longitudinal random effects: Topics by Science.gov

Sample records for longitudinal random effects

Predicting longitudinal trajectories of health probabilities with random-effects multinomial logit regression.

PubMed

Liu, Xian; Engel, Charles C

2012-12-20

Researchers often encounter longitudinal health data characterized with three or more ordinal or nominal categories. Random-effects multinomial logit models are generally applied to account for potential lack of independence inherent in such clustered data. When parameter estimates are used to describe longitudinal processes, however, random effects, both between and within individuals, need to be retransformed for correctly predicting outcome probabilities. This study attempts to go beyond existing work by developing a retransformation method that derives longitudinal growth trajectories of unbiased health probabilities. We estimated variances of the predicted probabilities by using the delta method. Additionally, we transformed the covariates' regression coefficients on the multinomial logit function, not substantively meaningful, to the conditional effects on the predicted probabilities. The empirical illustration uses the longitudinal data from the Asset and Health Dynamics among the Oldest Old. Our analysis compared three sets of the predicted probabilities of three health states at six time points, obtained from, respectively, the retransformation method, the best linear unbiased prediction, and the fixed-effects approach. The results demonstrate that neglect of retransforming random errors in the random-effects multinomial logit model results in severely biased longitudinal trajectories of health probabilities as well as overestimated effects of covariates on the probabilities. Copyright © 2012 John Wiley & Sons, Ltd.
A Randomized Trial of Longitudinal Effects of Low-Intensity Responsivity Education/Prelinguistic Milieu Teaching

ERIC Educational Resources Information Center

Warren, Steven F.; Fey, Marc E.; Finestack, Lizbeth, H.; Brady, Nancy C.; Bredin-Oja, Shelley L.; Fleming, Kandace K.

2008-01-01

Purpose: To evaluate the longitudinal effects of a 6-month course of responsivity education (RE)/prelinguistic milieu teaching (PMT) for young children with developmental delay. Method: Fifty-one children, age 24-33 months, with fewer than 10 expressive words were randomly assigned to early-treatment/no-treatment groups. All treatment was added as…
The Multigroup Multilevel Categorical Latent Growth Curve Models

ERIC Educational Resources Information Center

Hung, Lai-Fa

2010-01-01

Longitudinal data describe developmental patterns and enable predictions of individual changes beyond sampled time points. Major methodological issues in longitudinal data include modeling random effects, subject effects, growth curve parameters, and autoregressive residuals. This study embedded the longitudinal model within a multigroup…
The estimation of branching curves in the presence of subject-specific random effects.

PubMed

Elmi, Angelo; Ratcliffe, Sarah J; Guo, Wensheng

2014-12-20

Branching curves are a technique for modeling curves that change trajectory at a change (branching) point. Currently, the estimation framework is limited to independent data, and smoothing splines are used for estimation. This article aims to extend the branching curve framework to the longitudinal data setting where the branching point varies by subject. If the branching point is modeled as a random effect, then the longitudinal branching curve framework is a semiparametric nonlinear mixed effects model. Given existing issues with using random effects within a smoothing spline, we express the model as a B-spline based semiparametric nonlinear mixed effects model. Simple, clever smoothness constraints are enforced on the B-splines at the change point. The method is applied to Women's Health data where we model the shape of the labor curve (cervical dilation measured longitudinally) before and after treatment with oxytocin (a labor stimulant). Copyright © 2014 John Wiley & Sons, Ltd.
Bayesian analysis of longitudinal dyadic data with informative missing data using a dyadic shared-parameter model.

PubMed

Ahn, Jaeil; Morita, Satoshi; Wang, Wenyi; Yuan, Ying

2017-01-01

Analyzing longitudinal dyadic data is a challenging task due to the complicated correlations from repeated measurements and within-dyad interdependence, as well as potentially informative (or non-ignorable) missing data. We propose a dyadic shared-parameter model to analyze longitudinal dyadic data with ordinal outcomes and informative intermittent missing data and dropouts. We model the longitudinal measurement process using a proportional odds model, which accommodates the within-dyad interdependence using the concept of the actor-partner interdependence effects, as well as dyad-specific random effects. We model informative dropouts and intermittent missing data using a transition model, which shares the same set of random effects as the longitudinal measurement model. We evaluate the performance of the proposed method through extensive simulation studies. As our approach relies on some untestable assumptions on the missing data mechanism, we perform sensitivity analyses to evaluate how the analysis results change when the missing data mechanism is misspecified. We demonstrate our method using a longitudinal dyadic study of metastatic breast cancer.
Human comfort response to dominant random motions in longitudinal modes of aircraft motion

NASA Technical Reports Server (NTRS)

Stone, R. W., Jr.

1980-01-01

The effects of random vertical and longitudinal accelerations and pitching velocity passenger ride comfort responses were examined on the NASA Langley Visual Motion Simulator. Effects of power spectral density shape were studied for motions where the peak was between 0 and 2 Hz. The subjective rating data and the physical motion data obtained are presented without interpretation or detailed analysis. There existed motions in all other degrees of freedom as well as the particular pair of longitudinal airplane motions studied. These unwanted motions, caused by the characteristics of the simulator may have introduced some interactive effects on passenger responses.
Estimating correlation between multivariate longitudinal data in the presence of heterogeneity.

PubMed

Gao, Feng; Philip Miller, J; Xiong, Chengjie; Luo, Jingqin; Beiser, Julia A; Chen, Ling; Gordon, Mae O

2017-08-17

Estimating correlation coefficients among outcomes is one of the most important analytical tasks in epidemiological and clinical research. Availability of multivariate longitudinal data presents a unique opportunity to assess joint evolution of outcomes over time. Bivariate linear mixed model (BLMM) provides a versatile tool with regard to assessing correlation. However, BLMMs often assume that all individuals are drawn from a single homogenous population where the individual trajectories are distributed smoothly around population average. Using longitudinal mean deviation (MD) and visual acuity (VA) from the Ocular Hypertension Treatment Study (OHTS), we demonstrated strategies to better understand the correlation between multivariate longitudinal data in the presence of potential heterogeneity. Conditional correlation (i.e., marginal correlation given random effects) was calculated to describe how the association between longitudinal outcomes evolved over time within specific subpopulation. The impact of heterogeneity on correlation was also assessed by simulated data. There was a significant positive correlation in both random intercepts (ρ = 0.278, 95% CI: 0.121-0.420) and random slopes (ρ = 0.579, 95% CI: 0.349-0.810) between longitudinal MD and VA, and the strength of correlation constantly increased over time. However, conditional correlation and simulation studies revealed that the correlation was induced primarily by participants with rapid deteriorating MD who only accounted for a small fraction of total samples. Conditional correlation given random effects provides a robust estimate to describe the correlation between multivariate longitudinal data in the presence of unobserved heterogeneity (NCT00000125).
Mixed models approaches for joint modeling of different types of responses.

PubMed

Ivanova, Anna; Molenberghs, Geert; Verbeke, Geert

2016-01-01

In many biomedical studies, one jointly collects longitudinal continuous, binary, and survival outcomes, possibly with some observations missing. Random-effects models, sometimes called shared-parameter models or frailty models, received a lot of attention. In such models, the corresponding variance components can be employed to capture the association between the various sequences. In some cases, random effects are considered common to various sequences, perhaps up to a scaling factor; in others, there are different but correlated random effects. Even though a variety of data types has been considered in the literature, less attention has been devoted to ordinal data. For univariate longitudinal or hierarchical data, the proportional odds mixed model (POMM) is an instance of the generalized linear mixed model (GLMM; Breslow and Clayton, 1993). Ordinal data are conveniently replaced by a parsimonious set of dummies, which in the longitudinal setting leads to a repeated set of dummies. When ordinal longitudinal data are part of a joint model, the complexity increases further. This is the setting considered in this paper. We formulate a random-effects based model that, in addition, allows for overdispersion. Using two case studies, it is shown that the combination of random effects to capture association with further correction for overdispersion can improve the model's fit considerably and that the resulting models allow to answer research questions that could not be addressed otherwise. Parameters can be estimated in a fairly straightforward way, using the SAS procedure NLMIXED.
Zero-inflated count models for longitudinal measurements with heterogeneous random effects.

PubMed

Zhu, Huirong; Luo, Sheng; DeSantis, Stacia M

2017-08-01

Longitudinal zero-inflated count data arise frequently in substance use research when assessing the effects of behavioral and pharmacological interventions. Zero-inflated count models (e.g. zero-inflated Poisson or zero-inflated negative binomial) with random effects have been developed to analyze this type of data. In random effects zero-inflated count models, the random effects covariance matrix is typically assumed to be homogeneous (constant across subjects). However, in many situations this matrix may be heterogeneous (differ by measured covariates). In this paper, we extend zero-inflated count models to account for random effects heterogeneity by modeling their variance as a function of covariates. We show via simulation that ignoring intervention and covariate-specific heterogeneity can produce biased estimates of covariate and random effect estimates. Moreover, those biased estimates can be rectified by correctly modeling the random effects covariance structure. The methodological development is motivated by and applied to the Combined Pharmacotherapies and Behavioral Interventions for Alcohol Dependence (COMBINE) study, the largest clinical trial of alcohol dependence performed in United States with 1383 individuals.
Predictors for Physical Activity in Adolescent Girls Using Statistical Shrinkage Techniques for Hierarchical Longitudinal Mixed Effects Models

PubMed Central

Grant, Edward M.; Young, Deborah Rohm; Wu, Tong Tong

2015-01-01

We examined associations among longitudinal, multilevel variables and girls’ physical activity to determine the important predictors for physical activity change at different adolescent ages. The Trial of Activity for Adolescent Girls 2 study (Maryland) contributed participants from 8th (2009) to 11th grade (2011) (n=561). Questionnaires were used to obtain demographic, and psychosocial information (individual- and social-level variables); height, weight, and triceps skinfold to assess body composition; interviews and surveys for school-level data; and self-report for neighborhood-level variables. Moderate to vigorous physical activity minutes were assessed from accelerometers. A doubly regularized linear mixed effects model was used for the longitudinal multilevel data to identify the most important covariates for physical activity. Three fixed effects at the individual level and one random effect at the school level were chosen from an initial total of 66 variables, consisting of 47 fixed effects and 19 random effects variables, in additional to the time effect. Self-management strategies, perceived barriers, and social support from friends were the three selected fixed effects, and whether intramural or interscholastic programs were offered in middle school was the selected random effect. Psychosocial factors and friend support, plus a school’s physical activity environment, affect adolescent girl’s moderate to vigorous physical activity longitudinally. PMID:25928064
Causal mediation analysis for longitudinal data with exogenous exposure

PubMed Central

Bind, M.-A. C.; Vanderweele, T. J.; Coull, B. A.; Schwartz, J. D.

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. PMID:26272993
Individualizing drug dosage with longitudinal data.

PubMed

Zhu, Xiaolu; Qu, Annie

2016-10-30

We propose a two-step procedure to personalize drug dosage over time under the framework of a log-linear mixed-effect model. We model patients' heterogeneity using subject-specific random effects, which are treated as the realizations of an unspecified stochastic process. We extend the conditional quadratic inference function to estimate both fixed-effect coefficients and individual random effects on a longitudinal training data sample in the first step and propose an adaptive procedure to estimate new patients' random effects and provide dosage recommendations for new patients in the second step. An advantage of our approach is that we do not impose any distribution assumption on estimating random effects. Moreover, the new approach can accommodate more general time-varying covariates corresponding to random effects. We show in theory and numerical studies that the proposed method is more efficient compared with existing approaches, especially when covariates are time varying. In addition, a real data example of a clozapine study confirms that our two-step procedure leads to more accurate drug dosage recommendations. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Longitudinal data analysis with non-ignorable missing data.

PubMed

Tseng, Chi-hong; Elashoff, Robert; Li, Ning; Li, Gang

2016-02-01

A common problem in the longitudinal data analysis is the missing data problem. Two types of missing patterns are generally considered in statistical literature: monotone and non-monotone missing data. Nonmonotone missing data occur when study participants intermittently miss scheduled visits, while monotone missing data can be from discontinued participation, loss to follow-up, and mortality. Although many novel statistical approaches have been developed to handle missing data in recent years, few methods are available to provide inferences to handle both types of missing data simultaneously. In this article, a latent random effects model is proposed to analyze longitudinal outcomes with both monotone and non-monotone missingness in the context of missing not at random. Another significant contribution of this article is to propose a new computational algorithm for latent random effects models. To reduce the computational burden of high-dimensional integration problem in latent random effects models, we develop a new computational algorithm that uses a new adaptive quadrature approach in conjunction with the Taylor series approximation for the likelihood function to simplify the E-step computation in the expectation-maximization algorithm. Simulation study is performed and the data from the scleroderma lung study are used to demonstrate the effectiveness of this method. © The Author(s) 2012.
A mixed-effects regression model for longitudinal multivariate ordinal data.

PubMed

Liu, Li C; Hedeker, Donald

2006-03-01

A mixed-effects item response theory model that allows for three-level multivariate ordinal outcomes and accommodates multiple random subject effects is proposed for analysis of multivariate ordinal outcomes in longitudinal studies. This model allows for the estimation of different item factor loadings (item discrimination parameters) for the multiple outcomes. The covariates in the model do not have to follow the proportional odds assumption and can be at any level. Assuming either a probit or logistic response function, maximum marginal likelihood estimation is proposed utilizing multidimensional Gauss-Hermite quadrature for integration of the random effects. An iterative Fisher scoring solution, which provides standard errors for all model parameters, is used. An analysis of a longitudinal substance use data set, where four items of substance use behavior (cigarette use, alcohol use, marijuana use, and getting drunk or high) are repeatedly measured over time, is used to illustrate application of the proposed model.
Causal mediation analysis for longitudinal data with exogenous exposure.

PubMed

Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Accelerated longitudinal designs: An overview of modelling, power, costs and handling missing data.

PubMed

Galbraith, Sally; Bowden, Jack; Mander, Adrian

2017-02-01

Longitudinal studies are often used to investigate age-related developmental change. Whereas a single cohort design takes a group of individuals at the same initial age and follows them over time, an accelerated longitudinal design takes multiple single cohorts, each one starting at a different age. The main advantage of an accelerated longitudinal design is its ability to span the age range of interest in a shorter period of time than would be possible with a single cohort longitudinal design. This paper considers design issues for accelerated longitudinal studies. A linear mixed effect model is considered to describe the responses over age with random effects for intercept and slope parameters. Random and fixed cohort effects are used to cope with the potential bias accelerated longitudinal designs have due to multiple cohorts. The impact of other factors such as costs and the impact of dropouts on the power of testing or the precision of estimating parameters are examined. As duration-related costs increase relative to recruitment costs the best designs shift towards shorter duration and eventually cross-sectional design being best. For designs with the same duration but differing interval between measurements, we found there was a cutoff point for measurement costs relative to recruitment costs relating to frequency of measurements. Under our model of 30% dropout there was a maximum power loss of 7%.
Model Selection with the Linear Mixed Model for Longitudinal Data

ERIC Educational Resources Information Center

Ryoo, Ji Hoon

2011-01-01

Model building or model selection with linear mixed models (LMMs) is complicated by the presence of both fixed effects and random effects. The fixed effects structure and random effects structure are codependent, so selection of one influences the other. Most presentations of LMM in psychology and education are based on a multilevel or…
Analysis of baseline, average, and longitudinally measured blood pressure data using linear mixed models.

PubMed

Hossain, Ahmed; Beyene, Joseph

2014-01-01

This article compares baseline, average, and longitudinal data analysis methods for identifying genetic variants in genome-wide association study using the Genetic Analysis Workshop 18 data. We apply methods that include (a) linear mixed models with baseline measures, (b) random intercept linear mixed models with mean measures outcome, and (c) random intercept linear mixed models with longitudinal measurements. In the linear mixed models, covariates are included as fixed effects, whereas relatedness among individuals is incorporated as the variance-covariance structure of the random effect for the individuals. The overall strategy of applying linear mixed models decorrelate the data is based on Aulchenko et al.'s GRAMMAR. By analyzing systolic and diastolic blood pressure, which are used separately as outcomes, we compare the 3 methods in identifying a known genetic variant that is associated with blood pressure from chromosome 3 and simulated phenotype data. We also analyze the real phenotype data to illustrate the methods. We conclude that the linear mixed model with longitudinal measurements of diastolic blood pressure is the most accurate at identifying the known single-nucleotide polymorphism among the methods, but linear mixed models with baseline measures perform best with systolic blood pressure as the outcome.
A comparison of three random effects approaches to analyze repeated bounded outcome scores with an application in a stroke revalidation study.

PubMed

Molas, Marek; Lesaffre, Emmanuel

2008-12-30

Discrete bounded outcome scores (BOS), i.e. discrete measurements that are restricted on a finite interval, often occur in practice. Examples are compliance measures, quality of life measures, etc. In this paper we examine three related random effects approaches to analyze longitudinal studies with a BOS as response: (1) a linear mixed effects (LM) model applied to a logistic transformed modified BOS; (2) a model assuming that the discrete BOS is a coarsened version of a latent random variable, which after a logistic-normal transformation, satisfies an LM model; and (3) a random effects probit model. We consider also the extension whereby the variability of the BOS is allowed to depend on covariates. The methods are contrasted using a simulation study and on a longitudinal project, which documents stroke rehabilitation in four European countries using measures of motor and functional recovery. Copyright 2008 John Wiley & Sons, Ltd.
Spin dynamics of random Ising chain in coexisting transverse and longitudinal magnetic fields

NASA Astrophysics Data System (ADS)

Liu, Zhong-Qiang; Jiang, Su-Rong; Kong, Xiang-Mu; Xu, Yu-Liang

2017-05-01

The dynamics of the random Ising spin chain in coexisting transverse and longitudinal magnetic fields is studied by the recursion method. Both the spin autocorrelation function and its spectral density are investigated by numerical calculations. It is found that system's dynamical behaviors depend on the deviation σJ of the random exchange coupling between nearest-neighbor spins and the ratio rlt of the longitudinal and the transverse fields: (i) For rlt = 0, the system undergoes two crossovers from N independent spins precessing about the transverse magnetic field to a collective-mode behavior, and then to a central-peak behavior as σJ increases. (ii) For rlt ≠ 0, the system may exhibit a coexistence behavior of a collective-mode one and a central-peak one. When σJ is small (or large enough), system undergoes a crossover from a coexistence behavior (or a disordered behavior) to a central-peak behavior as rlt increases. (iii) Increasing σJ depresses effects of both the transverse and the longitudinal magnetic fields. (iv) Quantum random Ising chain in coexisting magnetic fields may exhibit under-damping and critical-damping characteristics simultaneously. These results indicate that changing the external magnetic fields may control and manipulate the dynamics of the random Ising chain.

Methods to Limit Attrition in Longitudinal Comparative Effectiveness Trials: Lessons from the Lithium Use for Bipolar Disorder (LiTMUS) Study

PubMed Central

Sylvia, Louisa G.; Reilly-Harrington, Noreen A.; Leon, Andrew C.; Kansky, Christine I.; Ketter, Terence A.; Calabrese, Joseph R.; Thase, Michael E.; Bowden, Charles L.; Friedman, Edward S.; Ostacher, Michael J.; Iosifescu, Dan V.; Severe, Joanne; Nierenberg, Andrew A.

2013-01-01

Background High attrition rates which occur frequently in longitudinal clinical trials of interventions for bipolar disorder limit the interpretation of results. Purpose The aim of this article is to present design approaches that limited attrition in the Lithium Use for Bipolar Disorder (LiTMUS) Study. Methods LiTMUS was a 6-month randomized, longitudinal multi-site comparative effectiveness trial that examined bipolar participants who were at least mildly ill. Participants were randomized to either low to moderate doses of lithium or no lithium, in addition to other treatments needed for mood stabilization administered in a guideline-informed, empirically supported, and personalized fashion (N=283). Results Components of the study design that may have contributed to the low attrition rate of the study included use of: (1) an intent-to-treat design; (2) a randomized adjunctive single-blind design; (3) participant reimbursement; (4) intent-to-attend the next study visit (includes a discussion of attendance obstacles when intention is low); (5) quality care with limited participant burden; and (6) target windows for study visits. Limitations Site differences and the effectiveness and tolerability data have not been analyzed yet. Conclusions These components of the LiTMUS study design may have reduced the probability of attrition which would inform the design of future randomized clinical effectiveness trials. PMID:22076437
Is Scientifically Based Reading Instruction Effective for Students with Below-Average IQs?

ERIC Educational Resources Information Center

Allor, Jill H.; Mathes, Patricia G.; Roberts, J. Kyle; Cheatham, Jennifer P.; Al Otaiba, Stephanie

2014-01-01

This longitudinal randomized-control trial investigated the effectiveness of scientifically based reading instruction for students with IQs ranging from 40 to 80, including students with intellectual disability (ID). Students were randomly assigned into treatment (n = 76) and contrast (n = 65) groups. Students in the treatment group received…
A Correlated Random Effects Model for Nonignorable Missing Data in Value-Added Assessment of Teacher Effects

ERIC Educational Resources Information Center

Karl, Andrew T.; Yang, Yan; Lohr, Sharon L.

2013-01-01

Value-added models have been widely used to assess the contributions of individual teachers and schools to students' academic growth based on longitudinal student achievement outcomes. There is concern, however, that ignoring the presence of missing values, which are common in longitudinal studies, can bias teachers' value-added scores.…
A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses

ERIC Educational Resources Information Center

Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini

2012-01-01

The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…
Log-gamma linear-mixed effects models for multiple outcomes with application to a longitudinal glaucoma study

PubMed Central

Zhang, Peng; Luo, Dandan; Li, Pengfei; Sharpsten, Lucie; Medeiros, Felipe A.

2015-01-01

Glaucoma is a progressive disease due to damage in the optic nerve with associated functional losses. Although the relationship between structural and functional progression in glaucoma is well established, there is disagreement on how this association evolves over time. In addressing this issue, we propose a new class of non-Gaussian linear-mixed models to estimate the correlations among subject-specific effects in multivariate longitudinal studies with a skewed distribution of random effects, to be used in a study of glaucoma. This class provides an efficient estimation of subject-specific effects by modeling the skewed random effects through the log-gamma distribution. It also provides more reliable estimates of the correlations between the random effects. To validate the log-gamma assumption against the usual normality assumption of the random effects, we propose a lack-of-fit test using the profile likelihood function of the shape parameter. We apply this method to data from a prospective observation study, the Diagnostic Innovations in Glaucoma Study, to present a statistically significant association between structural and functional change rates that leads to a better understanding of the progression of glaucoma over time. PMID:26075565
Multiple Kernel Learning with Random Effects for Predicting Longitudinal Outcomes and Data Integration

PubMed Central

Chen, Tianle; Zeng, Donglin

2015-01-01

Summary Predicting disease risk and progression is one of the main goals in many clinical research studies. Cohort studies on the natural history and etiology of chronic diseases span years and data are collected at multiple visits. Although kernel-based statistical learning methods are proven to be powerful for a wide range of disease prediction problems, these methods are only well studied for independent data but not for longitudinal data. It is thus important to develop time-sensitive prediction rules that make use of the longitudinal nature of the data. In this paper, we develop a novel statistical learning method for longitudinal data by introducing subject-specific short-term and long-term latent effects through a designed kernel to account for within-subject correlation of longitudinal measurements. Since the presence of multiple sources of data is increasingly common, we embed our method in a multiple kernel learning framework and propose a regularized multiple kernel statistical learning with random effects to construct effective nonparametric prediction rules. Our method allows easy integration of various heterogeneous data sources and takes advantage of correlation among longitudinal measures to increase prediction power. We use different kernels for each data source taking advantage of the distinctive feature of each data modality, and then optimally combine data across modalities. We apply the developed methods to two large epidemiological studies, one on Huntington's disease and the other on Alzheimer's Disease (Alzheimer's Disease Neuroimaging Initiative, ADNI) where we explore a unique opportunity to combine imaging and genetic data to study prediction of mild cognitive impairment, and show a substantial gain in performance while accounting for the longitudinal aspect of the data. PMID:26177419
Multivariate Longitudinal Analysis with Bivariate Correlation Test

PubMed Central

Adjakossa, Eric Houngla; Sadissou, Ibrahim; Hounkonnou, Mahouton Norbert; Nuel, Gregory

2016-01-01

In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model’s parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data. By using a likelihood ratio test, we test the significance of the correlations between the random effects of two dependent variables of the model, in order to investigate whether or not it is useful to model these dependent variables jointly. Simulation studies are done to assess both the parameter recovery performance of the EM estimators and the power of the test. Using two empirical data sets which are of longitudinal multivariate type and multivariate multilevel type, respectively, the usefulness of the test is illustrated. PMID:27537692
Multivariate Longitudinal Analysis with Bivariate Correlation Test.

PubMed

Adjakossa, Eric Houngla; Sadissou, Ibrahim; Hounkonnou, Mahouton Norbert; Nuel, Gregory

2016-01-01

In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model's parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data. By using a likelihood ratio test, we test the significance of the correlations between the random effects of two dependent variables of the model, in order to investigate whether or not it is useful to model these dependent variables jointly. Simulation studies are done to assess both the parameter recovery performance of the EM estimators and the power of the test. Using two empirical data sets which are of longitudinal multivariate type and multivariate multilevel type, respectively, the usefulness of the test is illustrated.
Longitudinal analysis of the strengths and difficulties questionnaire scores of the Millennium Cohort Study children in England using M-quantile random-effects regression.

PubMed

Tzavidis, Nikos; Salvati, Nicola; Schmid, Timo; Flouri, Eirini; Midouhas, Emily

2016-02-01

Multilevel modelling is a popular approach for longitudinal data analysis. Statistical models conventionally target a parameter at the centre of a distribution. However, when the distribution of the data is asymmetric, modelling other location parameters, e.g. percentiles, may be more informative. We present a new approach, M -quantile random-effects regression, for modelling multilevel data. The proposed method is used for modelling location parameters of the distribution of the strengths and difficulties questionnaire scores of children in England who participate in the Millennium Cohort Study. Quantile mixed models are also considered. The analyses offer insights to child psychologists about the differential effects of risk factors on children's outcomes.
Explicating the Conditions Under Which Multilevel Multiple Imputation Mitigates Bias Resulting from Random Coefficient-Dependent Missing Longitudinal Data.

PubMed

Gottfredson, Nisha C; Sterba, Sonya K; Jackson, Kristina M

2017-01-01

Random coefficient-dependent (RCD) missingness is a non-ignorable mechanism through which missing data can arise in longitudinal designs. RCD, for which we cannot test, is a problematic form of missingness that occurs if subject-specific random effects correlate with propensity for missingness or dropout. Particularly when covariate missingness is a problem, investigators typically handle missing longitudinal data by using single-level multiple imputation procedures implemented with long-format data, which ignores within-person dependency entirely, or implemented with wide-format (i.e., multivariate) data, which ignores some aspects of within-person dependency. When either of these standard approaches to handling missing longitudinal data is used, RCD missingness leads to parameter bias and incorrect inference. We explain why multilevel multiple imputation (MMI) should alleviate bias induced by a RCD missing data mechanism under conditions that contribute to stronger determinacy of random coefficients. We evaluate our hypothesis with a simulation study. Three design factors are considered: intraclass correlation (ICC; ranging from .25 to .75), number of waves (ranging from 4 to 8), and percent of missing data (ranging from 20 to 50%). We find that MMI greatly outperforms the single-level wide-format (multivariate) method for imputation under a RCD mechanism. For the MMI analyses, bias was most alleviated when the ICC is high, there were more waves of data, and when there was less missing data. Practical recommendations for handling longitudinal missing data are suggested.
Human comfort response to random motions with a dominant longitudinal motion

NASA Technical Reports Server (NTRS)

Stone, R. W., Jr.

1975-01-01

Subjective ride comfort response ratings were measured on the Langley Visual Motion Simulator with longitudinal acceleration inputs with various power spectra shapes and magnitudes. The results show only little influence of spectra shape on comfort response. The effects of magnitude on comfort response indicate the applicability of psychophysical precepts for comfort modeling.
An INAR(1) Negative Multinomial Regression Model for Longitudinal Count Data.

ERIC Educational Resources Information Center

Bockenholt, Ulf

1999-01-01

Discusses a regression model for the analysis of longitudinal count data in a panel study by adapting an integer-valued first-order autoregressive (INAR(1)) Poisson process to represent time-dependent correlation between counts. Derives a new negative multinomial distribution by combining INAR(1) representation with a random effects approach.…
Classroom Connectivity and Algebra 1 Achievement: A Three-Year Longitudinal Study

ERIC Educational Resources Information Center

Irving, Karen E.; Pape, Stephen J.; Owens, Douglas T.; Abrahamson, Louis; Silver, David; Sanalan, Vehbi A.

2016-01-01

Findings from three years of a longitudinal randomized control trial involving a national U.S. sample of Algebra 1 teachers and students are reported. The study examines the effects of a connected classroom technology (CCT) professional development and classroom intervention on student achievement when compared to classroom instruction with…
Increasing Young Children's Contact with Print during Shared Reading: Longitudinal Effects on Literacy Achievement

ERIC Educational Resources Information Center

Piasta, Shayne B.; Justice, Laura M.; McGinty, Anita S.; Kaderavek, Joan N.

2012-01-01

Longitudinal results for a randomized-controlled trial (RCT) assessing the impact of increasing preschoolers' attention to print during reading are reported. Four-year-old children (N = 550) in 85 classrooms experienced a 30-week shared reading program implemented by their teachers. Children in experimental classrooms experienced shared-book…
Bayesian inference for two-part mixed-effects model using skew distributions, with application to longitudinal semicontinuous alcohol data.

PubMed

Xing, Dongyuan; Huang, Yangxin; Chen, Henian; Zhu, Yiliang; Dagne, Getachew A; Baldwin, Julie

2017-08-01

Semicontinuous data featured with an excessive proportion of zeros and right-skewed continuous positive values arise frequently in practice. One example would be the substance abuse/dependence symptoms data for which a substantial proportion of subjects investigated may report zero. Two-part mixed-effects models have been developed to analyze repeated measures of semicontinuous data from longitudinal studies. In this paper, we propose a flexible two-part mixed-effects model with skew distributions for correlated semicontinuous alcohol data under the framework of a Bayesian approach. The proposed model specification consists of two mixed-effects models linked by the correlated random effects: (i) a model on the occurrence of positive values using a generalized logistic mixed-effects model (Part I); and (ii) a model on the intensity of positive values using a linear mixed-effects model where the model errors follow skew distributions including skew- t and skew-normal distributions (Part II). The proposed method is illustrated with an alcohol abuse/dependence symptoms data from a longitudinal observational study, and the analytic results are reported by comparing potential models under different random-effects structures. Simulation studies are conducted to assess the performance of the proposed models and method.
Multilevel Models for Intensive Longitudinal Data with Heterogeneous Autoregressive Errors: The Effect of Misspecification and Correction with Cholesky Transformation

PubMed Central

Jahng, Seungmin; Wood, Phillip K.

2017-01-01

Intensive longitudinal studies, such as ecological momentary assessment studies using electronic diaries, are gaining popularity across many areas of psychology. Multilevel models (MLMs) are most widely used analytical tools for intensive longitudinal data (ILD). Although ILD often have individually distinct patterns of serial correlation of measures over time, inferences of the fixed effects, and random components in MLMs are made under the assumption that all variance and autocovariance components are homogenous across individuals. In the present study, we introduced a multilevel model with Cholesky transformation to model ILD with individually heterogeneous covariance structure. In addition, the performance of the transformation method and the effects of misspecification of heterogeneous covariance structure were investigated through a Monte Carlo simulation. We found that, if individually heterogeneous covariances are incorrectly assumed as homogenous independent or homogenous autoregressive, MLMs produce highly biased estimates of the variance of random intercepts and the standard errors of the fixed intercept and the fixed effect of a level 2 covariate when the average autocorrelation is high. For intensive longitudinal data with individual specific residual covariance, the suggested transformation method showed lower bias in those estimates than the misspecified models when the number of repeated observations within individuals is 50 or more. PMID:28286490
Differential Susceptibility to Prevention: GABAergic, Dopaminergic, and Multilocus Effects

ERIC Educational Resources Information Center

Brody, Gene H.; Chen, Yi-fu; Beach, Steven R. H.

