determined. The 95% confidence intervals of power-coefficient b for HW were 0.74 to 0.80, encompassing the predicted value of 0.75, suggesting that HW increased proportionally with BW, as predicted by the allometric scaling laws. In contrast, the 95% confidence intervals of power-coefficient b for CO and SV as measured with flow probes were 0.40 to 0.56 and 0.39 to 0.61, respectively, and values obtained with the thermodilution technique were 0.34 to 0.53 and 0.40 to 0.62, respectively. Thus, the 95% confidence limits failed to encompass the predicted values of b for CO and SV of 0.75 and 1.0, respectively. In conclusion, although adult breeding sows display normal heart growth, cardiac performance appears to be disproportionately low for BW. This raises concern regarding the health status of adult breeding sows.

Comparison of Free-Breathing With Navigator-Triggered Technique in Diffusion Weighted Imaging for Evaluation of Small Hepatocellular Carcinoma: Effect on Image Quality and Intravoxel Incoherent Motion Parameters.

PubMed

Shan, Yan; Zeng, Meng-su; Liu, Kai; Miao, Xi-Yin; Lin, Jiang; Fu, Cai xia; Xu, Peng-ju

2015-01-01

To evaluate the effect on image quality and intravoxel incoherent motion (IVIM) parameters of small hepatocellular carcinoma (HCC) from choice of either free-breathing (FB) or navigator-triggered (NT) diffusion-weighted (DW) imaging. Thirty patients with 37 small HCCs underwent IVIM DW imaging using 12 b values (0-800 s/mm) with 2 sequences: NT, FB. A biexponential analysis with the Bayesian method yielded true diffusion coefficient (D), pseudodiffusion coefficient (D*), and perfusion fraction (f) in small HCCs and liver parenchyma. Apparent diffusion coefficient (ADC) was also calculated. The acquisition time and image quality scores were assessed for 2 sequences. Independent sample t test was used to compare image quality, signal intensity ratio, IVIM parameters, and ADC values between the 2 sequences; reproducibility of IVIM parameters, and ADC values between 2 sequences was assessed with the Bland-Altman method (BA-LA). Image quality with NT sequence was superior to that with FB acquisition (P = 0.02). The mean acquisition time for FB scheme was shorter than that of NT sequence (6 minutes 14 seconds vs 10 minutes 21 seconds ± 10 seconds P < 0.01). The signal intensity ratio of small HCCs did not vary significantly between the 2 sequences. The ADC and IVIM parameters from the 2 sequences show no significant difference. Reproducibility of D*and f parameters in small HCC was poor (BA-LA: 95% confidence interval, -180.8% to 189.2% for D* and -133.8% to 174.9% for f). A moderate reproducibility of D and ADC parameters was observed (BA-LA: 95% confidence interval, -83.5% to 76.8% for D and -74.4% to 88.2% for ADC) between the 2 sequences. The NT DW imaging technique offers no advantage in IVIM parameters measurements of small HCC except better image quality, whereas FB technique offers greater confidence in fitted diffusion parameters for matched acquisition periods.

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.

Hematology and serum clinical chemistry reference intervals for free-ranging Scandinavian gray wolves (Canis lupus).

PubMed

Thoresen, Stein I; Arnemo, Jon M; Liberg, Olof

2009-06-01

Scandinavian free-ranging wolves (Canis lupus) are endangered, such that laboratory data to assess their health status is increasingly important. Although wolves have been studied for decades, most biological information comes from captive animals. The objective of the present study was to establish reference intervals for 30 clinical chemical and 8 hematologic analytes in Scandinavian free-ranging wolves. All wolves were tracked and chemically immobilized from a helicopter before examination and blood sampling in the winter of 7 consecutive years (1998-2004). Seventy-nine blood samples were collected from 57 gray wolves, including 24 juveniles (24 samples), 17 adult females (25 samples), and 16 adult males (30 samples). Whole blood and serum samples were stored at refrigeration temperature for 1-3 days before hematologic analyses and for 1-5 days before serum biochemical analyses. Reference intervals were calculated as 95% confidence intervals except for juveniles where the minimum and maximum values were used. Significant differences were observed between adult and juvenile wolves for RBC parameters, alkaline phosphatase and amylase activities, and total protein, albumin, gamma-globulins, cholesterol, creatinine, calcium, chloride, magnesium, phosphate, and sodium concentrations. Compared with published reference values for captive wolves, reference intervals for free-ranging wolves reflected exercise activity associated with capture (higher creatine kinase activity, higher glucose concentration), and differences in nutritional status (higher urea concentration).

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

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…

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

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

Whole-lesion histogram analysis metrics of the apparent diffusion coefficient as a marker of breast lesions characterization at 1.5 T.

PubMed

Bougias, H; Ghiatas, A; Priovolos, D; Veliou, K; Christou, A

2017-05-01

To retrospectively assess the role of whole-lesion apparent diffusion coefficient (ADC) in the characterization of breast tumors by comparing different histogram metrics. 49 patients with 53 breast lesions underwent magnetic resonance imaging (MRI). ADC histogram parameters, including the mean, mode, 10th/50th/90th percentile, skewness, kurtosis, and entropy ADCs, were derived for the whole-lesion volume in each patient. Mann-Whitney U-test, area under the receiver-operating characteristic curve (AUC) were used for statistical analysis. The mean, mode and 10th/50th/90th percentile ADC values were significantly lower in malignant lesions compared with benign ones (all P < 0.0001), while skewness was significantly higher in malignant lesions P = 0.02. However, no significant difference was found between entropy and kurtosis values in malignant lesions compared with benign ones (P = 0.06 and P = 1.00, respectively). Univariate logistic regression showed that 10th and 50th percentile ADC yielded the highest AUC (0.985; 95% confidence interval [CI]: 0.902, 1.000 and 0.982; 95% confidence interval [CI]: 0.896, 1.000 respectively), whereas kurtosis value yielded the lowest AUC (0.500; 95% CI: 0.355, 0.645), indicating that 10th and 50th percentile ADC values may be more accurate for lesion discrimination. Whole-lesion ADC histogram analysis could be a helpful index in the characterization and differentiation between benign and malignant breast lesions with the 10th and 50th percentile ADC be the most accurate discriminators. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Excellent amino acid racemization results from Holocene sand dollars

NASA Astrophysics Data System (ADS)

Kosnik, M.; Kaufman, D. S.; Kowalewski, M.; Whitacre, K.

2015-12-01

Amino acid racemization (AAR) is widely used as a cost-effective method to date molluscs in time-averaging and taphonomic studies, but it has not been attempted for echinoderms despite their paleobiological importance. Here we demonstrate the feasibility of AAR geochronology in Holocene aged Peronella peronii (Echinodermata: Echinoidea) collected from Sydney Harbour (Australia). Using standard HPLC methods we determined the extent of AAR in 74 Peronella tests and performed replicate analyses on 18 tests. We sampled multiple areas of two individuals and identified the outer edge as a good sampling location. Multiple replicate analyses from the outer edge of 18 tests spanning the observed range of D/Ls yielded median coefficients of variation < 4% for Asp, Phe, Ala, and Glu D/L values, which overlaps with the analytical precision. Correlations between D/L values across 155 HPLC injections sampled from 74 individuals are also very high (pearson r2 > 0.95) for these four amino acids. The ages of 11 individuals spanning the observed range of D/L values were determined using 14C analyses, and Bayesian model averaging was used to determine the best AAR age model. The averaged age model was mainly composed of time-dependent reaction kinetics models (TDK, 71%) based on phenylalanine (Phe, 94%). Modelled ages ranged from 14 to 5539 yrs, and the median 95% confidence interval for the 74 analysed individuals is ±28% of the modelled age. In comparison, the median 95% confidence interval for the 11 calibrated 14C ages was ±9% of the median age estimate. Overall Peronella yields exceptionally high-quality AAR D/L values and appears to be an excellent substrate for AAR geochronology. This work opens the way for time-averaging and taphonomic studies of echinoderms similar to those in molluscs.

Competing risks model in screening for preeclampsia by maternal factors and biomarkers at 11-13 weeks gestation.

PubMed

O'Gorman, Neil; Wright, David; Syngelaki, Argyro; Akolekar, Ranjit; Wright, Alan; Poon, Leona C; Nicolaides, Kypros H

2016-01-01

Preeclampsia affects approximately 3% of all pregnancies and is a major cause of maternal and perinatal morbidity and death. In the last decade, extensive research has been devoted to early screening for preeclampsia with the aim of reducing the prevalence of the disease through pharmacologic intervention in the high-risk group starting from the first trimester of pregnancy. The purpose of this study was to develop a model for preeclampsia based on maternal demographic characteristics and medical history (maternal factors) and biomarkers. The data for this study were derived from prospective screening for adverse obstetric outcomes in women who attended for their routine first hospital visit at 11-13 weeks gestation in 2 maternity hospitals in England. We screened 35,948 singleton pregnancies that included 1058 pregnancies (2.9%) that experienced preeclampsia. Bayes theorem was used to combine the a priori risk from maternal factors with various combinations of uterine artery pulsatility index, mean arterial pressure, serum pregnancy-associated plasma protein-A, and placental growth factor multiple of the median values. Five-fold cross validation was used to assess the performance of screening for preeclampsia that delivered at <37 weeks gestation (preterm-preeclampsia) and ≥37 weeks gestation (term-preeclampsia) by models that combined maternal factors with individual biomarkers and their combination with screening by maternal factors alone. In pregnancies that experienced preeclampsia, the values of uterine artery pulsatility index and mean arterial pressure were increased, and the values of serum pregnancy-associated plasma protein-A and placental growth factor were decreased. For all biomarkers, the deviation from normal was greater for early than late preeclampsia; therefore, the performance of screening was related inversely to the gestational age at which delivery became necessary for maternal and/or fetal indications. Combined screening by maternal factors, uterine artery pulsatility index, mean arterial pressure, and placental growth factor predicted 75% (95% confidence interval, 70-80%) of preterm-preeclampsia and 47% (95% confidence interval, 44-51%) of term-preeclampsia, at a false-positive rate of 10%; inclusion of pregnancy-associated plasma protein-A did not improve the performance of screening. Such detection rates are superior to the respective values of 49% (95% confidence interval, 43-55%) and 38% (34-41%) that were achieved by screening with maternal factors alone. Combination of maternal factors and biomarkers provides effective first-trimester screening for preterm-preeclampsia. Copyright © 2016. Published by Elsevier Inc.

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.

Special physical examination tests for superior labrum anterior posterior shoulder tears are clinically limited and invalid: a diagnostic systematic review.

PubMed

Calvert, Eric; Chambers, Gordon Keith; Regan, William; Hawkins, Robert H; Leith, Jordan M

2009-05-01

The diagnosis of a superior labrum anterior posterior (SLAP) lesion through physical examination has been widely reported in the literature. Most of these studies report high sensitivities and specificities, and claim to be accurate, valid, and reliable. The purpose of this study was to critically evaluate these studies to determine if there was sufficient evidence to support the use of the SLAP physical examination tests as valid and reliable diagnostic test procedures. Strict epidemiologic methodology was used to obtain and collate all relevant articles. Sackett's guidelines were applied to all articles. Confidence intervals and likelihood ratios were determined. Fifteen of 29 relevant studies met the criteria for inclusion. Only one article met all of Sackett's critical appraisal criteria. Confidence intervals for both the positive and negative likelihood ratios contained the value 1. The current literature being used as a resource for teaching in medical schools and continuing education lacks the validity necessary to be useful. There are no good physical examination tests that exist for effectively diagnosing a SLAP lesion.

Peaks Over Threshold (POT): A methodology for automatic threshold estimation using goodness of fit p-value

NASA Astrophysics Data System (ADS)

Solari, Sebastián.; Egüen, Marta; Polo, María. José; Losada, Miguel A.

2017-04-01

Threshold estimation in the Peaks Over Threshold (POT) method and the impact of the estimation method on the calculation of high return period quantiles and their uncertainty (or confidence intervals) are issues that are still unresolved. In the past, methods based on goodness of fit tests and EDF-statistics have yielded satisfactory results, but their use has not yet been systematized. This paper proposes a methodology for automatic threshold estimation, based on the Anderson-Darling EDF-statistic and goodness of fit test. When combined with bootstrapping techniques, this methodology can be used to quantify both the uncertainty of threshold estimation and its impact on the uncertainty of high return period quantiles. This methodology was applied to several simulated series and to four precipitation/river flow data series. The results obtained confirmed its robustness. For the measured series, the estimated thresholds corresponded to those obtained by nonautomatic methods. Moreover, even though the uncertainty of the threshold estimation was high, this did not have a significant effect on the width of the confidence intervals of high return period quantiles.

Online physician review websites poorly correlate to a validated metric of patient satisfaction.

PubMed

Chen, Jennwood; Presson, Angela; Zhang, Chong; Ray, David; Finlayson, Samuel; Glasgow, Robert

2018-07-01

Physician review websites such as Vitals and Healthgrades are becoming an increasingly popular tool for patients to choose providers. We hypothesized that the scores of these surveys poorly represent the true value of patient satisfaction when compared to a validated survey instrument. Answers from Vitals and Healthgrades online surveys were compared to the Press Ganey Medical Practice Survey (PGMPS) for 200 faculty members at a university hospital for FY15. Weighted Pearson's correlation was used to compare Healthgrades and Vitals to PGMPS. While statistically significant, both Vitals and Healthgrades had very low correlations with the PGMPS with weighted coefficients of 0.18 (95% confidence interval: 0.02-0.34, P = 0.025) and 0.27 (95% confidence interval: 0.12-0.42, P < 0.001), respectively. Online physician rating websites such as Vitals and Healthgrades poorly correlate with the PGMPS, a validated measure of patient satisfaction. Patients should be aware of these limitations and, consequently, should have access to the most accurate measure of patient satisfaction. Copyright © 2018 Elsevier Inc. All rights reserved.