2013-01-01

Background: Randomized prevention trials provide a unique opportunity to test hypotheses about the interaction of genetic predispositions with contextual processes to create variations in phenotypes over time. Methods: Using two longitudinal, randomized prevention trials, molecular genetic and alcohol use outcome data were gathered from more than…
A Longitudinal Assessment of the Effectiveness of a School-Based Mentoring Program in Middle School

ERIC Educational Resources Information Center

Nunez, Jose Carlos; Rosario, Pedro; Vallejo, Guillermo; Gonzalez-Pienda, Julio Antonio

2013-01-01

This work assessed the efficacy of a middle-school-based mentoring program designed to increase student use of self-regulated learning (SRL) strategies, self-efficacy for and the perceived usefulness of SRL as well as mathematics and language achievement. A longitudinal cluster randomized trial study design obtained evidence that found…
Longitudinal Associations between Adolescent Alcohol Use and Parents' Sources of Knowledge

ERIC Educational Resources Information Center

Stavrinides, Panayiotis; Georgiou, Stelios; Demetriou, Andreas

2010-01-01

The aim of this study was to test the direction of effect in the relationship between parents' sources of knowledge (parental monitoring and child disclosure) and adolescent alcohol use. The participants were 215 adolescents and their mothers, randomly selected from urban and rural areas in Cyprus. A 3-month, two-timepoint longitudinal design was…
Longitudinal Evaluation of a Scale-up Model for Teaching Mathematics with Trajectories and Technologies: Persistence of Effects in the Third Year

ERIC Educational Resources Information Center

Clements, Douglas H.; Sarama, Julie; Wolfe, Christopher B.; Spitler, Mary Elaine

2013-01-01

Using a cluster randomized trial design, we evaluated the persistence of effects of a research-based model for scaling up educational interventions. The model was implemented in 42 schools in two city districts serving low-resource communities, randomly assigned to three conditions. In pre-kindergarten, the two experimental interventions were…

Extension of the Haseman-Elston regression model to longitudinal data.

PubMed

Won, Sungho; Elston, Robert C; Park, Taesung

2006-01-01

We propose an extension to longitudinal data of the Haseman and Elston regression method for linkage analysis. The proposed model is a mixed model having several random effects. As response variable, we investigate the sibship sample mean corrected cross-product (smHE) and the BLUP-mean corrected cross product (pmHE), comparing them with the original squared difference (oHE), the overall mean corrected cross-product (rHE), and the weighted average of the squared difference and the squared mean-corrected sum (wHE). The proposed model allows for the correlation structure of longitudinal data. Also, the model can test for gene x time interaction to discover genetic variation over time. The model was applied in an analysis of the Genetic Analysis Workshop 13 (GAW13) simulated dataset for a quantitative trait simulating systolic blood pressure. Independence models did not preserve the test sizes, while the mixed models with both family and sibpair random effects tended to preserve size well. Copyright 2006 S. Karger AG, Basel.
Interviewer effects on non-response propensity in longitudinal surveys: a multilevel modelling approach

PubMed Central

Vassallo, Rebecca; Durrant, Gabriele B; Smith, Peter W F; Goldstein, Harvey

2015-01-01

The paper investigates two different multilevel approaches, the multilevel cross-classified and the multiple-membership models, for the analysis of interviewer effects on wave non-response in longitudinal surveys. The models proposed incorporate both interviewer and area effects to account for the non-hierarchical structure, the influence of potentially more than one interviewer across waves and possible confounding of area and interviewer effects arising from the non-random allocation of interviewers across areas. The methods are compared by using a data set: the UK Family and Children Survey. PMID:25598587
Computer Assisted English Language Learning in Costa Rican Elementary Schools: An Experimental Study

ERIC Educational Resources Information Center

Alvarez-Marinelli, Horacio; Blanco, Marta; Lara-Alecio, Rafael; Irby, Beverly J.; Tong, Fuhui; Stanley, Katherine; Fan, Yinan

2016-01-01

This study presents first-year findings of a 25-week longitudinal project derived from a two-year longitudinal randomized trial study at the elementary school level in Costa Rica on effective computer-assisted language learning (CALL) approaches in an English as a foreign language (EFL) setting. A pre-test-post-test experimental group design was…
Multivariate longitudinal data analysis with mixed effects hidden Markov models.

PubMed

Raffa, Jesse D; Dubin, Joel A

2015-09-01

Multiple longitudinal responses are often collected as a means to capture relevant features of the true outcome of interest, which is often hidden and not directly measurable. We outline an approach which models these multivariate longitudinal responses as generated from a hidden disease process. We propose a class of models which uses a hidden Markov model with separate but correlated random effects between multiple longitudinal responses. This approach was motivated by a smoking cessation clinical trial, where a bivariate longitudinal response involving both a continuous and a binomial response was collected for each participant to monitor smoking behavior. A Bayesian method using Markov chain Monte Carlo is used. Comparison of separate univariate response models to the bivariate response models was undertaken. Our methods are demonstrated on the smoking cessation clinical trial dataset, and properties of our approach are examined through extensive simulation studies. © 2015, The International Biometric Society.
Longitudinal Study of a Cooperation-Driven, Socio-Scientific Issue Intervention on Promoting Students' Critical Thinking and Self-Regulation in Learning Science

ERIC Educational Resources Information Center

Wang, Hsin-Hui; Chen, Hsiang-Ting; Lin, Huann-shyang; Huang, Yu-Ning; Hong, Zuway-R

2017-01-01

This longitudinal study explored the effects of a Cooperation-driven Socioscientific Issue (CDSSI) intervention on junior high school students' perceptions of critical thinking (CT) and self-regulation (SR) in Taiwan. Forty-nine grade 7 students were randomly selected as an experimental group (EG) to attend a 3-semester 72-hour intervention; while…
Modeling Longitudinal Data Containing Non-Normal Within Subject Errors

NASA Technical Reports Server (NTRS)

Feiveson, Alan; Glenn, Nancy L.

2013-01-01

The mission of the National Aeronautics and Space Administration’s (NASA) human research program is to advance safe human spaceflight. This involves conducting experiments, collecting data, and analyzing data. The data are longitudinal and result from a relatively few number of subjects; typically 10 – 20. A longitudinal study refers to an investigation where participant outcomes and possibly treatments are collected at multiple follow-up times. Standard statistical designs such as mean regression with random effects and mixed–effects regression are inadequate for such data because the population is typically not approximately normally distributed. Hence, more advanced data analysis methods are necessary. This research focuses on four such methods for longitudinal data analysis: the recently proposed linear quantile mixed models (lqmm) by Geraci and Bottai (2013), quantile regression, multilevel mixed–effects linear regression, and robust regression. This research also provides computational algorithms for longitudinal data that scientists can directly use for human spaceflight and other longitudinal data applications, then presents statistical evidence that verifies which method is best for specific situations. This advances the study of longitudinal data in a broad range of applications including applications in the sciences, technology, engineering and mathematics fields.
A pattern-mixture model approach for handling missing continuous outcome data in longitudinal cluster randomized trials.

PubMed

Fiero, Mallorie H; Hsu, Chiu-Hsieh; Bell, Melanie L

2017-11-20

We extend the pattern-mixture approach to handle missing continuous outcome data in longitudinal cluster randomized trials, which randomize groups of individuals to treatment arms, rather than the individuals themselves. Individuals who drop out at the same time point are grouped into the same dropout pattern. We approach extrapolation of the pattern-mixture model by applying multilevel multiple imputation, which imputes missing values while appropriately accounting for the hierarchical data structure found in cluster randomized trials. To assess parameters of interest under various missing data assumptions, imputed values are multiplied by a sensitivity parameter, k, which increases or decreases imputed values. Using simulated data, we show that estimates of parameters of interest can vary widely under differing missing data assumptions. We conduct a sensitivity analysis using real data from a cluster randomized trial by increasing k until the treatment effect inference changes. By performing a sensitivity analysis for missing data, researchers can assess whether certain missing data assumptions are reasonable for their cluster randomized trial. Copyright © 2017 John Wiley & Sons, Ltd.
A longitudinal cluster-randomized controlled study on the accumulating effects of individualized literacy instruction on students' reading from first through third grade.

PubMed

Connor, Carol McDonald; Morrison, Frederick J; Fishman, Barry; Crowe, Elizabeth C; Al Otaiba, Stephanie; Schatschneider, Christopher

2013-08-01

Using a longitudinal cluster-randomized controlled design, we examined whether students' reading outcomes differed when they received 1, 2, or 3 years of individualized reading instruction from first through third grade, compared with a treated control group. More than 45% of students came from families living in poverty. Following students, we randomly assigned their teachers each year to deliver individualized reading instruction or a treated control condition intervention focused on mathematics. Students who received individualized reading instruction in all three grades showed the strongest reading skills by the end of third grade compared with those who received fewer years of such instruction. There was inconsistent evidence supporting a sustained first-grade treatment effect: Individualized instruction in first grade was necessary but not sufficient for stronger third-grade reading outcomes. These effects were achieved by regular classroom teachers who received professional development, which indicates that policies that support the use of evidence-based reading instruction and teacher training can yield increased student achievement.
Meta-Analysis of Effect Sizes Reported at Multiple Time Points Using General Linear Mixed Model.

PubMed

Musekiwa, Alfred; Manda, Samuel O M; Mwambi, Henry G; Chen, Ding-Geng

2016-01-01

Meta-analysis of longitudinal studies combines effect sizes measured at pre-determined time points. The most common approach involves performing separate univariate meta-analyses at individual time points. This simplistic approach ignores dependence between longitudinal effect sizes, which might result in less precise parameter estimates. In this paper, we show how to conduct a meta-analysis of longitudinal effect sizes where we contrast different covariance structures for dependence between effect sizes, both within and between studies. We propose new combinations of covariance structures for the dependence between effect size and utilize a practical example involving meta-analysis of 17 trials comparing postoperative treatments for a type of cancer, where survival is measured at 6, 12, 18 and 24 months post randomization. Although the results from this particular data set show the benefit of accounting for within-study serial correlation between effect sizes, simulations are required to confirm these results.
The Mixed Effects Trend Vector Model

ERIC Educational Resources Information Center

de Rooij, Mark; Schouteden, Martijn

2012-01-01

Maximum likelihood estimation of mixed effect baseline category logit models for multinomial longitudinal data can be prohibitive due to the integral dimension of the random effects distribution. We propose to use multidimensional unfolding methodology to reduce the dimensionality of the problem. As a by-product, readily interpretable graphical…
A model for incomplete longitudinal multivariate ordinal data.

PubMed

Liu, Li C

2008-12-30

In studies where multiple outcome items are repeatedly measured over time, missing data often occur. A longitudinal item response theory model is proposed for analysis of multivariate ordinal outcomes that are repeatedly measured. Under the MAR assumption, this model accommodates missing data at any level (missing item at any time point and/or missing time point). It allows for multiple random subject effects and the estimation of item discrimination parameters for the multiple outcome items. The covariates in the model can be at any level. Assuming either a probit or logistic response function, maximum marginal likelihood estimation is described utilizing multidimensional Gauss-Hermite quadrature for integration of the random effects. An iterative Fisher-scoring solution, which provides standard errors for all model parameters, is used. A data set from a longitudinal prevention study is used to motivate the application of the proposed model. In this study, multiple ordinal items of health behavior are repeatedly measured over time. Because of a planned missing design, subjects answered only two-third of all items at a given point. Copyright 2008 John Wiley & Sons, Ltd.
Weight loss is associated with improvements in cognitive function among overweight and obese people: A systematic review and meta-analysis.

PubMed

Veronese, Nicola; Facchini, Silvia; Stubbs, Brendon; Luchini, Claudio; Solmi, Marco; Manzato, Enzo; Sergi, Giuseppe; Maggi, Stefania; Cosco, Theodore; Fontana, Luigi

2017-01-01

Whilst obesity is associated with a higher risk of cognitive impairment, the influence of weight loss on cognitive function in obese/overweight people is equivocal. We conducted a meta-analysis of randomized controlled trials (RCTs) and longitudinal studies evaluating the influence of voluntary weight loss on cognitive function in obese/overweight individuals. Articles were acquired from a systematic search of major databases from inception till 01/2016. A random effect meta-analysis of weight loss interventions (diet, physical activity, bariatric surgery) on different cognitive domains (memory, attention, executive functions, language and motor speed) was conducted. Twenty studies (13 longitudinal studies=551 participants; 7 RCTs=328 treated vs. 140 controls) were included. Weight loss was associated with a significant improvement in attention and memory in both longitudinal studies and RCTs, whereas executive function and language improved in longitudinal and RCT studies, respectively. In conclusion, intentional weight loss in obese/overweight people is associated with improvements in performance across various cognitive domains. Future adequately powered RCTs are required to confirm/refute these findings. Copyright © 2016 Elsevier Ltd. All rights reserved.
Marginal and Random Intercepts Models for Longitudinal Binary Data with Examples from Criminology

ERIC Educational Resources Information Center

Long, Jeffrey D.; Loeber, Rolf; Farrington, David P.

2009-01-01

Two models for the analysis of longitudinal binary data are discussed: the marginal model and the random intercepts model. In contrast to the linear mixed model (LMM), the two models for binary data are not subsumed under a single hierarchical model. The marginal model provides group-level information whereas the random intercepts model provides…
Estimates of Intraclass Correlation Coefficients from Longitudinal Group-Randomized Trials of Adolescent HIV/STI/Pregnancy Prevention Programs

ERIC Educational Resources Information Center

Glassman, Jill R.; Potter, Susan C.; Baumler, Elizabeth R.; Coyle, Karin K.

2015-01-01

Introduction: Group-randomized trials (GRTs) are one of the most rigorous methods for evaluating the effectiveness of group-based health risk prevention programs. Efficiently designing GRTs with a sample size that is sufficient for meeting the trial's power and precision goals while not wasting resources exceeding them requires estimates of the…
Giant transversal particle diffusion in a longitudinal magnetic ratchet.

PubMed

Tierno, Pietro; Reimann, Peter; Johansen, Tom H; Sagués, Francesc

2010-12-03

We study the transversal motion of paramagnetic particles on a uniaxial garnet film, exhibiting a longitudinal ratchet effect in the presence of an oscillating magnetic field. Without the field, the thermal diffusion coefficient obtained by video microscopy is D(0) ≈ 3 × 10(-4) μm2/s. With the field, the transversal diffusion exhibits a giant enhancement by almost four decades and a pronounced maximum as a function of the driving frequency. We explain the experimental findings with a theoretical interpretation in terms of random disorder effects within the magnetic film.
The Norwegian Healthy Life Study: protocol for a pragmatic RCT with longitudinal follow-up on physical activity and diet for adults.

PubMed

Abildsnes, Eirik; Meland, Eivind; Mildestvedt, Thomas; Stea, Tonje H; Berntsen, Sveinung; Samdal, Gro Beate

2017-01-05

The Norwegian Directorate of Health recommends that Healthy Life Centres (HLCs) be established in primary health care to support behaviour change and reduce the risk of non-communicable diseases. The aim of the present study protocol is to present the rationale, design and methods of a combined pragmatic randomized controlled trial (RCT) and longitudinal cohort study of the effects of attending HLCs concerning physical activity, sedentary behaviour and diet and to explore how psychological well-being and motivational factors may mediate short- and long-term effects. The present study will combine a 6-month RCT with a longitudinal cohort study (24 months from baseline) conducted at six HLCs from June 2014 to Sept 2017. Participants are randomized to behavioural change interventions or a 6-month waiting list control group. A randomized trial of interventions in HLCs has the potential to influence the development of policy and practice for behaviour change interventions and patient education programmes in Norway. We discuss some of the important preconditions for obtaining valid results from a complex intervention and outline some of the characteristics of ecological approaches in health care research that can enable a pragmatic intervention study. The study was retrospectively registered on September 19, 2014 and is available online at ClinicalTrials.gov (ID: NCT02247219 ).
Bayesian informative dropout model for longitudinal binary data with random effects using conditional and joint modeling approaches.

PubMed

Chan, Jennifer S K

2016-05-01

Dropouts are common in longitudinal study. If the dropout probability depends on the missing observations at or after dropout, this type of dropout is called informative (or nonignorable) dropout (ID). Failure to accommodate such dropout mechanism into the model will bias the parameter estimates. We propose a conditional autoregressive model for longitudinal binary data with an ID model such that the probabilities of positive outcomes as well as the drop-out indicator in each occasion are logit linear in some covariates and outcomes. This model adopting a marginal model for outcomes and a conditional model for dropouts is called a selection model. To allow for the heterogeneity and clustering effects, the outcome model is extended to incorporate mixture and random effects. Lastly, the model is further extended to a novel model that models the outcome and dropout jointly such that their dependency is formulated through an odds ratio function. Parameters are estimated by a Bayesian approach implemented using the user-friendly Bayesian software WinBUGS. A methadone clinic dataset is analyzed to illustrate the proposed models. Result shows that the treatment time effect is still significant but weaker after allowing for an ID process in the data. Finally the effect of drop-out on parameter estimates is evaluated through simulation studies. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Semiparametric Bayesian classification with longitudinal markers

PubMed Central

De la Cruz-Mesía, Rolando; Quintana, Fernando A.; Müller, Peter

2013-01-01

Summary We analyse data from a study involving 173 pregnant women. The data are observed values of the β human chorionic gonadotropin hormone measured during the first 80 days of gestational age, including from one up to six longitudinal responses for each woman. The main objective in this study is to predict normal versus abnormal pregnancy outcomes from data that are available at the early stages of pregnancy. We achieve the desired classification with a semiparametric hierarchical model. Specifically, we consider a Dirichlet process mixture prior for the distribution of the random effects in each group. The unknown random-effects distributions are allowed to vary across groups but are made dependent by using a design vector to select different features of a single underlying random probability measure. The resulting model is an extension of the dependent Dirichlet process model, with an additional probability model for group classification. The model is shown to perform better than an alternative model which is based on independent Dirichlet processes for the groups. Relevant posterior distributions are summarized by using Markov chain Monte Carlo methods. PMID:24368871
At the Frontiers of Modeling Intensive Longitudinal Data: Dynamic Structural Equation Models for the Affective Measurements from the COGITO Study.

PubMed

Hamaker, E L; Asparouhov, T; Brose, A; Schmiedek, F; Muthén, B

2018-04-06

With the growing popularity of intensive longitudinal research, the modeling techniques and software options for such data are also expanding rapidly. Here we use dynamic multilevel modeling, as it is incorporated in the new dynamic structural equation modeling (DSEM) toolbox in Mplus, to analyze the affective data from the COGITO study. These data consist of two samples of over 100 individuals each who were measured for about 100 days. We use composite scores of positive and negative affect and apply a multilevel vector autoregressive model to allow for individual differences in means, autoregressions, and cross-lagged effects. Then we extend the model to include random residual variances and covariance, and finally we investigate whether prior depression affects later depression scores through the random effects of the daily diary measures. We end with discussing several urgent-but mostly unresolved-issues in the area of dynamic multilevel modeling.
The response of an airplane to random atmospheric disturbances

NASA Technical Reports Server (NTRS)

Diederich, Franklin W

1957-01-01

The statistical approach to the gust-load problem which consists in considering flight through turbulent air to be a stationary random process is extended by including the effect of lateral variation of the instantaneous gust intensity on the aerodynamic forces. The forces obtained in this manner are used in dynamic analyses of rigid and flexible airplanes free to move vertically, in pitch, and in roll. The effect of the interaction of longitudinal, vertical, and lateral gusts on the wing stresses is also considered.

A Two-Step Approach for Analysis of Nonignorable Missing Outcomes in Longitudinal Regression: an Application to Upstate KIDS Study.

PubMed

Liu, Danping; Yeung, Edwina H; McLain, Alexander C; Xie, Yunlong; Buck Louis, Germaine M; Sundaram, Rajeshwari

2017-09-01

Imperfect follow-up in longitudinal studies commonly leads to missing outcome data that can potentially bias the inference when the missingness is nonignorable; that is, the propensity of missingness depends on missing values in the data. In the Upstate KIDS Study, we seek to determine if the missingness of child development outcomes is nonignorable, and how a simple model assuming ignorable missingness would compare with more complicated models for a nonignorable mechanism. To correct for nonignorable missingness, the shared random effects model (SREM) jointly models the outcome and the missing mechanism. However, the computational complexity and lack of software packages has limited its practical applications. This paper proposes a novel two-step approach to handle nonignorable missing outcomes in generalized linear mixed models. We first analyse the missing mechanism with a generalized linear mixed model and predict values of the random effects; then, the outcome model is fitted adjusting for the predicted random effects to account for heterogeneity in the missingness propensity. Extensive simulation studies suggest that the proposed method is a reliable approximation to SREM, with a much faster computation. The nonignorability of missing data in the Upstate KIDS Study is estimated to be mild to moderate, and the analyses using the two-step approach or SREM are similar to the model assuming ignorable missingness. The two-step approach is a computationally straightforward method that can be conducted as sensitivity analyses in longitudinal studies to examine violations to the ignorable missingness assumption and the implications relative to health outcomes. © 2017 John Wiley & Sons Ltd.
The effect of indapamide versus hydrochlorothiazide on ventricular and arterial function in patients with hypertension and diabetes: results of a randomized trial.

PubMed

Vinereanu, Dragos; Dulgheru, Raluca; Magda, Stefania; Dragoi Galrinho, Ruxandra; Florescu, Maria; Cinteza, Mircea; Granger, Christopher; Ciobanu, Andrea O

2014-10-01

The objective of this study is to compare the effects of 2 types of diuretics, indapamide and hydrochlorothiazide, added to an angiotensin-converting enzyme inhibitor, on ventricular and arterial functions in patients with hypertension and diabetes. This is a prospective, randomized, active-controlled, PROBE design study in 56 patients (57 ± 9 years, 52% men) with mild-to-moderate hypertension and type 2 diabetes, with normal ejection fraction, randomized to either indapamide (1.5 mg Slow Release (SR)/day) or hydrochlorothiazide (25 mg/d), added to quinapril (10-40 mg/d). All patients had conventional, tissue Doppler and speckle tracking echocardiography and assessment of endothelial and arterial functions and biomarkers, at baseline and after 6 months. Baseline characteristics were similar between groups; systolic and diastolic blood pressures decreased similarly, by 15% and 9% on indapamide and by 17% and 10% on hydrochlorothiazide (P < .05). Mean longitudinal systolic velocity and longitudinal strain increased by 7% and 14% on indapamide (from 5.6 ± 1.8 to 6.0 ± 1.1 cm/s and from 16.2% ± 1.8% to 18.5% ± 1.1%, both P < .05), but did not change on hydrochlorothiazide (P < .05 for intergroup differences), whereas ejection fraction and radial systolic function did not change. Similarly, mean longitudinal early diastolic velocity increased by 31% on indapamide (P < .05), but did not change on hydrochlorothiazide (P < .05 for intergroup differences). These changes were associated with improved endothelial and arterial functions on indapamide, but not on hydrochlorothiazide. Indapamide was found to improve measures of endothelial and arterial functions and to increase longitudinal left ventricular function compared with hydrochlorothiazide in patients with hypertension and diabetes, after 6 months of treatment. This study suggests that indapamide, a thiazide-like diuretic, has important vascular effects that can improve ventriculoarterial coupling. Copyright © 2014 Mosby, Inc. All rights reserved.
Generalized linear mixed models with varying coefficients for longitudinal data.

PubMed

Zhang, Daowen

2004-03-01

The routinely assumed parametric functional form in the linear predictor of a generalized linear mixed model for longitudinal data may be too restrictive to represent true underlying covariate effects. We relax this assumption by representing these covariate effects by smooth but otherwise arbitrary functions of time, with random effects used to model the correlation induced by among-subject and within-subject variation. Due to the usually intractable integration involved in evaluating the quasi-likelihood function, the double penalized quasi-likelihood (DPQL) approach of Lin and Zhang (1999, Journal of the Royal Statistical Society, Series B61, 381-400) is used to estimate the varying coefficients and the variance components simultaneously by representing a nonparametric function by a linear combination of fixed effects and random effects. A scaled chi-squared test based on the mixed model representation of the proposed model is developed to test whether an underlying varying coefficient is a polynomial of certain degree. We evaluate the performance of the procedures through simulation studies and illustrate their application with Indonesian children infectious disease data.
Mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects for longitudinal-competing risks data analysis.

PubMed

Lu, Tao; Wang, Min; Liu, Guangying; Dong, Guang-Hui; Qian, Feng

2016-01-01

It is well known that there is strong relationship between HIV viral load and CD4 cell counts in AIDS studies. However, the relationship between them changes during the course of treatment and may vary among individuals. During treatments, some individuals may experience terminal events such as death. Because the terminal event may be related to the individual's viral load measurements, the terminal mechanism is non-ignorable. Furthermore, there exists competing risks from multiple types of events, such as AIDS-related death and other death. Most joint models for the analysis of longitudinal-survival data developed in literatures have focused on constant coefficients and assume symmetric distribution for the endpoints, which does not meet the needs for investigating the nature of varying relationship between HIV viral load and CD4 cell counts in practice. We develop a mixed-effects varying-coefficient model with skewed distribution coupled with cause-specific varying-coefficient hazard model with random-effects to deal with varying relationship between the two endpoints for longitudinal-competing risks survival data. A fully Bayesian inference procedure is established to estimate parameters in the joint model. The proposed method is applied to a multicenter AIDS cohort study. Various scenarios-based potential models that account for partial data features are compared. Some interesting findings are presented.
A Fast EM Algorithm for Fitting Joint Models of a Binary Response and Multiple Longitudinal Covariates Subject to Detection Limits

PubMed Central

Bernhardt, Paul W.; Zhang, Daowen; Wang, Huixia Judy

2014-01-01

Joint modeling techniques have become a popular strategy for studying the association between a response and one or more longitudinal covariates. Motivated by the GenIMS study, where it is of interest to model the event of survival using censored longitudinal biomarkers, a joint model is proposed for describing the relationship between a binary outcome and multiple longitudinal covariates subject to detection limits. A fast, approximate EM algorithm is developed that reduces the dimension of integration in the E-step of the algorithm to one, regardless of the number of random effects in the joint model. Numerical studies demonstrate that the proposed approximate EM algorithm leads to satisfactory parameter and variance estimates in situations with and without censoring on the longitudinal covariates. The approximate EM algorithm is applied to analyze the GenIMS data set. PMID:25598564
Longitudinal Care Improves Cessation in Smokers Who Do Not Initially Respond to Treatment by Increasing Cessation Self-Efficacy, Satisfaction, and Readiness to Quit: A Mediated Moderation Analysis

PubMed Central

Burns, Rachel J.; Rothman, Alexander J.; Fu, Steven S.; Lindgren, Bruce; Vock, David M.; Joseph, Anne M.

2015-01-01

Background The Tobacco Longitudinal Care study was a randomized controlled trial for smoking cessation. It demonstrated that longitudinal care for smoking cessation, in which telephone-based counseling and nicotine replacement therapy was offered for 12 months, was more effective than standard 8-week treatment. Purpose To identify for whom and how longitudinal care increased the likelihood of abstinence. Methods Mediated moderation analyses across three time points. Results There was a trend towards smokers who did not respond to treatment (i.e., were still smoking) by 21 days being more likely to be abstinent at 6 months if they received longitudinal care rather than usual care. Similarly, those who did not respond to treatment by 3 months were more likely to be abstinent at 12 months if they received longitudinal care. At both time points, the likelihood of abstinence did not differ across treatment conditions among participants who responded to treatment (i.e., quit smoking). The effect on 6-month outcomes was mediated by satisfaction and readiness to quit. Cessation self-efficacy, satisfaction, and readiness to quit mediated the effect on 12-month outcomes. The effect of treatment condition on the likelihood of abstinence at 18 months was not moderated by response to treatment at 6 months. Conclusions Smokers who did not respond to initial treatment benefited from longitudinal care. Differential effects of treatment condition were not observed among those who responded to early treatment. Conditional assignment to longitudinal care may be useful. Determining for whom and how interventions work over time will advance theory and practice. PMID:26373657
Longitudinal Care Improves Cessation in Smokers Who Do Not Initially Respond to Treatment by Increasing Cessation Self-Efficacy, Satisfaction, and Readiness to Quit: A Mediated Moderation Analysis.

PubMed

Burns, Rachel J; Rothman, Alexander J; Fu, Steven S; Lindgren, Bruce; Vock, David M; Joseph, Anne M

2016-02-01

The Tobacco Longitudinal Care study was a randomized controlled trial for smoking cessation. It demonstrated that longitudinal care for smoking cessation, in which telephone-based counseling and nicotine replacement therapy were offered for 12 months, was more effective than the standard 8-week treatment. This study aims to identify for whom and how longitudinal care increased the likelihood of abstinence. Mediated moderation analyses were utilized across three time points. There was a trend towards smokers who did not respond to treatment (i.e., were still smoking) by 21 days being more likely to be abstinent at 6 months if they received longitudinal care rather than usual care. Similarly, those who did not respond to treatment by 3 months were more likely to be abstinent at 12 months if they received longitudinal care. At both time points, the likelihood of abstinence did not differ across treatment conditions among participants who responded to treatment (i.e., quit smoking). The effect on 6-month outcomes was mediated by satisfaction and readiness to quit. Cessation self-efficacy, satisfaction, and readiness to quit mediated the effect on 12-month outcomes. The effect of treatment condition on the likelihood of abstinence at 18 months was not moderated by response to treatment at 6 months. Smokers who did not respond to initial treatment benefited from longitudinal care. Differential effects of treatment condition were not observed among those who responded to early treatment. Conditional assignment to longitudinal care may be useful. Determining for whom and how interventions work over time will advance theory and practice.
Development of Children at Risk for Adverse Outcomes Participating in Early Intervention in Developing Countries: A Randomized Controlled Trial

ERIC Educational Resources Information Center

Wallander, Jan L.; Bann, Carla M.; Biasini, Fred J.; Goudar, Shivaprasad S.; Pasha, Omrana; Chomba, Elwyn; McClure, Elizabeth; Carlo, Waldemar A.

2014-01-01

Background: Previous research has indicated positive effects of early developmental intervention (EDI) on the development of children in developing countries. Few studies, however, have examined longitudinally when differential treatment effects may be observed and whether differential outcomes are associated with exposure to different risk…
Physical Health Effects of Intimate Partner Abuse

ERIC Educational Resources Information Center

Sillito, Carrie LeFevre

2012-01-01

Although intimate partner violence has been recognized as both a social problem and health issue, the extent to which it is a health issue for both males and females in the general population is largely unknown. This longitudinal research uses data from the National Survey of Family and Households (1987-2003). Random effects logistic regression…
Avoiding Boundary Estimates in Hierarchical Linear Models through Weakly Informative Priors

ERIC Educational Resources Information Center

Chung, Yeojin; Rabe-Hesketh, Sophia; Gelman, Andrew; Dorie, Vincent; Liu, Jinchen

2012-01-01

Hierarchical or multilevel linear models are widely used for longitudinal or cross-sectional data on students nested in classes and schools, and are particularly important for estimating treatment effects in cluster-randomized trials, multi-site trials, and meta-analyses. The models can allow for variation in treatment effects, as well as…
Life Course Changes of Children and Well-Being of Parents

ERIC Educational Resources Information Center

Kalmijn, Matthijs; De Graaf, Paul M.

2012-01-01

How do children's life course transitions affect the well-being of their parents? Using a large panel survey among parents with longitudinal information on 2 randomly chosen children, the authors analyzed the effects of children's union formation, parenthood, and union dissolution on changes in depressive symptoms of parents. Negative effects were…
Effectiveness of a Playground Intervention for Antisocial, Prosocial, and Physical Activity Behaviors

ERIC Educational Resources Information Center

Mayfield, Carlene A.; Child, Stephanie; Weaver, Robert G.; Zarrett, Nicole; Beets, Michael W.; Moore, Justin B.

2017-01-01

Background: We examined the effectiveness of Peaceful Playgrounds™ (P2) to decrease antisocial behaviors (ASB) while increasing physical activity (PA) and prosocial behaviors (PSB) in elementary school children. Methods: A longitudinal, cluster-randomized design was employed in 4 elementary school playgrounds where students (third to fifth) from 2…
A Joint Model for Longitudinal Measurements and Survival Data in the Presence of Multiple Failure Types

PubMed Central

Elashoff, Robert M.; Li, Gang; Li, Ning

2009-01-01

Summary In this article we study a joint model for longitudinal measurements and competing risks survival data. Our joint model provides a flexible approach to handle possible nonignorable missing data in the longitudinal measurements due to dropout. It is also an extension of previous joint models with a single failure type, offering a possible way to model informatively censored events as a competing risk. Our model consists of a linear mixed effects submodel for the longitudinal outcome and a proportional cause-specific hazards frailty submodel (Prentice et al., 1978, Biometrics 34, 541-554) for the competing risks survival data, linked together by some latent random effects. We propose to obtain the maximum likelihood estimates of the parameters by an expectation maximization (EM) algorithm and estimate their standard errors using a profile likelihood method. The developed method works well in our simulation studies and is applied to a clinical trial for the scleroderma lung disease. PMID:18162112
On Models for Binomial Data with Random Numbers of Trials

PubMed Central

Comulada, W. Scott; Weiss, Robert E.

2010-01-01

Summary A binomial outcome is a count s of the number of successes out of the total number of independent trials n = s + f, where f is a count of the failures. The n are random variables not fixed by design in many studies. Joint modeling of (s, f) can provide additional insight into the science and into the probability π of success that cannot be directly incorporated by the logistic regression model. Observations where n = 0 are excluded from the binomial analysis yet may be important to understanding how π is influenced by covariates. Correlation between s and f may exist and be of direct interest. We propose Bayesian multivariate Poisson models for the bivariate response (s, f), correlated through random effects. We extend our models to the analysis of longitudinal and multivariate longitudinal binomial outcomes. Our methodology was motivated by two disparate examples, one from teratology and one from an HIV tertiary intervention study. PMID:17688514
Comparison of torsional and microburst longitudinal phacoemulsification: a prospective, randomized, masked clinical trial.

PubMed

Vasavada, Abhay R; Raj, Shetal M; Patel, Udayan; Vasavada, Vaishali; Vasavada, Viraj

2010-01-01

To compare intraoperative performance and postoperative outcome of three phacoemulsification technologies in patients undergoing microcoaxial phacoemulsification through 2.2-mm corneal incisions. The prospective, randomized, single-masked study included 360 eyes randomly assigned to torsional (Infiniti Vision System; Alcon Laboratories, Fort Worth, TX), microburst with longitudinal (Infiniti), or microburst with longitudinal (Legacy Everest, Alcon Laboratories) ultrasound. Assessments included surgical clock time, fluid volume, and intraoperative complications, central corneal thickness on day 1 and months 1 and 3 postoperatively, and endothelial cell density at 3 months postoperatively. Comparisons among groups were conducted. Torsional ultrasound required significantly less surgical clock time and fluid volume than the other groups. There were no intraoperative complications. Change in central corneal thickness and endothelial cell loss was significantly lower in the torsional ultrasound group at all postoperative visits (P < .001, Kruskal-Wallis test) compared to microburst longitudinal ultrasound modalities. Torsional ultrasound demonstrated quantitatively superior intraoperative performance and showed less increase in corneal thickness and less endothelial cell loss compared to microburst longitudinal ultrasound. Copyright 2010, SLACK Incorporated.
A comparison of methods for estimating the random effects distribution of a linear mixed model.

PubMed

Ghidey, Wendimagegn; Lesaffre, Emmanuel; Verbeke, Geert

2010-12-01

This article reviews various recently suggested approaches to estimate the random effects distribution in a linear mixed model, i.e. (1) the smoothing by roughening approach of Shen and Louis,(1) (2) the semi-non-parametric approach of Zhang and Davidian,(2) (3) the heterogeneity model of Verbeke and Lesaffre( 3) and (4) a flexible approach of Ghidey et al. (4) These four approaches are compared via an extensive simulation study. We conclude that for the considered cases, the approach of Ghidey et al. (4) often shows to have the smallest integrated mean squared error for estimating the random effects distribution. An analysis of a longitudinal dental data set illustrates the performance of the methods in a practical example.
An overview of longitudinal data analysis methods for neurological research.

PubMed

Locascio, Joseph J; Atri, Alireza

2011-01-01

The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1) repeated-measure analysis of covariance (ANCOVA), (2) ANCOVA for two time points, (3) generalized estimating equations and (4) latent growth curve/structural equation models.
Does the covariance structure matter in longitudinal modelling for the prediction of future CD4 counts?

PubMed

Taylor, J M; Law, N

1998-10-30

We investigate the importance of the assumed covariance structure for longitudinal modelling of CD4 counts. We examine how individual predictions of future CD4 counts are affected by the covariance structure. We consider four covariance structures: one based on an integrated Ornstein-Uhlenbeck stochastic process; one based on Brownian motion, and two derived from standard linear and quadratic random-effects models. Using data from the Multicenter AIDS Cohort Study and from a simulation study, we show that there is a noticeable deterioration in the coverage rate of confidence intervals if we assume the wrong covariance. There is also a loss in efficiency. The quadratic random-effects model is found to be the best in terms of correctly calibrated prediction intervals, but is substantially less efficient than the others. Incorrectly specifying the covariance structure as linear random effects gives too narrow prediction intervals with poor coverage rates. Fitting using the model based on the integrated Ornstein-Uhlenbeck stochastic process is the preferred one of the four considered because of its efficiency and robustness properties. We also use the difference between the future predicted and observed CD4 counts to assess an appropriate transformation of CD4 counts; a fourth root, cube root and square root all appear reasonable choices.
Effects of Simulated Interventions to Improve School Entry Academic Skills on Socioeconomic Inequalities in Educational Achievement

ERIC Educational Resources Information Center

Chittleborough, Catherine R.; Mittinty, Murthy N.; Lawlor, Debbie A.; Lynch, John W.

2014-01-01

Randomized controlled trial evidence shows that interventions before age 5 can improve skills necessary for educational success; the effect of these interventions on socioeconomic inequalities is unknown. Using trial effect estimates, and marginal structural models with data from the Avon Longitudinal Study of Parents and Children (n = 11,764,…
A varying-coefficient method for analyzing longitudinal clinical trials data with nonignorable dropout

PubMed Central

Forster, Jeri E.; MaWhinney, Samantha; Ball, Erika L.; Fairclough, Diane

2011-01-01

Dropout is common in longitudinal clinical trials and when the probability of dropout depends on unobserved outcomes even after conditioning on available data, it is considered missing not at random and therefore nonignorable. To address this problem, mixture models can be used to account for the relationship between a longitudinal outcome and dropout. We propose a Natural Spline Varying-coefficient mixture model (NSV), which is a straightforward extension of the parametric Conditional Linear Model (CLM). We assume that the outcome follows a varying-coefficient model conditional on a continuous dropout distribution. Natural cubic B-splines are used to allow the regression coefficients to semiparametrically depend on dropout and inference is therefore more robust. Additionally, this method is computationally stable and relatively simple to implement. We conduct simulation studies to evaluate performance and compare methodologies in settings where the longitudinal trajectories are linear and dropout time is observed for all individuals. Performance is assessed under conditions where model assumptions are both met and violated. In addition, we compare the NSV to the CLM and a standard random-effects model using an HIV/AIDS clinical trial with probable nonignorable dropout. The simulation studies suggest that the NSV is an improvement over the CLM when dropout has a nonlinear dependence on the outcome. PMID:22101223

Improving the Rank Precision of Population Health Measures for Small Areas with Longitudinal and Joint Outcome Models

PubMed Central

Athens, Jessica K.; Remington, Patrick L.; Gangnon, Ronald E.

2015-01-01

Objectives The University of Wisconsin Population Health Institute has published the County Health Rankings since 2010. These rankings use population-based data to highlight health outcomes and the multiple determinants of these outcomes and to encourage in-depth health assessment for all United States counties. A significant methodological limitation, however, is the uncertainty of rank estimates, particularly for small counties. To address this challenge, we explore the use of longitudinal and pooled outcome data in hierarchical Bayesian models to generate county ranks with greater precision. Methods In our models we used pooled outcome data for three measure groups: (1) Poor physical and poor mental health days; (2) percent of births with low birth weight and fair or poor health prevalence; and (3) age-specific mortality rates for nine age groups. We used the fixed and random effects components of these models to generate posterior samples of rates for each measure. We also used time-series data in longitudinal random effects models for age-specific mortality. Based on the posterior samples from these models, we estimate ranks and rank quartiles for each measure, as well as the probability of a county ranking in its assigned quartile. Rank quartile probabilities for univariate, joint outcome, and/or longitudinal models were compared to assess improvements in rank precision. Results The joint outcome model for poor physical and poor mental health days resulted in improved rank precision, as did the longitudinal model for age-specific mortality rates. Rank precision for low birth weight births and fair/poor health prevalence based on the univariate and joint outcome models were equivalent. Conclusion Incorporating longitudinal or pooled outcome data may improve rank certainty, depending on characteristics of the measures selected. For measures with different determinants, joint modeling neither improved nor degraded rank precision. This approach suggests a simple way to use existing information to improve the precision of small-area measures of population health. PMID:26098858
Using Design-Based Latent Growth Curve Modeling with Cluster-Level Predictor to Address Dependency

ERIC Educational Resources Information Center

Wu, Jiun-Yu; Kwok, Oi-Man; Willson, Victor L.

2014-01-01

The authors compared the effects of using the true Multilevel Latent Growth Curve Model (MLGCM) with single-level regular and design-based Latent Growth Curve Models (LGCM) with or without the higher-level predictor on various criterion variables for multilevel longitudinal data. They found that random effect estimates were biased when the…
Are Evidence-based Practices Associated With Effective Prevention of Hospital-acquired Pressure Ulcers in US Academic Medical Centers?

PubMed

Padula, William V; Gibbons, Robert D; Valuck, Robert J; Makic, Mary B F; Mishra, Manish K; Pronovost, Peter J; Meltzer, David O

2016-05-01

In 2008, the Centers for Medicare and Medicaid Services (CMS) established nonpayment policies resulting from costliness of hospital-acquired pressure ulcers (HAPUs) to hospitals. This prompted hospitals to adopt quality improvement (QI) interventions that increase use of evidence-based practices (EBPs) for HAPU prevention. To evaluate the longitudinal impact of CMS policy and QI adoption on HAPU rates. We characterized longitudinal adoption of 25 QI interventions that support EBPs through hospital leadership, staff, information technology, and performance and improvement. Quarterly counts of HAPU incidence and inpatient characteristics were collected from 55 University HealthSystem Consortium hospitals between 2007 and 2012. Mixed-effects regression models tested the longitudinal association of CMS policy, HAPU coding, and QI on HAPU rates. The models assumed level-2 random intercepts and random effects for CMS policy and EBP implementation to account for between-hospital variability in HAPU incidence. Controlling for all 25 QI interventions, specific updates to EBPs for HAPU prevention had a significant, though modest reduction on HAPU rates (-1.86 cases/quarter; P=0.002) and the effect of CMS nonpayment policy on HAPU prevention was much greater (-11.32 cases/quarter; P<0.001). HAPU rates were significantly lower after changes in CMS reimbursement. Reductions are associated with hospital-wide implementation of EBPs for HAPU prevention. Given that administrative data were used, it remains unknown whether these improvements were due to changes in coding or improved quality of care.
Are Evidence-based Practices Associated with Effective Prevention of Hospital-acquired Pressure Ulcers in U.S. Academic Medical Centers?

PubMed Central

Padula, William V.; Gibbons, Robert D.; Valuck, Robert J.; Makic, Mary Beth F.; Mishra, Manish K.; Pronovost, Peter J.; Meltzer, David O.

2016-01-01

Background In 2008, the Centers for Medicare and Medicaid Services (CMS) established nonpayment policies resulting from costliness of hospital-acquired pressure ulcers (HAPUs) to hospitals. This prompted hospitals to adopt quality improvement (QI) interventions that increase use of evidence-based practices (EBPs) for HAPU prevention. Objective To evaluate the longitudinal impact of CMS policy and QI adoption on HAPU rates. Methods We characterized longitudinal adoption of 25 QI interventions that support EBPs through hospital leadership, staff, information technology, and performance and improvement. Quarterly counts of HAPU incidence and inpatient characteristics were collected from 55 UHC hospitals between 2007–2012. Mixed-effects regression models tested the longitudinal association of CMS policy, HAPU coding and QI on HAPU rates. The models assumed level-2 random-intercepts and random effects for CMS policy and EBP implementation to account for between-hospital variability in HAPU incidence. Results Controlling for all 25 QI interventions, specific updates to EBPs for HAPU prevention had a significant, though modest reduction on HAPU rates (−1.86 cases/quarter; p=0.002) and the effect of CMS nonpayment policy on HAPU prevention was much greater (−11.32 cases/quarter; p<0.001). Conclusions HAPU rates were significantly lower following changes in CMS reimbursement. Reductions are associated with hospital-wide implementation of EBPs for HAPU prevention. Given that administrative data were used, it remains unknown whether these improvements were due to changes in coding or improved quality of care. PMID:27078824
Propagation of elastic wave in nanoporous material with distributed cylindrical nanoholes

NASA Astrophysics Data System (ADS)

Qiang, FangWei; Wei, PeiJun; Liu, XiQiang

2013-08-01

The effective propagation constants of plane longitudinal and shear waves in nanoporous material with random distributed parallel cylindrical nanoholes are studied. The surface elastic theory is used to consider the surface stress effects and to derive the nontraditional boundary condition on the surface of nanoholes. The plane wave expansion method is used to obtain the scattering waves from the single nanohole. The multiple scattering effects are taken into consideration by summing the scattered waves from all scatterers and performing the configuration averaging of random distributed scatterers. The effective propagation constants of coherent waves along with the associated dynamic effective elastic modulus are numerically evaluated. The influences of surface stress are discussed based on the numerical results.
A Semiparametric Approach to Simultaneous Covariance Estimation for Bivariate Sparse Longitudinal Data

PubMed Central

Das, Kiranmoy; Daniels, Michael J.

2014-01-01

Summary Estimation of the covariance structure for irregular sparse longitudinal data has been studied by many authors in recent years but typically using fully parametric specifications. In addition, when data are collected from several groups over time, it is known that assuming the same or completely different covariance matrices over groups can lead to loss of efficiency and/or bias. Nonparametric approaches have been proposed for estimating the covariance matrix for regular univariate longitudinal data by sharing information across the groups under study. For the irregular case, with longitudinal measurements that are bivariate or multivariate, modeling becomes more difficult. In this article, to model bivariate sparse longitudinal data from several groups, we propose a flexible covariance structure via a novel matrix stick-breaking process for the residual covariance structure and a Dirichlet process mixture of normals for the random effects. Simulation studies are performed to investigate the effectiveness of the proposed approach over more traditional approaches. We also analyze a subset of Framingham Heart Study data to examine how the blood pressure trajectories and covariance structures differ for the patients from different BMI groups (high, medium and low) at baseline. PMID:24400941
[Burnout and job satisfaction among nursing professionals].

PubMed

Figueiredo-Ferraz, Hugo; Grau-Alberola, Ester; Gil-Monte, Pedro R; García-Juesas, Juan A

2012-05-01

The purpose of this study was to examine the relationship between burnout and job satisfaction among nursing professionals. The sample consisted of 316 staff nurses. The study was longitudinal, and not randomized. The gap between Time 1 (T1) and Time 2 (T2) was one year. Hierarchical regression analysis showed empirical evidence of the significant and negative effect of burnout (i.e., Emotional exhaustion and Depersonalization dimensions) at T1 on job satisfaction in T2. Significant results were also obtained that showed the influence of job satisfaction at T1 on burnout at T2 (i.e., Depersonalization dimension). The study concludes that there is a bidirectional and longitudinal relationship between burnout and job satisfaction. However, longitudinal effects of burnout at T1 on job satisfaction on T2 (i.e., burnout as antecedent of job satisfaction) are stronger than vice-versa (i.e., job satisfaction as antecedent of burnout).
An Overview of Longitudinal Data Analysis Methods for Neurological Research

PubMed Central

Locascio, Joseph J.; Atri, Alireza

2011-01-01

The purpose of this article is to provide a concise, broad and readily accessible overview of longitudinal data analysis methods, aimed to be a practical guide for clinical investigators in neurology. In general, we advise that older, traditional methods, including (1) simple regression of the dependent variable on a time measure, (2) analyzing a single summary subject level number that indexes changes for each subject and (3) a general linear model approach with a fixed-subject effect, should be reserved for quick, simple or preliminary analyses. We advocate the general use of mixed-random and fixed-effect regression models for analyses of most longitudinal clinical studies. Under restrictive situations or to provide validation, we recommend: (1) repeated-measure analysis of covariance (ANCOVA), (2) ANCOVA for two time points, (3) generalized estimating equations and (4) latent growth curve/structural equation models. PMID:22203825
The balanced survivor average causal effect.

PubMed

Greene, Tom; Joffe, Marshall; Hu, Bo; Li, Liang; Boucher, Ken

2013-05-07

Statistical analysis of longitudinal outcomes is often complicated by the absence of observable values in patients who die prior to their scheduled measurement. In such cases, the longitudinal data are said to be "truncated by death" to emphasize that the longitudinal measurements are not simply missing, but are undefined after death. Recently, the truncation by death problem has been investigated using the framework of principal stratification to define the target estimand as the survivor average causal effect (SACE), which in the context of a two-group randomized clinical trial is the mean difference in the longitudinal outcome between the treatment and control groups for the principal stratum of always-survivors. The SACE is not identified without untestable assumptions. These assumptions have often been formulated in terms of a monotonicity constraint requiring that the treatment does not reduce survival in any patient, in conjunction with assumed values for mean differences in the longitudinal outcome between certain principal strata. In this paper, we introduce an alternative estimand, the balanced-SACE, which is defined as the average causal effect on the longitudinal outcome in a particular subset of the always-survivors that is balanced with respect to the potential survival times under the treatment and control. We propose a simple estimator of the balanced-SACE that compares the longitudinal outcomes between equivalent fractions of the longest surviving patients between the treatment and control groups and does not require a monotonicity assumption. We provide expressions for the large sample bias of the estimator, along with sensitivity analyses and strategies to minimize this bias. We consider statistical inference under a bootstrap resampling procedure.
Application of pattern mixture models to address missing data in longitudinal data analysis using SPSS.

PubMed

Son, Heesook; Friedmann, Erika; Thomas, Sue A

2012-01-01

Longitudinal studies are used in nursing research to examine changes over time in health indicators. Traditional approaches to longitudinal analysis of means, such as analysis of variance with repeated measures, are limited to analyzing complete cases. This limitation can lead to biased results due to withdrawal or data omission bias or to imputation of missing data, which can lead to bias toward the null if data are not missing completely at random. Pattern mixture models are useful to evaluate the informativeness of missing data and to adjust linear mixed model (LMM) analyses if missing data are informative. The aim of this study was to provide an example of statistical procedures for applying a pattern mixture model to evaluate the informativeness of missing data and conduct analyses of data with informative missingness in longitudinal studies using SPSS. The data set from the Patients' and Families' Psychological Response to Home Automated External Defibrillator Trial was used as an example to examine informativeness of missing data with pattern mixture models and to use a missing data pattern in analysis of longitudinal data. Prevention of withdrawal bias, omitted data bias, and bias toward the null in longitudinal LMMs requires the assessment of the informativeness of the occurrence of missing data. Missing data patterns can be incorporated as fixed effects into LMMs to evaluate the contribution of the presence of informative missingness to and control for the effects of missingness on outcomes. Pattern mixture models are a useful method to address the presence and effect of informative missingness in longitudinal studies.
The Influence of Neighborhood Characteristics and Parenting Practices on Academic Problems and Aggression Outcomes among Moderately to Highly Aggressive Children

ERIC Educational Resources Information Center

Barry, Tammy D.; Lochman, John E.; Fite, Paula J.; Wells, Karen C.; Colder, Craig R.

2012-01-01

The current study utilized a longitudinal design to examine the effects of neighborhood and parenting on 120 at-risk children's academic and aggressive outcomes, concurrently and at two later timepoints during the transition to middle school. Random effects regression models were estimated to examine whether neighborhood characteristics and harsh…
Three Randomized Experiments on the Longitudinal Effects of the Transcendental Meditation Technique on Cognition.

ERIC Educational Resources Information Center

So, Kam-Tim; Orme-Johnson, David W.

2001-01-01

Three studies of 362 high school students in 3 schools in Taiwan tested the hypothesis that regular practice of transcendental meditation (TM) for 6 to 12 months would improve cognitive ability. TM practice produced significant effects on all seven variables studies, and the TM technique was superior to contemplative meditation for five of the…
An approximate generalized linear model with random effects for informative missing data.

PubMed

Follmann, D; Wu, M

1995-03-01

This paper develops a class of models to deal with missing data from longitudinal studies. We assume that separate models for the primary response and missingness (e.g., number of missed visits) are linked by a common random parameter. Such models have been developed in the econometrics (Heckman, 1979, Econometrica 47, 153-161) and biostatistics (Wu and Carroll, 1988, Biometrics 44, 175-188) literature for a Gaussian primary response. We allow the primary response, conditional on the random parameter, to follow a generalized linear model and approximate the generalized linear model by conditioning on the data that describes missingness. The resultant approximation is a mixed generalized linear model with possibly heterogeneous random effects. An example is given to illustrate the approximate approach, and simulations are performed to critique the adequacy of the approximation for repeated binary data.
A comparison of multiple imputation methods for incomplete longitudinal binary data.

PubMed

Yamaguchi, Yusuke; Misumi, Toshihiro; Maruo, Kazushi

2018-01-01

Longitudinal binary data are commonly encountered in clinical trials. Multiple imputation is an approach for getting a valid estimation of treatment effects under an assumption of missing at random mechanism. Although there are a variety of multiple imputation methods for the longitudinal binary data, a limited number of researches have reported on relative performances of the methods. Moreover, when focusing on the treatment effect throughout a period that has often been used in clinical evaluations of specific disease areas, no definite investigations comparing the methods have been available. We conducted an extensive simulation study to examine comparative performances of six multiple imputation methods available in the SAS MI procedure for longitudinal binary data, where two endpoints of responder rates at a specified time point and throughout a period were assessed. The simulation study suggested that results from naive approaches of a single imputation with non-responders and a complete case analysis could be very sensitive against missing data. The multiple imputation methods using a monotone method and a full conditional specification with a logistic regression imputation model were recommended for obtaining unbiased and robust estimations of the treatment effect. The methods were illustrated with data from a mental health research.
KiVa Anti-Bullying Program in Italy: Evidence of Effectiveness in a Randomized Control Trial.

PubMed

Nocentini, Annalaura; Menesini, Ersilia

2016-11-01

The present study aims to evaluate the effectiveness of the KiVa anti-bullying program in Italy through a randomized control trial of students in grades 4 and 6. The sample involved 2042 students (51 % female; grade 4, mean age = 8.85; ds = 0.43; grade 6, mean age = 10.93; ds = 0.50); 13 comprehensive schools were randomly assigned into intervention (KiVa) or control (usual school provision) conditions. Different outcomes (bullying, victimization, pro-bullying attitudes, pro-victim attitudes, empathy toward victims), analyses (longitudinal mixed model with multiple-item scales; longitudinal prevalence of bullies and victims using Olweus' single question), and estimates of effectiveness (Cohen's d; odds ratios) were considered in order to compare the Italian results with those from other countries. Multilevel models showed that KiVa reduced bullying and victimization and increased pro-victim attitudes and empathy toward the victim in grade 4, with effect sizes from 0.24 to 0.40. In grade 6, KiVa reduced bullying, victimization, and pro-bullying attitudes; the effects were smaller as compared to grade 4, yet significant (d ≥ 0.20). Finally, using Olweus dichotomous definition of bullies and victims, results showed that the odds of being a victim were 1.93 times higher for a control student than for a KiVa student in grade 4. Overall, the findings provide evidence of the effectiveness of the program in Italy; the discussion will focus on factors that influenced successfully the transportability of the KiVa program in Italy.
MIXOR: a computer program for mixed-effects ordinal regression analysis.

PubMed

Hedeker, D; Gibbons, R D

1996-03-01

MIXOR provides maximum marginal likelihood estimates for mixed-effects ordinal probit, logistic, and complementary log-log regression models. These models can be used for analysis of dichotomous and ordinal outcomes from either a clustered or longitudinal design. For clustered data, the mixed-effects model assumes that data within clusters are dependent. The degree of dependency is jointly estimated with the usual model parameters, thus adjusting for dependence resulting from clustering of the data. Similarly, for longitudinal data, the mixed-effects approach can allow for individual-varying intercepts and slopes across time, and can estimate the degree to which these time-related effects vary in the population of individuals. MIXOR uses marginal maximum likelihood estimation, utilizing a Fisher-scoring solution. For the scoring solution, the Cholesky factor of the random-effects variance-covariance matrix is estimated, along with the effects of model covariates. Examples illustrating usage and features of MIXOR are provided.
Genetic structured antedependence and random regression models applied to the longitudinal feed conversion ratio in growing Large White pigs.

PubMed

Huynh-Tran, V H; Gilbert, H; David, I

2017-11-01

The objective of the present study was to compare a random regression model, usually used in genetic analyses of longitudinal data, with the structured antedependence (SAD) model to study the longitudinal feed conversion ratio (FCR) in growing Large White pigs and to propose criteria for animal selection when used for genetic evaluation. The study was based on data from 11,790 weekly FCR measures collected on 1,186 Large White male growing pigs. Random regression (RR) using orthogonal polynomial Legendre and SAD models was used to estimate genetic parameters and predict FCR-based EBV for each of the 10 wk of the test. The results demonstrated that the best SAD model (1 order of antedependence of degree 2 and a polynomial of degree 2 for the innovation variance for the genetic and permanent environmental effects, i.e., 12 parameters) provided a better fit for the data than RR with a quadratic function for the genetic and permanent environmental effects (13 parameters), with Bayesian information criteria values of -10,060 and -9,838, respectively. Heritabilities with the SAD model were higher than those of RR over the first 7 wk of the test. Genetic correlations between weeks were higher than 0.68 for short intervals between weeks and decreased to 0.08 for the SAD model and -0.39 for RR for the longest intervals. These differences in genetic parameters showed that, contrary to the RR approach, the SAD model does not suffer from border effect problems and can handle genetic correlations that tend to 0. Summarized breeding values were proposed for each approach as linear combinations of the individual weekly EBV weighted by the coefficients of the first or second eigenvector computed from the genetic covariance matrix of the additive genetic effects. These summarized breeding values isolated EBV trajectories over time, capturing either the average general value or the slope of the trajectory. Finally, applying the SAD model over a reduced period of time suggested that similar selection choices would result from the use of the records from the first 8 wk of the test. To conclude, the SAD model performed well for the genetic evaluation of longitudinal phenotypes.
Testing Models for the Contributions of Genes and Environment to Developmental Change in Adolescent Depression

PubMed Central

Eaves, Lindon J.; Maes, Hermine; Silberg, Judy L.

2015-01-01

We tested two models to identify the genetic and environmental processes underlying longitudinal changes in depression among adolescents. The first assumes that observed changes in covariance structure result from the unfolding of inherent, random individual differences in the overall levels and rates of change in depression over time (random growth curves). The second assumes that observed changes are due to time-specific random effects (innovations) accumulating over time (autoregressive effects). We found little evidence of age-specific genetic effects or persistent genetic innovations. Instead, genetic effects are consistent with a gradual unfolding in the liability to depression and rates of change with increasing age. Likewise, the environment also creates significant individual differences in overall levels of depression and rates of change. However, there are also time-specific environmental experiences that persist with fidelity. The implications of these differing genetic and environmental mechanisms in the etiology of depression are considered. PMID:25894924
Testing Models for the Contributions of Genes and Environment to Developmental Change in Adolescent Depression.

PubMed

Gillespie, Nathan A; Eaves, Lindon J; Maes, Hermine; Silberg, Judy L

2015-07-01

We tested two models to identify the genetic and environmental processes underlying longitudinal changes in depression among adolescents. The first assumes that observed changes in covariance structure result from the unfolding of inherent, random individual differences in the overall levels and rates of change in depression over time (random growth curves). The second assumes that observed changes are due to time-specific random effects (innovations) accumulating over time (autoregressive effects). We found little evidence of age-specific genetic effects or persistent genetic innovations. Instead, genetic effects are consistent with a gradual unfolding in the liability to depression and rates of change with increasing age. Likewise, the environment also creates significant individual differences in overall levels of depression and rates of change. However, there are also time-specific environmental experiences that persist with fidelity. The implications of these differing genetic and environmental mechanisms in the etiology of depression are considered.
Capturing the Cumulative Effects of School Reform: An 11-Year Study of the Impacts of America's Choice on Student Achievement

ERIC Educational Resources Information Center

May, Henry; Supovitz, Jonathan A.

2006-01-01

This article presents the results of an 11-year longitudinal study of the impact of America's Choice comprehensive school reform (CSR) design on student learning gains in Rochester, New York. A quasi-experimental interrupted time-series approach using Bayesian hierarchical growth curve analysis with crossed random effects is used to compare the…

Clustering of longitudinal data by using an extended baseline: A new method for treatment efficacy clustering in longitudinal data.

PubMed

Schramm, Catherine; Vial, Céline; Bachoud-Lévi, Anne-Catherine; Katsahian, Sandrine

2018-01-01

Heterogeneity in treatment efficacy is a major concern in clinical trials. Clustering may help to identify the treatment responders and the non-responders. In the context of longitudinal cluster analyses, sample size and variability of the times of measurements are the main issues with the current methods. Here, we propose a new two-step method for the Clustering of Longitudinal data by using an Extended Baseline. The first step relies on a piecewise linear mixed model for repeated measurements with a treatment-time interaction. The second step clusters the random predictions and considers several parametric (model-based) and non-parametric (partitioning, ascendant hierarchical clustering) algorithms. A simulation study compares all options of the clustering of longitudinal data by using an extended baseline method with the latent-class mixed model. The clustering of longitudinal data by using an extended baseline method with the two model-based algorithms was the more robust model. The clustering of longitudinal data by using an extended baseline method with all the non-parametric algorithms failed when there were unequal variances of treatment effect between clusters or when the subgroups had unbalanced sample sizes. The latent-class mixed model failed when the between-patients slope variability is high. Two real data sets on neurodegenerative disease and on obesity illustrate the clustering of longitudinal data by using an extended baseline method and show how clustering may help to identify the marker(s) of the treatment response. The application of the clustering of longitudinal data by using an extended baseline method in exploratory analysis as the first stage before setting up stratified designs can provide a better estimation of treatment effect in future clinical trials.
Marginal and Random Intercepts Models for Longitudinal Binary Data With Examples From Criminology.

PubMed

Long, Jeffrey D; Loeber, Rolf; Farrington, David P

2009-01-01

Two models for the analysis of longitudinal binary data are discussed: the marginal model and the random intercepts model. In contrast to the linear mixed model (LMM), the two models for binary data are not subsumed under a single hierarchical model. The marginal model provides group-level information whereas the random intercepts model provides individual-level information including information about heterogeneity of growth. It is shown how a type of numerical averaging can be used with the random intercepts model to obtain group-level information, thus approximating individual and marginal aspects of the LMM. The types of inferences associated with each model are illustrated with longitudinal criminal offending data based on N = 506 males followed over a 22-year period. Violent offending indexed by official records and self-report were analyzed, with the marginal model estimated using generalized estimating equations and the random intercepts model estimated using maximum likelihood. The results show that the numerical averaging based on the random intercepts can produce prediction curves almost identical to those obtained directly from the marginal model parameter estimates. The results provide a basis for contrasting the models and the estimation procedures and key features are discussed to aid in selecting a method for empirical analysis.
The Influence of Small Class Size, Duration, Intensity, and Heterogeneity on Head Start Fade

ERIC Educational Resources Information Center

Huss, Christopher D.

2010-01-01

The researcher conducted a nonexperimental study to investigate and analyze the influence of reduced class sizes, intensity (all day and every day), duration (five years), and heterogeneity (random class assignment) on the Head Start Fade effect. The researcher employed retrospective data analysis using a longitudinal explanatory design on data…
NON-RANDOM CELL KILLING IN CRYOPRESERVATION: IMPLICATIONS FOR PERFORMANCE OF THE BATTERY OF LEUKOCYTE TESTS (BLT) - I. TOXIC AND IMMUNOTOXIC EFFECTS

EPA Science Inventory

To eliminate between-tests error in longitudinal studies, for specimen sharing, convenient scheduling, etc., it is necessary to freeze freshly separated leukocytes as well as non-transformed, continuous T lymphocyte (CTL) lines. o test the efficacy of a programmable reezer (tempe...
Modeling Growth in Electronic Learning Environments Using a Longitudinal Random Item Response Model

ERIC Educational Resources Information Center

Kadengye, Damazo T.; Ceulemans, Eva; Van Den Noortgate, Wim

2015-01-01

In educational environments, monitoring persons' progress over time may help teachers to evaluate the effectiveness of their teaching procedures. Electronic learning environments are increasingly being used as part of formal education and resulting datasets can be used to understand and to improve the environment. This study presents…
Marginalized zero-altered models for longitudinal count data.