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…

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.

Fatigue failure of materials under broad band random vibrations

NASA Technical Reports Server (NTRS)

Huang, T. C.; Lanz, R. W.

1971-01-01

The fatigue life of material under multifactor influence of broad band random excitations has been investigated. Parameters which affect the fatigue life are postulated to be peak stress, variance of stress and the natural frequency of the system. Experimental data were processed by the hybrid computer. Based on the experimental results and regression analysis a best predicting model has been found. All values of the experimental fatigue lives are within the 95% confidence intervals of the predicting equation.

Methods for the accurate estimation of confidence intervals on protein folding ϕ-values

PubMed Central

Ruczinski, Ingo; Sosnick, Tobin R.; Plaxco, Kevin W.

2006-01-01

ϕ-Values provide an important benchmark for the comparison of experimental protein folding studies to computer simulations and theories of the folding process. Despite the growing importance of ϕ measurements, however, formulas to quantify the precision with which ϕ is measured have seen little significant discussion. Moreover, a commonly employed method for the determination of standard errors on ϕ estimates assumes that estimates of the changes in free energy of the transition and folded states are independent. Here we demonstrate that this assumption is usually incorrect and that this typically leads to the underestimation of ϕ precision. We derive an analytical expression for the precision of ϕ estimates (assuming linear chevron behavior) that explicitly takes this dependence into account. We also describe an alternative method that implicitly corrects for the effect. By simulating experimental chevron data, we show that both methods accurately estimate ϕ confidence intervals. We also explore the effects of the commonly employed techniques of calculating ϕ from kinetics estimated at non-zero denaturant concentrations and via the assumption of parallel chevron arms. We find that these approaches can produce significantly different estimates for ϕ (again, even for truly linear chevron behavior), indicating that they are not equivalent, interchangeable measures of transition state structure. Lastly, we describe a Web-based implementation of the above algorithms for general use by the protein folding community. PMID:17008714

MTB-DR-RIF 9G test: Detection and discrimination of tuberculosis and multi-drug resistant tuberculosis strains.

PubMed

Song, Keum-Soo; Nimse, Satish Balasaheb; Cho, Nam Hoon; Sung, Nackmoon; Kim, Hee-Jin; Yang, Jeongseong; Kim, Taisun

2015-12-01

This report describes the evaluation of the novel MTB-DR-RIF 9G test for the accurate detection and discrimination of Mycobacterium tuberculosis (MTB) and rifampicin-resistant M. tuberculosis (MTB-DR-RIF) in the clinical samples. The procedure included the amplification of a nucleotide fragment of the rpoB gene of the MTB and MTB-DR-RIF strains and their hybridization with the immobilized probes. The MTB-DR-RIF 9G test was evaluated for its ability to detect and discriminate MTB and MTB-DR-RIF strains in 113 known clinical samples. The accuracy of the MTB-DR-RIF 9G test was determined by comparing its results with sequencing analysis and drug susceptibility testing. The sensitivity and specificity of the MTB-DR-RIF 9G test at 95% confidence interval were found to be 95.4% (89.5-98.5) and 100% (69.2-100), respectively. The positive predictive value and negative predictive value of the MTB-DR-RIF 9G test at 95% confidence interval were found to be 100% (85.0-95.9) and 66.7% (38.4-88.18), respectively. Sequencing analysis of all samples indicated that the mutations present in the regions identified with the MTB-DR-RIF 9G assay can be detected accurately. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acoustic analysis of swallowing sounds: a new technique for assessing dysphagia.

PubMed

Santamato, Andrea; Panza, Francesco; Solfrizzi, Vincenzo; Russo, Anna; Frisardi, Vincenza; Megna, Marisa; Ranieri, Maurizio; Fiore, Pietro

2009-07-01

To perform acoustic analysis of swallowing sounds, using a microphone and a notebook computer system, in healthy subjects and patients with dysphagia affected by neurological diseases, testing the positive/negative predictive value of a pathological pattern of swallowing sounds for penetration/aspiration. Diagnostic test study, prospective, not blinded, with the penetration/aspiration evaluated by fibreoptic endoscopy of swallowing as criterion standard. Data from a previously recorded database of normal swallowing sounds for 60 healthy subjects according to gender, age, and bolus consistency was compared with those of 15 patients with dysphagia from a university hospital referral centre who were affected by various neurological diseases. Mean duration of the swallowing sounds and post-swallowing apnoea were recorded. Penetration/aspiration was verified by fibreoptic endoscopy of swallowing in all patients with dysphagia. The mean duration of swallowing sounds for a liquid bolus of 10 ml water was significantly different between patients with dysphagia and healthy patients. We also described patterns of swallowing sounds and tested the negative/positive predictive values of post-swallowing apnoea for penetration/aspiration verified by fibreoptic endoscopy of swallowing (sensitivity 0.67 (95% confidence interval 0.24-0.94); specificity 1.00 (95% confidence interval 0.56-1.00)). The proposed technique for recording and measuring swallowing sounds could be incorporated into the bedside evaluation, but it should not replace the use of more diagnostic and valuable measures.

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.

Fecal Calprotectin Levels Are Closely Correlated with the Absence of Relevant Mucosal Lesions in Postoperative Crohn's Disease.

PubMed

Garcia-Planella, Esther; Mañosa, Míriam; Cabré, Eduard; Marín, Laura; Gordillo, Jordi; Zabana, Yamile; Boix, Jaume; Sáinz, Sergio; Domènech, Eugeni

2016-12-01

Fecal calprotectin (FC) is the best noninvasive biomarker of disease activity in inflammatory bowel disease. Its correlation with endoscopic mucosal lesions could save inconvenient, expensive, and repeated endoscopic examinations in particular clinical settings. To assess the correlation between FC and the existence and severity of endoscopic postoperative recurrence (POR), a group of clinically stable outpatients with Crohn's disease for whom an ileocolonoscopy was routinely planned to assess POR were invited to collect a stool sample before starting bowel cleansing to measure FC. POR was graded by means of Rutgeerts endoscopic score. One hundred nineteen ileocolonoscopies were included, 42% with endoscopic POR. FC was significantly lower in the absence of endoscopic POR and in the absence of any endoscopic lesion. The area under the receiver operating characteristic curve was 0.76 (95% confidence interval, 0.68-0.85) for the diagnosis of the absence of lesions and 0.75 (95% confidence interval, 0.66-0.84) for endoscopic POR. Better sensitivity and negative predictive value were observed when combining FC and serum C-reactive protein (CRP), leading to a sensitivity of 82%, a specificity of 53%, and negative and positive predictive values of 81% and 54%, respectively, for the prediction of endoscopic POR with a combination of FC 100 μg/g and CRP 5 mg/L cutoff values. FC correlates closely with endoscopic POR in clinically stable postoperative patients with Crohn's disease and, when used in combination with CRP, might save endoscopic examinations and allow for a high-grade suspicion of endoscopic POR in the long-term monitoring of these patients.

Insomnia with physiological hyperarousal is associated with hypertension.

PubMed

Li, Yun; Vgontzas, Alexandros N; Fernandez-Mendoza, Julio; Bixler, Edward O; Sun, Yuanfeng; Zhou, Junying; Ren, Rong; Li, Tao; Tang, Xiangdong

2015-03-01

Previous studies have suggested that insomnia with objective short sleep duration is associated with a higher risk of hypertension, and it has been speculated that the underlying mechanism is physiological hyperarousal. In this study, we tested whether insomnia with physiological hyperarousal measured by Multiple Sleep Latency Test (MSLT), a standard test of sleepiness/alertness, is associated with increased risk of hypertension. Two hundred nineteen chronic insomniacs and 96 normal sleepers were included in this study. Chronic insomnia was defined based on standard diagnostic criteria with symptoms lasting ≥6 months. All subjects underwent 1 night in laboratory polysomnography followed by a standard MSLT. We used the median mean MSLT value (ie, >14 minutes) and the 75th percentile of mean MSLT value (ie, >17 minutes) to define hyperarousal. Hypertension was defined based either on blood pressure measures or on diagnosis treatment by a physician. After controlling for age, sex, body mass index, apnea-hypopnea index, diabetes mellitus, smoking, alcohol, and caffeine use, insomnia combined with MSLT >14 minutes increased the odds of hypertension by 300% (odds ratio=3.27; 95% confidence interval=1.20-8.96), whereas insomnia combined with MSLT >17 minutes increased even further the odds of hypertension by 400% (odds ratio=4.33; 95% confidence interval=1.48-12.68) compared with normal sleepers with MSLT ≤14 minutes. Insomnia associated with physiological hyperarousal is associated with a significant risk of hypertension. Long MSLT values may be a reliable index of the physiological hyperarousal and biological severity of chronic insomnia. © 2015 American Heart Association, Inc.

Robust characterization of small grating boxes using rotating stage Mueller matrix polarimeter

NASA Astrophysics Data System (ADS)

Foldyna, M.; De Martino, A.; Licitra, C.; Foucher, J.

2010-03-01

In this paper we demonstrate the robustness of the Mueller matrix polarimetry used in multiple-azimuth configuration. We first demonstrate the efficiency of the method for the characterization of small pitch gratings filling 250 μm wide square boxes. We used a Mueller matrix polarimeter directly installed in the clean room has motorized rotating stage allowing the access to arbitrary conical grating configurations. The projected beam spot size could be reduced to 60x25 μm, but for the measurements reported here this size was 100x100 μm. The optimal values of parameters of a trapezoidal profile model, acquired for each azimuthal angle separately using a non-linear least-square minimization algorithm, are shown for a typical grating. Further statistical analysis of the azimuth-dependent dimensional parameters provided realistic estimates of the confidence interval giving direct information about the accuracy of the results. The mean values and the standard deviations were calculated for 21 different grating boxes featuring in total 399 measured spectra and fits. The results for all boxes are summarized in a table which compares the optical method to the 3D-AFM. The essential conclusion of our work is that the 3D-AFM values always fall into the confidence intervals provided by the optical method, which means that we have successfully estimated the accuracy of our results without using direct comparison with another, non-optical, method. Moreover, this approach may provide a way to improve the accuracy of grating profile modeling by minimizing the standard deviations evaluated from multiple-azimuths results.

The value of FATS expression in predicting sensitivity to radiotherapy in breast cancer

PubMed Central

Zhang, Tiemei; Sun, Tao; Su, Yi; Zhao, Jing; Mu, Kun; Jin, Zhao; Gao, Ming; Liu, Juntian; Gu, Lin

2017-01-01

Purpose The fragile-site associated tumor suppressor (FATS) is a newly identified tumor suppressor involved in radiation-induced tumorigenesis. The purpose of this study was to characterize FATS expression in breast cancers about radiotherapy benefit, patient characteristics, and prognosis. Results The expression of FATS mRNA was silent or downregulated in 95.2% of breast cancer samples compared with paired normal controls (P < .0001). Negative status of FATS was correlated with higher nuclear grade (P = .01) and shorter disease-free survival (DFS) of breast cancer (P = .036). In a multivariate analysis, FATS expression showed favorable prognostic value for DFS (odds ratio, 0.532; 95% confidence interval, 0.299 to 0.947; (P = .032). Furthermore, improved survival time was seen in FATS-positive patients receiving radiotherapy (P = .006). The results of multivariate analysis revealed independent prognostic value of FATS expression in predicting longer DFS (odds ratio, 0.377; 95% confidence interval, 0.176 to 0.809; P = 0.012) for patients receiving adjuvant radiotherapy. In support of this, reduction of FATS expression in breast cancer cell lines, FATS positive group significantly sensitized than Knock-down of FATS group. Materials and Methods Tissue samples from 156 breast cancer patients and 42 controls in tumor bank were studied. FATS gene expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). FATS function was examined in breast cancer cell lines using siRNA knock-downs and colony forming assays after irradiation. Conclusions FATS status is a biomarker in breast cancer to identify individuals likely to benefit from radiotherapy. PMID:28402275

Poor Positive Predictive Value of Lyme Disease Serologic Testing in an Area of Low Disease Incidence

PubMed Central

Lantos, Paul M.; Branda, John A.; Boggan, Joel C.; Chudgar, Saumil M.; Wilson, Elizabeth A.; Ruffin, Felicia; Fowler, Vance; Auwaerter, Paul G.; Nigrovic, Lise E.

2015-01-01

Background. Lyme disease is diagnosed by 2-tiered serologic testing in patients with a compatible clinical illness, but the significance of positive test results in low-prevalence regions has not been investigated. Methods. We reviewed the medical records of patients who tested positive for Lyme disease with standardized 2-tiered serologic testing between 2005 and 2010 at a single hospital system in a region with little endemic Lyme disease. Based on clinical findings, we calculated the positive predictive value of Lyme disease serology. Next, we reviewed the outcome of serologic testing in patients with select clinical syndromes compatible with disseminated Lyme disease (arthritis, cranial neuropathy, or meningitis). Results. During the 6-year study period 4723 patients were tested for Lyme disease, but only 76 (1.6%) had positive results by established laboratory criteria. Among 70 seropositive patients whose medical records were available for review, 12 (17%; 95% confidence interval, 9%–28%) were found to have Lyme disease (6 with documented travel to endemic regions). During the same time period, 297 patients with a clinical illness compatible with disseminated Lyme disease underwent 2-tiered serologic testing. Six of them (2%; 95% confidence interval, 0.7%–4.3%) were seropositive, 3 with documented travel and 1 who had an alternative diagnosis that explained the clinical findings. Conclusions. In this low-prevalence cohort, fewer than 20% of positive Lyme disease tests are obtained from patients with clinically likely Lyme disease. Positive Lyme disease test results may have little diagnostic value in this setting. PMID:26195017

The use of a physiologically-based extraction test to assess relationships between bioaccessible metals in urban soil and neurodevelopmental conditions in children.

PubMed

Hong, Jie; Wang, Yinding; McDermott, Suzanne; Cai, Bo; Aelion, C Marjorie; Lead, Jamie

2016-05-01

Intellectual disability (ID) and cerebral palsy (CP) are serious neurodevelopment conditions and low birth weight (LBW) is correlated with both ID and CP. The actual causes and mechanisms for each of these child outcomes are not well understood. In this study, the relationship between bioaccessible metal concentrations in urban soil and these child conditions were investigated. A physiologically based extraction test (PBET) mimicking gastric and intestinal processes was applied to measure the bio-accessibility of four metals (cadmium (Cd), chromium (Cr), nickel (Ni), and lead (Pb)) in urban soil, and a Bayesian Kriging method was used to estimate metal concentrations in geocoded maternal residential sites. The results showed that bioaccessible metal concentrations of Cd, Ni, and Pb in the intestinal phase were statistically significantly associated with the child outcomes. Lead and nickel were associated with ID, lead and cadmium was associated with LBW, and cadmium was associated with CP. The total concentrations and stomach concentrations were not correlated to significant effects in any of the analyses. For lead, an estimated threshold value was found that was statistically significant in predicting low birth weight. The change point test was statistically significant (p value = 0.045) at an intestine threshold level of 9.2 mg/kg (95% confidence interval 8.9-9.4, p value = 0.0016), which corresponds to 130.6 mg/kg of total Pb concentration in the soil. This is a narrow confidence interval for an important relationship. Published by Elsevier Ltd.

The value of FATS expression in predicting sensitivity to radiotherapy in breast cancer.

PubMed

Zhang, Jun; Wu, Nan; Zhang, Tiemei; Sun, Tao; Su, Yi; Zhao, Jing; Mu, Kun; Jin, Zhao; Gao, Ming; Liu, Juntian; Gu, Lin

2017-06-13

The fragile-site associated tumor suppressor (FATS) is a newly identified tumor suppressor involved in radiation-induced tumorigenesis. The purpose of this study was to characterize FATS expression in breast cancers about radiotherapy benefit, patient characteristics, and prognosis. The expression of FATS mRNA was silent or downregulated in 95.2% of breast cancer samples compared with paired normal controls (P < .0001). Negative status of FATS was correlated with higher nuclear grade (P = .01) and shorter disease-free survival (DFS) of breast cancer (P = .036). In a multivariate analysis, FATS expression showed favorable prognostic value for DFS (odds ratio, 0.532; 95% confidence interval, 0.299 to 0.947; (P = .032). Furthermore, improved survival time was seen in FATS-positive patients receiving radiotherapy (P = .006). The results of multivariate analysis revealed independent prognostic value of FATS expression in predicting longer DFS (odds ratio, 0.377; 95% confidence interval, 0.176 to 0.809; P = 0.012) for patients receiving adjuvant radiotherapy. In support of this, reduction of FATS expression in breast cancer cell lines, FATS positive group significantly sensitized than Knock-down of FATS group. Tissue samples from 156 breast cancer patients and 42 controls in tumor bank were studied. FATS gene expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). FATS function was examined in breast cancer cell lines using siRNA knock-downs and colony forming assays after irradiation. FATS status is a biomarker in breast cancer to identify individuals likely to benefit from radiotherapy.

Acoustic Radiation Force Impulse Quantification in the Evaluation of Renal Parenchyma Elasticity in Pediatric Patients With Chronic Kidney Disease: Preliminary Results.

PubMed

Bilgici, Meltem Ceyhan; Bekci, Tumay; Genc, Gurkan; Tekcan, Demet; Tomak, Leman

2017-08-01

To evaluate renal parenchymal elasticity with acoustic radiation force impulse imaging in pediatric patients with chronic kidney disease (CKD) and compare with healthy volunteers. Thirty-eight healthy volunteers and 30 pediatric CKD patients were enrolled in this prospective study. The shear wave velocity (SW) values of both kidneys in CKD patients and healthy volunteers were evaluated. The mean SW in healthy volunteers was 2.21 ± 0.34 m/s, whereas the same value was 1.81 ± 0.49, 1.72 ± 0.63, 1.66 ± 0.29, 1.48 ± 0.37, and 1.23 ± 0.27 for stages 1, 2, 3, 4, and 5 in CKD patients, respectively. The SW was significantly lower for each stage in the CKD patients compared with healthy volunteers. Acoustic radiation force impulse could not predict the different stages of CKD, with the exception of stage 5. The cut-off value for predicting CKD was 1.81 m/s; at this threshold, sensitivity was 76.5% and specificity was 92.1% (area under the curve = 0.870 [95% confidence interval: 0.750-0.990]; P < .001). Interobserver agreement expressed as intraclass coefficient correlation was 0.65 (95% confidence interval: 0.34 to 0.83; P < .001). Acoustic radiation force impulse may be a potentially useful tool in detecting CKD in pediatric patients. © 2017 by the American Institute of Ultrasound in Medicine.

The effect of Fisher information matrix approximation methods in population optimal design calculations.

PubMed

Strömberg, Eric A; Nyberg, Joakim; Hooker, Andrew C

2016-12-01

With the increasing popularity of optimal design in drug development it is important to understand how the approximations and implementations of the Fisher information matrix (FIM) affect the resulting optimal designs. The aim of this work was to investigate the impact on design performance when using two common approximations to the population model and the full or block-diagonal FIM implementations for optimization of sampling points. Sampling schedules for two example experiments based on population models were optimized using the FO and FOCE approximations and the full and block-diagonal FIM implementations. The number of support points was compared between the designs for each example experiment. The performance of these designs based on simulation/estimations was investigated by computing bias of the parameters as well as through the use of an empirical D-criterion confidence interval. Simulations were performed when the design was computed with the true parameter values as well as with misspecified parameter values. The FOCE approximation and the Full FIM implementation yielded designs with more support points and less clustering of sample points than designs optimized with the FO approximation and the block-diagonal implementation. The D-criterion confidence intervals showed no performance differences between the full and block diagonal FIM optimal designs when assuming true parameter values. However, the FO approximated block-reduced FIM designs had higher bias than the other designs. When assuming parameter misspecification in the design evaluation, the FO Full FIM optimal design was superior to the FO block-diagonal FIM design in both of the examples.

Zinc supplements for treating thalassaemia and sickle cell disease.

PubMed

Swe, Kye Mon Min; Abas, Adinegara B L; Bhardwaj, Amit; Barua, Ankur; Nair, N S

2013-06-28

Haemoglobinopathies, inherited disorders of haemoglobin synthesis (thalassaemia) or structure (sickle cell disease), are responsible for significant morbidity and mortality throughout the world. The WHO estimates that, globally, 5% of adults are carriers of a haemoglobin condition, 2.9% are carriers of thalassaemia and 2.3% are carriers of sickle cell disease. Carriers are found worldwide as a result of migration of various ethnic groups to different regions of the world. Zinc is an easily available supplement and intervention programs have been carried out to prevent deficiency in people with thalassaemia or sickle cell anaemia. It is important to evaluate the role of zinc supplementation in the treatment of thalassaemia and sickle cell anaemia to reduce deaths due to complications. To assess the effect of zinc supplementation in the treatment of thalassaemia and sickle cell disease. We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of most recent search: 01 February 2013. Randomised, placebo-controlled trials of zinc supplements for treating thalassaemia or sickle cell disease administered at least once a week for at least a month. Two review authors assessed the eligibility and risk of bias of the included trials, extracted and analysed data and wrote the review. We summarised results using risk ratios or rate ratios for dichotomous data and mean differences for continuous data. We combined trial results where appropriate. We identified nine trials for inclusion with all nine contributing outcome data. Two trials reported on people with thalassaemia (n = 152) and seven on sickle cell anaemia (n = 307).In people with thalassaemia, in one trial, the serum zinc level value showed no difference between the zinc supplemented group and the control group, mean difference 47.40 (95% confidence interval -12.95 to 107.99). Regarding anthropometry, in one trial, height velocity was significantly increased in patients who received zinc supplementation for one to seven years duration, mean difference 3.37 (95% confidence interval 2.36 to 4.38) (total number of participants = 26). In one trial, however, there was no difference in body mass index between treatment groups.Zinc acetate supplementation for three months (in one trial) and one year (in two trials) (total number of participants = 71) was noted to increase the serum zinc level significantly in patients with sickle cell anaemia, mean difference 14.90 (95% confidence interval 6.94 to 22.86) and 20.25 (95% confidence interval 11.73 to 28.77) respectively. There was no significant difference in haemoglobin level between intervention and control groups, at either three months (one trial) or one year (one trial), mean difference 0.06 (95% confidence interval -0.84 to 0.96) and mean difference -0.07 (95% confidence interval -1.40 to 1.26) respectively. Regarding anthropometry, one trial showed no significant changes in body mass index or weight after one year of zinc acetate supplementation. In patients with sickle cell disease, the total number of sickle cell crises at one year were significantly decreased in the zinc sulphate supplemented group as compared to controls, mean difference -2.83 (95% confidence interval -3.51 to -2.15) (total participants 130), but not in zinc acetate group, mean difference 1.54 (95% confidence interval -2.01 to 5.09) (total participants 22). In one trial at three months and another at one year, the total number of clinical infections were significantly decreased in the zinc supplemented group as compared to controls, mean difference 0.05 (95% confidence interval 0.01 - 0.43) (total number of participants = 36), and mean difference -7.64 (95% confidence interval -10.89 to -4.39) (total number of participants = 21) respectively. According to the results, there is no evidence from randomised controlled trials to indicate any benefit of zinc supplementation with regards to serum zinc level in patients with thalassaemia. However, height velocity was noted to increase among those who received this intervention.There is mixed evidence on the benefit of using zinc supplementation in people with sickle cell disease. For instance, there is evidence that zinc supplementation for one year increased the serum zinc levels in patients with sickle cell disease. However, though serum zinc level was raised in patients receiving zinc supplementation, haemoglobin level and anthropometry measurements were not significantly different between groups. Evidence of benefit is seen with the reduction in the number of sickle cell crises among sickle cell patients who received one year of zinc sulphate supplementation and with the reduction in the total number of clinical infections among sickle cell patients who received zinc supplementation for both three months and for one year.The conclusion is based on the data from a small group of trials,which were generally of good quality, with a low risk of bias. The authors recommend that more trials on zinc supplementation in thalassaemia and sickle cell disease be conducted given that the literature has shown the benefits of zinc in these types of diseases.

Reference intervals for selected serum biochemistry analytes in cheetahs Acinonyx jubatus.

PubMed

Hudson-Lamb, Gavin C; Schoeman, Johan P; Hooijberg, Emma H; Heinrich, Sonja K; Tordiffe, Adrian S W

2016-02-26

Published haematologic and serum biochemistry reference intervals are very scarce for captive cheetahs and even more for free-ranging cheetahs. The current study was performed to establish reference intervals for selected serum biochemistry analytes in cheetahs. Baseline serum biochemistry analytes were analysed from 66 healthy Namibian cheetahs. Samples were collected from 30 captive cheetahs at the AfriCat Foundation and 36 free-ranging cheetahs from central Namibia. The effects of captivity-status, age, sex and haemolysis score on the tested serum analytes were investigated. The biochemistry analytes that were measured were sodium, potassium, magnesium, chloride, urea and creatinine. The 90% confidence interval of the reference limits was obtained using the non-parametric bootstrap method. Reference intervals were preferentially determined by the non-parametric method and were as follows: sodium (128 mmol/L - 166 mmol/L), potassium (3.9 mmol/L - 5.2 mmol/L), magnesium (0.8 mmol/L - 1.2 mmol/L), chloride (97 mmol/L - 130 mmol/L), urea (8.2 mmol/L - 25.1 mmol/L) and creatinine (88 µmol/L - 288 µmol/L). Reference intervals from the current study were compared with International Species Information System values for cheetahs and found to be narrower. Moreover, age, sex and haemolysis score had no significant effect on the serum analytes in this study. Separate reference intervals for captive and free-ranging cheetahs were also determined. Captive cheetahs had higher urea values, most likely due to dietary factors. This study is the first to establish reference intervals for serum biochemistry analytes in cheetahs according to international guidelines. These results can be used for future health and disease assessments in both captive and free-ranging cheetahs.

NADiA ProsVue prostate-specific antigen slope is an independent prognostic marker for identifying men at reduced risk of clinical recurrence of prostate cancer after radical prostatectomy.