PubMed

Tabb, Loni Philip; Tchetgen, Eric J Tchetgen; Wellenius, Greg A; Coull, Brent A

2016-10-01

Count data often exhibit more zeros than predicted by common count distributions like the Poisson or negative binomial. In recent years, there has been considerable interest in methods for analyzing zero-inflated count data in longitudinal or other correlated data settings. A common approach has been to extend zero-inflated Poisson models to include random effects that account for correlation among observations. However, these models have been shown to have a few drawbacks, including interpretability of regression coefficients and numerical instability of fitting algorithms even when the data arise from the assumed model. To address these issues, we propose a model that parameterizes the marginal associations between the count outcome and the covariates as easily interpretable log relative rates, while including random effects to account for correlation among observations. One of the main advantages of this marginal model is that it allows a basis upon which we can directly compare the performance of standard methods that ignore zero inflation with that of a method that explicitly takes zero inflation into account. We present simulations of these various model formulations in terms of bias and variance estimation. Finally, we apply the proposed approach to analyze toxicological data of the effect of emissions on cardiac arrhythmias.
Marginalized zero-altered models for longitudinal count data

PubMed Central

Tabb, Loni Philip; Tchetgen, Eric J. Tchetgen; Wellenius, Greg A.; Coull, Brent A.

2015-01-01

Count data often exhibit more zeros than predicted by common count distributions like the Poisson or negative binomial. In recent years, there has been considerable interest in methods for analyzing zero-inflated count data in longitudinal or other correlated data settings. A common approach has been to extend zero-inflated Poisson models to include random effects that account for correlation among observations. However, these models have been shown to have a few drawbacks, including interpretability of regression coefficients and numerical instability of fitting algorithms even when the data arise from the assumed model. To address these issues, we propose a model that parameterizes the marginal associations between the count outcome and the covariates as easily interpretable log relative rates, while including random effects to account for correlation among observations. One of the main advantages of this marginal model is that it allows a basis upon which we can directly compare the performance of standard methods that ignore zero inflation with that of a method that explicitly takes zero inflation into account. We present simulations of these various model formulations in terms of bias and variance estimation. Finally, we apply the proposed approach to analyze toxicological data of the effect of emissions on cardiac arrhythmias. PMID:27867423
Randomized controlled trial in rural Ethiopia to assess a portable water treatment device.

PubMed

Boisson, Sophie; Schmidt, Wolf-Peter; Berhanu, Tsegahiwot; Gezahegn, Henock; Clasen, Thomas

2009-08-01

We conducted a randomized controlled trial to assess the Lifestraw Personal pipe-style water treatment device among a rural population in Ethiopia. A total of 313 households (including 1516 persons) were randomly assigned either to an intervention group in which each householder received a Lifestraw Personal or a control. Households were visited fortnightly over a five-month intervention period and asked to report any episode of diarrhea during the previous week. A random sample of 160 devices was tested each month to assess the presence of thermotolerant coliforms (TTC) and residual iodine in treated water and to measure flow rate under simulated use. Members of the intervention group had 25% fewer weeks with diarrhea than those of the control group (longitudinal prevalence ratio = 0.75; 95% CI 0.60; 0.95). All 718 filtered water samples were free of TTC, were free of detectable iodine disinfectant, and showed a constant flow rate over time. After the five-month intervention period, 34% of participants reported use of device in the preceding week and 13% reported consistent use. While the device was associated with a 25% reduction in longitudinal prevalence of diarrhea, low levels of use suggest that much of this effect is likely to be attributable to reporting bias that is common in open trials with nonobjective outcomes.
Performance of time-varying predictors in multilevel models under an assumption of fixed or random effects.

PubMed

Baird, Rachel; Maxwell, Scott E

2016-06-01

Time-varying predictors in multilevel models are a useful tool for longitudinal research, whether they are the research variable of interest or they are controlling for variance to allow greater power for other variables. However, standard recommendations to fix the effect of time-varying predictors may make an assumption that is unlikely to hold in reality and may influence results. A simulation study illustrates that treating the time-varying predictor as fixed may allow analyses to converge, but the analyses have poor coverage of the true fixed effect when the time-varying predictor has a random effect in reality. A second simulation study shows that treating the time-varying predictor as random may have poor convergence, except when allowing negative variance estimates. Although negative variance estimates are uninterpretable, results of the simulation show that estimates of the fixed effect of the time-varying predictor are as accurate for these cases as for cases with positive variance estimates, and that treating the time-varying predictor as random and allowing negative variance estimates performs well whether the time-varying predictor is fixed or random in reality. Because of the difficulty of interpreting negative variance estimates, 2 procedures are suggested for selection between fixed-effect and random-effect models: comparing between fixed-effect and constrained random-effect models with a likelihood ratio test or fitting a fixed-effect model when an unconstrained random-effect model produces negative variance estimates. The performance of these 2 procedures is compared. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
A joint modeling and estimation method for multivariate longitudinal data with mixed types of responses to analyze physical activity data generated by accelerometers.

PubMed

Li, Haocheng; Zhang, Yukun; Carroll, Raymond J; Keadle, Sarah Kozey; Sampson, Joshua N; Matthews, Charles E

2017-11-10

A mixed effect model is proposed to jointly analyze multivariate longitudinal data with continuous, proportion, count, and binary responses. The association of the variables is modeled through the correlation of random effects. We use a quasi-likelihood type approximation for nonlinear variables and transform the proposed model into a multivariate linear mixed model framework for estimation and inference. Via an extension to the EM approach, an efficient algorithm is developed to fit the model. The method is applied to physical activity data, which uses a wearable accelerometer device to measure daily movement and energy expenditure information. Our approach is also evaluated by a simulation study. Copyright © 2017 John Wiley & Sons, Ltd.
Self-rated health in Canadian immigrants: analysis of the Longitudinal Survey of Immigrants to Canada.

PubMed

Setia, Maninder Singh; Lynch, John; Abrahamowicz, Michal; Tousignant, Pierre; Quesnel-Vallee, Amelie

2011-03-01

Using a multi-level random effects logistic model, we examine the contribution of source country, individual characteristics and post-migration experiences to the self-rated health (SRH) of 2468 male and 2614 female immigrants from the Longitudinal Survey of Immigrants to Canada (2001-2005). Sex/gender differences were found for all categories of health determinants. Source country characteristics explained away some ethnic differentials in health and had independent negative effects, particularly among women. Thus, women from countries lower on the development index appear at greater risk of poor SRH, and should be at the forefront of public health programmes aimed at new immigrants in Canada. Copyright © 2011 Elsevier Ltd. All rights reserved.
Ready-to-use supplementary food increases fat mass and BMI in Haitian school-aged children.

PubMed

Iannotti, Lora L; Henretty, Nicole M; Delnatus, Jacques Raymond; Previl, Windy; Stehl, Tom; Vorkoper, Susan; Bodden, Jaime; Maust, Amanda; Smidt, Rachel; Nash, Marilyn L; Tamimie, Courtney A; Owen, Bridget C; Wolff, Patricia B

2015-04-01

In Haiti and other countries, large-scale investments in school feeding programs have been made with marginal evidence of nutrition outcomes. We aimed to examine the effectiveness of a fortified ready-to-use supplementary food (RUSF), Mamba, on reduced anemia and improved body composition in school-aged children compared to an unfortified cereal bar, Tablet Yo, and control groups. A cluster, randomized trial with children ages 3-13 y (n = 1167) was conducted in the north of Haiti. Six schools were matched and randomized to the control group, Tablet Yo group (42 g, 165 kcal), or Mamba group (50 g, 260 kcal, and >75% of the RDA for critical micronutrients). Children in the supplementation groups received the snack daily for 100 d, and all were followed longitudinally for hemoglobin concentrations, anthropometry, and bioelectrical impedance measures: baseline (December 2012), midline (March 2013), and endline (June 2013). Parent surveys were conducted at baseline and endline to examine secondary outcomes of morbidities and dietary intakes. Longitudinal regression modeling using generalized least squares and logit with random effects tested the main effects. At baseline,14.0% of children were stunted, 14.5% underweight, 9.1% thin, and 73% anemic. Fat mass percentage (mean ± SD) was 8.1% ± 4.3% for boys and 12.5% ± 4.4% for girls. In longitudinal modeling, Mamba supplementation increased body mass index z score (regression coefficient ± SEE) 0.25 ± 0.06, fat mass 0.45 ± 0.14 kg, and percentage fat mass 1.28% ± 0.27% compared with control at each time point (P < 0.001). Among boys, Mamba increased fat mass (regression coefficient ± SEE) 0.73 ± 0.19 kg and fat-free mass 0.62 ± 0.34 kg compared with control (P < 0.001). Mamba reduced the odds of developing anemia by 28% compared to control (adjusted OR: 0.72; 95% CI: 0.57, 0.91; P < 0.001). No treatment effect was found for hemoglobin concentration. To our knowledge, this is the first study to give evidence of body composition effects from an RUSF in school-aged children. © 2015 American Society for Nutrition.
Randomized Controlled Trial of Group-Based Culturally Specific Cognitive Behavioral Therapy Among African American Smokers.

PubMed

Webb Hooper, Monica; Antoni, Michael H; Okuyemi, Kolawole; Dietz, Noella A; Resnicow, Ken

2017-03-01

This study tested the efficacy of group-based culturally specific cognitive behavioral therapy (CBT) for smoking cessation among low-income African Americans. Participants (N = 342; 63.8% male; M = 49.5 years old; M cigarettes per day = 18) were randomly assigned to eight sessions of group-based culturally specific or standard CBT, plus 8 weeks of transdermal nicotine patches. Biochemically verified 7-day point prevalence abstinence (ppa) was assessed at the end-of-therapy (ie, CBT) (EOT), and 3-, 6-, and 12-month follow-ups. Primary outcomes were the longitudinal intervention effect over the 12-month follow-up period, and 7-day ppa at the 6-month follow-up. Secondary outcomes included 7-day ppa at the EOT and 12-month follow-up, and intervention ratings. Generalized linear mixed modeling tested the longitudinal effect and logistic regression tested effects at specific timepoints. Generalized linear mixed modeling demonstrated a longitudinal effect of intervention condition. Specifically, 7-day ppa was two times (P = .02) greater following culturally specific CBT versus standard CBT when tested across all timepoints. Analyses by timepoint found no significant difference at 6 or 12 months, yet culturally specific CBT was efficacious at the EOT (62.5% vs. 51.5% abstinence, P = .05) and the 3-month follow-up (36.4% vs. 22.9% abstinence, P = .007). Finally, intervention ratings in both conditions were high, with no significant differences. Culturally specific CBT had a positive longitudinal effect on smoking cessation compared to a standard approach; however, the effects were driven by short-term successes. We recommend the use of group-based culturally specific CBT in this population when possible, and future research on methods to prevent long-term relapse. Culturally specific interventions are one approach to address smoking-related health disparities; however, evidence for their efficacy in African Americans is equivocal. Moreover, the methodological limitations of the existing literature preclude an answer to this fundamental question. We found a positive longitudinal effect of culturally specific CBT versus standard CBT for smoking cessation across the follow-up period. Analyses by assessment point revealed that the overall effect was driven by early successes. Best practices for treating tobacco use in this population should attend to ethnocultural factors, but when this is not possible, standard CBT is an alternative approach for facilitating long-term abstinence. © The Author 2016. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Mediation analysis with time varying exposures and mediators

PubMed Central

VanderWeele, Tyler J.; Tchetgen Tchetgen, Eric J.

2016-01-01

Summary In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the “mediational g-formula.” When there is no mediation, the mediational g-formula reduces to Robins’ regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl’s mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators. PMID:28824285
Mediation analysis with time varying exposures and mediators.

PubMed

VanderWeele, Tyler J; Tchetgen Tchetgen, Eric J

2017-06-01

In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "mediational g-formula." When there is no mediation, the mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl's mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators.
Effects of Aromatherapy Massage on Pregnant Women's Stress and Immune Function: A Longitudinal, Prospective, Randomized Controlled Trial.

PubMed

Chen, Pao-Ju; Chou, Cheng-Chen; Yang, Luke; Tsai, Yu-Lun; Chang, Yue-Cune; Liaw, Jen-Jiuan

2017-10-01

This study's aims are to examine the effects of aromatherapy massage on women's stress and immune function during pregnancy. This longitudinal, prospective, randomized controlled trial recruited 52 healthy pregnant women from a prenatal clinic in Taipei using convenience sampling. The participants were randomly assigned to the intervention (n = 24) or control (n = 28) group using Clinstat block randomization. The intervention group received 70 min of aromatherapy massage with 2% lavender essential oil every other week (10 times in total) for 20 weeks; the control group received only routine prenatal care. In both groups, participants' salivary cortisol and immunoglobulin A (IgA) levels were collected before and after the intervention group received aromatherapy massage (every month from 16 to 36 weeks gestation) and were analyzed using enzyme-linked immunosorbent assay. The pregnant women in the intervention group had lower salivary cortisol (p < 0.001) and higher IgA (p < 0.001) levels immediately after aromatherapy massage than those in the control group, which did not receive massage treatment. Comparing the long-term effects of aromatherapy massage on salivary IgA levels between groups at different times, the study found that the pretest salivary IgA levels at 32 (p = 0.002) and 36 (p < 0.001) weeks gestational age (GA) were significantly higher than the pretest IgA at 16 weeks GA (baseline). This study presented evidence that aromatherapy massage could significantly decrease stress and enhance immune function in pregnant women. The findings can guide clinicians or midwives in providing aromatherapy massage to women throughout the pregnancy.
Mindfulness in the Maintenance of Cognitive Capacities in Alzheimer's Disease: A Randomized Clinical Trial.

PubMed

Quintana-Hernández, Domingo J; Miró-Barrachina, María T; Ibáñez-Fernández, Ignacio J; Pino, Angelo Santana-Del; Quintana-Montesdeoca, María P; Rodríguez-de Vera, Bienvenida; Morales-Casanova, David; Pérez-Vieitez, María Del Carmen; Rodríguez-García, Javier; Bravo-Caraduje, Noelia

2016-01-01

The Canary Islands longitudinal study on non-pharmacological treatments showed the overall effectiveness of mindfulness in Alzheimer's disease (AD). However, no specific data on the maintenance of cognitive capacities were presented. To determine whether the practice of mindfulness modifies the course of cognitive impairment in AD. Longitudinal, non-inferiority and equivalence, randomized clinical trial, repeated-measures design, with three experimental groups and one control group. Patients with AD who voluntarily attended the Lidia García Foundation (n = 502). Only those who were treated with donepezil and MMSE ≥18 were included (n = 120). Over a two-year period, each group carried out three weekly sessions of stimulation based on mindfulness, cognitive stimulation therapy, and progressive muscle relaxation. Cognitive assessment CAMDEX-R (MMSE and CAMCOG). Repeated-measures ANOVA (p < 0.05) and the effect size Cohen's d were performed. The mindfulness group showed significant scores compared with the control and muscle relaxation groups (p < 0.05), while mindfulness and cognitive stimulation therapy were equivalent (p≥0.05). Group cognitive stimulation evolved better than the control (p < 0.05) group but not better than the muscle relaxation group (p≥0.05). The effect size compared over two years was large for the mindfulness group (p≥0.80), moderate for the relaxation group (p≥0.50), and low for the cognitive stimulation group (p≥0.20). The practice of mindfulness maintained cognitive function over a period of two years. This longitudinal study suggests that mindfulness can be used as a non-pharmacological treatment to slow cognitive impairment in AD.
Neuroprotection after a first episode of mania: a randomized controlled maintenance trial comparing the effects of lithium and quetiapine on grey and white matter volume

PubMed Central

Berk, M; Dandash, O; Daglas, R; Cotton, S M; Allott, K; Fornito, A; Suo, C; Klauser, P; Liberg, B; Henry, L; Macneil, C; Hasty, M; McGorry, P; Pantelis, Cs; Yücel, M

2017-01-01

Lithium and quetiapine are effective treatments for bipolar disorder, but their potential neuroprotective effects in humans remain unclear. A single blinded equivalence randomized controlled maintenance trial was conducted in a prospective cohort of first-episode mania (FEM) patients (n=26) to longitudinally compare the putative protective effects of lithium and quetapine on grey and white matter volume. A healthy control sample was also collected (n=20). Using structural MRI scans, voxel-wise grey and white matter volumes at baseline and changes over time in response to treatment were investigated. Patients were assessed at three time points (baseline, 3 and 12-month follow-up), whereas healthy controls were assessed at two time points (baseline and 12-month follow-up). Patients were randomized to lithium (serum level 0.6 mmol l−1, n=20) or quetiapine (flexibly dosed up to 800 mg per day, n=19) monotherapy. At baseline, compared with healthy control subjects, patients with FEM showed reduced grey matter in the orbitofrontal cortex, anterior cingulate, inferior frontal gyrus and cerebellum. In addition, patients had reduced internal capsule white matter volume bilaterally (t1,66>3.20, P<0.01). Longitudinally, there was a significant treatment × time effect only in the white matter of the left internal capsule (F2,112=8.54, P<0.01). Post hoc testing showed that, compared with baseline, lithium was more effective than quetiapine in slowing the progression of white matter volume reduction after 12 months (t1,24=3.76, P<0.01). Our data support the role of lithium but not quetiapine therapy in limiting white matter reduction early in the illness course after FEM. PMID:28117843
Improved longitudinal gray and white matter atrophy assessment via application of a 4-dimensional hidden Markov random field model.

PubMed

Dwyer, Michael G; Bergsland, Niels; Zivadinov, Robert

2014-04-15

SIENA and similar techniques have demonstrated the utility of performing "direct" measurements as opposed to post-hoc comparison of cross-sectional data for the measurement of whole brain (WB) atrophy over time. However, gray matter (GM) and white matter (WM) atrophy are now widely recognized as important components of neurological disease progression, and are being actively evaluated as secondary endpoints in clinical trials. Direct measures of GM/WM change with advantages similar to SIENA have been lacking. We created a robust and easily-implemented method for direct longitudinal analysis of GM/WM atrophy, SIENAX multi-time-point (SIENAX-MTP). We built on the basic halfway-registration and mask composition components of SIENA to improve the raw output of FMRIB's FAST tissue segmentation tool. In addition, we created LFAST, a modified version of FAST incorporating a 4th dimension in its hidden Markov random field model in order to directly represent time. The method was validated by scan-rescan, simulation, comparison with SIENA, and two clinical effect size comparisons. All validation approaches demonstrated improved longitudinal precision with the proposed SIENAX-MTP method compared to SIENAX. For GM, simulation showed better correlation with experimental volume changes (r=0.992 vs. 0.941), scan-rescan showed lower standard deviations (3.8% vs. 8.4%), correlation with SIENA was more robust (r=0.70 vs. 0.53), and effect sizes were improved by up to 68%. Statistical power estimates indicated a potential drop of 55% in the number of subjects required to detect the same treatment effect with SIENAX-MTP vs. SIENAX. The proposed direct GM/WM method significantly improves on the standard SIENAX technique by trading a small amount of bias for a large reduction in variance, and may provide more precise data and additional statistical power in longitudinal studies. Copyright © 2013 Elsevier Inc. All rights reserved.
The Impact of TCARE[R] on Service Recommendation, Use, and Caregiver Well-Being

ERIC Educational Resources Information Center

Kwak, Jung; Montgomery, Rhonda J. V.; Kosloski, Karl; Lang, Josh

2011-01-01

Purpose of the Study: Findings are reported from a study that examined the effects of the Tailored Caregiver Assessment and Referral (TCARE[R]) protocol, a care management process designed to help family caregivers, on care planning and caregiver outcomes. Design and Methods: A longitudinal, randomized controlled trial was conducted with 97…

The College Application Gauntlet: A Systematic Analysis of the Steps to Four-Year College Enrollment

ERIC Educational Resources Information Center

Klasik, Daniel

2012-01-01

Few studies have examined the steps to college enrollment between college aspiration and college enrollment and how these steps might present a barrier to four-year college enrollment. This study used data from the Education Longitudinal Study: 2002 and employed a multivariate random effects logistic framework to examine the completion of nine…
Longitudinal Effects of Induction on Teaching Skills and Attrition Rates of Beginning Teachers

ERIC Educational Resources Information Center

Helms-Lorenz, Michelle; van de Grift, Wim; Maulana, Ridwan

2016-01-01

The teaching profession faces a shortage as well as a decline of teaching skills. A possible way to mitigate this is to implement evidence-based induction arrangements. Seventy-one schools with 338 beginning secondary education teachers were randomly allocated to an experimental or a control group. The experimental schools used induction…
Prevention of Cyberbullying and Cyber Victimization: Evaluation of the ViSC Social Competence Program

ERIC Educational Resources Information Center

Gradinger, Petra; Yanagida, Takuya; Strohmeier, Dagmar; Spiel, Christiane

2015-01-01

It is well-documented that cyberbullying and victimization co-occur with traditional forms indicating that they share similar mechanisms. Therefore, it was hypothesized that the general antibullying program ViSC might also be effective in tackling these new forms of bullying. A longitudinal randomized control group design has been applied to…
Literacy Coaching to Improve Student Reading Achievement: A Multi-Level Mediation Model

ERIC Educational Resources Information Center

Matsumura, Lindsay Clare; Garnier, Helen E.; Spybrook, Jessaca

2013-01-01

In a longitudinal group-randomized trial, we explore the key role of the quality of classroom text discussions in mediating the effects of Content-Focused Coaching (CFC) on student reading achievement (2983 students, 167 teachers). Schools in the United States serving large numbers of minority and English language learning (ELL) students from…
Children's Executive Function and High-Calorie, Low-Nutrient Food Intake: Mediating Effects of Child-Perceived Adult Fast Food Intake

ERIC Educational Resources Information Center

Tate, Eleanor B.; Unger, Jennifer B.; Chou, Chih-Ping; Spruijt-Metz, Donna; Pentz, Mary Ann; Riggs, Nathaniel R.

2015-01-01

Objective: This study tested the relationships among child executive function (EF), child-perceived parent fast food intake, and child self-reported subsequent consumption of high-calorie, low-nutrient (HCLN) food. Design: One year and 6-month longitudinal observation from a larger randomized controlled trial. Setting. Southern California…
Mendelian randomization analysis of a time-varying exposure for binary disease outcomes using functional data analysis methods.

PubMed

Cao, Ying; Rajan, Suja S; Wei, Peng

2016-12-01

A Mendelian randomization (MR) analysis is performed to analyze the causal effect of an exposure variable on a disease outcome in observational studies, by using genetic variants that affect the disease outcome only through the exposure variable. This method has recently gained popularity among epidemiologists given the success of genetic association studies. Many exposure variables of interest in epidemiological studies are time varying, for example, body mass index (BMI). Although longitudinal data have been collected in many cohort studies, current MR studies only use one measurement of a time-varying exposure variable, which cannot adequately capture the long-term time-varying information. We propose using the functional principal component analysis method to recover the underlying individual trajectory of the time-varying exposure from the sparsely and irregularly observed longitudinal data, and then conduct MR analysis using the recovered curves. We further propose two MR analysis methods. The first assumes a cumulative effect of the time-varying exposure variable on the disease risk, while the second assumes a time-varying genetic effect and employs functional regression models. We focus on statistical testing for a causal effect. Our simulation studies mimicking the real data show that the proposed functional data analysis based methods incorporating longitudinal data have substantial power gains compared to standard MR analysis using only one measurement. We used the Framingham Heart Study data to demonstrate the promising performance of the new methods as well as inconsistent results produced by the standard MR analysis that relies on a single measurement of the exposure at some arbitrary time point. © 2016 WILEY PERIODICALS, INC.
Probability of atrial fibrillation after ablation: Using a parametric nonlinear temporal decomposition mixed effects model.

PubMed

Rajeswaran, Jeevanantham; Blackstone, Eugene H; Ehrlinger, John; Li, Liang; Ishwaran, Hemant; Parides, Michael K

2018-01-01

Atrial fibrillation is an arrhythmic disorder where the electrical signals of the heart become irregular. The probability of atrial fibrillation (binary response) is often time varying in a structured fashion, as is the influence of associated risk factors. A generalized nonlinear mixed effects model is presented to estimate the time-related probability of atrial fibrillation using a temporal decomposition approach to reveal the pattern of the probability of atrial fibrillation and their determinants. This methodology generalizes to patient-specific analysis of longitudinal binary data with possibly time-varying effects of covariates and with different patient-specific random effects influencing different temporal phases. The motivation and application of this model is illustrated using longitudinally measured atrial fibrillation data obtained through weekly trans-telephonic monitoring from an NIH sponsored clinical trial being conducted by the Cardiothoracic Surgery Clinical Trials Network.
Effective-medium theory of elastic waves in random networks of rods.

PubMed

Katz, J I; Hoffman, J J; Conradi, M S; Miller, J G

2012-06-01

We formulate an effective medium (mean field) theory of a material consisting of randomly distributed nodes connected by straight slender rods, hinged at the nodes. Defining wavelength-dependent effective elastic moduli, we calculate both the static moduli and the dispersion relations of ultrasonic longitudinal and transverse elastic waves. At finite wave vector k the waves are dispersive, with phase and group velocities decreasing with increasing wave vector. These results are directly applicable to networks with empty pore space. They also describe the solid matrix in two-component (Biot) theories of fluid-filled porous media. We suggest the possibility of low density materials with higher ratios of stiffness and strength to density than those of foams, aerogels, or trabecular bone.
The Stability of Perceived Pubertal Timing across Adolescence

PubMed Central

Cance, Jessica Duncan; Ennett, Susan T.; Morgan-Lopez, Antonio A.; Foshee, Vangie A.

2011-01-01

It is unknown whether perceived pubertal timing changes as puberty progresses or whether it is an important component of adolescent identity formation that is fixed early in pubertal development. The purpose of this study is to examine the stability of perceived pubertal timing among a school-based sample of rural adolescents aged 11 to 17 (N=6,425; 50% female; 53% White). Two measures of pubertal timing were used, stage-normative, based on the Pubertal Development Scale, a self-report scale of secondary sexual characteristics, and peer-normative, a one-item measure of perceived pubertal timing. Two longitudinal methods were used: one-way random effects ANOVA models and latent class analysis. When calculating intraclass correlation coefficients using the one-way random effects ANOVA models, which is based on the average reliability from one time point to the next, both measures had similar, but poor, stability. In contrast, latent class analysis, which looks at the longitudinal response pattern of each individual and treats deviation from that pattern as measurement error, showed three stable and distinct response patterns for both measures: always early, always on-time, and always late. Study results suggest instability in perceived pubertal timing from one age to the next, but this instability is likely due to measurement error. Thus, it may be necessary to take into account the longitudinal pattern of perceived pubertal timing across adolescence rather than measuring perceived pubertal timing at one point in time. PMID:21983873
Effect of food prices on the prevalence of obesity among young adults.

PubMed

Han, E; Powell, L M

2011-03-01

To examine the extent to which various food prices were associated with the obesity status of young adults. Retrospective cohort study of 6537 men and 5324 women in the USA using panel data from the Monitoring the Future Surveys (1992-2003), which were merged with two food-at-home and one food-away-from-home price measures from the American Chamber of Commerce Researchers Association. Longitudinal individual random effect and fixed effect models were estimated. This study found that food prices did not have a significant effect on the prevalence of obesity among young female adults. For young adult men, an individual random effect estimator suggested that a 10% increase in the price of fast food was associated with a 13.2% decrease in the probability of obesity, but this effect lost its economic and statistical significance once individual fixed effects were controlled for in the estimation. Overall, the results imply that observed time-varying individual characteristics, such as working status, marital status and school enrolment status, may over-ride the effect of changes in food prices for young adults. More research employing longitudinal data is necessary to determine if food subsidies or taxes, particularly soft drink and fast food taxes or subsidies for fruit and vegetables, could be effective policy measures to curtail the increasing prevalence of obesity among young adults. Copyright © 2010 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
Conditional Monte Carlo randomization tests for regression models.

PubMed

Parhat, Parwen; Rosenberger, William F; Diao, Guoqing

2014-08-15

We discuss the computation of randomization tests for clinical trials of two treatments when the primary outcome is based on a regression model. We begin by revisiting the seminal paper of Gail, Tan, and Piantadosi (1988), and then describe a method based on Monte Carlo generation of randomization sequences. The tests based on this Monte Carlo procedure are design based, in that they incorporate the particular randomization procedure used. We discuss permuted block designs, complete randomization, and biased coin designs. We also use a new technique by Plamadeala and Rosenberger (2012) for simple computation of conditional randomization tests. Like Gail, Tan, and Piantadosi, we focus on residuals from generalized linear models and martingale residuals from survival models. Such techniques do not apply to longitudinal data analysis, and we introduce a method for computation of randomization tests based on the predicted rate of change from a generalized linear mixed model when outcomes are longitudinal. We show, by simulation, that these randomization tests preserve the size and power well under model misspecification. Copyright © 2014 John Wiley & Sons, Ltd.
Accelerated telomere shortening: Tracking the lasting impact of early institutional care at the cellular level.

PubMed

Humphreys, Kathryn L; Esteves, Kyle; Zeanah, Charles H; Fox, Nathan A; Nelson, Charles A; Drury, Stacy S

2016-12-30

Studies examining the association between early adversity and longitudinal changes in telomere length within the same individual are rare, yet are likely to provide novel insight into the subsequent lasting effects of negative early experiences. We sought to examine the association between institutional care history and telomere shortening longitudinally across middle childhood and into adolescence. Buccal DNA was collected 2-4 times, between the ages of 6 and 15 years, in 79 children enrolled in the Bucharest Early Intervention Project (BEIP), a longitudinal study exploring the impact of early institutional rearing on child health and development. Children with a history of early institutional care (n=50) demonstrated significantly greater telomere shortening across middle childhood and adolescence compared to never institutionalized children (n=29). Among children with a history of institutional care, randomization to high quality foster care was not associated with differential telomere attrition across development. Cross-sectional analysis of children randomized to the care as usual group indicated shorter telomere length was associated with greater percent of the child's life spent in institutional care up to age 8. These results suggest that early adverse care from severe psychosocial deprivation may be embedded at the molecular genetic level through accelerated telomere shortening. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Accelerated telomere shortening: Tracking the lasting impact of early institutional care at the cellular level

PubMed Central

Humphreys, Kathryn L.; Esteves, Kyle; Zeanah, Charles H; Fox, Nathan A; Nelson, Charles A.; Drury, Stacy S.

2016-01-01

Studies examining the association between early adversity and longitudinal changes in telomere length within the same individual are rare, yet are likely to provide novel insight into the subsequent lasting effects of negative early experiences. We sought to examine the association between institutional care history and telomere shortening longitudinally across middle childhood and into adolescence. Buccal DNA was collected 2 to 4 times, between the ages of 6 and 15 years, in 79 children enrolled in the Bucharest Early Intervention Project (BEIP), a longitudinal study exploring the impact of early institutional rearing on child health and development. Children with a history of early institutional care (n=50) demonstrated significantly greater telomere shortening across middle childhood and adolescence compared to never institutionalized children (n=29). Among children with a history of institutional care, randomization to high quality foster care was not associated with differential telomere attrition across development. Cross-sectional analysis of children randomized to the care as usual group indicated shorter telomere length was associated with greater percent of the child’s life spent in institutional care up to age 8. These results suggest that early adverse care from severe psychosocial deprivation may be embedded at the molecular genetic level through accelerated telomere shortening. PMID:27677058
Transversely polarized source cladding for an optical fiber

NASA Technical Reports Server (NTRS)

Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

1994-01-01

An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented transversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.
Comparative Effectiveness of PCI Education's "PCI Reading Program": Phase 2--A Report of a Comparison Group Study in Brevard Public Schools and Miami-Dade County Public Schools. Research Summary

ERIC Educational Resources Information Center

Empirical Education Inc., 2010

2010-01-01

PCI Education sought scientifically based evidence on the comparative effectiveness of the "PCI Reading Program" through a five-year longitudinal study. Phase 1 of the study consisted of a randomized control trial studying the efficacy of the "PCI Reading Program-Level One" that was conducted in the 2007-2008 in Miami-Dade…
Comparative Effectiveness of TI-84 Graphing Calculators on Algebra I and Geometry Outcomes: A Report of Randomized Experiments in the East Side Union High School District and San Diego Unified School District. Research Report

ERIC Educational Resources Information Center

Miller, Gloria I.; Jaciw, Andrew; Hoshiko, Brandon; Wei, Xin

2007-01-01

Texas Instruments has undertaken a research program with the goal of producing scientifically-based evidence of the effectiveness of graphing calculators and the "TI-Navigator"[TM] classroom networking system in the context of a professional development and curriculum framework. The program includes a two-year longitudinal study. The…
Circle of life: rationale, design, and baseline results of an HIV prevention intervention among young American Indian adolescents of the Northern Plains.