PubMed

Moul, Judd W; Lilja, Hans; Semmes, O John; Lance, Raymond S; Vessella, Robert L; Fleisher, Martin; Mazzola, Clarisse; Sarno, Mark J; Stevens, Barbara; Klem, Robert E; McDermed, Jonathan E; Triebell, Melissa T; Adams, Thomas H

2012-12-01

To validate the hypothesis that men displaying serum prostate-specific antigen (PSA) slopes ≤ 2.0 pg/mL/mo after prostatectomy, measured using a new immuno-polymerase chain reaction diagnostic test (NADiA ProsVue), have a reduced risk of clinical recurrence as determined by positive biopsy, imaging findings, or death from prostate cancer. From 4 clinical sites, we selected a cohort of 304 men who had been followed up for 17.6 years after prostatectomy for clinical recurrence. We assessed the prognostic value of a PSA slope cutpoint of 2.0 pg/mL/mo against established risk factors to identify men at low risk of clinical recurrence using uni- and multivariate Cox proportional hazards regression and Kaplan-Meier analyses. The univariate hazard ratio of a PSA slope >2.0 pg/mL/mo was 18.3 (95% confidence interval 10.6-31.8) compared with a slope ≤ 2.0 pg/mL/mo (P <.0001). The median disease-free survival interval was 4.8 years vs >10 years in the 2 groups (P <.0001). The multivariate hazard ratio for PSA slope with the covariates of preprostatectomy PSA, pathologic stage, and Gleason score was 9.8 (95% confidence interval 5.4-17.8), an 89.8% risk reduction for men with PSA slopes ≤ 2.0 pg/mL/mo (P <.0001). The Gleason score (<7 vs ≥ 7) was the only other significant predictor (hazard ratio 5.4, 95% confidence interval 2.1-13.8, P = .0004). Clinical recurrence after radical prostatectomy is difficult to predict using established risk factors. We have demonstrated that a NADiA ProsVue PSA slope of ≤ 2.0 pg/mL/mo after prostatectomy is prognostic for a reduced risk of prostate cancer recurrence and adds predictive power to the established risk factors. Copyright © 2012 Elsevier Inc. All rights reserved.

Post Hoc Analyses of Randomized Clinical Trial for the Effect of Clopidogrel Added to Aspirin on Kidney Function.

PubMed

Ikeme, Jesse C; Pergola, Pablo E; Scherzer, Rebecca; Shlipak, Michael G; Benavente, Oscar R; Peralta, Carmen A

2017-07-07

Despite the high burden of CKD, few specific therapies are available that can halt disease progression. In animal models, clopidogrel has emerged as a potential therapy to preserve kidney function. The effect of clopidogrel on kidney function in humans has not been established. The Secondary Prevention of Small Subcortical Strokes Study randomized participants with prior lacunar stroke to treatment with aspirin or aspirin plus clopidogrel. We compared annual eGFR decline and incidence of rapid eGFR decline (≥30% from baseline) using generalized estimating equations and interval-censored proportional hazards regression, respectively. We also stratified our analyses by baseline eGFR, systolic BP target, and time after randomization. At randomization, median age was 62 (interquartile range, 55-71) years old; 36% had a history of diabetes, 90% had hypertension, and the median eGFR was 81 (interquartile range, 65-94) ml/min per 1 m 2 . Persons receiving aspirin plus clopidogrel had an average annual change in kidney function of -1.39 (95% confidence interval, -1.15 to -1.62) ml/min per 1.73 m 2 per year compared with -1.52 (95% confidence interval, -1.30 to -1.74) ml/min per 1.73 m 2 per year among persons receiving aspirin only ( P =0.42). Rapid kidney function decline occurred in 21% of participants receiving clopidogrel plus aspirin compared with 22% of participants receiving aspirin plus placebo (hazard ratio, 0.94; 95% confidence interval, 0.79 to 1.10; P =0.42). Findings did not vary by baseline eGFR, time after randomization, or systolic BP target (all P values for interaction were >0.3). We found no effect of clopidogrel added to aspirin compared with aspirin alone on kidney function decline among persons with prior lacunar stroke. Copyright © 2017 by the American Society of Nephrology.

Altered blood glucose concentration is associated with risk of death among patients with community-acquired Gram-negative rod bacteremia.

PubMed

Peralta, Galo; Sánchez, M Blanca; Garrido, J Carlos; Ceballos, Begoña; Mateos, Fátima; De Benito, Inés; Roiz, M Pía

2010-06-22

Altered blood glucose concentration is commonly observed in patients with sepsis, even among those without hypoglycemic treatments or history of diabetes mellitus. These alterations in blood glucose are potentially detrimental, although the precise relationship with outcome in patients with bacteremia has not been yet determined. A retrospective cohort study design for analyzing patients with Gram negative rod bacteremia was employed, with the main outcome measure being in-hospital mortality. Patients were stratified in quintiles accordingly deviation of the blood glucose concentration from a central value with lowest mortality. Cox proportional-hazards regression model was used for determining the relationship of same day of bacteremia blood glucose and death. Of 869 patients identified 63 (7.4%) died. Same day of bacteremia blood glucose concentration had a U-shaped relationship with in-hospital mortality. The lowest mortality (2%) was detected in the range of blood glucose concentration from 150 to 160 mg/dL. Greater deviation of blood glucose concentration from the central value of this range (155 mg/dL, reference value) was directly associated with higher risk of death (p = 0.002, chi for trend). The low-risk group (quintile 1) had a mortality of 3.3%, intermediate-risk group (quintiles 2, 3 and 4) a mortality of 7.1%, and the high-risk group (quintile 5) a mortality of 12.05%. In a multivariable Cox regression model, the hazard ratio for death among patients in the intermediate-risk group as compared with that in the low risk group was 2.88 (95% confidence interval, 1.01 to 8.18; P = 0.048), and for the high risk group it was 4.26 (95% confidence interval, 1.41 to 12.94; P = 0.01). Same day of bacteremia blood glucose concentration is related with outcome of patients with Gram-negative rod bacteremia. Lowest mortality is detected in patients with blood glucose concentration in an interval of 150-160 mg/dL. Deviations from these values are associated with an increased risk of death.

Altered blood glucose concentration is associated with risk of death among patients with community-acquired Gram-negative rod bacteremia

PubMed Central

2010-01-01

Background Altered blood glucose concentration is commonly observed in patients with sepsis, even among those without hypoglycemic treatments or history of diabetes mellitus. These alterations in blood glucose are potentially detrimental, although the precise relationship with outcome in patients with bacteremia has not been yet determined. Methods A retrospective cohort study design for analyzing patients with Gram negative rod bacteremia was employed, with the main outcome measure being in-hospital mortality. Patients were stratified in quintiles accordingly deviation of the blood glucose concentration from a central value with lowest mortality. Cox proportional-hazards regression model was used for determining the relationship of same day of bacteremia blood glucose and death. Results Of 869 patients identified 63 (7.4%) died. Same day of bacteremia blood glucose concentration had a U-shaped relationship with in-hospital mortality. The lowest mortality (2%) was detected in the range of blood glucose concentration from 150 to 160 mg/dL. Greater deviation of blood glucose concentration from the central value of this range (155 mg/dL, reference value) was directly associated with higher risk of death (p = 0.002, chi for trend). The low-risk group (quintile 1) had a mortality of 3.3%, intermediate-risk group (quintiles 2, 3 and 4) a mortality of 7.1%, and the high-risk group (quintile 5) a mortality of 12.05%. In a multivariable Cox regression model, the hazard ratio for death among patients in the intermediate-risk group as compared with that in the low risk group was 2.88 (95% confidence interval, 1.01 to 8.18; P = 0.048), and for the high risk group it was 4.26 (95% confidence interval, 1.41 to 12.94; P = 0.01). Conclusions Same day of bacteremia blood glucose concentration is related with outcome of patients with Gram-negative rod bacteremia. Lowest mortality is detected in patients with blood glucose concentration in an interval of 150-160 mg/dL. Deviations from these values are associated with an increased risk of death. PMID:20569435

Influence of air quality model resolution on uncertainty associated with health impacts

NASA Astrophysics Data System (ADS)

Thompson, T. M.; Selin, N. E.

2012-10-01

We use regional air quality modeling to evaluate the impact of model resolution on uncertainty associated with the human health benefits resulting from proposed air quality regulations. Using a regional photochemical model (CAMx), we ran a modeling episode with meteorological inputs simulating conditions as they occurred during August through September 2006 (a period representative of conditions leading to high ozone), and two emissions inventories (a 2006 base case and a 2018 proposed control scenario, both for Houston, Texas) at 36, 12, 4 and 2 km resolution. The base case model performance was evaluated for each resolution against daily maximum 8-h averaged ozone measured at monitoring stations. Results from each resolution were more similar to each other than they were to measured values. Population-weighted ozone concentrations were calculated for each resolution and applied to concentration response functions (with 95% confidence intervals) to estimate the health impacts of modeled ozone reduction from the base case to the control scenario. We found that estimated avoided mortalities were not significantly different between the 2, 4 and 12 km resolution runs, but the 36 km resolution may over-predict some potential health impacts. Given the cost/benefit analysis requirements motivated by Executive Order 12866 as it applies to the Clean Air Act, the uncertainty associated with human health impacts and therefore the results reported in this study, we conclude that health impacts calculated from population weighted ozone concentrations obtained using regional photochemical models at 36 km resolution fall within the range of values obtained using fine (12 km or finer) resolution modeling. However, in some cases, 36 km resolution may not be fine enough to statistically replicate the results achieved using 2, 4 or 12 km resolution. On average, when modeling at 36 km resolution, an estimated 5 deaths per week during the May through September ozone season are avoided because of ozone reductions resulting from the proposed emissions reductions (95% confidence interval was 2-8). When modeling at 2, 4 or 12 km finer scale resolution, on average 4 deaths are avoided due to the same reductions (95% confidence interval was 1-7). Study results show that ozone modeling at a resolution finer than 12 km is unlikely to reduce uncertainty in benefits analysis for this specific region. We suggest that 12 km resolution may be appropriate for uncertainty analyses of health impacts due to ozone control scenarios, in areas with similar chemistry, meteorology and population density, but that resolution requirements should be assessed on a case-by-case basis and revised as confidence intervals for concentration-response functions are updated.

The effect of omega-3 supplementation on pregnancy outcomes by smoking status.

PubMed

Kuper, Spencer G; Abramovici, Adi R; Jauk, Victoria C; Harper, Lorie M; Biggio, Joseph R; Tita, Alan T

2017-10-01

Smoking during pregnancy is associated with adverse maternal and neonatal outcomes such as preterm delivery, intrauterine growth restriction, stillbirth, and low birth weight. Because smoking causes oxidative stress, some have suggested using antioxidants to counteract the effects of oxidative stress. Smokers have lower serum levels of omega-3 fatty acids, an important antioxidant, and thus, investigating whether omega-3 supplementation in smokers reduces adverse maternal and neonatal outcomes represents an important area of research. To investigate whether the antioxidant effect of omega-3 fatty acid supplementation on the incidence of adverse pregnancy outcomes differs between smokers and nonsmokers. Secondary analysis of a multicenter randomized controlled trial of omega-3 supplementation for preterm delivery prevention in women with a singleton pregnancy and a history of a previous singleton spontaneous preterm delivery. Subjects were randomized to begin omega-3 or placebo before 22 weeks, which was continued until delivery. All women received 17 alpha-hydroxyprogesterone caproate intramuscularly weekly beginning between 16 and 20 weeks of gestation and continued until 36 weeks of gestation or delivery, whichever occurred first. The primary outcome was spontaneous preterm delivery. Secondary outcomes were indicated preterm delivery, any preterm delivery (spontaneous and indicated), pregnancy-associated hypertension (gestational hypertension and preeclampsia), a neonatal composite (retinopathy of prematurity, intraventricular hemorrhage grade III or IV, patent ductus arteriosus, necrotizing enterocolitis, sepsis, respiratory morbidity, or perinatal death), low birth weight (<2500 g), small for gestational age (less than the 10th percentile), and neonatal intensive care unit or intermediate nursery admission. The study population was stratified into smokers and nonsmokers, and the incidence of each outcome was compared by omega-3 supplementation versus placebo in each subgroup. Zelen tests were performed to test for homogeneity of effect in smokers and nonsmokers. Of 851 subjects included in the analysis, 136 (16%) smoked. Baseline characteristics between omega-3 and placebo groups did not differ in smokers or nonsmokers. Omega-3 supplementation was associated with a lower risk of spontaneous preterm delivery in smokers (relative risk, 0.56, 95% confidence interval, 0.36-0.87) but not in nonsmokers (relative risk 1.04, 95% confidence interval 0.84-1.29); P value for interaction = 0.013. Low birth weight was also less frequent in smokers receiving omega-3 supplementation (relative risk 0.57, 95% confidence interval 0.36-0.90) compared with nonsmokers (relative risk 0.93, 95% confidence interval 0.71-1.24); P value for interaction = 0.047. The effect on other secondary outcomes did not differ significantly between smokers and nonsmokers. Omega-3 supplementation in smokers may have a protective effect against recurrent spontaneous preterm delivery and low birth weight. Copyright © 2017 Elsevier Inc. All rights reserved.

Thrombus Aspiration in ST-Segment-Elevation Myocardial Infarction: An Individual Patient Meta-Analysis: Thrombectomy Trialists Collaboration.

PubMed

Jolly, Sanjit S; James, Stefan; Džavík, Vladimír; Cairns, John A; Mahmoud, Karim D; Zijlstra, Felix; Yusuf, Salim; Olivecrona, Goran K; Renlund, Henrik; Gao, Peggy; Lagerqvist, Bo; Alazzoni, Ashraf; Kedev, Sasko; Stankovic, Goran; Meeks, Brandi; Frøbert, Ole

2017-01-10

Thrombus aspiration during percutaneous coronary intervention (PCI) for the treatment of ST-segment-elevation myocardial infarction (STEMI) has been widely used; however, recent trials have questioned its value and safety. In this meta-analysis, we, the trial investigators, aimed to pool the individual patient data from these trials to determine the benefits and risks of thrombus aspiration during PCI in patients with ST-segment-elevation myocardial infarction. Included were large (n≥1000), randomized, controlled trials comparing manual thrombectomy and PCI alone in patients with ST-segment-elevation myocardial infarction. Individual patient data were provided by the leadership of each trial. The prespecified primary efficacy outcome was cardiovascular mortality within 30 days, and the primary safety outcome was stroke or transient ischemic attack within 30 days. The 3 eligible randomized trials (TAPAS [Thrombus Aspiration During Percutaneous Coronary Intervention in Acute Myocardial Infarction], TASTE [Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia], and TOTAL [Trial of Routine Aspiration Thrombectomy With PCI Versus PCI Alone in Patients With STEMI]) enrolled 19 047 patients, of whom 18 306 underwent PCI and were included in the primary analysis. Cardiovascular death at 30 days occurred in 221 of 9155 patients (2.4%) randomized to thrombus aspiration and 262 of 9151 (2.9%) randomized to PCI alone (hazard ratio, 0.84; 95% confidence interval, 0.70-1.01; P=0.06). Stroke or transient ischemic attack occurred in 66 (0.8%) randomized to thrombus aspiration and 46 (0.5%) randomized to PCI alone (odds ratio, 1.43; 95% confidence interval, 0.98-2.10; P=0.06). There were no significant differences in recurrent myocardial infarction, stent thrombosis, heart failure, or target vessel revascularization. In the subgroup with high thrombus burden (TIMI [Thrombolysis in Myocardial Infarction] thrombus grade ≥3), thrombus aspiration was associated with fewer cardiovascular deaths (170 [2.5%] versus 205 [3.1%]; hazard ratio, 0.80; 95% confidence interval, 0.65-0.98; P=0.03) and with more strokes or transient ischemic attacks (55 [0.9%] versus 34 [0.5%]; odds ratio, 1.56; 95% confidence interval, 1.02-2.42, P=0.04). However, the interaction P values were 0.32 and 0.34, respectively. Routine thrombus aspiration during PCI for ST-segment-elevation myocardial infarction did not improve clinical outcomes. In the high thrombus burden group, the trends toward reduced cardiovascular death and increased stroke or transient ischemic attack provide a rationale for future trials of improved thrombus aspiration technologies in this high-risk subgroup. URLs: http://www.ClinicalTrials.gov http://www.crd.york.ac.uk/prospero/. Unique identifiers: NCT02552407 and CRD42015025936. © 2016 American Heart Association, Inc.

Cross correlation anomaly detection system

NASA Technical Reports Server (NTRS)

Micka, E. Z. (Inventor)

1975-01-01

This invention provides a method for automatically inspecting the surface of an object, such as an integrated circuit chip, whereby the data obtained by the light reflected from the surface, caused by a scanning light beam, is automatically compared with data representing acceptable values for each unique surface. A signal output provided indicated of acceptance or rejection of the chip. Acceptance is based on predetermined statistical confidence intervals calculated from known good regions of the object being tested, or their representative values. The method can utilize a known good chip, a photographic mask from which the I.C. was fabricated, or a computer stored replica of each pattern being tested.

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…

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...

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.

Bone mineral density is decreased in fibromyalgia syndrome: a systematic review and meta-analysis.

PubMed

Upala, Sikarin; Yong, Wai Chung; Sanguankeo, Anawin

2017-04-01

Previous studies have shown that fibromyalgia syndrome (FMS) is associated with low level of physical activity and exercise, which may lead to an increased risk of osteoporosis. However, studies of bone mineral density (BMD) in fibromyalgia have shown conflicting results. Thus, we conducted a systematic review and meta-analysis to better characterize the association between FMS and BMD. A comprehensive search of the databases MEDLINE and EMBASE was performed from inception through May 2016. The inclusion criterion was the observational studies' assessment of the association between fibromyalgia and bone mineral density in adult subjects. Fibromyalgia was diagnosed in accordance with the American College of Rheumatology criteria for the diagnosis of fibromyalgia syndrome. BMD was measured at the lumbar spine and femoral neck by dual-energy X-ray absorptiometry. Pooled mean difference (MD) of BMD at each site and 95% confidence interval (CI) were calculated using a random-effect, generic inverse variance method. The between-study heterogeneity of effect size was quantified using the Q statistic and I 2 . Data were extracted from four observational studies involving 680 subjects. At lumbar spine (L2-L4), BMD is significantly decreased in patients with FMS compared with controls with pooled MD of -0.02 (95% CI -0.03 to -0.01, P value = 0.003, I 2  = 0%) (Fig. 1). At femoral neck, BMD is not significantly decreased in patients with FMS compared with controls with pooled MD of 0.01 (95% CI -0.02 to 0.01, P value = 0.23, I 2  = 0%) (Fig. 2). In this meta-analysis, we observe that BMD at lumbar spine is decreased in FMS compared with normal individuals. Patients with FMS should be assessed for risk of osteoporosis. Fig. 1 Forest plot of bone mineral density at the lumbar spine, for patients with and without fibromyalgia syndrome. CI-confidence interval Fig. 2 Forest plot of bone mineral density at the femoral neck, for patients with and without fibromyalgia syndrome. CI-confidence interval.

Evaluation of ascitic soluble human leukocyte antigen-G for distinguishing malignant ascites from benign ascites.

PubMed

Sun, Juan; Chang, Yan-Xiang; Niu, Chun-Yan

2017-11-01

The overexpression of soluble human leukocyte antigen-G is associated with malignant tumours. The purpose of our study was to detect soluble human leukocyte antigen-G concentrations in ascites and to evaluate the value of ascitic soluble human leukocyte antigen-G for the diagnosis of malignant ascites. Enzyme-linked immunosorbent assay was used to detect soluble human leukocyte antigen-G levels in 64 patients with malignant ascites and 30 patients with benign ascites. Receiver operating characteristic curves were used to evaluate the diagnostic efficacy of ascitic soluble human leukocyte antigen-G for the detection of malignant ascites. Ascitic soluble human leukocyte antigen-G levels were significantly higher in the malignant ascites group than in the benign ascites group (20.718 ± 3.215 versus 12.467 ± 3.678 µg/L, t = 7.425, p < 0.001). The area under the receiver operating characteristic curve for ascitic soluble human leukocyte antigen-G was 0.957 (95% confidence interval, 0.872-0.992). At a cut-off value of 19.60 µg/L, the sensitivity and specificity of ascitic soluble human leukocyte antigen-G were 87.5% (95% confidence interval, 71.0%-96.5%) and 100% (95% confidence interval, 88.4%-100%), respectively. With respect to area under the receiver operating characteristic curve, sensitivity and specificity, ascitic carcinoembryonic antigen (0.810, 68.75% and 83.33%, respectively) and carbohydrate antigen 19-9 (0.710, 65.63% and 70%, respectively) significantly differed (all p < 0.05). In malignant ascites that were cytology-negative and biopsy-positive, the rate of positivity for ascitic soluble human leukocyte antigen-G was 75%, which was higher than the corresponding rates for ascitic carcinoembryonic antigen (31.25%) and carbohydrate antigen 19-9 (6.25%; both p < 0.05). In conclusion, The detection of ascitic soluble human leukocyte antigen-G exhibited good performance for diagnosing malignant ascites, and particularly those that were cytology-negative and biopsy-positive.

Predicting changes in quality of life and emotional distress in Chinese patients with lung, gastric, and colon-rectal cancer diagnoses: the role of psychological resilience.

PubMed

Ye, Zeng Jie; Qiu, Hong Zhong; Li, Peng Fei; Liang, Mu Zi; Zhu, Yun Fei; Zeng, Zhen; Hu, Guang Yun; Wang, Shu Ni; Quan, Xiao Ming

2017-06-01

Patients with cancer often experience considerable emotional distress, which decreases their quality of life (QOL). Resilience is defined as the psychological characteristics that promote positive adaptation in the face of stress and adversity; however, the relationships among QOL, resilience, and emotional distress in patients with cancer, especially Chinese patients with cancer, are under-researched in the literature. Quality of Life Questionnaire Core 30 items, Zung Self-Rating Anxiety Scale, and the Zung Self-Rating Depression Scale were applied in this study. Univariate correlated analysis and multivariate logistic regression analysis were used to test the associations among resilience, emotional distress, and QOL with a sample of 276 participants. A Sobel test was conducted to determine whether the indirect effect of resilience was significant. The mean ratings of QOL (59.2), resilience (20.8), anxiety (43.1), and depression (47.7) were reported. The correlations between resilience and QOL in patients with lung cancer were significantly increased compared with patients with gastric or colorectal cancer (Spearman coefficient squares of 0.284, 0.189, and 0.227, respectively). The highest quartile of the resilience level was associated with a 64% (odds ratio = 0.36, 95% confidence interval = 0.17-0.75, P = .006), 70% (odds ratio = 0.30, 95% confidence interval = 0.14-0.63), and 90% (odds ratio = 0.10, 95% confidence interval = 0.04-0.26, P < .001) reduction in the risk of emotional distress compared with the lowest quartile. The Sobel test indicated a buffering effect of resilience that was significant for depression (Sobel value = 2.002, P = .045) but not anxiety (Sobel value = 1.336, P = .182). The present study suggests that psychological resilience is positively associated with QOL and may comprise a robust buffer between depression and QOL in Chinese patients with cancer. Copyright © 2016 John Wiley & Sons, Ltd.

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.

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.

Value of Computed Tomographic Perfusion-Based Patient Selection for Intra-Arterial Acute Ischemic Stroke Treatment.

PubMed

Borst, Jordi; Berkhemer, Olvert A; Roos, Yvo B W E M; van Bavel, Ed; van Zwam, Wim H; van Oostenbrugge, Robert J; van Walderveen, Marianne A A; Lingsma, Hester F; van der Lugt, Aad; Dippel, Diederik W J; Yoo, Albert J; Marquering, Henk A; Majoie, Charles B L M

2015-12-01

The utility of computed tomographic perfusion (CTP)-based patient selection for intra-arterial treatment of acute ischemic stroke has not been proven in randomized trials and requires further study in a cohort that was not selected based on CTP. Our objective was to study the relationship between CTP-derived parameters and outcome and treatment effect in patients with acute ischemic stroke because of a proximal intracranial arterial occlusion. We included 175 patients who underwent CTP in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in The Netherlands (MR CLEAN). Association of CTP-derived parameters (ischemic-core volume, penumbra volume, and percentage ischemic core) with outcome was estimated with multivariable ordinal logistic regression as an adjusted odds ratio for a shift in the direction of a better outcome on the modified Rankin Scale. Interaction between CTP-derived parameters and treatment effect was determined using multivariable ordinal logistic regression. Interaction with treatment effect was also tested for mismatch (core <70 mL; penumbra core >1.2; penumbra core >10 mL). The adjusted odds ratio for improved functional outcome for ischemic core, percentage ischemic core, and penumbra were 0.79 per 10 mL (95% confidence interval: 0.71-0.89; P<0.001), 0.82 per 10% (95% confidence interval: 0.66-0.90; P=0.002), and 0.97 per 10 mL (96% confidence interval: 0.92-1.01; P=0.15), respectively. No significant interaction between any of the CTP-derived parameters and treatment effect was observed. We observed no significant interaction between mismatch and treatment effect. CTP seems useful for predicting functional outcome, but cannot reliably identify patients who will not benefit from intra-arterial therapy. © 2015 American Heart Association, Inc.

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.

Pretransplant thymic function predicts acute rejection in antithymocyte globulin-treated renal transplant recipients.

PubMed

Bamoulid, Jamal; Courivaud, Cécile; Crepin, Thomas; Carron, Clémence; Gaiffe, Emilie; Roubiou, Caroline; Laheurte, Caroline; Moulin, Bruno; Frimat, Luc; Rieu, Philippe; Mousson, Christiane; Durrbach, Antoine; Heng, Anne-Elisabeth; Rebibou, Jean-Michel; Saas, Philippe; Ducloux, Didier

2016-05-01

Lack of clear identification of patients at high risk of acute rejection hampers the ability to individualize immunosuppressive therapy. Here we studied whether thymic function may predict acute rejection in antithymocyte globulin (ATG)-treated renal transplant recipients in 482 patients prospectively studied during the first year post-transplant of which 86 patients experienced acute rejection. Only CD45RA(+)CD31(+)CD4(+) T cell (recent thymic emigrant [RTE]) frequency (RTE%) was marginally associated with acute rejection in the whole population. This T-cell subset accounts for 26% of CD4(+) T cells. Pretransplant RTE% was significantly associated with acute rejection in ATG-treated patients (hazard ratio, 1.04; 95% confidence interval, 1.01-1.08) for each increased percent in RTE/CD4(+) T cells), but not in anti-CD25 monoclonal (αCD25 mAb)-treated patients. Acute rejection was significantly more frequent in ATG-treated patients with high pretransplant RTE% (31.2% vs. 16.4%) or absolute number of RTE/mm(3) (31.7 vs. 16.1). This difference was not found in αCD25 monclonal antibody-treated patients. Highest values of both RTE% (>31%, hazard ratio, 2.50; 95% confidence interval, 1.09-5.74) and RTE/mm(3) (>200/mm(3), hazard ratio, 3.71; 95% confidence interval, 1.59-8.70) were predictive of acute rejection in ATG-treated patients but not in patients having received αCD25 monoclonal antibody). Results were confirmed in a retrospective cohort using T-cell receptor excision circle levels as a marker of thymic function. Thus, pretransplant thymic function predicts acute rejection in ATG-treated patients. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Audit of lymphadenectomy in lung cancer resections using a specimen collection kit and checklist.