PubMed

Kaufman, Carol E; Mitchell, Christina M; Beals, Janette; Desserich, Jennifer A; Wheeler, Cindy; Keane, Ellen M; Whitesell, Nancy Rumbaugh; Sam, Angela; Sedey, Cory

2010-03-01

In spite of significant disparities in sexual health outcomes for American Indian youth, no studies exist examining the effectiveness of HIV-prevention interventions. Circle of Life is an HIV-prevention intervention specifically developed for American Indian middle-school youth. We describe the rationale, methodology, and baseline results of a longitudinal randomized trial of Circle of Life conducted among American Indian youth aged 11-15 in a reservation community. The innovative design includes two pre-intervention waves to determine patterns of behavior prior to the intervention that might be associated with a differential impact of the intervention on sexual risk. We used one-way analysis of variance and chi-square tests to test for significant differences between randomized group assignment at each baseline wave and generalized estimating equations (GEE) to test significant differences in the rate of change in outcomes by group longitudinally. We present the collaborative and adaptive strategies for consenting, assenting, and data collection methodology in this community. Achieved response rates are comparable to other similar studies. Results from the two baseline waves indicate that few outcomes significantly varied by randomized intervention assignment. Ten percent of youth reported having had sex at Wave 1, rising to 15% at Wave 2. Among those who had had sex, the majority (>70%) reported using a condom at last sex. The project is well positioned to carry out the longitudinal assessments of the intervention to determine the overall impact of the Circle of Life and the differential impact by pre-intervention patterns of behavior across youth.
Height reduction among prenatally exposed atomic-bomb survivors: A longitudinal study of growth

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

Nakashima, Eiji; Funamoto, Sachiyo; Carter, R.L.

Using a random coefficient regression model, sex-specific longitudinal analyses of height were made on 801 (392 male and 409 female) atomic-bomb survivors exposed in utero to detect dose effects on standing height. The data set resulted from repeated measurements of standing height of adolescents (age 10-18 y). The dose effect, if any, was assumed to be linear. Gestational ages at the time of radiation exposure were divided into trimesters. Since an earlier longitudinal data analysis has demonstrated radiation effects on height, the emphasis in this paper is on the interaction between dose and gestational age at exposure and radiation effectsmore » on the age of occurrence of the adolescent growth spurt. For males, a cubic polynomial growth-curve model applied to the data was affected significantly by radiation. The dose by trimester interaction effect was not significant. The onset of adolescent growth spurt was estimated at about 13 y at 0 Gy. There was no effect of radiation on the adolescent growth spurt For females, a quadratic polynomial growth-curve model was fitted to the data. The dose effect was significant, while the dose by trimester interaction was again not significant. 27 refs., 3 figs., 4 tabs.« less
Longitudinal Analysis of the Relationship between Symptoms and Quality of Life in Veterans Treated for Posttraumatic Stress Disorder

ERIC Educational Resources Information Center

Schnurr, Paula P.; Hayes, Andrew F.; Lunney, Carole A.; McFall, Miles; Uddo, Madeline

2006-01-01

This study examined how change in posttraumatic stress disorder (PTSD) symptoms relates to change in quality of life. The sample consisted of 325 male Vietnam veterans with chronic PTSD who participated in a randomized trial of group psychotherapy. Latent growth modeling was used to test for synchronous effects of PTSD symptom change on…
The Effect of Integrated Basic Education Programs on Women's Social and Economic Well-Being in Bolivia.

ERIC Educational Resources Information Center

Hua, Haiyan; Burchfield, Shirley

A large-scale longitudinal study in Bolivia examined the relationship between adult women's basic education and their social and economic well-being and development. A random sample of 1,600 participants and 600 nonparticipants, aged 15-45, was tracked for 3 years (the final sample included 717 participants and 224 controls). The four adult…

Random Fields and Collective Effects in Molecular Magnets

DTIC Science & Technology

2018-01-29

longitudinal fields the final state consists of only partially reversed spins. Further, we measured the front speed as a function of applied magnetic...field. The theory of magnetic deflagration, together with a modification that takes into account the partial spin reversal, fits the transverse field...Conference Paper or Presentation Conference Name: APS March Meeting 2016 Conference Location: Baltimore, Paper Title: Time-resolved Measurements
Cancer-related fatigue--mechanisms, risk factors, and treatments.

PubMed

Bower, Julienne E

2014-10-01

Fatigue is one of the most common adverse effects of cancer that might persist for years after treatment completion in otherwise healthy survivors. Cancer-related fatigue causes disruption in all aspects of quality of life and might be a risk factor of reduced survival. The prevalence and course of fatigue in patients with cancer have been well characterized and there is growing understanding of the underlying biological mechanisms. Inflammation seems to have a key role in fatigue before, during, and after cancer-treatment. However, there is a considerable variability in the presentation of cancer-related fatigue, much of which is not explained by disease-related or treatment-related characteristics, suggesting that host factors might be important in the development and persistence of this symptom. Indeed, longitudinal studies have identified genetic, biological, psychosocial, and behavioural risk factors associated with cancer-related fatigue. Although no current gold-standard treatment for fatigue is available, a variety of intervention approaches have shown beneficial effects in randomized controlled trials, including physical activity, psychosocial, mind-body, and pharmacological treatments. This Review describes the mechanisms, risk factors, and possible interventions for cancer-related fatigue, focusing on recent longitudinal studies and randomized trials that have targeted fatigued patients.
A longitudinal study of the relationships between the Big Five personality traits and body size perception.

PubMed

Hartmann, Christina; Siegrist, Michael

2015-06-01

The present study investigated the longitudinal development of body size perception in relation to different personality traits. A sample of Swiss adults (N=2905, 47% men), randomly selected from the telephone book, completed a questionnaire on two consecutive years (2012, 2013). Body size perception was assessed with the Contour Drawing Rating Scale and personality traits were assessed with a short version of the Big Five Inventory. Longitudinal analysis of change indicated that men and women scoring higher on conscientiousness perceived themselves as thinner one year later. In contrast, women scoring higher on neuroticism perceived their body size as larger one year later. No significant effect was observed for men scoring higher on neuroticism. These results were independent of weight changes, body mass index, age, and education. Our findings suggest that personality traits contribute to body size perception among adults. Copyright © 2015 Elsevier Ltd. All rights reserved.
Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

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

Diniz, Ginetom S., E-mail: ginetom@gmail.com; Ulloa, Sergio E.

2014-07-14

We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size andmore » state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.« less
Examining solutions to missing data in longitudinal nursing research.

PubMed

Roberts, Mary B; Sullivan, Mary C; Winchester, Suzy B

2017-04-01

Longitudinal studies are highly valuable in pediatrics because they provide useful data about developmental patterns of child health and behavior over time. When data are missing, the value of the research is impacted. The study's purpose was to (1) introduce a three-step approach to assess and address missing data and (2) illustrate this approach using categorical and continuous-level variables from a longitudinal study of premature infants. A three-step approach with simulations was followed to assess the amount and pattern of missing data and to determine the most appropriate imputation method for the missing data. Patterns of missingness were Missing Completely at Random, Missing at Random, and Not Missing at Random. Missing continuous-level data were imputed using mean replacement, stochastic regression, multiple imputation, and fully conditional specification (FCS). Missing categorical-level data were imputed using last value carried forward, hot-decking, stochastic regression, and FCS. Simulations were used to evaluate these imputation methods under different patterns of missingness at different levels of missing data. The rate of missingness was 16-23% for continuous variables and 1-28% for categorical variables. FCS imputation provided the least difference in mean and standard deviation estimates for continuous measures. FCS imputation was acceptable for categorical measures. Results obtained through simulation reinforced and confirmed these findings. Significant investments are made in the collection of longitudinal data. The prudent handling of missing data can protect these investments and potentially improve the scientific information contained in pediatric longitudinal studies. © 2017 Wiley Periodicals, Inc.
The effects of prosocial video games on prosocial behaviors: international evidence from correlational, longitudinal, and experimental studies.

PubMed

Gentile, Douglas A; Anderson, Craig A; Yukawa, Shintaro; Ihori, Nobuko; Saleem, Muniba; Ming, Lim Kam; Shibuya, Akiko; Liau, Albert K; Khoo, Angeline; Bushman, Brad J; Rowell Huesmann, L; Sakamoto, Akira

2009-06-01

Although dozens of studies have documented a relationship between violent video games and aggressive behaviors, very little attention has been paid to potential effects of prosocial games. Theoretically, games in which game characters help and support each other in nonviolent ways should increase both short-term and long-term prosocial behaviors. We report three studies conducted in three countries with three age groups to test this hypothesis. In the correlational study, Singaporean middle-school students who played more prosocial games behaved more prosocially. In the two longitudinal samples of Japanese children and adolescents, prosocial game play predicted later increases in prosocial behavior. In the experimental study, U.S. undergraduates randomly assigned to play prosocial games behaved more prosocially toward another student. These similar results across different methodologies, ages, and cultures provide robust evidence of a prosocial game content effect, and they provide support for the General Learning Model.
The Effects of Prosocial Video Games on Prosocial Behaviors: International Evidence from Correlational, Longitudinal, and Experimental Studies

PubMed Central

Gentile, Douglas A.; Anderson, Craig A.; Yukawa, Shintaro; Ihori, Nobuko; Saleem, Muniba; Ming, Lim Kam; Shibuya, Akiko; Liau, Albert K.; Khoo, Angeline; Bushman, Brad J.; Huesmann, L. Rowell; Sakamoto, Akira

2009-01-01

Although dozens of studies have documented a relation between violent video games and aggressive behaviors, very little attention has been paid to potential effects of prosocial games. Theoretically, games in which game characters help and support each other in nonviolent ways should increase both short-term and long-term prosocial behaviors. We report three studies conducted in three countries with three age groups to test this hypothesis. In the correlational study, Singaporean middle-school students who played more prosocial games behaved more prosocially. In the two longitudinal samples of Japanese children and adolescents, prosocial game play predicted later increases in prosocial behavior. In the experimental study, U.S. undergraduates randomly assigned to play prosocial games behaved more prosocially toward another student. These similar results across different methodologies, ages, and cultures provide robust evidence a prosocial game content effect, and provide support for the General Learning Model. PMID:19321812
A Repeated Trajectory Class Model for Intensive Longitudinal Categorical Outcome

PubMed Central

Lin, Haiqun; Han, Ling; Peduzzi, Peter N.; Murphy, Terrence E.; Gill, Thomas M.; Allore, Heather G.

2014-01-01

This paper presents a novel repeated latent class model for a longitudinal response that is frequently measured as in our prospective study of older adults with monthly data on activities of daily living (ADL) for more than ten years. The proposed method is especially useful when the longitudinal response is measured much more frequently than other relevant covariates. The repeated trajectory classes represent distinct temporal patterns of the longitudinal response wherein an individual’s membership in the trajectory classes may renew or change over time. Within a trajectory class, the longitudinal response is modeled by a class-specific generalized linear mixed model. Effectively, an individual may remain in a trajectory class or switch to another as the class membership predictors are updated periodically over time. The identification of a common set of trajectory classes allows changes among the temporal patterns to be distinguished from local fluctuations in the response. An informative event such as death is jointly modeled by class-specific probability of the event through shared random effects. We do not impose the conditional independence assumption given the classes. The method is illustrated by analyzing the change over time in ADL trajectory class among 754 older adults with 70500 person-months of follow-up in the Precipitating Events Project. We also investigate the impact of jointly modeling the class-specific probability of the event on the parameter estimates in a simulation study. The primary contribution of our paper is the periodic updating of trajectory classes for a longitudinal categorical response without assuming conditional independence. PMID:24519416
Modeling Achievement Trajectories when Attrition Is Informative

ERIC Educational Resources Information Center

Feldman, Betsy J.; Rabe-Hesketh, Sophia

2012-01-01

In longitudinal education studies, assuming that dropout and missing data occur completely at random is often unrealistic. When the probability of dropout depends on covariates and observed responses (called "missing at random" [MAR]), or on values of responses that are missing (called "informative" or "not missing at random" [NMAR]),…
Assessment of the effect of population and diary sampling methods on estimation of school-age children exposure to fine particles.

PubMed

Che, W W; Frey, H Christopher; Lau, Alexis K H

2014-12-01

Population and diary sampling methods are employed in exposure models to sample simulated individuals and their daily activity on each simulation day. Different sampling methods may lead to variations in estimated human exposure. In this study, two population sampling methods (stratified-random and random-random) and three diary sampling methods (random resampling, diversity and autocorrelation, and Markov-chain cluster [MCC]) are evaluated. Their impacts on estimated children's exposure to ambient fine particulate matter (PM2.5 ) are quantified via case studies for children in Wake County, NC for July 2002. The estimated mean daily average exposure is 12.9 μg/m(3) for simulated children using the stratified population sampling method, and 12.2 μg/m(3) using the random sampling method. These minor differences are caused by the random sampling among ages within census tracts. Among the three diary sampling methods, there are differences in the estimated number of individuals with multiple days of exposures exceeding a benchmark of concern of 25 μg/m(3) due to differences in how multiday longitudinal diaries are estimated. The MCC method is relatively more conservative. In case studies evaluated here, the MCC method led to 10% higher estimation of the number of individuals with repeated exposures exceeding the benchmark. The comparisons help to identify and contrast the capabilities of each method and to offer insight regarding implications of method choice. Exposure simulation results are robust to the two population sampling methods evaluated, and are sensitive to the choice of method for simulating longitudinal diaries, particularly when analyzing results for specific microenvironments or for exposures exceeding a benchmark of concern. © 2014 Society for Risk Analysis.
Analysis of longitudinal "time series" data in toxicology.

PubMed

Cox, C; Cory-Slechta, D A

1987-02-01

Studies focusing on chronic toxicity or on the time course of toxicant effect often involve repeated measurements or longitudinal observations of endpoints of interest. Experimental design considerations frequently necessitate between-group comparisons of the resulting trends. Typically, procedures such as the repeated-measures analysis of variance have been used for statistical analysis, even though the required assumptions may not be satisfied in some circumstances. This paper describes an alternative analytical approach which summarizes curvilinear trends by fitting cubic orthogonal polynomials to individual profiles of effect. The resulting regression coefficients serve as quantitative descriptors which can be subjected to group significance testing. Randomization tests based on medians are proposed to provide a comparison of treatment and control groups. Examples from the behavioral toxicology literature are considered, and the results are compared to more traditional approaches, such as repeated-measures analysis of variance.
Research Assistants Caught in Limbo: Considering Their Role in Quantitative, Longitudinal Research with Vulnerable Populations.

PubMed

Zerger, Suzanne; Pridham, Katherine Francombe; Plenert, Erin; Newberry, Caitlin; Whisler, Adam; Fernando, Indira; Ahmed, Naveed

2015-11-01

Research assistants (RAs) play a variety of roles that are critical in making research happen and in determining its quality and effectiveness. Yet their locus of power in the production of knowledge stands in sharp contrast to their relative powerlessness in the hierarchical research organization. This article explores the experiences of RAs engaged in a randomized controlled longitudinal field trial of a Housing First intervention for individuals experiencing homelessness and mental illness in Toronto. They encountered several unexpected effects of navigating the power ascribed to them by both study participants and community service providers. This study underscores the importance of acknowledging that RAs are the face of the research study in the field, and of better understanding implications associated with that fact, especially when marginalized populations and their providers are involved.
Longitudinal Pediatric Palliative Care: Quality of Life & Spiritual Struggle (FACE): design and methods.

PubMed

Dallas, Ronald H; Wilkins, Megan L; Wang, Jichuan; Garcia, Ana; Lyon, Maureen E

2012-09-01

As life expectancy increases for adolescents ever diagnosed with AIDS due to treatment advances, the optimum timing of advance care planning is unclear. Left unprepared for end-of-life (EOL) decisions, families may encounter miscommunication and disagreements, resulting in families being charged with neglect, court battles and even legislative intervention. Advanced care planning (ACP) is a valuable tool rarely used with adolescents. The Longitudinal Pediatric Palliative Care: Quality of Life & Spiritual Struggle study is a two-arm, randomized controlled trial assessing the effectiveness of a disease specific FAmily CEntered (FACE) advanced care planning intervention model among adolescents diagnosed with AIDS, aimed at relieving psychological, spiritual, and physical suffering, while maximizing quality of life through facilitated conversations about ACP. Participants will include 130 eligible dyads (adolescent and family decision-maker) from four urban cities in the United States, randomized to either the FACE intervention or a Healthy Living Control. Three 60-minute sessions will be conducted at weekly intervals. The dyads will be assessed at baseline as well as 3-, 6-, 12-, and 18-month post-intervention. The primary outcome measures will be in congruence with EOL treatment preferences, decisional conflict, and quality of communication. The mediating and moderating effects of threat appraisal, HAART adherence, and spiritual struggle on the relationships among FACE and quality of life and hospitalization/dialysis use will also be assessed. This study will be the first longitudinal study of an AIDS-specific model of ACP with adolescents. If successful, this intervention could quickly translate into clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.
Peer Influence, Genetic Propensity, and Binge Drinking: A Natural Experiment and a Replication.

PubMed

Guo, Guang; Li, Yi; Wang, Hongyu; Cai, Tianji; Duncan, Greg J

2015-11-01

The authors draw data from the College Roommate Study (ROOM) and the National Longitudinal Study of Adolescent Health to investigate gene-environment interaction effects on youth binge drinking. In ROOM, the environmental influence was measured by the precollege drinking behavior of randomly assigned roommates. Random assignment safeguards against friend selection and removes the threat of gene-environment correlation that makes gene-environment interaction effects difficult to interpret. On average, being randomly assigned a drinking peer as opposed to a nondrinking peer increased college binge drinking by 0.5-1.0 episodes per month, or 20%-40% the average amount of binge drinking. However, this peer influence was found only among youths with a medium level of genetic propensity for alcohol use; those with either a low or high genetic propensity were not influenced by peer drinking. A replication of the findings is provided in data drawn from Add Health. The study shows that gene-environment interaction analysis can uncover social-contextual effects likely to be missed by traditional sociological approaches.
Protecting Children from the Consequences of Divorce: A Longitudinal Study of the Effects of Parenting on Children's Coping Processes

ERIC Educational Resources Information Center

Velez, Clorinda E.; Wolchik, Sharlene A.; Tein, Jenn-Yun; Sandler, Irwin

2011-01-01

This study examines whether intervention-induced changes in mother-child relationship quality and discipline led to short-term (6 months) and long-term (6 years) changes in children's coping processes in a sample of 240 youth aged 9-12 years when assessed initially. Data were from a randomized, experimental trial of a parenting-focused preventive…
WWC Review of the Report "Increasing Young Children's Contact with Print during Shared Reading: Longitudinal Effects on Literacy Achievement"

ERIC Educational Resources Information Center

What Works Clearinghouse, 2012

2012-01-01

The study examined the impact of the "Project STAR" ("Sit Together and Read") reading program on the literacy skills of preschool students. Researchers randomly assigned 85 preschool classrooms in Ohio to one of three study groups at the start of the 2004-05 or 2005-06 school years: (1) A high-dose intervention group, in which…
"Learn Young, Learn Fair", a Stress Management Program for Fifth and Sixth Graders: Longitudinal Results from an Experimental Study

ERIC Educational Resources Information Center

Kraag, Gerda; Van Breukelen, Gerard J. P.; Kok, Gerjo; Hosman, Clemens

2009-01-01

Background: This study examined the effects of a universal stress management program (Learn Young, Learn Fair) on stress, coping, anxiety and depression in fifth and sixth grade children. Methods: Fifty-two schools (1467 children) participated in a clustered randomized controlled trial. Data was collected in the fall of 2002, the spring of 2003,…
A Family Focused Randomized Controlled Trial to Prevent Adolescent Alcohol and Tobacco Use: The Moderating Roles of Positive Parenting and Adolescent Gender

ERIC Educational Resources Information Center

Jones, Deborah J.; Olson, Ardis L.; Forehand, Rex; Gaffney, Cecelia A.; Zens, Michael S.; Bau, J. J.

2005-01-01

Four years of longitudinal data from 2,153 families with a 5th- or 6th-grade preadolescent participating in a family-focused pediatric primary-care-based prevention program were used to examine whether prevention effects were moderated by positive parenting and/or adolescent gender. Alcohol and tobacco use, internalizing problems, and…
A Longitudinal Study of Illinois State Scholarship Commission Monetary Award Recipients, 1967-1974.

ERIC Educational Resources Information Center

Boyd, Joseph D.; Fenske, Robert H.

The present effectiveness and future direction of monetary award programs administered by the Illinois State Scholarship Commission is examined in three surveys. A random sample of 1,000 was drawn from the total number of scholarship recipients during the 1967-68 and 1970-71 academic years; 2,000 from the 1973-74 survey. It is shown that: (1)…
Motivational Climate, 2×2 Achievement Goal Orientation and Dominance, Self-Regulation, and Physical Activity in Pre-Service Teacher Education

ERIC Educational Resources Information Center

Cecchini-Estrada, José-Antonio; Méndez-Giménez, Antonio

2017-01-01

This longitudinal study investigated the effects of a mastery motivational climate in physical education (PE) classes on 2×2 achievement goal orientation and dominance, self-regulated learning (SRL), and physical activity (PA) in leisure time. A total of 408 (264 women, 144 men) university students were randomly assigned to two groups:…

Effects of the TCARE® intervention on caregiver burden and depressive symptoms: preliminary findings from a randomized controlled study.

PubMed

Montgomery, Rhonda J V; Kwak, Jung; Kosloski, Karl; O'Connell Valuch, Katharine

2011-09-01

We examined the effects of a manualized care management protocol specifically designed for care managers working with caregivers, the Tailored Caregiver Assessment and Referral® (TCARE®) protocol, on caregiver identity discrepancy, burden, and depressive symptoms. Preliminary data from a longitudinal, randomized, controlled intervention study with 266 family caregivers served by 52 care managers in 4 states were analyzed using repeated measures random effects regression procedures. Caregivers in the intervention and control groups were repeatedly assessed for up to 9 months on caregiver identity discrepancy, 3 areas of caregiving burden-objective, relationship, and stress burdens; depression; and intention for nursing home placement. We found significant group by time interaction effects for caregiver identity discrepancy, relationship burden, stress burden, depression, and intention for nursing home placement. Caregivers in the intervention group experienced significant improvement on these measures, whereas caregivers in the control group worsened on these measures over time. The preliminary findings provide strong support for effectiveness of the TCARE® protocol on improving caregiver well-being and mental health outcomes.
Effects of the TCARE® Intervention on Caregiver Burden and Depressive Symptoms: Preliminary Findings From a Randomized Controlled Study

PubMed Central

Kwak, Jung; Kosloski, Karl; O’Connell Valuch, Katharine

2011-01-01

Objectives. We examined the effects of a manualized care management protocol specifically designed for care managers working with caregivers, the Tailored Caregiver Assessment and Referral® (TCARE®) protocol, on caregiver identity discrepancy, burden, and depressive symptoms. Methods. Preliminary data from a longitudinal, randomized, controlled intervention study with 266 family caregivers served by 52 care managers in 4 states were analyzed using repeated measures random effects regression procedures. Caregivers in the intervention and control groups were repeatedly assessed for up to 9 months on caregiver identity discrepancy, 3 areas of caregiving burden—objective, relationship, and stress burdens; depression; and intention for nursing home placement. Results. We found significant group by time interaction effects for caregiver identity discrepancy, relationship burden, stress burden, depression, and intention for nursing home placement. Caregivers in the intervention group experienced significant improvement on these measures, whereas caregivers in the control group worsened on these measures over time. Discussion. The preliminary findings provide strong support for effectiveness of the TCARE® protocol on improving caregiver well-being and mental health outcomes. PMID:21840840
Gene expression models for prediction of longitudinal dispersion coefficient in streams

NASA Astrophysics Data System (ADS)

Sattar, Ahmed M. A.; Gharabaghi, Bahram

2015-05-01

Longitudinal dispersion is the key hydrologic process that governs transport of pollutants in natural streams. It is critical for spill action centers to be able to predict the pollutant travel time and break-through curves accurately following accidental spills in urban streams. This study presents a novel gene expression model for longitudinal dispersion developed using 150 published data sets of geometric and hydraulic parameters in natural streams in the United States, Canada, Europe, and New Zealand. The training and testing of the model were accomplished using randomly-selected 67% (100 data sets) and 33% (50 data sets) of the data sets, respectively. Gene expression programming (GEP) is used to develop empirical relations between the longitudinal dispersion coefficient and various control variables, including the Froude number which reflects the effect of reach slope, aspect ratio, and the bed material roughness on the dispersion coefficient. Two GEP models have been developed, and the prediction uncertainties of the developed GEP models are quantified and compared with those of existing models, showing improved prediction accuracy in favor of GEP models. Finally, a parametric analysis is performed for further verification of the developed GEP models. The main reason for the higher accuracy of the GEP models compared to the existing regression models is that exponents of the key variables (aspect ratio and bed material roughness) are not constants but a function of the Froude number. The proposed relations are both simple and accurate and can be effectively used to predict the longitudinal dispersion coefficients in natural streams.
Does oral language underpin the development of later behavior problems? A longitudinal meta-analysis.

PubMed

Chow, Jason C; Ekholm, Erik; Coleman, Heather

2018-05-24

The purpose of this article is to estimate the overall weighted mean effect of the relation between early language skills and later behavior problems in school-aged children. A systematic literature search yielded 19,790 unduplicated reports, and a structured search strategy and identification procedure yielded 25 unique data sets, with 114 effect sizes for analysis. Eligible reports were then coded, and effect sizes were extracted and synthesized via robust variance estimation and random-effects meta-analytic techniques. The overall correlation between early language and later behavior problems was negative and small (r = -.14, 95% confidence interval [CI] [-.16, -.11]), and controlling for demographic variables did not reduce the magnitude of the inverse relationship between language skill and problem behavior (r = -.16). Moderator analyses identified receptive language, parent-reported behavior measures, gender, and age as significant predictors of the association between language and behavior. This article corroborates the consistent findings of previous meta-analytic and longitudinal studies and further identifies areas, particularly around measurement, for future research. Furthermore, prospective longitudinal evaluations of the relations between language deficits and behavior problems with different types of measures (teacher-/parent-report, direct assessment, classroom observation) is warranted. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Examining Solutions to Missing Data in Longitudinal Nursing Research

PubMed Central

Roberts, Mary B.; Sullivan, Mary C.; Winchester, Suzy B.

2017-01-01

Purpose Longitudinal studies are highly valuable in pediatrics because they provide useful data about developmental patterns of child health and behavior over time. When data are missing, the value of the research is impacted. The study’s purpose was to: (1) introduce a 3-step approach to assess and address missing data; (2) illustrate this approach using categorical and continuous level variables from a longitudinal study of premature infants. Methods A three-step approach with simulations was followed to assess the amount and pattern of missing data and to determine the most appropriate imputation method for the missing data. Patterns of missingness were Missing Completely at Random, Missing at Random, and Not Missing at Random. Missing continuous-level data were imputed using mean replacement, stochastic regression, multiple imputation, and fully conditional specification. Missing categorical-level data were imputed using last value carried forward, hot-decking, stochastic regression, and fully conditional specification. Simulations were used to evaluate these imputation methods under different patterns of missingness at different levels of missing data. Results The rate of missingness was 16–23% for continuous variables and 1–28% for categorical variables. Fully conditional specification imputation provided the least difference in mean and standard deviation estimates for continuous measures. Fully conditional specification imputation was acceptable for categorical measures. Results obtained through simulation reinforced and confirmed these findings. Practice Implications Significant investments are made in the collection of longitudinal data. The prudent handling of missing data can protect these investments and potentially improve the scientific information contained in pediatric longitudinal studies. PMID:28425202
Advanced Issues in Propensity Scores: Longitudinal and Missing Data

ERIC Educational Resources Information Center

Kupzyk, Kevin A.; Beal, Sarah J.

2017-01-01

In order to investigate causality in situations where random assignment is not possible, propensity scores can be used in regression adjustment, stratification, inverse-probability treatment weighting, or matching. The basic concepts behind propensity scores have been extensively described. When data are longitudinal or missing, the estimation and…
[Effectiveness of educational interventions conducted in latin america for the prevention of overweight and obesity in scholar children from 6-17 years old; a systematic review].

PubMed

Mancipe Navarrete, Jenny Alejandra; Garcia Villamil, Shanen Samanta; Correa Bautista, Jorge Enrique; Meneses-Echávez, José Francisco; González-Jiménez, Emilio; Schmidt Rio-Valle, Jacqueline

2014-10-03

Overweight and obesity are serious public health problem, which is specially among children populations. To determine the effectiveness of educational interventions conducted in Latino America for the prevention of overweight and obesity in scholar children from 6 to 17 years old. Metodology: MEDLINE, LILACS and EMBASE were searched between february and may 2014 to retrieve randomized controlled trials and longitudinal studies that evaluated the effects of educational interventions intended to retrieve randomized controlled trials and longitudinal studies aiming to prevent overweight and obesity among Latinoamerican children. Risk of bias was evaluated using the PEDro scale and the CASPe tool. Twenty one studies were included (n=12,092). Different types of educational interventions were identified, such as nutritional campaigns, physical activity practice and environmental changes. Mixed approaches combining nutritional campaigns, physical activity promotion and enviromental changes were the most effective interventions, since their results produced the largest improvements in the overweight and obesity of children. None evidence of reporting bias was observed. Educational interventions performed in the educational environment that combined an adequate nutrition and the promotion of physical activity practice, are more effective for preventing overweight and obesity in Latino American children, although familiar interventions are also encouraged approach, associated with better responses on the behavioral change in scholar children. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.
Identifying and separating the effects of practice and of cognitive ageing during a large longitudinal study of elderly community residents.

PubMed

Rabbitt, P; Diggle, P; Smith, D; Holland, F; Mc Innes, L

2001-01-01

In protracted longitudinal studies of cognitive changes in old age volunteers must be repeatedly tested. Even with intervals of several years between assessment, this raises the possibility that improvements due to practice mask other changes. This problem is much more acute in brief studies of cognitive changes associated with progressive pathologies such as Alzheimer's disease or the effects of clinical interventions. Both types of study also encounter problems of selective dropout of frail and less able individuals leaving relatively 'elite' survivors. An analysis of data from repeated testing at 2-3 years intervals on the AH4 (1) intelligence test is presented to illustrate how a random effects model can be used to identify and disassociate age-related changes and practice effects at the population level, after effects of selective dropout and of background demographical variables have been taken into consideration. This analysis also provides some new, substantive empirical findings. Age-related changes are relatively slight between 49 and 70 years but much more marked between 70 and 80 years. Even with assessment points, several years apart the population average effect of practice is large relative to that of age-related change. Variation between individuals increases as samples age, providing the first clear evidence from a longitudinal study for marked individual differences in trajectories of cognitive ageing.
Two-year changes in refractive error and related biometric factors in an adult Chinese population.

PubMed

He, Mingguang; Kong, Xiangbin; Chen, Qianyun; Zeng, Yangfa; Huang, Yuanzhou; Zhang, Jian; Morgan, Ian G; Meltzer, Mirjam E; Jin, Ling; Congdon, Nathan

2014-08-01

This article provides, to our knowledge, the first longitudinal population-based data on refractive error (RE) in Chinese persons. To study cohort effects and changes associated with aging in REs among Chinese adults. A 2-year, longitudinal population-based cohort study was conducted in southern China. Participants, identified using cluster random sampling, included residents of Yuexiu District, Guangzhou, China, aged 35 years or older who had undergone no previous eye surgery. Participants underwent noncycloplegic automated refraction and keratometry in December 2008 and December 2010; in a random 50% sample of the participants, anterior segment ocular coherence tomography measurement of lens thickness, as well as measurement of axial length and anterior chamber depth by partial coherence laser interferometry, were performed. Two-year change in spherical equivalent refraction (RE), lens thickness, axial length, and anterior chamber depth in the right eye. A total of 745 individuals underwent biometric testing in both 2008 and 2010 (2008 mean [SD] age, 52.2 [11.5] years; 53.7% women). Mean RE showed a 2-year hyperopic shift from -0.44 (2.21) to -0.31 (2.26) diopters (D) (difference, +0.13; 95% CI, 0.11 to 0.16). A consistent 2-year hyperopic shift of 0.09 to 0.22 D was observed among participants aged 35 to 64 years when stratifying by decade, suggesting that a substantial change in RE with aging may occur during this 30-year period. Cross-sectionally, RE increased only in the cohort younger than 50 years (0.11 D/y; 95% CI, 0.06 to 0.16). In the cross-sectional data, axial length decreased at -0.06 mm/y (95% CI, -0.09 to -0.04), although the 2-year change in axial length was positive and thus could not explain the cross-sectional difference. These latter results suggest a cohort effect, with greater myopia developing among younger persons. This first Chinese population-based longitudinal study of RE provides evidence for both important longitudinal aging changes and cohort effects, most notably greater myopia prevalence among younger persons.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Shashaank; Belianinov, Alex; Okatan, Mahmut B

(001)pc textured K0.5Na0.5NbO3 (KNN) ceramic was found to exhibit a 65% improvement in the longitudinal piezoelectric response as compared to its random counterpart. Piezoresponse force microscopy study revealed the existence of larger 180 and non-180 domains for textured ceramic as compared to that of the random ceramic. Improvement in piezoresponse by the development of (001)pc texture is discussed in terms of the crystallographic nature of KNN and domain morphology. A comparative analysis performed with a rhombohedral composition suggested that the improvement in longitudinal piezoresponse of polycrystalline ceramics by the development of (001)pc texture is limited by the crystal structure.
A panel multinomial logit analysis of elderly living arrangements: evidence from Aging In Manitoba longitudinal data, Canada.

PubMed

Sarma, Sisira; Simpson, Wayne

2007-12-01

Utilizing a unique longitudinal survey linked with home care use data, this paper analyzes the determinants of elderly living arrangements in Manitoba, Canada using a random effects multinomial logit model that accounts for unobserved individual heterogeneity. Because current home ownership is potentially endogenous in a living arrangements choice model, we use prior home ownership as an instrument. We also use prior home care use as an instrument for home care and use a random coefficient framework to account for unobserved health status. After controlling for relevant socio-demographic factors and accounting for unobserved individual heterogeneity, we find that home care and home ownership reduce the probability of living in a nursing home. Consistent with previous studies, we find that age is a strong predictor of nursing home entry. We also find that married people, those who have lived longer in the same community, and those who are healthy are more likely to live independently and less likely to be institutionalized or to cohabit with individuals other than their spouse.
The impact of a prevention delivery system on perceived social capital: the PROSPER project.

PubMed

Chilenski, Sarah M; Ang, Patricia M; Greenberg, Mark T; Feinberg, Mark E; Spoth, Richard

2014-04-01

The current study examined the impact of the PROSPER delivery system for evidence-based prevention programs on multiple indicators of social capital in a rural and semi-rural community sample. Utilizing a randomized blocked design, 317 individuals in 28 communities across two states were interviewed at three time points over the course of 2.5 years. Bridging, linking, and the public life skills forms of social capital were assessed via community members' and leaders' reports on the perceptions of school functioning and the Cooperative Extension System, collaboration among organizations, communication and collaboration around youth problems, and other measures. Longitudinal mixed model results indicate significant improvements in some aspects of bridging and linking social capital in PROSPER intervention communities. Given the strength of the longitudinal and randomized research design, results advance prevention science by suggesting that community collaborative prevention initiatives can significantly impact community social capital in a rural and semi-rural sample. Future research should further investigate changes in social capital in different contexts and how changes in social capital relate to other intervention effects.
Stress management and mind-body medicine: a randomized controlled longitudinal evaluation of students' health and effects of a behavioral group intervention at a middle-size German university (SM-MESH).

PubMed

Esch, Tobias; Sonntag, Ulrike; Esch, Sonja Maren; Thees, Stefanie

2013-01-01

Student life can be stressful. Hence, we started a regular mind-body medical stress management program in 2006. By today, more than 500 students took part and evaluations showed significant results, especially with regard to a reduction of stress warning signals. For further analysis, we now decided to run a randomized controlled longitudinal trial. Participating students at Coburg University were randomized into an intervention (n = 24) or a waitlist control group (n = 19). The intervention group completed 3 sets (pre/post/follow-up) and the control group 2 sets (pre/post) of self-administered questionnaires. The questionnaires included: SF-12 Health Survey, Perceived Stress Scale (PSS), Sense of Coherence (SOC-L9), Visual Analogue Scale (VAS) concerning stress, and the Stress Warning Signs (SWS) scale. Randomly selected participants of the intervention group were also queried in qualitative interviews. The intervention consisted of an 8 week stress management group program (mind-body medical stress reduction - MBMSR). Follow-up measures were taken after 6 months. Virtually, no drop-out occurred. Our study showed significant effects in the intervention group concerning SF-12 Mental Component Scale (p = 0.05), SF-12 Physical Component Scale (p = 0.001), VAS (in general, p = 0.001) and SWS (emotional reactions, p <0.001), underlined by qualitative results, which showed a higher quality of life. The effectiveness of an MBMSR program in a group of supposedly healthy students could be demonstrated. Findings suggest that stress management might be given importance at universities that care for the performance, the quality of life, and stress-health status of their students, acknowledging and accounting for the challenging circumstances of university life, as well as the specific needs of the modern student population. Copyright © 2013 S. Karger AG, Basel.
Detecting and analyzing research communities in longitudinal scientific networks.

PubMed

Leone Sciabolazza, Valerio; Vacca, Raffaele; Kennelly Okraku, Therese; McCarty, Christopher

2017-01-01

A growing body of evidence shows that collaborative teams and communities tend to produce the highest-impact scientific work. This paper proposes a new method to (1) Identify collaborative communities in longitudinal scientific networks, and (2) Evaluate the impact of specific research institutes, services or policies on the interdisciplinary collaboration between these communities. First, we apply community-detection algorithms to cross-sectional scientific collaboration networks and analyze different types of co-membership in the resulting subgroups over time. This analysis summarizes large amounts of longitudinal network data to extract sets of research communities whose members have consistently collaborated or shared collaborators over time. Second, we construct networks of cross-community interactions and estimate Exponential Random Graph Models to predict the formation of interdisciplinary collaborations between different communities. The method is applied to longitudinal data on publication and grant collaborations at the University of Florida. Results show that similar institutional affiliation, spatial proximity, transitivity effects, and use of the same research services predict higher degree of interdisciplinary collaboration between research communities. Our application also illustrates how the identification of research communities in longitudinal data and the analysis of cross-community network formation can be used to measure the growth of interdisciplinary team science at a research university, and to evaluate its association with research policies, services or institutes.
Detecting and analyzing research communities in longitudinal scientific networks

PubMed Central

Vacca, Raffaele; Kennelly Okraku, Therese; McCarty, Christopher

2017-01-01

A growing body of evidence shows that collaborative teams and communities tend to produce the highest-impact scientific work. This paper proposes a new method to (1) Identify collaborative communities in longitudinal scientific networks, and (2) Evaluate the impact of specific research institutes, services or policies on the interdisciplinary collaboration between these communities. First, we apply community-detection algorithms to cross-sectional scientific collaboration networks and analyze different types of co-membership in the resulting subgroups over time. This analysis summarizes large amounts of longitudinal network data to extract sets of research communities whose members have consistently collaborated or shared collaborators over time. Second, we construct networks of cross-community interactions and estimate Exponential Random Graph Models to predict the formation of interdisciplinary collaborations between different communities. The method is applied to longitudinal data on publication and grant collaborations at the University of Florida. Results show that similar institutional affiliation, spatial proximity, transitivity effects, and use of the same research services predict higher degree of interdisciplinary collaboration between research communities. Our application also illustrates how the identification of research communities in longitudinal data and the analysis of cross-community network formation can be used to measure the growth of interdisciplinary team science at a research university, and to evaluate its association with research policies, services or institutes. PMID:28797047
A manual control theory analysis of vertical situation displays for STOL aircraft

NASA Technical Reports Server (NTRS)

Baron, S.; Levison, W. H.

1973-01-01

Pilot-vehicle-display systems theory is applied to the analysis of proposed vertical situation displays for manual control in approach-to-landing of a STOL aircraft. The effects of display variables on pilot workload and on total closed-loop system performance was calculated using an optimal-control model for the human operator. The steep approach of an augmentor wing jet STOL aircraft was analyzed. Both random turbulence and mean-wind shears were considered. Linearized perturbation equations were used to describe longitudinal and lateral dynamics of the aircraft. The basic display configuration was one that abstracted the essential status information (including glide-slope and localizer errors) of an EADI display. Proposed flight director displays for both longitudinal and lateral control were also investigated.
Regression analysis of longitudinal data with correlated censoring and observation times.

PubMed

Li, Yang; He, Xin; Wang, Haiying; Sun, Jianguo

2016-07-01

Longitudinal data occur in many fields such as the medical follow-up studies that involve repeated measurements. For their analysis, most existing approaches assume that the observation or follow-up times are independent of the response process either completely or given some covariates. In practice, it is apparent that this may not be true. In this paper, we present a joint analysis approach that allows the possible mutual correlations that can be characterized by time-dependent random effects. Estimating equations are developed for the parameter estimation and the resulted estimators are shown to be consistent and asymptotically normal. The finite sample performance of the proposed estimators is assessed through a simulation study and an illustrative example from a skin cancer study is provided.
Neurorehabilitation in Parkinson's Disease: A Critical Review of Cognitive Rehabilitation Effects on Cognition and Brain.

PubMed

Díez-Cirarda, María; Ibarretxe-Bilbao, Naroa; Peña, Javier; Ojeda, Natalia

2018-01-01

Parkinson's disease (PD) patients experience cognitive impairment which has been related to reduced quality of life and functional disability. These symptoms usually progress until dementia occurs. Some studies have been published assessing the efficacy of cognitive treatments on improving cognition, functional outcome, and producing changes in brain activity. A critical review was performed to present up-to-date neurorehabilitation effects of cognitive rehabilitation in PD, with special emphasis on the efficacy on cognition, quality of life aspects, brain changes, and the longitudinal maintenance of these changes. After exclusions, 13 studies were reviewed, including 6 randomized controlled trials for the efficacy on cognition, 2 randomized controlled trials regarding the brain changes after cognitive training, and 5 studies which evaluated the long-term effects of cognitive treatments. Cognitive rehabilitation programs have demonstrated to be effective on improving cognitive functions, but more research is needed focusing on the efficacy on improving behavioral aspects and producing brain changes in patients with PD. Moreover, there is a need of randomized controlled trials with long-term follow-up periods.
The Effect of Cognitive Therapy on Structural Social Capital: Results From a Randomized Controlled Trial Among Sexual Violence Survivors in the Democratic Republic of the Congo

PubMed Central

Bolton, Paul A.; Annan, Jeannie; Kaysen, Debra; Robinette, Katie; Cetinoglu, Talita; Wachter, Karin; Bass, Judith K.

2014-01-01

Objectives. We evaluated changes in social capital following group-based cognitive processing therapy (CPT) for female survivors of sexual violence. Methods. We compared CPT with individual support in a cluster-randomized trial in villages in South Kivu province, Democratic Republic of the Congo. Local psychosocial assistants delivered the interventions from April through July 2011. We evaluated differences between CPT and individual support conditions for structural social capital (i.e., time spent with nonkin social network, group membership and participation, and the size of financial and instrumental support networks) and emotional support seeking. We analyzed intervention effects with longitudinal random effects models. Results. We obtained small to medium effect size differences for 2 study outcomes. Women in the CPT villages increased group membership and participation at 6-month follow-up and emotional support seeking after the intervention compared with women in the individual support villages. Conclusions. Results support the efficacy of group CPT to increase dimensions of social capital among survivors of sexual violence in a low-income conflict-affected context. PMID:25033113
Scale of reference bias and the evolution of health.

PubMed

Groot, Wim

2003-09-01

The analysis of subjective measures of well-being-such as self-reports by individuals about their health status is frequently hampered by the problem of scale of reference bias. A particular form of scale of reference bias is age norming. In this study we corrected for scale of reference bias by allowing for individual specific effects in an equation on subjective health. A random effects ordered response model was used to analyze scale of reference bias in self-reported health measures. The results indicate that if we do not control for unobservable individual specific effects, the response to a subjective health state measure suffers from age norming. Age norming can be controlled for by a random effects estimation technique using longitudinal data. Further, estimates are presented on the rate of depreciation of health. Finally, simulations of life expectancy indicate that the estimated model provides a reasonably good fit of the true life expectancy.

Regional gray matter volume increases following 7days of voluntary wheel running exercise: a longitudinal VBM study in rats.

PubMed

Sumiyoshi, Akira; Taki, Yasuyuki; Nonaka, Hiroi; Takeuchi, Hikaru; Kawashima, Ryuta

2014-09-01

The effects of physical exercise on brain morphology in rodents have been well documented in histological studies. However, to further understand when and where morphological changes occur in the whole brain, a noninvasive neuroimaging method allowing an unbiased, comprehensive, and longitudinal investigation of brain morphology should be used. In this study, we investigated the effects of 7days of voluntary wheel running exercise on regional gray matter volume (rGMV) using longitudinal voxel-based morphometry (VBM) in rats. Eighteen pairs of adult male naïve Wistar rats were randomized to the exercise or control condition (one rat for each condition from each pair). Each rat was scanned in a 7.0-T MRI scanner at three time points: before exercise, after 7days of exercise, and after 7days of follow-up. The T2-weighted MRI images were segmented using the rat brain tissue priors that were recently published by our laboratory, and the intra- and inter-subject template creation steps were followed. Longitudinal VBM analysis revealed significant increases in rGMV in the motor, somatosensory, association, and visual cortices in the exercise group. Among these brain regions, rGMV changes in the motor cortex were positively correlated with the total distance that was run during the 7days of exercise. In addition, the effects of 7days of exercise on rGMV persisted after 7days of follow-up. These results support the utility of a longitudinal VBM study in rats and provide new insights into experience-dependent structural brain plasticity in naïve adult animals. Copyright © 2014 Elsevier Inc. All rights reserved.
Improved power for characterizing longitudinal amyloid-β PET changes and evaluating amyloid-modifying treatments with a cerebral white matter reference region.

PubMed

Chen, Kewei; Roontiva, Auttawut; Thiyyagura, Pradeep; Lee, Wendy; Liu, Xiaofen; Ayutyanont, Napatkamon; Protas, Hillary; Luo, Ji Luo; Bauer, Robert; Reschke, Cole; Bandy, Daniel; Koeppe, Robert A; Fleisher, Adam S; Caselli, Richard J; Landau, Susan; Jagust, William J; Weiner, Michael W; Reiman, Eric M

2015-04-01

In this article, we describe an image analysis strategy with improved power for tracking longitudinal amyloid-β (Aβ) PET changes and evaluating Aβ-modifying treatments. Our aims were to compare the power of template-based cerebellar, pontine, and cerebral white matter reference regions to track 24-mo florbetapir standardized uptake value (SUV) ratio (SUVR) changes; to relate those changes to 24-mo clinical declines; and to evaluate Aβ-modifying treatments in Aβ-positive (Aβ+) and Aβ-negative (Aβ-) patients with probable Alzheimer dementia (pAD), in patients with mild cognitive impairment (MCI), in cognitively normal controls (NCs), and in cognitively normal apolipoprotein E4 (APOE4) carriers and noncarriers. We used baseline and follow-up (∼24 mo) florbetapir PET scans from 332 Aβ+ and Aβ- subjects participating in the multicenter Alzheimer's Disease Neuroimaging Initiative. Each of the proposed analyses included 31 pAD patients, 187 MCI patients, and 114 NCs. Cerebral-to-white matter, cerebellar, and pontine SUVRs were characterized in terms of their longitudinal variability; their power to track longitudinal fibrillar Aβ increases in Aβ+ and Aβ- subgroups and cognitively normal APOE4 carriers and noncarriers; the sample sizes needed to detect attenuated accumulation of or clearance of fibrillar Aβ accumulation in randomized clinical trials; and their ability to relate 24-mo fibrillar Aβ increases to clinical declines. As predicted, cerebral-to-white matter SUVR changes were significantly less variable and had significantly greater power to detect 24-mo fibrillar Aβ increases and evaluate Aβ-modifying treatment effects in Aβ+ pAD, MCI, and NC subjects and cognitively normal APOE4 carriers. They were also distinguished by the ability to detect significant associations between 24-mo Aβ increases and clinical declines. A cerebral white matter reference region may improve the power to track longitudinal fibrillar Aβ increases, to characterize their relationship to longitudinal clinical declines, and to evaluate Aβ-modifying treatments in randomized clinical trials. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
The Effects of the Determinants of Women's Movement Into and Out of Male-dominated Occupations on Occupational Sex Segregation.

ERIC Educational Resources Information Center

Sheridan, Jennifer T.

Although occupational sex segregation has decreased over the last 25 years, it is still a major social concern primarily because of the role it plays in perpetuating the gender wage gap. This paper uses data from the Wisconsin Longitudinal Study, a study that followed a random sample of 10,317 high school graduates, to assess the determinants of…
Determinants of Anemia and Hemoglobin Concentration in Haitian School-Aged Children

PubMed Central

Iannotti, Lora L.; Delnatus, Jacques R.; Odom, Audrey R.; Eaton, Jacob C.; Griggs, Jennifer J.; Brown, Sarah; Wolff, Patricia B.

2015-01-01

Anemia diminishes oxygen transport in the body, resulting in potentially irreversible growth and developmental consequences for children. Limited evidence for determinants of anemia exists for school-aged children. We conducted a cluster randomized controlled trial in Haiti from 2012 to 2013 to test the efficacy of a fortified school snack. Children (N = 1,047) aged 3–13 years were followed longitudinally at three time points for hemoglobin (Hb) concentrations, anthropometry, and bioelectrical impedance measures. Dietary intakes, infectious disease morbidities, and socioeconomic and demographic factors were collected at baseline and endline. Longitudinal regression modeling with generalized least squares and logit models with random effects identified anemia risk factors beyond the intervention effect. At baseline, 70.6% of children were anemic and 2.6% were severely anemic. Stunting increased the odds of developing anemia (adjusted odds ratio [OR]: 1.48, 95% confidence interval [CI]: 1.05–2.08) and severe anemia (adjusted OR: 2.47, 95% CI: 1.30–4.71). Parent-reported vitamin A supplementation and deworming were positively associated with Hb concentrations, whereas fever and poultry ownership showed a negative relationship with Hb concentration and increased odds of severe anemia, respectively. Further research should explore the full spectrum of anemia etiologies in school children, including genetic causes. PMID:26350448
Longitudinal study of a cooperation-driven, socio-scientific issue intervention on promoting students' critical thinking and self-regulation in learning science

NASA Astrophysics Data System (ADS)

Wang, Hsin-Hui; Chen, Hsiang-Ting; Lin, Huann-shyang; Huang, Yu-Ning; Hong, Zuway-R.

2017-10-01

This longitudinal study explored the effects of a Cooperation-driven Socioscientific Issue (CDSSI) intervention on junior high school students' perceptions of critical thinking (CT) and self-regulation (SR) in Taiwan. Forty-nine grade 7 students were randomly selected as an experimental group (EG) to attend a 3-semester 72-hour intervention; while another 49 grade 7 students from the same school were randomly selected as the comparison group (CG). All participants completed a 4-wave student questionnaire to assess their perceptions of CT and SR. In addition, 8 target students from the EG with the lowest scores on either CT or SR were purposefully recruited for weekly observation. These target students and their teachers were interviewed one month after the intervention in each semester. Analyses of covariance and paired-wise t-tests revealed that the EG students' perceptions of CT and SR in learning science were improved during the study and were significantly better than their counterparts' at the end of the study. Systematic interview and classroom observation results were consistent with the quantitative findings. This study adds empirical evidence and provides insights into how CDSSI can be integrated into planning and implementing effective pedagogical strategies aimed at increasing students' perceptions of CT and SR in learning science.
Functional Nonlinear Mixed Effects Models For Longitudinal Image Data

PubMed Central

Luo, Xinchao; Zhu, Lixing; Kong, Linglong; Zhu, Hongtu

2015-01-01

Motivated by studying large-scale longitudinal image data, we propose a novel functional nonlinear mixed effects modeling (FN-MEM) framework to model the nonlinear spatial-temporal growth patterns of brain structure and function and their association with covariates of interest (e.g., time or diagnostic status). Our FNMEM explicitly quantifies a random nonlinear association map of individual trajectories. We develop an efficient estimation method to estimate the nonlinear growth function and the covariance operator of the spatial-temporal process. We propose a global test and a simultaneous confidence band for some specific growth patterns. We conduct Monte Carlo simulation to examine the finite-sample performance of the proposed procedures. We apply FNMEM to investigate the spatial-temporal dynamics of white-matter fiber skeletons in a national database for autism research. Our FNMEM may provide a valuable tool for charting the developmental trajectories of various neuropsychiatric and neurodegenerative disorders. PMID:26213453
Parenthood and the Quality of Experience in Daily Life: A Longitudinal Study

ERIC Educational Resources Information Center

Fave, Antonella Delle; Massimini, Fausto

2004-01-01

This longitudinal study analyzes the time budget and the quality of experience reported by new parents. Five primiparous couples were repeatedly administered Experience Sampling Method. They carried pagers sending random signals 6-8 times a day; at the signal reception, they filled out forms sampling current thoughts, activities, and the quality…
Using Fit Indexes to Select a Covariance Model for Longitudinal Data

ERIC Educational Resources Information Center

Liu, Siwei; Rovine, Michael J.; Molenaar, Peter C. M.

2012-01-01

This study investigated the performance of fit indexes in selecting a covariance structure for longitudinal data. Data were simulated to follow a compound symmetry, first-order autoregressive, first-order moving average, or random-coefficients covariance structure. We examined the ability of the likelihood ratio test (LRT), root mean square error…
Predicting Posttraumatic Stress Symptoms Longitudinally in a Representative Sample of Hospitalized Injured Adolescents

ERIC Educational Resources Information Center

Zatzick, Douglas F.; Grossman, David C.; Russo, Joan; Pynoos, Robert; Berliner, Lucy; Jurkovich, Gregory; Sabin, Janice A.; Katon, Wayne; Ghesquiere, Angela; McCauley, Elizabeth; Rivara, Frederick P.

2006-01-01

Objective: Adolescents constitute a high-risk population for traumatic physical injury, yet few longitudinal investigations have assessed the development of posttraumatic stress disorder (PTSD) symptoms over time in representative samples. Method: Between July 2002 and August 2003,108 randomly selected injured adolescent patients ages 12 to 18 and…
A TWO-STATE MIXED HIDDEN MARKOV MODEL FOR RISKY TEENAGE DRIVING BEHAVIOR

PubMed Central

Jackson, John C.; Albert, Paul S.; Zhang, Zhiwei

2016-01-01

This paper proposes a joint model for longitudinal binary and count outcomes. We apply the model to a unique longitudinal study of teen driving where risky driving behavior and the occurrence of crashes or near crashes are measured prospectively over the first 18 months of licensure. Of scientific interest is relating the two processes and predicting crash and near crash outcomes. We propose a two-state mixed hidden Markov model whereby the hidden state characterizes the mean for the joint longitudinal crash/near crash outcomes and elevated g-force events which are a proxy for risky driving. Heterogeneity is introduced in both the conditional model for the count outcomes and the hidden process using a shared random effect. An estimation procedure is presented using the forward–backward algorithm along with adaptive Gaussian quadrature to perform numerical integration. The estimation procedure readily yields hidden state probabilities as well as providing for a broad class of predictors. PMID:27766124
Doubly robust estimation of generalized partial linear models for longitudinal data with dropouts.

PubMed

Lin, Huiming; Fu, Bo; Qin, Guoyou; Zhu, Zhongyi

2017-12-01

We develop a doubly robust estimation of generalized partial linear models for longitudinal data with dropouts. Our method extends the highly efficient aggregate unbiased estimating function approach proposed in Qu et al. (2010) to a doubly robust one in the sense that under missing at random (MAR), our estimator is consistent when either the linear conditional mean condition is satisfied or a model for the dropout process is correctly specified. We begin with a generalized linear model for the marginal mean, and then move forward to a generalized partial linear model, allowing for nonparametric covariate effect by using the regression spline smoothing approximation. We establish the asymptotic theory for the proposed method and use simulation studies to compare its finite sample performance with that of Qu's method, the complete-case generalized estimating equation (GEE) and the inverse-probability weighted GEE. The proposed method is finally illustrated using data from a longitudinal cohort study. © 2017, The International Biometric Society.
Hurdle models for multilevel zero-inflated data via h-likelihood.

PubMed

Molas, Marek; Lesaffre, Emmanuel

2010-12-30

Count data often exhibit overdispersion. One type of overdispersion arises when there is an excess of zeros in comparison with the standard Poisson distribution. Zero-inflated Poisson and hurdle models have been proposed to perform a valid likelihood-based analysis to account for the surplus of zeros. Further, data often arise in clustered, longitudinal or multiple-membership settings. The proper analysis needs to reflect the design of a study. Typically random effects are used to account for dependencies in the data. We examine the h-likelihood estimation and inference framework for hurdle models with random effects for complex designs. We extend the h-likelihood procedures to fit hurdle models, thereby extending h-likelihood to truncated distributions. Two applications of the methodology are presented. Copyright © 2010 John Wiley & Sons, Ltd.
UNSTEADY DISPERSION IN RANDOM INTERMITTENT FLOW

EPA Science Inventory

The longitudinal dispersion coefficient of a conservative tracer was calculated from flow tests in a dead-end pipe loop system. Flow conditions for these tests ranged from laminar to transitional flow, and from steady to intermittent and random. Two static mixers linked in series...
Comparison of endothelial changes and power settings between torsional and longitudinal phacoemulsification.

PubMed

Reuschel, Anna; Bogatsch, Holger; Barth, Thomas; Wiedemann, Renate

2010-11-01

To compare the intraoperative and postoperative outcomes of conventional longitudinal phacoemulsification and torsional phacoemulsification. Department of Ophthalmology, University of Leipzig, Germany. Randomized single-center clinical trial. Eyes with senile cataract were randomized to have phacoemulsification using the Infiniti Vision System and the torsional mode (OZil) or conventional longitudinal mode. Primary outcomes were corrected distance visual acuity (CDVA) and central endothelial cell density (ECD), calculated according to the Conference on Harmonisation-E9 Guidelines in which missing values were substituted by the median in each group (primary analysis) and the loss was then calculated using actual data (secondary analysis). Secondary outcomes were ultrasound (US) time, cumulative dissipated energy (CDE), and percentage total equivalent power in position 3. Postoperative follow-up was at 3 months. The mean preoperative CDVA was 0.41 logMAR in the torsional group and 0.38 logMAR in the longitudinal group, improving to 0.07 logMAR postoperatively in both groups. The mean ECD loss was 7.2% ± 4.6% in the torsional group (72 patients) and 7.1% ± 4.4% in the longitudinal group (76 patients), with no statistically significant differences in the primary analysis (P = .342) or secondary analysis (P = .906). The mean US time, CDE, and percentage total equivalent power in position 3 were statistically significantly lower in the torsional group (98 patients) than in the longitudinal group (94 patients) (P<.001). The torsional mode was as safe as the longitudinal mode in phacoemulsification for age-related cataract. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Functional Additive Mixed Models

PubMed Central

Scheipl, Fabian; Staicu, Ana-Maria; Greven, Sonja

2014-01-01

We propose an extensive framework for additive regression models for correlated functional responses, allowing for multiple partially nested or crossed functional random effects with flexible correlation structures for, e.g., spatial, temporal, or longitudinal functional data. Additionally, our framework includes linear and nonlinear effects of functional and scalar covariates that may vary smoothly over the index of the functional response. It accommodates densely or sparsely observed functional responses and predictors which may be observed with additional error and includes both spline-based and functional principal component-based terms. Estimation and inference in this framework is based on standard additive mixed models, allowing us to take advantage of established methods and robust, flexible algorithms. We provide easy-to-use open source software in the pffr() function for the R-package refund. Simulations show that the proposed method recovers relevant effects reliably, handles small sample sizes well and also scales to larger data sets. Applications with spatially and longitudinally observed functional data demonstrate the flexibility in modeling and interpretability of results of our approach. PMID:26347592
Sexual Identity Mobility and Depressive Symptoms: A Longitudinal Analysis of Sexual Minority Women

PubMed Central

Everett, Bethany; Talley, Amelia; Hughes, Tonda; Wilsnack, Sharon; Johnson, Timothy P.

2016-01-01

Sexual minority identity (bisexual, lesbian) is a known risk factor for depression in women. This study examines a facet of minority stress prevalent among women—sexual identity mobility—as an identity-related contributor to higher levels of depressive symptoms. We used three waves of data from the Chicago Health and Life Experiences of Women (CHLEW) study, a longitudinal study of sexual minority women (N = 306). Random effects OLS regression models were constructed to examine the effect of sexual-identity changes on depressive symptoms. We found that 25.6% of the sample reported a sexual-identity change between Wave I and Wave II, and 24.91% reported a sexual identity change between Waves II and III. Women who reported a change in sexual identity also reported more depressive symptoms subsequent to identity change. This effect was moderated by the number of years participants’ had reported their baseline identity and by whether the participant had initiated a romantic relationship with a male partner. PMID:27255306
Functional Additive Mixed Models.

PubMed

Scheipl, Fabian; Staicu, Ana-Maria; Greven, Sonja

2015-04-01

We propose an extensive framework for additive regression models for correlated functional responses, allowing for multiple partially nested or crossed functional random effects with flexible correlation structures for, e.g., spatial, temporal, or longitudinal functional data. Additionally, our framework includes linear and nonlinear effects of functional and scalar covariates that may vary smoothly over the index of the functional response. It accommodates densely or sparsely observed functional responses and predictors which may be observed with additional error and includes both spline-based and functional principal component-based terms. Estimation and inference in this framework is based on standard additive mixed models, allowing us to take advantage of established methods and robust, flexible algorithms. We provide easy-to-use open source software in the pffr() function for the R-package refund. Simulations show that the proposed method recovers relevant effects reliably, handles small sample sizes well and also scales to larger data sets. Applications with spatially and longitudinally observed functional data demonstrate the flexibility in modeling and interpretability of results of our approach.
Markov Transition Model to Dementia with Death as a Competing Event.

PubMed

Wei, Shaoceng; Xu, Liou; Kryscio, Richard J

2014-12-01

This study evaluates the effect of death as a competing event to the development of dementia in a longitudinal study of the cognitive status of elderly subjects. A multi-state Markov model with three transient states: intact cognition, mild cognitive impairment (M.C.I.) and global impairment (G.I.) and one absorbing state: dementia is used to model the cognitive panel data; transitions among states depend on four covariates age, education, prior state (intact cognition, or M.C.I., or G.I.) and the presence/absence of an apolipoprotein E-4 allele (APOE4). A Weibull model and a Cox proportional hazards (Cox PH) model are used to fit the survival from death based on age at entry and the APOE4 status. A shared random effect correlates this survival time with the transition model. Simulation studies determine the sensitivity of the maximum likelihood estimates to the violations of the Weibull and Cox PH model assumptions. Results are illustrated with an application to the Nun Study, a longitudinal cohort of 672 participants 75+ years of age at baseline and followed longitudinally with up to ten cognitive assessments per nun.
Markov Transition Model to Dementia with Death as a Competing Event

PubMed Central

Wei, Shaoceng; Xu, Liou; Kryscio, Richard J.

2014-01-01

This study evaluates the effect of death as a competing event to the development of dementia in a longitudinal study of the cognitive status of elderly subjects. A multi-state Markov model with three transient states: intact cognition, mild cognitive impairment (M.C.I.) and global impairment (G.I.) and one absorbing state: dementia is used to model the cognitive panel data; transitions among states depend on four covariates age, education, prior state (intact cognition, or M.C.I., or G.I.) and the presence/absence of an apolipoprotein E-4 allele (APOE4). A Weibull model and a Cox proportional hazards (Cox PH) model are used to fit the survival from death based on age at entry and the APOE4 status. A shared random effect correlates this survival time with the transition model. Simulation studies determine the sensitivity of the maximum likelihood estimates to the violations of the Weibull and Cox PH model assumptions. Results are illustrated with an application to the Nun Study, a longitudinal cohort of 672 participants 75+ years of age at baseline and followed longitudinally with up to ten cognitive assessments per nun. PMID:25110380
The re-identification risk of Canadians from longitudinal demographics

PubMed Central

2011-01-01

Background The public is less willing to allow their personal health information to be disclosed for research purposes if they do not trust researchers and how researchers manage their data. However, the public is more comfortable with their data being used for research if the risk of re-identification is low. There are few studies on the risk of re-identification of Canadians from their basic demographics, and no studies on their risk from their longitudinal data. Our objective was to estimate the risk of re-identification from the basic cross-sectional and longitudinal demographics of Canadians. Methods Uniqueness is a common measure of re-identification risk. Demographic data on a 25% random sample of the population of Montreal were analyzed to estimate population uniqueness on postal code, date of birth, and gender as well as their generalizations, for periods ranging from 1 year to 11 years. Results Almost 98% of the population was unique on full postal code, date of birth and gender: these three variables are effectively a unique identifier for Montrealers. Uniqueness increased for longitudinal data. Considerable generalization was required to reach acceptably low uniqueness levels, especially for longitudinal data. Detailed guidelines and disclosure policies on how to ensure that the re-identification risk is low are provided. Conclusions A large percentage of Montreal residents are unique on basic demographics. For non-longitudinal data sets, the three character postal code, gender, and month/year of birth represent sufficiently low re-identification risk. Data custodians need to generalize their demographic information further for longitudinal data sets. PMID:21696636

Ozil IP torsional mode versus combined torsional/longitudinal microcoaxial phacoemulsification.