PubMed

Osarogiagbon, Raymond U; Sareen, Srishti; Eke, Ransome; Yu, Xinhua; McHugh, Laura M; Kernstine, Kemp H; Putnam, Joe B; Robbins, Edward T

2015-02-01

Audits of operative summaries and pathology reports reveal wide discordance in identifying the extent of lymphadenectomy performed (the communication gap). We tested the ability of a prelabeled lymph node specimen collection kit and checklist to narrow the communication gap between operating surgeons, pathologists, and auditors of surgeons' operation notes. We conducted a prospective single cohort study of lung cancer resections performed with a lymph node collection kit from November 2010 to January 2013. We used the kappa statistic to compare surgeon claims on a checklist of lymph node stations harvested intraoperatively with pathology reports and an independent audit of surgeons' operative summaries. Lymph node collection procedures were classified into four groups based on the anatomic origin of resected lymph nodes: mediastinal lymph node dissection, systematic sampling, random sampling, and no sampling. From the pathology reports, 73% of 160 resections had a mediastinal lymph node dissection or systematic sampling procedure, 27% had random sampling. The concordance with surgeon claims was 80% (kappa statistic 0.69, 95% confidence interval: 0.60 to 0.79). Concordance between independent audits of the operation notes and either the pathology report (kappa 0.14, 95% confidence interval: 0.04 to 0.23) or surgeon claims (kappa 0.09, 95% confidence interval: 0.03 to 0.22) was poor. A prelabeled specimen collection kit and checklist significantly narrowed the communication gap between surgeons and pathologists in identifying the extent of lymphadenectomy. Audit of surgeons' operation notes did not accurately reflect the procedure performed, bringing its value for quality improvement work into question. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Importance of Abnormal Chloride Homeostasis in Stable Chronic Heart Failure.

PubMed

Grodin, Justin L; Verbrugge, Frederik H; Ellis, Stephen G; Mullens, Wilfried; Testani, Jeffrey M; Tang, W H Wilson

2016-01-01

The aim of this analysis was to determine the long-term prognostic value of lower serum chloride in patients with stable chronic heart failure. Electrolyte abnormalities are prevalent in patients with chronic heart failure. Little is known regarding the prognostic implications of lower serum chloride. Serum chloride was measured in 1673 consecutively consented stable patients with a history of heart failure undergoing elective diagnostic coronary angiography. All patients were followed for 5-year all-cause mortality, and survival models were adjusted for variables that confounded the chloride-risk relationship. The average chloride level was 102 ± 4 mEq/L. Over 6772 person-years of follow-up, there were 547 deaths. Lower chloride (per standard deviation decrease) was associated with a higher adjusted risk of mortality (hazard ratio 1.29, 95% confidence interval 1.12-1.49; P < 0.001). Chloride levels net-reclassified risk in 10.4% (P = 0.03) when added to a multivariable model (with a resultant C-statistic of 0.70), in which sodium levels were not prognostic (P = 0.30). In comparison to those with above first quartile chloride (≥ 101 mEq/L) and sodium (≥ 138 meq/L), subjects with first quartile chloride had a higher adjusted mortality risk, whether they had first quartile sodium (hazard ratio 1.35, 95% confidence interval 1.08-1.69; P = 0.008) or higher (hazard ratio 1.43, 95% confidence interval 1.12-1.85; P = 0.005). However, subjects with first quartile sodium but above first quartile chloride had no association with mortality (P = 0.67). Lower serum chloride levels are independently and incrementally associated with increased mortality risk in patients with chronic heart failure. A better understanding of the biological role of serum chloride is warranted. © 2015 American Heart Association, Inc.

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.

Effects of inhaled corticosteroids on airway inflammation in chronic obstructive pulmonary disease: a systematic review and meta-analysis

PubMed Central

Jen, Rachel; Rennard, Stephen I; Sin, Don D

2012-01-01

Background: Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation in the small airways. The effect of inhaled corticosteroids (ICS) on lung inflammation in COPD remains uncertain. We sought to determine the effects of ICS on inflammatory indices in bronchial biopsies and bronchoalveolar lavage fluid of patients with COPD. Methods: We searched Medline, Embase, Cinahl, and the Cochrane database for randomized, controlled clinical trials that used bronchial biopsies and bronchoalveolar lavage to evaluate the effects of ICS in stable COPD. For each chosen study, we calculated the mean differences in the concentrations of inflammatory cells before and after treatment in both intervention and control groups. These values were then converted into standardized mean differences (SMD) to accommodate the differences in patient selection, clinical treatment, and biochemical procedures that were employed across the original studies. If significant heterogeneity was present (P < 0.1), then a random effects model was used to pool the original data; otherwise, a fixed effects model was used. Results: We identified eight original studies that met the inclusion criteria. Four studies used bronchial biopsies (n =102 participants) and showed that ICS were effective in reducing CD4 and CD8 cell counts (SMD, −0.52 units and −0.66 units, 95% confidence interval). The five studies used bronchoalveolar lavage fluid (n =309), which together showed that ICS reduced neutrophil and lymphocyte counts (SMD, −0.64 units and −0.64 units, 95% confidence interval). ICS on the other hand significantly increased macrophage counts (SMD, 0.68 units, 95% confidence interval) in bronchoalveolar lavage fluid. Conclusion: ICS has important immunomodulatory effects in airways with COPD that may explain its beneficial effect on exacerbations and enhanced risk of pneumonia. PMID:23055709

Association Between Troponin Levels and Embolic Stroke of Undetermined Source.

PubMed

Merkler, Alexander E; Gialdini, Gino; Murthy, Santosh B; Salehi Omran, Setareh; Moya, Antonio; Lerario, Michael P; Chong, Ji; Okin, Peter M; Weinsaft, Jonathan W; Safford, Monika M; Fink, Matthew E; Navi, Babak B; Iadecola, Costantino; Kamel, Hooman

2017-09-22

Our aim was to determine whether patients with embolic strokes of undetermined source (ESUS) have higher rates of elevated troponin than patients with noncardioembolic strokes. CAESAR (The Cornell Acute Stroke Academic Registry) prospectively enrolled all adults with acute stroke from 2011 to 2014. Two neurologists used standard definitions to retrospectively ascertain the etiology of stroke, with a third resolving disagreements. In this analysis we included patients with ESUS and, as controls, patients with small- and large-artery strokes; only patients with a troponin measured within 24 hours of stroke onset were included. A troponin elevation was defined as a value exceeding our laboratory's upper limit (0.04 ng/mL) without a clinically recognized acute ST-segment elevation myocardial infarction. Multiple logistic regression was used to evaluate the association between troponin elevation and ESUS after adjustment for demographics, stroke severity, insular infarction, and vascular risk factors. In a sensitivity analysis we excluded patients diagnosed with atrial fibrillation after discharge. Among 512 patients, 243 (47.5%) had ESUS, and 269 (52.5%) had small- or large-artery stroke. In multivariable analysis an elevated troponin was independently associated with ESUS (odds ratio 3.3; 95% confidence interval 1.2, 8.8). This result was unchanged after excluding patients diagnosed with atrial fibrillation after discharge (odds ratio 3.4; 95% confidence interval 1.3, 9.1), and the association remained significant when troponin was considered a continuous variable (odds ratio for log[troponin], 1.4; 95% confidence interval 1.1, 1.7). Elevations in cardiac troponin are more common in patients with ESUS than in those with noncardioembolic strokes. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Task shifting to clinical officer-led echocardiography screening for detecting rheumatic heart disease in Malawi, Africa.

PubMed

Sims Sanyahumbi, Amy; Sable, Craig A; Karlsten, Melissa; Hosseinipour, Mina C; Kazembe, Peter N; Minard, Charles G; Penny, Daniel J

2017-08-01

Echocardiographic screening for rheumatic heart disease in asymptomatic children may result in early diagnosis and prevent progression. Physician-led screening is not feasible in Malawi. Task shifting to mid-level providers such as clinical officers may enable more widespread screening. Hypothesis With short-course training, clinical officers can accurately screen for rheumatic heart disease using focussed echocardiography. A total of eight clinical officers completed three half-days of didactics and 2 days of hands-on echocardiography training. Clinical officers were evaluated by performing screening echocardiograms on 20 children with known rheumatic heart disease status. They indicated whether children should be referred for follow-up. Referral was indicated if mitral regurgitation measured more than 1.5 cm or there was any measurable aortic regurgitation. The κ statistic was calculated to measure referral agreement with a paediatric cardiologist. Sensitivity and specificity were estimated using a generalised linear mixed model, and were calculated on the basis of World Heart Federation diagnostic criteria. The mean κ statistic comparing clinical officer referrals with the paediatric cardiologist was 0.72 (95% confidence interval: 0.62, 0.82). The κ value ranged from a minimum of 0.57 to a maximum of 0.90. For rheumatic heart disease diagnosis, sensitivity was 0.91 (95% confidence interval: 0.86, 0.95) and specificity was 0.65 (95% confidence interval: 0.57, 0.72). There was substantial agreement between clinical officers and paediatric cardiologists on whether to refer. Clinical officers had a high sensitivity in detecting rheumatic heart disease. With short-course training, clinical officer-led echo screening for rheumatic heart disease is a viable alternative to physician-led screening in resource-limited settings.

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.

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.

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.

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.

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.

Unit Hydrograph Peaking Analysis for Goose Creek Watershed in Virginia: A Case Study

DTIC Science & Technology

2017-05-01

ER D C/ CH L TR -1 7- 6 Unit Hydrograph Peaking Analysis for Goose Creek Watershed in Virginia: A Case Study Co as ta l a nd H yd ra...default. ERDC/CHL TR-17-6 May 2017 Unit Hydrograph Peaking Analysis for Goose Creek Watershed in Virginia: A Case Study Nawa Raj Pradhan and...confidence interval precipitation depths to the watershed in addition to the 50% value. This study concluded that a design event with a return period greater

Unit Hydrograph Peaking Analysis for Goose Creek Watershed in Virginia: A Case Study

DTIC Science & Technology

2017-05-01

increment would not exceed 1.5 times the designed unit peak. The purpose of this study is to analyze the validity of this UHPF range of the Goose...confidence interval precipitation depths to the watershed in addition to the 50% value. This study concluded that a design event with a return period greater...In this study , the physically based GSSHA model was deployed to obtain corresponding design discharge from probable rainfall events. 3.2.1 GSSHA

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…

Prognostic value of the physical examination in patients with heart failure and atrial fibrillation: insights from the AF-CHF trial (atrial fibrillation and chronic heart failure).

PubMed

Caldentey, Guillem; Khairy, Paul; Roy, Denis; Leduc, Hugues; Talajic, Mario; Racine, Normand; White, Michel; O'Meara, Eileen; Guertin, Marie-Claude; Rouleau, Jean L; Ducharme, Anique

2014-02-01

This study sought to assess the prognostic value of physical examination in a modern treated heart failure population. The physical examination is the cornerstone of the evaluation and monitoring of patients with heart failure. Yet, the prognostic value of congestive signs (i.e., peripheral edema, jugular venous distension, a third heart sound, and pulmonary rales) has not been assessed in the current era. A post-hoc analysis was conducted on all 1,376 patients, 81% male, mean age 67 ± 11 years, with symptomatic left ventricular systolic dysfunction enrolled in the AF-CHF (Atrial Fibrillation and Congestive Heart Failure) trial. The prognostic value of baseline physical examination findings was assessed in univariate and multivariate Cox regression analyses. Peripheral edema was observed in 425 (30.9%), jugular venous distension in 297 (21.6%), a third heart sound in 207 (15.0%), and pulmonary rales in 178 (12.9%) patients. Death from cardiovascular causes occurred in 357 (25.9%) patients over a mean follow-up of 37 ± 19 months. All 4 physical examination findings were associated with cardiovascular mortality in univariate analyses (all p values <0.01). In multivariate analyses, taking all 4 signs as potential covariates, only rales (hazard ratio 1.41; 95% confidence interval: 1.07 to 1.86; p = 0.013) and peripheral edema (hazard ratio: 1.25; 95% confidence interval: 1.00 to 1.57; p = 0.048) were associated with cardiovascular mortality, independent of other variables. In the modern era, congestive signs on the physical examination (i.e., peripheral edema, jugular venous distension, a third heart sound, and pulmonary rales) continue to provide important prognostic information in patients with congestive heart failure. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Differentiation Between Luminal-A and Luminal-B Breast Cancer Using Intravoxel Incoherent Motion and Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

PubMed

Kawashima, Hiroko; Miyati, Tosiaki; Ohno, Naoki; Ohno, Masako; Inokuchi, Masafumi; Ikeda, Hiroko; Gabata, Toshifumi

2017-12-01

The study aimed to investigate whether intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) can differentiate luminal-B from luminal-A breast cancer MATERIALS AND METHODS: Biexponential analyses of IVIM and DCE MRI were performed using a 3.0-T MRI scanner, involving 134 patients with 137 pathologically confirmed luminal-type invasive breast cancers. Luminal-type breast cancer was categorized as luminal-B breast cancer (LBBC, Ki-67 ≧ 14%) or luminal-A breast cancer (LABC, Ki-67 < 14%). Quantitative parameters from IVIM (pure diffusion coefficient [D], perfusion-related diffusion coefficient [D*], and fraction [f]) and DCE MRI (initial percentage of enhancement and signal enhancement ratio [SER]) were calculated. The apparent diffusion coefficient (ADC) was also calculated using monoexponential fitting. We correlated these data with the Ki-67 status. The D and ADC values of LBBC were significantly lower than those of LABC (P = 0.028, P = 0.037). The SER of LBBC was significantly higher than that of LABC (P = 0.004). A univariate analysis showed that a significantly lower D (<0.847 x 10 -3 mm 2 /s), lower ADC (<0.960 × 10 -3 mm 2 /s), and higher SER (>1.071) values were associated with LBBC (all P values <0.01), compared to LABC. In a multivariate analysis, a higher SER (>1.071; odds ratio: 3.0099, 95% confidence interval: 1.4246-6.3593; P = 0.003) value and a lower D (<0.847 × 10 -3 mm 2 /s; odds ratio: 2.6878, 95% confidence interval: 1.0445-6.9162; P = 0.040) value were significantly associated with LBBC, compared to LABC. The SER derived from DCE MRI and the D derived from IVIM are associated independently with the Ki-67 status in patients with luminal-type breast cancer. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Effects of Training and Feedback on Accuracy of Predicting Rectosigmoid Neoplastic Lesions and Selection of Surveillance Intervals by Endoscopists Performing Optical Diagnosis of Diminutive Polyps.