PubMed

Helvacioglu, Firat; Tunc, Zeki; Yeter, Celal; Oguzhan, Hasan; Sencan, Sadik

2012-01-01

To compare the safety and efficacy of microcoaxial phacoemulsification surgeries performed with the Ozil Intelligent Phaco (IP) torsional mode and combined torsional/longitudinal ultrasound (US) mode using the Infiniti Vision System (Alcon Laboratories). In this prospective randomized comparative study, 60 eyes were assigned to 2.2-mm microcoaxial phacoemulsification using the Ozil IP torsional mode (group 1) or combined torsional/longitudinal US mode (group 2). The primary outcome measures were US time (UST), cumulative dissipated energy (CDE), longitudinal and torsional ultrasound amplitudes, mean operation time, mean volume of balanced salt solution (BSS) used, and surgical complications. Both groups included 30 eyes. Mean UST, CDE, and longitudinal and torsional ultrasound amplitudes in group 1 were 1 minute 15±34.33 seconds, 8.74±5.64, 0.43±0.74, and 25.56±8.56, respectively, and these parameters in group 2 were 1 minute 40±51.44 seconds, 9.28±5.99, 3.64±1.55, and 3.71±1.34, respectively. UST and longitudinal amplitudes were found to be significantly low in group 1 (p<0.001, p<0.001), whereas torsional amplitude was found to be significantly high in this group (p=0.001). Mean volumes of BSS used in groups 1 and 2 were 63.30±18.00 cc and 84.50±28.65 cc, respectively (p=0.001). The Ozil IP torsional mode may provide more effective lens removal than the combined torsional/longitudinal US mode with a lower UST and volume of BSS used.
Dispersivity of Bidisperse Packings of Spheres and Evidence for Distinct Random Structures

NASA Astrophysics Data System (ADS)

Scheven, U. M.

2018-05-01

The intrinsic longitudinal and transverse dispersivity of bidisperse random packings of spheres with size ratio 5 ∶1 was determined by pulsed field gradient nuclear magnetic resonance, in the dilute regime where small spheres occupy between 0% and 5% of the packings' volume. Small spheres plugging pores systematically raise the mechanical transverse and longitudinal dispersivity above that of reference packings of monodisperse spheres. NMR-derived porosities, widths of velocity distributions, and dispersivities reveal distinct states of structural disorder above and below a relative sphere concentration n /N =1 , where n and N are the number densities of small and large spheres.
Permeability of model porous medium formed by random discs

NASA Astrophysics Data System (ADS)

Gubaidullin, A. A.; Gubkin, A. S.; Igoshin, D. E.; Ignatev, P. A.

2018-03-01

Two-dimension model of the porous medium with skeleton of randomly located overlapping discs is proposed. The geometry and computational grid are built in open package Salome. Flow of Newtonian liquid in longitudinal and transverse directions is calculated and its flow rate is defined. The numerical solution of the Navier-Stokes equations for a given pressure drop at the boundaries of the area is realized in the open package OpenFOAM. Calculated value of flow rate is used for defining of permeability coefficient on the base of Darcy law. For evaluating of representativeness of computational domain the permeability coefficients in longitudinal and transverse directions are compered.
Results of endocapsular phacofracture debulking of hard cataracts.

PubMed

Davison, James A

2015-01-01

To present a phacoemulsification technique for hard cataracts and compare postoperative results using two different ultrasonic tip motions during quadrant removal. A phacoemulsification technique which employs in situ fracture and endocapsular debulking for hard cataracts is presented. The prospective study included 56 consecutive cases of hard cataract (LOCS III NC [Lens Opacification Classification System III, nuclear color], average 4.26), which were operated using the Infiniti machine and the Partial Kelman tip. Longitudinal tip movement was used for sculpting for all cases which were randomized to receive longitudinal or torsional/interjected longitudinal (Intelligent Phaco [IP]) strategies for quadrant removal. Measurements included cumulative dissipated energy (CDE), 3 months postoperative surgically induced astigmatism (SIA), and corneal endothelial cell density (ECD) losses. No complications were recorded in any of the cases. Respective overall and longitudinal vs IP means were as follows: CDE, 51.6±15.6 and 55.7±15.5 vs 48.6±15.1; SIA, 0.36±0.2 D and 0.4±0.2 D vs 0.3±0.2 D; and mean ECD loss, 4.1%±10.8% and 5.9%±13.4% vs 2.7%±7.8%. The differences between longitudinal and IP were not significant for any of the three categories. The endocapsular phacofracture debulking technique is safe and effective for phacoemulsification of hard cataracts using longitudinal or torsional IP strategies for quadrant removal with the Infiniti machine and Partial Kelman tip.
Influence of mono-axis random vibration on reading activity.

PubMed

Bhiwapurkar, M K; Saran, V H; Harsha, S P; Goel, V K; Berg, Mats

2010-01-01

Recent studies on train passengers' activities found that many passengers were engaged in some form of work, e.g., reading and writing, while traveling by train. A majority of the passengers reported that their activities were disturbed by vibrations or motions during traveling. A laboratory study was therefore set up to study how low-frequency random vibrations influence the difficulty to read. The study involved 18 healthy male subjects of 23 to 32 yr of age group. Random vibrations were applied in the frequency range (1-10 Hz) at 0.5, 1.0 and 1.5 m/s(2) rms amplitude along three directions (longitudinal, lateral and vertical). The effect of vibration on reading activity was investigated by giving a word chain in two different font types (Times New Roman and Arial) and three different sizes (10, 12 and 14 points) of font for each type. Subjects performed reading tasks under two sitting positions (with backrest support and leaning over a table). The judgments of perceived difficulty to read were rated using 7-point discomfort judging scale. The result shows that reading difficulty increases with increasing vibration magnitudes and found to be maximum in longitudinal direction, but with leaning over a table position. In comparison with Times New Roman type and sizes of font, subjects perceived less difficulty with Arial type for all font sizes under all vibration magnitude.
Sensitivity Analysis of Mixed Models for Incomplete Longitudinal Data

ERIC Educational Resources Information Center

Xu, Shu; Blozis, Shelley A.

2011-01-01

Mixed models are used for the analysis of data measured over time to study population-level change and individual differences in change characteristics. Linear and nonlinear functions may be used to describe a longitudinal response, individuals need not be observed at the same time points, and missing data, assumed to be missing at random (MAR),…
Family and Psychosocial Risk Factors in a Longitudinal Epidemiological Study of Adolescents.

ERIC Educational Resources Information Center

Cuffe, Steven P.; McKeown, Robert E.; Addy, Cheryl L.; Garrison, Carol Z.

2005-01-01

Objective: To study the association of family and social risk factors with psychopathology in a longitudinal study of adolescents. Method: From 1986 to 1988, 3,419 seventh through ninth graders were screened with the Center for Epidemiologic Studies Depression Scale. The top decile scorers and a random sample of the remainder were interviewed…
Identification and estimation of survivor average causal effects.

PubMed

Tchetgen Tchetgen, Eric J

2014-09-20

In longitudinal studies, outcomes ascertained at follow-up are typically undefined for individuals who die prior to the follow-up visit. In such settings, outcomes are said to be truncated by death and inference about the effects of a point treatment or exposure, restricted to individuals alive at the follow-up visit, could be biased even if as in experimental studies, treatment assignment were randomized. To account for truncation by death, the survivor average causal effect (SACE) defines the effect of treatment on the outcome for the subset of individuals who would have survived regardless of exposure status. In this paper, the author nonparametrically identifies SACE by leveraging post-exposure longitudinal correlates of survival and outcome that may also mediate the exposure effects on survival and outcome. Nonparametric identification is achieved by supposing that the longitudinal data arise from a certain nonparametric structural equations model and by making the monotonicity assumption that the effect of exposure on survival agrees in its direction across individuals. A novel weighted analysis involving a consistent estimate of the survival process is shown to produce consistent estimates of SACE. A data illustration is given, and the methods are extended to the context of time-varying exposures. We discuss a sensitivity analysis framework that relaxes assumptions about independent errors in the nonparametric structural equations model and may be used to assess the extent to which inference may be altered by a violation of key identifying assumptions. © 2014 The Authors. Statistics in Medicine published by John Wiley & Sons, Ltd.
Identification and estimation of survivor average causal effects

PubMed Central

Tchetgen, Eric J Tchetgen

2014-01-01

In longitudinal studies, outcomes ascertained at follow-up are typically undefined for individuals who die prior to the follow-up visit. In such settings, outcomes are said to be truncated by death and inference about the effects of a point treatment or exposure, restricted to individuals alive at the follow-up visit, could be biased even if as in experimental studies, treatment assignment were randomized. To account for truncation by death, the survivor average causal effect (SACE) defines the effect of treatment on the outcome for the subset of individuals who would have survived regardless of exposure status. In this paper, the author nonparametrically identifies SACE by leveraging post-exposure longitudinal correlates of survival and outcome that may also mediate the exposure effects on survival and outcome. Nonparametric identification is achieved by supposing that the longitudinal data arise from a certain nonparametric structural equations model and by making the monotonicity assumption that the effect of exposure on survival agrees in its direction across individuals. A novel weighted analysis involving a consistent estimate of the survival process is shown to produce consistent estimates of SACE. A data illustration is given, and the methods are extended to the context of time-varying exposures. We discuss a sensitivity analysis framework that relaxes assumptions about independent errors in the nonparametric structural equations model and may be used to assess the extent to which inference may be altered by a violation of key identifying assumptions. © 2014 The Authors. Statistics in Medicine published by John Wiley & Sons, Ltd. PMID:24889022
Longitudinal analysis of bioaccumulative contaminants in freshwater fishes

USGS Publications Warehouse

Sun, Jielun; Kim, Y.; Schmitt, C.J.

2003-01-01

The National Contaminant Biomonitoring Program (NCBP) was initiated in 1967 as a component of the National Pesticide Monitoring program. It consists of periodic collection of freshwater fish and other samples and the analysis of the concentrations of persistent environmental contaminants in these samples. For the analysis, the common approach has been to apply the mixed two-way ANOVA model to combined data. A main disadvantage of this method is that it cannot give a detailed temporal trend of the concentrations since the data are grouped. In this paper, we present an alternative approach that performs a longitudinal analysis of the information using random effects models. In the new approach, no grouping is needed and the data are treated as samples from continuous stochastic processes, which seems more appropriate than ANOVA for the problem.
Effects of Transcranial Direct Current Stimulation With Sensory Modulation on Stroke Motor Rehabilitation: A Randomized Controlled Trial.

PubMed

Koh, Chia-Lin; Lin, Jau-Hong; Jeng, Jiann-Shing; Huang, Sheau-Ling; Hsieh, Ching-Lin

2017-12-01

To test whether a multistrategy intervention enhanced recovery immediately and longitudinally in patients with severe to moderate upper extremity (UE) paresis. Double-blind, randomized controlled trial with placebo control. Outpatient department of a local medical center. People (N=25) with chronic stroke were randomly assigned to 1 of 2 groups: a transcranial direct current stimulation with sensory modulation (tDCS-SM) group (n=14; mean age ± SD, 55.3±11.4y) or a control group (n=11; mean age ± SD, 56.9±13.5y). Eight-week intervention. The tDCS-SM group received bilateral tDCS, bilateral cutaneous anesthesia, and high repetitions of passive movements on the paretic hand. The control group received the same passive movements but with sham tDCS and sham anesthesia. During the experiment, all participants continued their regular rehabilitation. Voluntary UE movement, spasticity, UE function, and basic activities of daily living. Outcomes were assessed at baseline, at postintervention, and at 3- and 6-month follow-ups. No significant differences were found between groups. However, there was a trend that the voluntary UE movement improved more in the tDCS-SM group than in the control group, with a moderate immediate effect (partial η 2 [η p 2 ]=.14, P=.07) and moderate long-term effects (3-mo follow-up: η p 2 =.17, P=.05; 6-mo follow-up: η p 2 =.12, P=.10). Compared with the control group, the tDCS-SM group had a trend of a small immediate effect (η p 2 =.02-.04) on reducing spasticity, but no long-term effect. A trend of small immediate and long-term effects in favor of tDCS-SM was found on UE function and daily function recovery (η p 2 =.02-.09). Accompanied with traditional rehabilitation, tDCS-SM had a nonsignificant trend of having immediate and longitudinal effects on voluntary UE movement recovery in patients with severe to moderate UE paresis after stroke, but its effects on spasticity reduction and functional recovery may be limited. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
Fitting Nonlinear Ordinary Differential Equation Models with Random Effects and Unknown Initial Conditions Using the Stochastic Approximation Expectation-Maximization (SAEM) Algorithm.

PubMed

Chow, Sy-Miin; Lu, Zhaohua; Sherwood, Andrew; Zhu, Hongtu

2016-03-01

The past decade has evidenced the increased prevalence of irregularly spaced longitudinal data in social sciences. Clearly lacking, however, are modeling tools that allow researchers to fit dynamic models to irregularly spaced data, particularly data that show nonlinearity and heterogeneity in dynamical structures. We consider the issue of fitting multivariate nonlinear differential equation models with random effects and unknown initial conditions to irregularly spaced data. A stochastic approximation expectation-maximization algorithm is proposed and its performance is evaluated using a benchmark nonlinear dynamical systems model, namely, the Van der Pol oscillator equations. The empirical utility of the proposed technique is illustrated using a set of 24-h ambulatory cardiovascular data from 168 men and women. Pertinent methodological challenges and unresolved issues are discussed.
FITTING NONLINEAR ORDINARY DIFFERENTIAL EQUATION MODELS WITH RANDOM EFFECTS AND UNKNOWN INITIAL CONDITIONS USING THE STOCHASTIC APPROXIMATION EXPECTATION–MAXIMIZATION (SAEM) ALGORITHM

PubMed Central

Chow, Sy- Miin; Lu, Zhaohua; Zhu, Hongtu; Sherwood, Andrew

2014-01-01

The past decade has evidenced the increased prevalence of irregularly spaced longitudinal data in social sciences. Clearly lacking, however, are modeling tools that allow researchers to fit dynamic models to irregularly spaced data, particularly data that show nonlinearity and heterogeneity in dynamical structures. We consider the issue of fitting multivariate nonlinear differential equation models with random effects and unknown initial conditions to irregularly spaced data. A stochastic approximation expectation–maximization algorithm is proposed and its performance is evaluated using a benchmark nonlinear dynamical systems model, namely, the Van der Pol oscillator equations. The empirical utility of the proposed technique is illustrated using a set of 24-h ambulatory cardiovascular data from 168 men and women. Pertinent methodological challenges and unresolved issues are discussed. PMID:25416456
On the repeated measures designs and sample sizes for randomized controlled trials.

PubMed

Tango, Toshiro

2016-04-01

For the analysis of longitudinal or repeated measures data, generalized linear mixed-effects models provide a flexible and powerful tool to deal with heterogeneity among subject response profiles. However, the typical statistical design adopted in usual randomized controlled trials is an analysis of covariance type analysis using a pre-defined pair of "pre-post" data, in which pre-(baseline) data are used as a covariate for adjustment together with other covariates. Then, the major design issue is to calculate the sample size or the number of subjects allocated to each treatment group. In this paper, we propose a new repeated measures design and sample size calculations combined with generalized linear mixed-effects models that depend not only on the number of subjects but on the number of repeated measures before and after randomization per subject used for the analysis. The main advantages of the proposed design combined with the generalized linear mixed-effects models are (1) it can easily handle missing data by applying the likelihood-based ignorable analyses under the missing at random assumption and (2) it may lead to a reduction in sample size, compared with the simple pre-post design. The proposed designs and the sample size calculations are illustrated with real data arising from randomized controlled trials. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Longitudinal Examination of Aggression and Study Skills from Middle to High School: Implications for Dropout Prevention

ERIC Educational Resources Information Center

Orpinas, Pamela; Raczynski, Katherine; Hsieh, Hsien-Lin; Nahapetyan, Lusine; Horne, Arthur M.

2018-01-01

Background: High school completion provides health and economic benefits. The purpose of this study is to describe dropout rates based on longitudinal trajectories of aggression and study skills using teacher ratings. Methods: The sample consisted of 620 randomly selected sixth graders. Every year from Grade 6 to 12, a teacher completed a…
Contemporary Options for Longitudinal Follow-Up: Lessons Learned from a Cohort of Urban Adolescents

ERIC Educational Resources Information Center

Tobler, Amy L.; Komro, Kelli A.

2011-01-01

This study reports efforts to locate and survey participants in Project Northland Chicago (PNC), a longitudinal, group-randomized trial of an alcohol preventive intervention for racial/ethnic minority, urban, early-adolescents, 3-4 years following the end of the intervention. Data were collected annually among students from 6th-8th grade and then…
Bridging the Gap: A Longitudinal Study of the Relationship between Pedagogical Continuity and Early Chinese Literacy Acquisition

ERIC Educational Resources Information Center

Li, Hui; Rao, Nirmala; Tse, Shek Kam

2011-01-01

This longitudinal study examined the relationship between pedagogical continuity in literacy education and early literacy development by comparing Chinese children in Hong Kong and Shenzhen. Stratified random sampling was used to select 24 preschool and Primary 1 classes in four communities catering to middle-class families in each city. The 24…
A Study of Ontogenetic and Generational Change in Adolescent Personality by Means of Multivariate Longitudinal Sequences: Phase II. Final Report.

ERIC Educational Resources Information Center

Nesselroade, John R.; Baltes, Paul B.

Assessment of the relationship between ontogenetic (individual) and generational (historical) change in adolescent personality development was the focus of this study. The total sample included 1000 male and female adolescents (ages 13-18) randomly drawn from 32 public school systems in West Virginia following a design using longitudinal sequences…
The Longitudinal Impact of a Universal School-Based Social-Emotional and Literacy Intervention on Classroom Climate and Teacher Processes and Practices

ERIC Educational Resources Information Center

Brown, Joshua L.; Jones, Stephanie M.; Aber, J. Lawrence

2010-01-01

This presentation capitalizes on a three-year, longitudinal, school-randomized trial of the 4Rs Program, a comprehensive, school-based social-emotional and literacy program for elementary schools, to test intervention induced changes in features of classroom climate and key dimensions of teacher affective and pedagogical processes and practices…
Differential Cost Avoidance and Successful Criminal Careers: Random or Rational?

ERIC Educational Resources Information Center

Kazemian, Lila; Le Blanc, Marc

2007-01-01

Using a sample of adjudicated French Canadian males from the Montreal Two Samples Longitudinal Study, this article investigates individual and social characteristics associated with differential cost avoidance. The main objective of this study is to determine whether such traits are randomly distributed across differential degrees of cost…

Aircraft adaptive learning control

NASA Technical Reports Server (NTRS)

Lee, P. S. T.; Vanlandingham, H. F.

1979-01-01

The optimal control theory of stochastic linear systems is discussed in terms of the advantages of distributed-control systems, and the control of randomly-sampled systems. An optimal solution to longitudinal control is derived and applied to the F-8 DFBW aircraft. A randomly-sampled linear process model with additive process and noise is developed.
Who Benefits from Gender Responsive Treatment? Accounting for Abuse History on Longitudinal Outcomes for Women in Prison.

PubMed

Saxena, Preeta; Messina, Nena; Grella, Christine E

2014-04-01

This study explores outcome variation among women offenders who participated in gender-responsive substance abuse treatment (GRT). In order to identify subgroups of participants that may differentially benefit from this treatment, secondary analyses examined the interaction between randomization into GRT and a history of abuse (physical/sexual) on depression and number of substances used post- treatment. The sample consisted of 115 incarcerated women assessed at baseline and 6- and 12-months post parole. Longitudinal regression showed that women reporting abuse randomized into GRT had significantly reduced odds of depression ( OR = .29, p < .05, 95% CI = .10 - .86) and lowered rates of number of substances used ( IRR = .52, p < .05, 95% CI = 0.28-0.98), in comparison to those who reported abuse and were randomized to the non-GRT group. GRT for women offenders who have experienced prior abuse would maximize the benefits of the trauma-informed, gender-sensitive intervention.
Presymptomatic and longitudinal neuroimaging in neurodegeneration--from snapshots to motion picture: a systematic review.

PubMed

Schuster, Christina; Elamin, Marwa; Hardiman, Orla; Bede, Peter

2015-10-01

Recent quantitative neuroimaging studies have been successful in capturing phenotype and genotype-specific changes in dementia syndromes, amyotrophic lateral sclerosis, Parkinson's disease and other neurodegenerative conditions. However, the majority of imaging studies are cross-sectional, despite the obvious superiority of longitudinal study designs in characterising disease trajectories, response to therapy, progression rates and evaluating the presymptomatic phase of neurodegenerative conditions. The aim of this work is to perform a systematic review of longitudinal imaging initiatives in neurodegeneration focusing on methodology, optimal statistical models, follow-up intervals, attrition rates, primary study outcomes and presymptomatic studies. Longitudinal imaging studies were identified from 'PubMed' and reviewed from 1990 to 2014. The search terms 'longitudinal', 'MRI', 'presymptomatic' and 'imaging' were utilised in combination with one of the following degenerative conditions; Alzheimer's disease, amyotrophic lateral sclerosis/motor neuron disease, frontotemporal dementia, Huntington's disease, multiple sclerosis, Parkinson's disease, ataxia, HIV, alcohol abuse/dependence. A total of 423 longitudinal imaging papers and 103 genotype-based presymptomatic studies were identified and systematically reviewed. Imaging techniques, follow-up intervals and attrition rates showed significant variation depending on the primary diagnosis. Commonly used statistical models included analysis of annualised percentage change, mixed and random effect models, and non-linear cumulative models with acceleration-deceleration components. Although longitudinal imaging studies have the potential to provide crucial insights into the presymptomatic phase and natural trajectory of neurodegenerative processes a standardised design is required to enable meaningful data interpretation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Enhancement of Electron Acceleration in Laser Wakefields by Random Fields

NASA Astrophysics Data System (ADS)

Tataronis, J. A.; Petržílka, V.

1999-11-01

There is increasing evidence that intense laser pulses can accelerate electrons to high energies. The energy appears to increase with the distance over which the electrons are accelerated. This is difficult to explain by electron trapping in a single wakefield wave.^1 We demonstrate that enhanced electron acceleration can arise in inhomogeneous laser wakefields through the effects of spontaneously excited random fields. This acceleration mechanism is analogous to fast electron production by random fields near rf antennae in fusion devices and helicon plasma sources.^2 Electron acceleration in a transverse laser wave due to random field effects was recently found.^3 In the present study we solve numerically the governing equations of an ensemble of test electrons in a longitudinal electric wakefield perturbed by random fields. [1pt] Supported by the Czech grant IGA A1043701 and the U.S. DOE under grant No. DE-FG02-97ER54398. [1pt] 1. A. Pukhov and J. Meyer-ter-Vehn, in Superstrong Fields in Plasmas, AIP Conf. Proc. 426, p. 93 (1997). 2. V. Petržílka, J. A. Tataronis, et al., in Proc. Varenna - Lausanne Fusion Theory Workshop, p. 95 (1998). 3. J. Meyer-ter-Vehn and Z. M. Sheng, Phys. Plasmas 6, 641 (1999).
Longitudinal safety evaluation of electric vehicles with the partial wireless charging lane on freeways.

PubMed

Li, Ye; Wang, Wei; Xing, Lu; Fan, Qi; Wang, Hao

2018-02-01

As an environment friendly transportation mode, the electric vehicle (EV) has drawn an increasing amount of attention from governments, vehicle manufactories and researchers recently. One of the biggest issue impeding EV's popularization associates with the charging process. The wireless charging lane (WCL) has been proposed as a convenient charging facility for EVs. Due to the high costs, the application of WCL on the entire freeways is impractical in the near future, while the partial WCL (PWCL) may be a feasible solution. This study aims to evaluate longitudinal safety of EVs with PWCL on freeways based on simulations. The simulation experiments are firstly designed, including deployment of PWCL on freeways and distribution of state of charge (SOC) of EVs. Then, a vehicle behavior model for EVs is proposed based on the intelligent driver model (IDM). Two surrogate safety measures, derived from time-to-collision (TTC), are utilized as indicators for safety evaluations. Sensitivity analysis is also conducted for related factors. Results show that the distribution of EVs' SOC significantly affect longitudinal safety when the PWCL is utilized. The low SOC in traffic consisting of EVs has the negative effect on longitudinal safety. The randomness and incompliance of EV drivers worsens the safety performance. The sensitivity analysis indicates that the larger maximum deceleration rate results in the higher longitudinal crash risks of EVs, while the length of PWCL has no monotonous effect. Different TTC thresholds also show no impact on results. A case study shows the consistent results. Based on the findings, several suggestions are discussed for EVs' safety improvement. Results of this study provide useful information for freeway safety when EVs are applied in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.
A structured framework for assessing sensitivity to missing data assumptions in longitudinal clinical trials.

PubMed

Mallinckrodt, C H; Lin, Q; Molenberghs, M

2013-01-01

The objective of this research was to demonstrate a framework for drawing inference from sensitivity analyses of incomplete longitudinal clinical trial data via a re-analysis of data from a confirmatory clinical trial in depression. A likelihood-based approach that assumed missing at random (MAR) was the primary analysis. Robustness to departure from MAR was assessed by comparing the primary result to those from a series of analyses that employed varying missing not at random (MNAR) assumptions (selection models, pattern mixture models and shared parameter models) and to MAR methods that used inclusive models. The key sensitivity analysis used multiple imputation assuming that after dropout the trajectory of drug-treated patients was that of placebo treated patients with a similar outcome history (placebo multiple imputation). This result was used as the worst reasonable case to define the lower limit of plausible values for the treatment contrast. The endpoint contrast from the primary analysis was - 2.79 (p = .013). In placebo multiple imputation, the result was - 2.17. Results from the other sensitivity analyses ranged from - 2.21 to - 3.87 and were symmetrically distributed around the primary result. Hence, no clear evidence of bias from missing not at random data was found. In the worst reasonable case scenario, the treatment effect was 80% of the magnitude of the primary result. Therefore, it was concluded that a treatment effect existed. The structured sensitivity framework of using a worst reasonable case result based on a controlled imputation approach with transparent and debatable assumptions supplemented a series of plausible alternative models under varying assumptions was useful in this specific situation and holds promise as a generally useful framework. Copyright © 2012 John Wiley & Sons, Ltd.
Beneficial effects of growth hormone treatment on cognition in children with Prader-Willi syndrome: a randomized controlled trial and longitudinal study.

PubMed

Siemensma, Elbrich P C; Tummers-de Lind van Wijngaarden, Roderick F A; Festen, Dederieke A M; Troeman, Zyrhea C E; van Alfen-van der Velden, A A E M Janielle; Otten, Barto J; Rotteveel, Joost; Odink, Roelof J H; Bindels-de Heus, G C B Karen; van Leeuwen, Mariette; Haring, Danny A J P; Oostdijk, Wilma; Bocca, Gianni; Mieke Houdijk, E C A; van Trotsenburg, A S Paul; Hoorweg-Nijman, J J Gera; van Wieringen, Hester; Vreuls, René C F M; Jira, Petr E; Schroor, Eelco J; van Pinxteren-Nagler, Evelyn; Willem Pilon, Jan; Lunshof, L Bert; Hokken-Koelega, Anita C S

2012-07-01

Knowledge about the effects of GH treatment on cognitive functioning in children with Prader-Willi syndrome (PWS) is limited. Fifty prepubertal children aged 3.5 to 14 yr were studied in a randomized controlled GH trial during 2 yr, followed by a longitudinal study during 4 yr of GH treatment. Cognitive functioning was measured biennially by short forms of the WPPSI-R or WISC-R, depending on age. Total IQ (TIQ) score was estimated based on two subtest scores. During the randomized controlled trial, mean sd scores of all subtests and mean TIQ score remained similar compared to baseline in GH-treated children with PWS, whereas in untreated controls mean subtest sd scores and mean TIQ score decreased and became lower compared to baseline. This decline was significant for the Similarities (P = 0.04) and Vocabulary (P = 0.03) subtests. After 4 yr of GH treatment, mean sd scores on the Similarities and Block design subtests were significantly higher than at baseline (P = 0.01 and P = 0.03, respectively), and scores on Vocabulary and TIQ remained similar compared to baseline. At baseline, children with a maternal uniparental disomy had a significantly lower score on the Block design subtest (P = 0.01) but a larger increment on this subtest during 4 yr of GH treatment than children with a deletion. Lower baseline scores correlated significantly with higher increases in Similarities (P = 0.04) and Block design (P < 0.0001) sd scores. Our study shows that GH treatment prevents deterioration of certain cognitive skills in children with PWS on the short term and significantly improves abstract reasoning and visuospatial skills during 4 yr of GH treatment. Furthermore, children with a greater deficit had more benefit from GH treatment.
Application of an Extended Parabolic Equation to the Calculation of the Mean Field and the Transverse and Longitudinal Mutual Coherence Functions Within Atmospheric Turbulence

NASA Technical Reports Server (NTRS)

Manning, Robert M.

2005-01-01

Solutions are derived for the generalized mutual coherence function (MCF), i.e., the second order moment, of a random wave field propagating through a random medium within the context of the extended parabolic equation. Here, "generalized" connotes the consideration of both the transverse as well as the longitudinal second order moments (with respect to the direction of propagation). Such solutions will afford a comparison between the results of the parabolic equation within the pararaxial approximation and those of the wide-angle extended theory. To this end, a statistical operator method is developed which gives a general equation for an arbitrary spatial statistical moment of the wave field. The generality of the operator method allows one to obtain an expression for the second order field moment in the direction longitudinal to the direction of propagation. Analytical solutions to these equations are derived for the Kolmogorov and Tatarskii spectra of atmospheric permittivity fluctuations within the Markov approximation.
[Study protocol on the effect of the economic crisis on mortality and reproductive health and health inequalities in Spain].