PubMed

Vleugels, Jasper L A; Dijkgraaf, Marcel G W; Hazewinkel, Yark; Wanders, Linda K; Fockens, Paul; Dekker, Evelien

2018-05-01

Real-time differentiation of diminutive polyps (1-5 mm) during endoscopy could replace histopathology analysis. According to guidelines, implementation of optical diagnosis into routine practice would require it to identify rectosigmoid neoplastic lesions with a negative predictive value (NPV) of more than 90%, using histologic findings as a reference, and agreement with histology-based surveillance intervals for more than 90% of cases. We performed a prospective study with 39 endoscopists accredited to perform colonoscopies on participants with positive results from fecal immunochemical tests in the Bowel Cancer Screening Program at 13 centers in the Netherlands. Endoscopists were trained in optical diagnosis using a validated module (Workgroup serrAted polypS and Polyposis). After meeting predefined performance thresholds in the training program, the endoscopists started a 1-year program (continuation phase) in which they performed narrow band imaging analyses during colonoscopies of participants in the screening program and predicted histological findings with confidence levels. The endoscopists were randomly assigned to groups that received feedback or no feedback on the accuracy of their predictions. Primary outcome measures were endoscopists' abilities to identify rectosigmoid neoplastic lesions (using histology as a reference) with NPVs of 90% or more, and selecting surveillance intervals that agreed with those determined by histology for at least 90% of cases. Of 39 endoscopists initially trained, 27 (69%) completed the training program. During the continuation phase, these 27 endoscopists performed 3144 colonoscopies in which 4504 diminutive polyps were removed. The endoscopists identified neoplastic lesions with a pooled NPV of 90.8% (95% confidence interval 88.6-92.6); their proposed surveillance intervals agreed with those determined by histologic analysis for 95.4% of cases (95% confidence interval 94.0-96.6). Findings did not differ between the group that did vs did not receive feedback. Sixteen endoscopists (59%) identified rectosigmoid neoplastic lesions with NPVs greater than 90% and selected surveillance intervals in agreement with those determined from histology for more than 90% of patients. In a prospective study following a validated training module, we found that a selected group of endoscopists identified rectosigmoid neoplastic lesions with pooled NPVs greater than 90% and accurately selected surveillance intervals for more than 90% of patients over the course of 1 year. Providing regular interim feedback on the accuracy of neoplastic lesion prediction and surveillance interval selection did not lead to differences in those endpoints. Monitoring is suggested, as individual performance varied. ClinicalTrials.gov no: NCT02516748; Netherland Trial Register: NTR4635. Copyright © 2018 AGA Institute. Published by Elsevier Inc. All rights reserved.

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.

Reanalysis of cancer mortality in Japanese A-bomb survivors exposed to low doses of radiation: bootstrap and simulation methods

PubMed Central

2009-01-01

Background The International Commission on Radiological Protection (ICRP) recommended annual occupational dose limit is 20 mSv. Cancer mortality in Japanese A-bomb survivors exposed to less than 20 mSv external radiation in 1945 was analysed previously, using a latency model with non-linear dose response. Questions were raised regarding statistical inference with this model. Methods Cancers with over 100 deaths in the 0 - 20 mSv subcohort of the 1950-1990 Life Span Study are analysed with Poisson regression models incorporating latency, allowing linear and non-linear dose response. Bootstrap percentile and Bias-corrected accelerated (BCa) methods and simulation of the Likelihood Ratio Test lead to Confidence Intervals for Excess Relative Risk (ERR) and tests against the linear model. Results The linear model shows significant large, positive values of ERR for liver and urinary cancers at latencies from 37 - 43 years. Dose response below 20 mSv is strongly non-linear at the optimal latencies for the stomach (11.89 years), liver (36.9), lung (13.6), leukaemia (23.66), and pancreas (11.86) and across broad latency ranges. Confidence Intervals for ERR are comparable using Bootstrap and Likelihood Ratio Test methods and BCa 95% Confidence Intervals are strictly positive across latency ranges for all 5 cancers. Similar risk estimates for 10 mSv (lagged dose) are obtained from the 0 - 20 mSv and 5 - 500 mSv data for the stomach, liver, lung and leukaemia. Dose response for the latter 3 cancers is significantly non-linear in the 5 - 500 mSv range. Conclusion Liver and urinary cancer mortality risk is significantly raised using a latency model with linear dose response. A non-linear model is strongly superior for the stomach, liver, lung, pancreas and leukaemia. Bootstrap and Likelihood-based confidence intervals are broadly comparable and ERR is strictly positive by bootstrap methods for all 5 cancers. Except for the pancreas, similar estimates of latency and risk from 10 mSv are obtained from the 0 - 20 mSv and 5 - 500 mSv subcohorts. Large and significant cancer risks for Japanese survivors exposed to less than 20 mSv external radiation from the atomic bombs in 1945 cast doubt on the ICRP recommended annual occupational dose limit. PMID:20003238

Global longitudinal strain corrected by RR interval is a superior predictor of all-cause mortality in patients with systolic heart failure and atrial fibrillation.

PubMed

Modin, Daniel; Sengeløv, Morten; Jørgensen, Peter Godsk; Bruun, Niels Eske; Olsen, Flemming Javier; Dons, Maria; Fritz Hansen, Thomas; Jensen, Jan Skov; Biering-Sørensen, Tor

2018-04-01

Quantification of systolic function in patients with atrial fibrillation (AF) is challenging. A novel approach, based on RR interval correction, to counteract the varying heart cycle lengths in AF has recently been proposed. Whether this method is superior in patients with systolic heart failure (HFrEF) with AF remains unknown. This study investigates the prognostic value of RR interval-corrected peak global longitudinal strain {GLSc = GLS/[RR^(1/2)]} in relation to all-cause mortality in HFrEF patients displaying AF during echocardiographic examination. Echocardiograms from 151 patients with HFrEF and AF during examination were analysed offline. Peak global longitudinal strain (GLS) was averaged from 18 myocardial segments obtained from three apical views. GLS was indexed with the square root of the RR interval {GLSc = GLS/[RR^(1/2)]}. Endpoint was all-cause mortality. During a median follow-up of 2.7 years, 40 patients (26.5%) died. Neither uncorrected GLS (P = 0.056) nor left ventricular ejection fraction (P = 0.053) was significantly associated with all-cause mortality. After RR^(1/2) indexation, GLSc became a significant predictor of all-cause mortality (hazard ratio 1.16, 95% confidence interval 1.02-1.22, P = 0.014, per %/s^(1/2) decrease). GLSc remained an independent predictor of mortality after multivariable adjustment (age, sex, mean heart rate, mean arterial blood pressure, left atrial volume index, and E/e') (hazard ratio 1.17, 95% confidence interval 1.05-1.31, P = 0.005 per %/s^(1/2) decrease). Decreasing {GLSc = GLS/[RR^(1/2)]}, but not uncorrected GLS nor left ventricular ejection fraction, was significantly associated with increased risk of all-cause mortality in HFrEF patients with AF and remained an independent predictor after multivariable adjustment. © 2017 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

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…

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.

Total lymphocyte count as a predictor of absolute CD4+ count and CD4+ percentage in HIV-infected persons.

PubMed

Blatt, S P; Lucey, C R; Butzin, C A; Hendrix, C W; Lucey, D R

1993-02-03

To determine whether the total lymphocyte count (TLC) accurately predicts a low absolute CD4+ T-cell count and CD4+ percentage in persons infected with human immunodeficiency virus (HIV). Retrospective analysis of data collected in the US Air Force HIV Natural History Study. Military medical center that performs annual medical evaluation of all HIV-infected US Air Force personnel. A total of 828 consecutive patients with no prior history of zidovudine use, evaluated from January 1985 through July 1991. For patients with multiple observations over time, a single data point within each 6-month interval was included in the analysis (N = 2866). The sensitivity, specificity, and likelihood ratio (LR) of the TLC, in the range of 1.00 x 10(9)/L to 2.00 x 10(9)/L, in predicting an absolute CD4+ T-cell count less than 0.20 x 10(9)/L or a CD4+ percentage less than 20% were calculated. In addition, the LR and pretest probability of significant immunosuppression were used to calculate posttest probabilities of a low CD4+ count for a given TLC value. The LR of the TLC in predicting an absolute CD4+ count < 0.20 x 10(9)/L increased from 2.4 (95% confidence interval, 2.2 to 2.5) for all TLCs less than 2.00 x 10(9)/L, to 33.2 (95% confidence interval, 24.1 to 45.7) for all TLCs less than 1.00 x 10(9)/L. The specificity for this prediction increased from 57% to 97% over this range. The LR also increased from 1.4 (95% confidence interval, 1.3 to 1.6) for all TLCs less than 2.00 x 10(9)/L to 9.7 (95% confidence interval, 7.1 to 13.1) for all TLCs less than 1.00 x 10(9)/L in predicting a CD4+ percentage less than 20%. The TLC, between 1.00 x 10(9)/L and 2.00 x 10(9)/L, appears to be a useful predictor of significant immunosuppression as measured by a CD4+ T-cell count less than 0.20 x 10(9)/L in HIV-infected persons. The LR for a given TLC value and the pretest probability of immunosuppression can be used to determine the posttest probability of significant immunosuppression in individual patients. For example, in a patient with a TLC less than 1.50 x 10(9)/L and a pretest probability of 16%, the posttest probability of a low CD4+ T-cell count increases to 53%. In contrast, a TLC greater than 2.00 x 10(9)/L in an individual with a pretest probability of 30% will decrease the posttest probability of a low CD4+ T-cell count to less than 4%. Physicians should find these data useful to help predict the risk for opportunistic infection among HIV-infected persons who present with syndromes that are potentially compatible with opportunistic infection but who have not had recent or prior CD4+ T-cell analysis.

Bioequivalence and Pharmacokinetic Evaluation Study of Acetaminophen vs. Acetaminophen Plus Caffeine Tablets in Healthy Mexican Volunteers.

PubMed

Guzmán, Nora Angélica Núñez; Molina, Daniel Ruiz; Núñez, Benigno Figueroa; Soto-Sosa, Juan Carlos; Abarca, Jorge Eduardo Herrera

2016-12-01

The aim of this clinical trial was to establish the bioequivalence of two tablets containing acetaminophen 650 mg (reference) and acetaminophen 650 mg plus caffeine 65 mg (test), administered orally, in fasting conditions in healthy Mexican volunteers. Blood samples were taken from 21 male and five female individuals, during a 24-h period, to characterize the pharmacokinetic profile of acetaminophen. Plasma samples were quantified by ultra-performance liquid chromatography, tandem mass spectrometry. Pharmacokinetic metrics (maximum plasma concentration, area under the curve from time zero to the last sampling time, and area under the curve from time zero to infinity) were used to determine the 90 % confidence interval of the test/reference coefficient. The geometric mean values for maximum plasma concentration obtained for the reference and test products were 9.46 ± 34.21 and 9.72 ± 32.38 µg/mL, respectively, whereas for the area under the curve from time zero to the last sampling time the values obtained were 34.93 ± 32.58 and 35.89 ± 31.03 µg h/mL for the reference and test formulations, respectively. The 90 % confidence intervals were within the acceptance range (80-125 %). The test product was bioequivalent to the reference product. A faster absorption was seen in the test formulation in the Mexican population.

[Interobserver reliability of the Glasgow coma scale in critically ill patients with neurological and/or neurosurgical disease].

PubMed

Sánchez-Sánchez, M M; Sánchez-Izquierdo, R; Sánchez-Muñoz, E I; Martínez-Yegles, I; Fraile-Gamo, M P; Arias-Rivera, S

2014-01-01

The Glasgow coma scale (GCS) is a common tool used for neurological assessment of critically ill patients. Despite its widespread use, the GCS has some limitations, as sometimes different observers may value differently the same response. To evaluate the interobserver agreement, among intensive care nurses with a minimum of 3 years experience, both in the overall estimate of GCS and for each of its components. Prospective observational study including 110 neurological and/or neurosurgical patients conducted in a critical care unit of 18 beds, from October 2010 until December 2012. Registered variables: Demographic characteristics, reason for admission, overall GCS and its components. The neurological evaluation was conducted by a minimum of 3 nurses. One of them applied an algorithm and consensual assessment technique and all, independently, valued response to stimuli. Interobserver agreement was measured using the intraclass correlation coefficient (ICC) for a confidence interval (CI) of 95%. The study was approved by the Ethics Committee for Clinical Trails. The intraclass correlation coefficient (confident interval) for scale was: Overall GCS: 0.989 (0.985-0.992); ocular response: 0.981 (0.974-0.986); verbal response: 0.971 (0.960-0.979); motor response: 0.987 (0.982-0.991). In our cohort of patients we observed a high level of consistency in the application of both the GCS as in each of its components. Copyright © 2013 Elsevier España, S.L. y SEEIUC. All rights reserved.

An evaluation of inferential procedures for adaptive clinical trial designs with pre-specified rules for modifying the sample size.

PubMed

Levin, Gregory P; Emerson, Sarah C; Emerson, Scott S

2014-09-01

Many papers have introduced adaptive clinical trial methods that allow modifications to the sample size based on interim estimates of treatment effect. There has been extensive commentary on type I error control and efficiency considerations, but little research on estimation after an adaptive hypothesis test. We evaluate the reliability and precision of different inferential procedures in the presence of an adaptive design with pre-specified rules for modifying the sampling plan. We extend group sequential orderings of the outcome space based on the stage at stopping, likelihood ratio statistic, and sample mean to the adaptive setting in order to compute median-unbiased point estimates, exact confidence intervals, and P-values uniformly distributed under the null hypothesis. The likelihood ratio ordering is found to average shorter confidence intervals and produce higher probabilities of P-values below important thresholds than alternative approaches. The bias adjusted mean demonstrates the lowest mean squared error among candidate point estimates. A conditional error-based approach in the literature has the benefit of being the only method that accommodates unplanned adaptations. We compare the performance of this and other methods in order to quantify the cost of failing to plan ahead in settings where adaptations could realistically be pre-specified at the design stage. We find the cost to be meaningful for all designs and treatment effects considered, and to be substantial for designs frequently proposed in the literature. © 2014, The International Biometric Society.

Novel forecasting approaches using combination of machine learning and statistical models for flood susceptibility mapping.

PubMed

Shafizadeh-Moghadam, Hossein; Valavi, Roozbeh; Shahabi, Himan; Chapi, Kamran; Shirzadi, Ataollah

2018-07-01

In this research, eight individual machine learning and statistical models are implemented and compared, and based on their results, seven ensemble models for flood susceptibility assessment are introduced. The individual models included artificial neural networks, classification and regression trees, flexible discriminant analysis, generalized linear model, generalized additive model, boosted regression trees, multivariate adaptive regression splines, and maximum entropy, and the ensemble models were Ensemble Model committee averaging (EMca), Ensemble Model confidence interval Inferior (EMciInf), Ensemble Model confidence interval Superior (EMciSup), Ensemble Model to estimate the coefficient of variation (EMcv), Ensemble Model to estimate the mean (EMmean), Ensemble Model to estimate the median (EMmedian), and Ensemble Model based on weighted mean (EMwmean). The data set covered 201 flood events in the Haraz watershed (Mazandaran province in Iran) and 10,000 randomly selected non-occurrence points. Among the individual models, the Area Under the Receiver Operating Characteristic (AUROC), which showed the highest value, belonged to boosted regression trees (0.975) and the lowest value was recorded for generalized linear model (0.642). On the other hand, the proposed EMmedian resulted in the highest accuracy (0.976) among all models. In spite of the outstanding performance of some models, nevertheless, variability among the prediction of individual models was considerable. Therefore, to reduce uncertainty, creating more generalizable, more stable, and less sensitive models, ensemble forecasting approaches and in particular the EMmedian is recommended for flood susceptibility assessment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Low-level lead exposure and the IQ of children. A meta-analysis of modern studies

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

Needleman, H.L.; Gatsonis, C.A.

1990-02-02

We identified 24 modern studies of childhood exposures to lead in relation to IQ. From this population, 12 that employed multiple regression analysis with IQ as the dependent variable and lead as the main effect and that controlled for nonlead covariates were selected for a quantitative, integrated review or meta-analysis. The studies were grouped according to type of tissue analyzed for lead. There were 7 blood and 5 tooth lead studies. Within each group, we obtained joint P values by two different methods and average effect sizes as measured by the partial correlation coefficients. We also investigated the sensitivity ofmore » the results to any single study. The sample sizes ranged from 75 to 724. The sign of the regression coefficient for lead was negative in 11 of 12 studies. The negative partial r's for lead ranged from -.27 to -.003. The power to find an effect was limited, below 0.6 in 7 of 12 studies. The joint P values for the blood lead studies were less than .0001 for both methods of analysis (95% confidence interval for group partial r, -.15 {plus minus} .05), while for the tooth lead studies they were .0005 and .004, respectively (95% confidence interval for group partial r, -.08 {plus minus} .05). The hypothesis that lead impairs children's IQ at low dose is strongly supported by this quantitative review. The effect is robust to the impact of any single study.« less

Urinary excretion of uranium in adult inhabitants of the Czech Republic.

PubMed

Malátová, Irena; Bečková, Věra; Kotík, Lukáš

2016-02-01

The main aim of this study was to determine and evaluate urinary excretion of uranium in the general public of the Czech Republic. This value should serve as a baseline for distinguishing possible increase in uranium content in population living near legacy sites of mining and processing uranium ores and also to help to distinguish the proportion of the uranium content in urine among uranium miners resulting from inhaled dust. The geometric mean of the uranium concentration in urine of 74 inhabitants of the Czech Republic was 0.091 mBq/L (7.4 ng/L) with the 95% confidence interval 0.071-0.12 mBq/L (5.7-9.6 ng/L) respectively. The geometric mean of the daily excretion was 0.15 mBq/d (12.4 ng/d) with the 95% confidence interval 0.12-0.20 mBq/d (9.5-16.1 ng/d) respectively. Despite the legacy of uranium mines and plants processing uranium ore in the Czech Republic, the levels of uranium in urine and therefore, also human body content of uranium, is similar to other countries, esp. Germany, Slovenia and USA. Significant difference in the daily urinary excretion of uranium was found between individuals using public supply and private water wells as a source of drinking water. Age dependence of daily urinary excretion of uranium was not found. Mean values and their range are comparable to other countries, esp. Germany, Slovenia and USA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Neighbourhood socioeconomic deprivation and health-related quality of life: A multilevel analysis

PubMed Central

Ribeiro, Ana Isabel; Severo, Milton; Barros, Henrique; Fraga, Sílvia

2017-01-01

Objective To assess the relationship between socioeconomic deprivation and health-related quality of life in urban neighbourhoods, using a multilevel approach. Methods Of the population-based cohort EPIPorto, 1154 georeferenced participants completed the 36-Item Short-Form Health Survey. Neighbourhood socioeconomic deprivation classes were estimated using latent-class analysis. Multilevel models measured clustering and contextual effects of neighbourhood deprivation on physical and mental HRQoL. Results Residents from the least deprived neighbourhoods had higher physical HRQoL. Neighbourhood socioeconomic deprivation together with individual-level variables (age, gender and education) and health-related factors (smoking, alcohol consumption, sedentariness and chronic diseases) explained 98% of the total between-neighbourhood variance. Neighbourhood socioeconomic deprivation was significantly associated with physical health when comparing least and most deprived neighbourhoods (class 2—beta coefficient: -0.60; 95% confidence interval:-1.76;-0.56; class 3 –beta coefficient: -2.28; 95% confidence interval:-3.96;-0.60), and as neighbourhood deprivation increases, a decrease in all values of physical health dimensions (physical functioning, role physical, bodily pain and general health) was also observed. Regarding the mental health dimension, no neighbourhood clustering or contextual effects were found. However, as neighbourhood deprivation increases, the values of vitality and role emotional dimensions significantly decreased. Conclusion Neighbourhood socioeconomic deprivation is associated with HRQoL, affecting particularly physical health. This study suggests that to improve HRQoL, people and places should be targeted simultaneously. PMID:29236719

Equivalent statistics and data interpretation.

PubMed

Francis, Gregory

2017-08-01

Recent reform efforts in psychological science have led to a plethora of choices for scientists to analyze their data. A scientist making an inference about their data must now decide whether to report a p value, summarize the data with a standardized effect size and its confidence interval, report a Bayes Factor, or use other model comparison methods. To make good choices among these options, it is necessary for researchers to understand the characteristics of the various statistics used by the different analysis frameworks. Toward that end, this paper makes two contributions. First, it shows that for the case of a two-sample t test with known sample sizes, many different summary statistics are mathematically equivalent in the sense that they are based on the very same information in the data set. When the sample sizes are known, the p value provides as much information about a data set as the confidence interval of Cohen's d or a JZS Bayes factor. Second, this equivalence means that different analysis methods differ only in their interpretation of the empirical data. At first glance, it might seem that mathematical equivalence of the statistics suggests that it does not matter much which statistic is reported, but the opposite is true because the appropriateness of a reported statistic is relative to the inference it promotes. Accordingly, scientists should choose an analysis method appropriate for their scientific investigation. A direct comparison of the different inferential frameworks provides some guidance for scientists to make good choices and improve scientific practice.

Indoor radon regulation using tabulated values of temporal radon variation.

PubMed

Tsapalov, Andrey; Kovler, Konstantin

2018-03-01

Mass measurements of indoor radon concentrations have been conducted for about 30 years. In most of the countries, a national reference/action/limit level is adopted, limiting the annual average indoor radon (AAIR) concentration. However, until now, there is no single and generally accepted international protocol for determining the AAIR with a known confidence interval, based on measurements of different durations. Obviously, as the duration of measurements increases, the uncertainty of the AAIR estimation decreases. The lack of the information about the confidence interval of the determined AAIR level does not allow correct comparison with the radon reference level. This greatly complicates development of an effective indoor radon measurement protocol and strategy. The paper proposes a general principle of indoor radon regulation, based on the simple criteria widely used in metrology, and introduces a new parameter - coefficient of temporal radon variation K V (t) that depends on the measurement duration and determines the uncertainty of the AAIR. An algorithm for determining K V (t) based on the results of annual continuous radon monitoring in experimental rooms is proposed. Included are indoor radon activity concentrations and equilibrium equivalent concentration (EEC) of radon progeny. The monitoring was conducted in 10 selected experimental rooms located in 7 buildings, mainly in the Moscow region (Russia), from 2006 to 2013. The experimental and tabulated values of K V (t) and also the values of the coefficient of temporal EEC variation depending on the mode and duration of the measurements were obtained. The recommendations to improve the efficiency and reliability of indoor radon regulation are given. The importance of taking into account the geological factors is discussed. The representativity of the results of the study is estimated and the approach for their verification is proposed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genetic and Environmental Influences on Sleep, Pain, and Depression Symptoms in a Community Sample of Twins.

PubMed

Gasperi, Marianna; Herbert, Matthew; Schur, Ellen; Buchwald, Dedra; Afari, Niloofar

We used quantitative genetic methods to evaluate whether sleep quality, pain, and depression symptoms share a common genetic diathesis, to estimate the genetic and environmental sources of covariance among these symptoms, and to test for possible causal relationships. A community sample of 400 twins from the University of Washington Twin Registry completed standardized self-report questionnaires. We used biometric modeling to assess genetic and environmental contribution to the association between sleep quality measured by the Pittsburgh Sleep Quality Index, pain measured by the Brief Pain Inventory, and depression symptoms measured by the Brief Symptom Inventory. Trivariate Cholesky structural equation models were used to decompose correlations among the phenotypes. Heritability was estimated at 37% (95% confidence interval = 20%-51%) for sleep quality, 25% (9%-41%) for pain, and 39% (22%-53%) for depression. Nonshared environmental influences accounted for the remaining variance. The genetic correlation between sleep quality and pain had an rg value of .69 (95% confidence interval [CI] = 0.33-0.97), rg value of .56 (95% CI = 0.55-0.98) between pain and depression, and rg value of .61 (95% CI = 0.44-0.88) between depression and sleep quality. Nonshared environmental overlap was present between pain and sleep quality as well as depression and sleep quality. The link between sleep quality, pain, and depression was primarily explained by shared genetic influences. The genetic factors influencing sleep quality and pain were highly correlated even when accounting for depression. Findings support the hypothesis of a genetic link between depression and pain as well as potential causality for the association of sleep quality with pain and depression.

Diagnosis of catheter-related bloodstream infections among pediatric oncology patients lacking a peripheral culture, using differential time to detection.

PubMed

Gaur, Aditya H; Flynn, Patricia M; Heine, Daniel J; Giannini, Mary Anne; Shenep, Jerry L; Hayden, Randall T

2005-05-01

Current methods for in situ diagnosis of catheter-related bloodstream infections require concurrent collection of central venous catheter (CVC) and peripheral vein (PV) blood cultures. Both the pain and inconvenience of PV cultures are undesirable. A prospective study was conducted (August 2002 to March 2004) to assess the accuracy of diagnosing catheter-related bloodstream infections based on the difference in time to detection of blood cultures drawn concurrently from 2 lumens of a multilumen CVC. This difference in time to detection between 2 lumens was compared with results of the standard criterion with paired CVC and PV blood cultures. Twenty-one infectious episodes were categorized as catheter-related bloodstream infections and 38 as non-catheter-related bloodstream infections. With a cutoff in difference in time to detection between 2 lumens of > or =180 minutes, the sensitivity of this test to diagnose a catheter-related bloodstream infection was 61% (95% confidence interval, 39-80%) and the specificity was 94% (95% confidence interval, 82-99%). In 4 of 7 episodes with false-negative results, the colony counts in cultures from both lumens were >400 colony-forming units/mL (maximal value reported), indicating the limitation of this method when both lumens of the catheter are colonized. With the pretest probability of catheter-related bloodstream infections ranging from 28% to 54%, the positive predictive value of a difference in time to detection between 2 lumens of > or =180 minutes for diagnosis of catheter-related bloodstream infections ranged from 81% to 93% and the negative predictive value ranged from 67% to 86%. Within the context of its limitations, this novel method provides an alternative for diagnosing catheter-related bloodstream infections among patients with a CVC, without PV cultures.