PubMed

Pérez, Glòria; Gotsens, Mercè; Palència, Laia; Marí-Dell'Olmo, Marc; Domínguez-Berjón, M Felicitas; Rodríguez-Sanz, Maica; Puig, Vanessa; Bartoll, Xavier; Gandarillas, Ana; Martín, Unai; Bacigalupe, Amaia; Díez, Elia; Ruiz, Miguel; Esnaola, Santiago; Calvo, Montserrat; Sánchez, Pablo; Luque Fernández, Miguel Ángel; Borrell, Carme

The aim is to present the protocol of the two sub-studies on the effect of the economic crisis on mortality and reproductive health and health inequalities in Spain. Substudy 1: describe the evolution of mortality and reproductive health between 1990 and 2013 through a longitudinal ecological study in the Autonomous Communities. This study will identify changes caused by the economic crisis in trends or reproductive health and mortality indicators using panel data (17 Autonomous Communities per study year) and adjusting Poisson models with random effects variance. Substudy 2: analyse inequalities by socioeconomic deprivation in mortality and reproductive health in several areas of Spain. An ecological study analysing trends in the pre-crisis (1999-2003 and 2004-2008) and crisis (2009-2013) periods will be performed. Random effects models Besag York and Mollié will be adjusted to estimate mortality indicators softened in reproductive health and census tracts. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.
A randomized clinical trial aimed at preventing poor psychosocial and glycemic outcomes in teens with type 1 diabetes (T1D)

PubMed Central

Weissberg-Benchell, Jill; Rausch, Joseph; Iturralde, Esti; Jedraszko, Aneta; Hood, Korey

2016-01-01

Adolescents with type 1 diabetes have an increased risk for a variety of emotional and behavioral challenges as well as negative diabetes outcomes. This study was designed to compare the effectiveness of a depression-prevention, resilience promotion program with an advanced diabetes education program. Each program consisted of 9 group-based sessions. There were 264 adolescents enrolled in this multi-site randomized clinical trial. The primary outcomes were depressive symptoms and glycemic control; secondary outcomes included resilience skills, diabetes management and adherence, and diabetes-specific distress. The goal of the present paper is to describe the study design, the intervention, and the baseline characteristics of the sample. Preliminary data suggests that enrollment, randomization and retention were successful. Longitudinal follow-up and examination of mechanisms of action as they relate to psychosocial and glycemic outcomes will be explored in the future. PMID:27267154
Results of endocapsular phacofracture debulking of hard cataracts

PubMed Central

Davison, James A

2015-01-01

Purpose/aim of the study To present a phacoemulsification technique for hard cataracts and compare postoperative results using two different ultrasonic tip motions during quadrant removal. Materials and methods A phacoemulsification technique which employs in situ fracture and endocapsular debulking for hard cataracts is presented. The prospective study included 56 consecutive cases of hard cataract (LOCS III NC [Lens Opacification Classification System III, nuclear color], average 4.26), which were operated using the Infiniti machine and the Partial Kelman tip. Longitudinal tip movement was used for sculpting for all cases which were randomized to receive longitudinal or torsional/interjected longitudinal (Intelligent Phaco [IP]) strategies for quadrant removal. Measurements included cumulative dissipated energy (CDE), 3 months postoperative surgically induced astigmatism (SIA), and corneal endothelial cell density (ECD) losses. Results No complications were recorded in any of the cases. Respective overall and longitudinal vs IP means were as follows: CDE, 51.6±15.6 and 55.7±15.5 vs 48.6±15.1; SIA, 0.36±0.2 D and 0.4±0.2 D vs 0.3±0.2 D; and mean ECD loss, 4.1%±10.8% and 5.9%±13.4% vs 2.7%±7.8%. The differences between longitudinal and IP were not significant for any of the three categories. Conclusion The endocapsular phacofracture debulking technique is safe and effective for phacoemulsification of hard cataracts using longitudinal or torsional IP strategies for quadrant removal with the Infiniti machine and Partial Kelman tip. PMID:26203213
What It's Like to Grow Older: The Aging Perceptions of People with an Intellectual Disability in Ireland

ERIC Educational Resources Information Center

Burke, Eilish; McCarron, Mary; Carroll, Rachael; McGlinchey, Eimear; McCallion, Philip

2014-01-01

The Intellectual Disability Supplement to The Irish Longitudinal Study on Ageing is a national longitudinal study on the aging of people with an intellectual disability (ID) using a randomly selected sample of people with ID over the age of 40. In total, 367 people with an ID completed the aging perception self-report only section. Over 57% of…
The Philadelphia Education Longitudinal Study (PELS): Report on the Transition to High School in the School District of Philadelphia.

ERIC Educational Resources Information Center

Neild, Ruth Curran; Weiss, Christopher C.

The Philadelphia Education Longitudinal Study (PELS) on the transition to ninth grade in Philadelphia highlights the high school choice process, course failure rates during ninth grade, and parents' responses to the transition to high school. The PELS study followed a city-wide random sample of public school students from the summer after eighth…
Longitudinal impact of the project PATHS on adolescent risk behavior: what happened after five years?

PubMed

Shek, Daniel T L; Yu, Lu

2012-01-01

The present study investigated the longitudinal impact of the Project PATHS, a large-scale curriculum-based positive youth development program in Hong Kong, on the development of adolescents' risk behavior over a period of five years. Using a longitudinal randomized controlled design, eight waves of data were collected from 19 experimental schools in which students participated in the Project PATHS (N = 2,850 at Wave 8) and 24 control schools without joining the Project PATHS (N = 3,640 at Wave 8). At each wave, students responded to measures assessing their current risk behaviors, including delinquency, use of different types of drug, and their intentions of participating in risk behaviors in the future. Results demonstrated that adolescents receiving the program exhibited significantly slower increases in delinquent behaviors and substance use as compared to the control participants. During two years after the completion of the program, differences in youth risk behaviors in the two groups still existed. These results suggest that the Project PATHS has long-term effect in preventing adolescent problem behavior through promoting positive youth development.
Revisiting typhoid fever surveillance in low and middle income countries: lessons from systematic literature review of population-based longitudinal studies.

PubMed

Mogasale, Vittal; Mogasale, Vijayalaxmi V; Ramani, Enusa; Lee, Jung Seok; Park, Ju Yeon; Lee, Kang Sung; Wierzba, Thomas F

2016-01-29

The control of typhoid fever being an important public health concern in low and middle income countries, improving typhoid surveillance will help in planning and implementing typhoid control activities such as deployment of new generation Vi conjugate typhoid vaccines. We conducted a systematic literature review of longitudinal population-based blood culture-confirmed typhoid fever studies from low and middle income countries published from 1(st) January 1990 to 31(st) December 2013. We quantitatively summarized typhoid fever incidence rates and qualitatively reviewed study methodology that could have influenced rate estimates. We used meta-analysis approach based on random effects model in summarizing the hospitalization rates. Twenty-two papers presented longitudinal population-based and blood culture-confirmed typhoid fever incidence estimates from 20 distinct sites in low and middle income countries. The reported incidence and hospitalizations rates were heterogeneous as well as the study methodology across the sites. We elucidated how the incidence rates were underestimated in published studies. We summarized six categories of under-estimation biases observed in these studies and presented potential solutions. Published longitudinal typhoid fever studies in low and middle income countries are geographically clustered and the methodology employed has a potential for underestimation. Future studies should account for these limitations.
Estimating mono- and bi-phasic regression parameters using a mixture piecewise linear Bayesian hierarchical model

PubMed Central

Zhao, Rui; Catalano, Paul; DeGruttola, Victor G.; Michor, Franziska

2017-01-01

The dynamics of tumor burden, secreted proteins or other biomarkers over time, is often used to evaluate the effectiveness of therapy and to predict outcomes for patients. Many methods have been proposed to investigate longitudinal trends to better characterize patients and to understand disease progression. However, most approaches assume a homogeneous patient population and a uniform response trajectory over time and across patients. Here, we present a mixture piecewise linear Bayesian hierarchical model, which takes into account both population heterogeneity and nonlinear relationships between biomarkers and time. Simulation results show that our method was able to classify subjects according to their patterns of treatment response with greater than 80% accuracy in the three scenarios tested. We then applied our model to a large randomized controlled phase III clinical trial of multiple myeloma patients. Analysis results suggest that the longitudinal tumor burden trajectories in multiple myeloma patients are heterogeneous and nonlinear, even among patients assigned to the same treatment cohort. In addition, between cohorts, there are distinct differences in terms of the regression parameters and the distributions among categories in the mixture. Those results imply that longitudinal data from clinical trials may harbor unobserved subgroups and nonlinear relationships; accounting for both may be important for analyzing longitudinal data. PMID:28723910
Fitting parametric random effects models in very large data sets with application to VHA national data

PubMed Central

2012-01-01

Background With the current focus on personalized medicine, patient/subject level inference is often of key interest in translational research. As a result, random effects models (REM) are becoming popular for patient level inference. However, for very large data sets that are characterized by large sample size, it can be difficult to fit REM using commonly available statistical software such as SAS since they require inordinate amounts of computer time and memory allocations beyond what are available preventing model convergence. For example, in a retrospective cohort study of over 800,000 Veterans with type 2 diabetes with longitudinal data over 5 years, fitting REM via generalized linear mixed modeling using currently available standard procedures in SAS (e.g. PROC GLIMMIX) was very difficult and same problems exist in Stata’s gllamm or R’s lme packages. Thus, this study proposes and assesses the performance of a meta regression approach and makes comparison with methods based on sampling of the full data. Data We use both simulated and real data from a national cohort of Veterans with type 2 diabetes (n=890,394) which was created by linking multiple patient and administrative files resulting in a cohort with longitudinal data collected over 5 years. Methods and results The outcome of interest was mean annual HbA1c measured over a 5 years period. Using this outcome, we compared parameter estimates from the proposed random effects meta regression (REMR) with estimates based on simple random sampling and VISN (Veterans Integrated Service Networks) based stratified sampling of the full data. Our results indicate that REMR provides parameter estimates that are less likely to be biased with tighter confidence intervals when the VISN level estimates are homogenous. Conclusion When the interest is to fit REM in repeated measures data with very large sample size, REMR can be used as a good alternative. It leads to reasonable inference for both Gaussian and non-Gaussian responses if parameter estimates are homogeneous across VISNs. PMID:23095325
Education and Psychological Distress of Older Chinese: Exploring the Longitudinal Relationship and Its Subgroup Variations.

PubMed

Zhang, Wei; Chen, Huashuai; Feng, Qiushi

2015-10-01

The goal of this study is to examine whether and how education predicts distress for older Chinese and whether this association varies by age, gender, and rural/urban residence. The random-effect panel model and Heckman selection model were used to analyze four waves of data with a total sample size of 54,405 from the Chinese Longitudinal Healthy Longevity Survey. We found the following: (a) There is a persistent and negative association between education and distress among older Chinese; (b) education predicts lower levels of distress over time and this is particularly true for males, urban residents, and the young-old; and (c) the effect of education on distress is largely explained by physical health, economic conditions, and a three-dimensional framework of leisure-time activities. Our findings strengthen the external validity of the relationship between education and health and suggest the dynamic patterns on the subgroup variations within the association in China. © The Author(s) 2015.
Peer influence processes for youth delinquency and depression.

PubMed

Reynolds, Andrew D; Crea, Thomas M

2015-08-01

This study explores the multiple factors that account for peer influence processes of adolescent delinquency and depression using data from Waves I and II of the National Longitudinal Study of Adolescent to Adult Health (Add Health). Random-effects longitudinal negative binomial models were used to predict depression and delinquency, controlling for social connection variables to account for selection bias. Findings suggest peer depression and delinquency are both predictive of youth delinquency, while peer influences of depression are much more modest. Youth who are more connected to parents and communities and who are more popular within their networks are more susceptible to peer influence, while self-regulating youth are less susceptible. We find support for theories of popularity-socialization as well as weak-ties in explaining social network factors that amplify or constrain peer influence. We argue that practitioners working with youth should consider network-informed interventions to improve program efficacy and avoid iatrogenic effects. Copyright © 2015 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.
Impact of the Project P.A.T.H.S. in the junior secondary school years: objective outcome evaluation based on eight waves of longitudinal data.

PubMed

Shek, Daniel T L; Ma, Cecilia M S

2012-01-01

To assess the effectiveness of the Tier 1 Program of the Project P.A.T.H.S., a randomized group trial with eight waves of data collected was carried out. At the fifth year of data collection, 19 experimental schools (n = 2, 662 students) and 24 control schools (n = 3, 272 students) participated in the study. Analyses based on individual growth curve modeling showed that participants in the experimental schools displayed better positive youth development than did participants in the control schools in terms of different indicators derived from the Chinese Positive Youth Development Scale, including moral competence and behavioral competence and cognitive behavioral competencies. Significant results were also found when examining the trajectories of psychological development among control and experimental participants who perceived the program to be beneficial. Findings based on longitudinal objective outcome evaluation strongly suggest that the Project P.A.T.H.S. is effective in promoting positive development in Hong Kong secondary school students.

A framework for understanding cancer comparative effectiveness research data needs.

PubMed

Carpenter, William R; Meyer, Anne-Marie; Abernethy, Amy P; Stürmer, Til; Kosorok, Michael R

2012-11-01

Randomized controlled trials remain the gold standard for evaluating cancer intervention efficacy. Randomized trials are not always feasible, practical, or timely and often don't adequately reflect patient heterogeneity and real-world clinical practice. Comparative effectiveness research can leverage secondary data to help fill knowledge gaps randomized trials leave unaddressed; however, comparative effectiveness research also faces shortcomings. The goal of this project was to develop a new model and inform an evolving framework articulating cancer comparative effectiveness research data needs. We examined prevalent models and conducted semi-structured discussions with 76 clinicians and comparative effectiveness research researchers affiliated with the Agency for Healthcare Research and Quality's cancer comparative effectiveness research programs. A new model was iteratively developed and presents cancer comparative effectiveness research and important measures in a patient-centered, longitudinal chronic care model better reflecting contemporary cancer care in the context of the cancer care continuum, rather than a single-episode, acute-care perspective. Immediately relevant for federally funded comparative effectiveness research programs, the model informs an evolving framework articulating cancer comparative effectiveness research data needs, including evolutionary enhancements to registries and epidemiologic research data systems. We discuss elements of contemporary clinical practice, methodology improvements, and related needs affecting comparative effectiveness research's ability to yield findings clinicians, policy makers, and stakeholders can confidently act on. Copyright © 2012 Elsevier Inc. All rights reserved.
A framework for understanding cancer comparative effectiveness research data needs

PubMed Central

Carpenter, William R; Meyer, Anne-Marie; Abernethy, Amy P.; Stürmer, Til; Kosorok, Michael R.

2012-01-01

Objective Randomized controlled trials remain the gold standard for evaluating cancer intervention efficacy. Randomized trials are not always feasible, practical, or timely, and often don’t adequately reflect patient heterogeneity and real-world clinical practice. Comparative effectiveness research can leverage secondary data to help fill knowledge gaps randomized trials leave unaddressed; however, comparative effectiveness research also faces shortcomings. The goal of this project was to develop a new model and inform an evolving framework articulating cancer comparative effectiveness research data needs. Study Design and Setting We examined prevalent models and conducted semi-structured discussions with 76 clinicians and comparative effectiveness research researchers affiliated with the Agency for Healthcare Research and Quality’s cancer comparative effectiveness research programs. Results A new model was iteratively developed, and presents cancer comparative effectiveness research and important measures in a patient-centered, longitudinal chronic care model better-reflecting contemporary cancer care in the context of the cancer care continuum, rather than a single-episode, acute-care perspective. Conclusion Immediately relevant for federally-funded comparative effectiveness research programs, the model informs an evolving framework articulating cancer comparative effectiveness research data needs, including evolutionary enhancements to registries and epidemiologic research data systems. We discuss elements of contemporary clinical practice, methodology improvements, and related needs affecting comparative effectiveness research’s ability to yield findings clinicians, policymakers, and stakeholders can confidently act on. PMID:23017633
An investigation of emotion dynamics in major depressive disorder patients and healthy persons using sparse longitudinal networks.

PubMed

de Vos, Stijn; Wardenaar, Klaas J; Bos, Elisabeth H; Wit, Ernst C; Bouwmans, Mara E J; de Jonge, Peter

2017-01-01

Differences in within-person emotion dynamics may be an important source of heterogeneity in depression. To investigate these dynamics, researchers have previously combined multilevel regression analyses with network representations. However, sparse network methods, specifically developed for longitudinal network analyses, have not been applied. Therefore, this study used this approach to investigate population-level and individual-level emotion dynamics in healthy and depressed persons and compared this method with the multilevel approach. Time-series data were collected in pair-matched healthy persons and major depressive disorder (MDD) patients (n = 54). Seven positive affect (PA) and seven negative affect (NA) items were administered electronically at 90 times (30 days; thrice per day). The population-level (healthy vs. MDD) and individual-level time series were analyzed using a sparse longitudinal network model based on vector autoregression. The population-level model was also estimated with a multilevel approach. Effects of different preprocessing steps were evaluated as well. The characteristics of the longitudinal networks were investigated to gain insight into the emotion dynamics. In the population-level networks, longitudinal network connectivity was strongest in the healthy group, with nodes showing more and stronger longitudinal associations with each other. Individually estimated networks varied strongly across individuals. Individual variations in network connectivity were unrelated to baseline characteristics (depression status, neuroticism, severity). A multilevel approach applied to the same data showed higher connectivity in the MDD group, which seemed partly related to the preprocessing approach. The sparse network approach can be useful for the estimation of networks with multiple nodes, where overparameterization is an issue, and for individual-level networks. However, its current inability to model random effects makes it less useful as a population-level approach in case of large heterogeneity. Different preprocessing strategies appeared to strongly influence the results, complicating inferences about network density.
Analysis of Longitudinal Outcome Data with Missing Values in Total Knee Arthroplasty.

PubMed

Kang, Yeon Gwi; Lee, Jang Taek; Kang, Jong Yeal; Kim, Ga Hye; Kim, Tae Kyun

2016-01-01

We sought to determine the influence of missing data on the statistical results, and to determine which statistical method is most appropriate for the analysis of longitudinal outcome data of TKA with missing values among repeated measures ANOVA, generalized estimating equation (GEE) and mixed effects model repeated measures (MMRM). Data sets with missing values were generated with different proportion of missing data, sample size and missing-data generation mechanism. Each data set was analyzed with three statistical methods. The influence of missing data was greater with higher proportion of missing data and smaller sample size. MMRM tended to show least changes in the statistics. When missing values were generated by 'missing not at random' mechanism, no statistical methods could fully avoid deviations in the results. Copyright © 2016 Elsevier Inc. All rights reserved.
Application of laser Doppler velocimeter to chemical vapor laser system

NASA Technical Reports Server (NTRS)

Gartrell, Luther R.; Hunter, William W., Jr.; Lee, Ja H.; Fletcher, Mark T.; Tabibi, Bagher M.

1993-01-01

A laser Doppler velocimeter (LDV) system was used to measure iodide vapor flow fields inside two different-sized tubes. Typical velocity profiles across the laser tubes were obtained with an estimated +/-1 percent bias and +/-0.3 to 0.5 percent random uncertainty in the mean values and +/-2.5 percent random uncertainty in the turbulence-intensity values. Centerline velocities and turbulence intensities for various longitudinal locations ranged from 13 to 17.5 m/sec and 6 to 20 percent, respectively. In view of these findings, the effects of turbulence should be considered for flow field modeling. The LDV system provided calibration data for pressure and mass flow systems used routinely to monitor the research laser gas flow velocity.
A Randomized Educational Intervention Trial to Determine the Effect of Online Education on the Quality of Resident-Delivered Care.

PubMed

Dolan, Brigid M; Yialamas, Maria A; McMahon, Graham T

2015-09-01

There is limited research on whether online formative self-assessment and learning can change the behavior of medical professionals. We sought to determine if an adaptive longitudinal online curriculum in bone health would improve resident physicians' knowledge, and change their behavior regarding prevention of fragility fractures in women. We used a randomized control trial design in which 50 internal medicine resident physicians at a large academic practice were randomized to either receive a standard curriculum in bone health care alone, or to receive it augmented with an adaptive, longitudinal, online formative self-assessment curriculum delivered via multiple-choice questions. Outcomes were assessed 10 months after the start of the intervention. Knowledge outcomes were measured by a multiple-choice question examination. Clinical outcomes were measured by chart review, including bone density screening rate, calculation of the fracture risk assessment tool (FRAX) score, and rate of appropriate bisphosphonate prescription. Compared to the control group, residents participating in the intervention had higher scores on the knowledge test at the end of the study. Bone density screening rates and appropriate use of bisphosphonates were significantly higher in the intervention group compared with the control group. FRAX score reporting did not differ between the groups. Residents participating in a novel adaptive online curriculum outperformed peers in knowledge of fragility fracture prevention and care practices to prevent fracture. Online adaptive education can change behavior to improve patient care.
A Randomized Educational Intervention Trial to Determine the Effect of Online Education on the Quality of Resident-Delivered Care

PubMed Central

Dolan, Brigid M.; Yialamas, Maria A.; McMahon, Graham T.

2015-01-01

Background There is limited research on whether online formative self-assessment and learning can change the behavior of medical professionals. Objective We sought to determine if an adaptive longitudinal online curriculum in bone health would improve resident physicians' knowledge, and change their behavior regarding prevention of fragility fractures in women. Methods We used a randomized control trial design in which 50 internal medicine resident physicians at a large academic practice were randomized to either receive a standard curriculum in bone health care alone, or to receive it augmented with an adaptive, longitudinal, online formative self-assessment curriculum delivered via multiple-choice questions. Outcomes were assessed 10 months after the start of the intervention. Knowledge outcomes were measured by a multiple-choice question examination. Clinical outcomes were measured by chart review, including bone density screening rate, calculation of the fracture risk assessment tool (FRAX) score, and rate of appropriate bisphosphonate prescription. Results Compared to the control group, residents participating in the intervention had higher scores on the knowledge test at the end of the study. Bone density screening rates and appropriate use of bisphosphonates were significantly higher in the intervention group compared with the control group. FRAX score reporting did not differ between the groups. Conclusions Residents participating in a novel adaptive online curriculum outperformed peers in knowledge of fragility fracture prevention and care practices to prevent fracture. Online adaptive education can change behavior to improve patient care. PMID:26457142
Cardio-autonomic control and wellbeing due to oscillating color light exposure.

PubMed

Grote, Vincent; Kelz, Christina; Goswami, Nandu; Stossier, Harald; Tafeit, Erwin; Moser, Maximilian

2013-04-10

We investigated the cardio-autonomic and psychological effects of colored light cycling with the wavelength of ultradian rhythms. In two consecutive experiments, an explorative, longitudinal test followed by a randomized crossover design, 20 healthy subjects each were exposed to oscillating red, green and blue light. Heart rate, heart rate variability (HRV) and subjective wellbeing were measured. Significant effects of the oscillating color light exposure were observed for heart rate and cardio-autonomic control rhythms, derived from HRV (p≤.001). These effects on HRV were replicated in the second experiment in comparison to a similar white light exposure protocol (p≤.05). Vigilance showed improvement over the two weeks (p≤.001) in the longitudinal study. External color light cycling at the wavelength of blood pressure oscillations appears to amplify the endogenous autonomic oscillations. This leads to an optimization of cardio-autonomic control; an effect that was reflected shortly after the onset of the light exposure sessions by the increase of heart rate variability. From the results, we conclude that it takes repeated light exposure session to foster the positive effects on the psychological aspects, as we observed an increase of subjectively perceived mood only in the longitudinal study, not for the crossover design study. The results of our study imply some possible health effects of a color light exposure that is adjusted to 10 s and 1 min oscillations of humans' ultradian rhythms. These novel results show possible applications of oscillating visual inputs to the activation of processes connected to physiological regulation. Copyright © 2013 Elsevier Inc. All rights reserved.
Real longitudinal data analysis for real people: building a good enough mixed model.

PubMed

Cheng, Jing; Edwards, Lloyd J; Maldonado-Molina, Mildred M; Komro, Kelli A; Muller, Keith E

2010-02-20

Mixed effects models have become very popular, especially for the analysis of longitudinal data. One challenge is how to build a good enough mixed effects model. In this paper, we suggest a systematic strategy for addressing this challenge and introduce easily implemented practical advice to build mixed effects models. A general discussion of the scientific strategies motivates the recommended five-step procedure for model fitting. The need to model both the mean structure (the fixed effects) and the covariance structure (the random effects and residual error) creates the fundamental flexibility and complexity. Some very practical recommendations help to conquer the complexity. Centering, scaling, and full-rank coding of all the predictor variables radically improve the chances of convergence, computing speed, and numerical accuracy. Applying computational and assumption diagnostics from univariate linear models to mixed model data greatly helps to detect and solve the related computational problems. Applying computational and assumption diagnostics from the univariate linear models to the mixed model data can radically improve the chances of convergence, computing speed, and numerical accuracy. The approach helps to fit more general covariance models, a crucial step in selecting a credible covariance model needed for defensible inference. A detailed demonstration of the recommended strategy is based on data from a published study of a randomized trial of a multicomponent intervention to prevent young adolescents' alcohol use. The discussion highlights a need for additional covariance and inference tools for mixed models. The discussion also highlights the need for improving how scientists and statisticians teach and review the process of finding a good enough mixed model. (c) 2009 John Wiley & Sons, Ltd.
What is measured by hyper-Rayleigh scattering from a liquid?

NASA Astrophysics Data System (ADS)

Rodriquez, Micheal B.; Shelton, David P.

2018-04-01

Polarization and angle dependence of hyper-Rayleigh scattering (HRS) measured for liquid acetonitrile and dimethyl sulfoxide (DMSO) is analyzed in terms of contributions from randomly oriented molecules and additional contributions produced during intermolecular collisions and induced by the electric field of dissolved ions. All three contributions show the effect of long-range correlation, and the correlation functions are determined using the HRS observations combined with the results of molecular dynamics simulations. HRS from acetonitrile is polarized transverse to the scattering vector. This is due to long-range molecular orientation correlation produced by the dipole-dipole interaction, and correlation at distances r > 100 nm must be included to account for the HRS observations. Analysis of the HRS measurements for acetonitrile determines the length scale a = 0.185 nm for the long-range longitudinal and transverse orientation correlation functions BL=-2 BT=a3/r3. Transverse polarized collision-induced HRS is also observed for acetonitrile, indicating long-range correlation of intermolecular modes. Strong longitudinal HRS is induced by the radial electric field of dissolved ions in acetonitrile. For DMSO, the angle between the molecular dipole and the vector part of the first hyperpolarizability tensor is about 100°. As a result, HRS from the randomly oriented molecules in DMSO is nearly unaffected by dipole correlation, and ion-induced HRS is weak. The strong longitudinal polarized HRS observed for DMSO is due to the collision-induced contribution, indicating long-range correlation of intermolecular modes. The HRS observations require correlation that has r-3 long-range asymptotic form, for molecular orientation and for intermolecular vibration and libration, for both acetonitrile and DMSO.
Faraday polarization fluctuations of satellite beacon signals

NASA Technical Reports Server (NTRS)

Lee, M. C.; Klobuchar, J. A.

1988-01-01

The anisotropic effects of random density irregularities in causing Faraday polarization fluctuations of VHF radio signals are examined, taking both rod-like and sheet-like irregularities into consideration. It is found that the variance of Faraday polarization fluctuations depends on the ratio of perpendicular to parallel correlation lengths. The anisotropic effect of rod-like ionospheric irregularities are shown to be most appreciable for longitudinal propagation. The anisotropic effect of sheet-like ionospheric irregularities, however, is not strongly dependent on the radio propagation angle. During transionospheric propagation at large angles with respect to the geomagnetic field, sheet-like irregularities may cause greater Faraday polarization fluctuations than rod-like irregularities.
Validity and reliability of global operative assessment of laparoscopic skills (GOALS) in novice trainees performing a laparoscopic cholecystectomy.

PubMed

Kramp, Kelvin H; van Det, Marc J; Hoff, Christiaan; Lamme, Bas; Veeger, Nic J G M; Pierie, Jean-Pierre E N

2015-01-01

Global Operative Assessment of Laparoscopic Skills (GOALS) assessment has been designed to evaluate skills in laparoscopic surgery. A longitudinal blinded study of randomized video fragments was conducted to estimate the validity and reliability of GOALS in novice trainees. In total, 10 trainees each performed 6 consecutive laparoscopic cholecystectomies. Sixty procedures were recorded on video. Video fragments of (1) opening of the peritoneum; (2) dissection of Calot's triangle and achievement of critical view of safety; and (3) dissection of the gallbladder from the liver bed were blinded, randomized, and rated by 2 consultant surgeons using GOALS. Also, a grade was given for overall competence. The correlation of GOALS with live observation Objective Structured Assessment of Technical Skills (OSATS) scores was calculated. Construct validity was estimated using the Friedman 2-way analysis of variance by ranks and the Wilcoxon signed-rank test. The interrater reliability was calculated using the absolute and consistency agreement 2-way random-effects model intraclass correlation coefficient. A high correlation was found between mean GOALS score (r = 0.879, p = 0.021) and mean OSATS score. The GOALS score increased significantly across the 6 procedures (p = 0.002). The trainees performed significantly better on their sixth when compared with their first cholecystectomy (p = 0.004). The consistency agreement interrater reliability was 0.37 for the mean GOALS score (p = 0.002) and 0.55 for overall competence (p < 0.001) of the 3 video fragments. The validity observed in this randomized blinded longitudinal study supports the existing evidence that GOALS is a valid tool for assessment of novice trainees. A relatively low reliability was found in this study. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.
Analysis of multivariate longitudinal kidney function outcomes using generalized linear mixed models.

PubMed

Jaffa, Miran A; Gebregziabher, Mulugeta; Jaffa, Ayad A

2015-06-14

Renal transplant patients are mandated to have continuous assessment of their kidney function over time to monitor disease progression determined by changes in blood urea nitrogen (BUN), serum creatinine (Cr), and estimated glomerular filtration rate (eGFR). Multivariate analysis of these outcomes that aims at identifying the differential factors that affect disease progression is of great clinical significance. Thus our study aims at demonstrating the application of different joint modeling approaches with random coefficients on a cohort of renal transplant patients and presenting a comparison of their performance through a pseudo-simulation study. The objective of this comparison is to identify the model with best performance and to determine whether accuracy compensates for complexity in the different multivariate joint models. We propose a novel application of multivariate Generalized Linear Mixed Models (mGLMM) to analyze multiple longitudinal kidney function outcomes collected over 3 years on a cohort of 110 renal transplantation patients. The correlated outcomes BUN, Cr, and eGFR and the effect of various covariates such patient's gender, age and race on these markers was determined holistically using different mGLMMs. The performance of the various mGLMMs that encompass shared random intercept (SHRI), shared random intercept and slope (SHRIS), separate random intercept (SPRI) and separate random intercept and slope (SPRIS) was assessed to identify the one that has the best fit and most accurate estimates. A bootstrap pseudo-simulation study was conducted to gauge the tradeoff between the complexity and accuracy of the models. Accuracy was determined using two measures; the mean of the differences between the estimates of the bootstrapped datasets and the true beta obtained from the application of each model on the renal dataset, and the mean of the square of these differences. The results showed that SPRI provided most accurate estimates and did not exhibit any computational or convergence problem. Higher accuracy was demonstrated when the level of complexity increased from shared random coefficient models to the separate random coefficient alternatives with SPRI showing to have the best fit and most accurate estimates.
Longitudinal Mediation Analysis with Time-varying Mediators and Exposures, with Application to Survival Outcomes

PubMed Central

Zheng, Wenjing; van der Laan, Mark

2017-01-01

In this paper, we study the effect of a time-varying exposure mediated by a time-varying intermediate variable. We consider general longitudinal settings, including survival outcomes. At a given time point, the exposure and mediator of interest are influenced by past covariates, mediators and exposures, and affect future covariates, mediators and exposures. Right censoring, if present, occurs in response to past history. To address the challenges in mediation analysis that are unique to these settings, we propose a formulation in terms of random interventions based on conditional distributions for the mediator. This formulation, in particular, allows for well-defined natural direct and indirect effects in the survival setting, and natural decomposition of the standard total effect. Upon establishing identifiability and the corresponding statistical estimands, we derive the efficient influence curves and establish their robustness properties. Applying Targeted Maximum Likelihood Estimation, we use these efficient influence curves to construct multiply robust and efficient estimators. We also present an inverse probability weighted estimator and a nested non-targeted substitution estimator for these parameters. PMID:29387520
The long-term effects of the Kangaroo Mother Care intervention on cognitive functioning: Results from a longitudinal study.

PubMed

Ropars, Stéphanie; Tessier, Réjean; Charpak, Nathalie; Uriza, Luis Felipe

2018-01-01

This study aimed to evaluate the long-term effects of the Kangaroo Mother Care (KMC) intervention on the intellectual and attentional functioning of young adults born with low birth weight. Three hundred infants were randomly assigned at birth in one of two interventions, KMC or traditional care (TC), and completed cognitive tests at adulthood (19-21 years after recruitment). The main results show that participants with a neurological vulnerability at 6 months had higher IQ and sustained attention scores at adulthood if they had received KMC than if they had received TC.
Proceedings of the 1993 Particle Accelerator Conference Held in Washington, DC on May 17-20, 1993. Volume 4

DTIC Science & Technology

1994-05-18

operating current till the lim- ited meaning of 20 A. Besides the random winding brought IV. THE TESTS to the nonuniformity of the turns distribution on...that we had failed to recognise problems with nonuniform However, the same considerations that limited the effective saturation in the bulk of the...decreasing L.Clearly, the poles must be profiled longitudinally to con- The net (horizontal) angular deflection experienced by a trol nonuniform
Maintaining Engagement in Long-term Interventions with Relational Agents

PubMed Central

Bickmore, Timothy; Schulman, Daniel; Yin, Langxuan

2011-01-01

We discuss issues in designing virtual humans for applications which require long-term voluntary use, and the problem of maintaining engagement with users over time. Concepts and theories related to engagement from a variety of disciplines are reviewed. We describe a platform for conducting studies into long-term interactions between humans and virtual agents, and present the results of two longitudinal randomized controlled experiments in which the effect of manipulations of agent behavior on user engagement was assessed. PMID:21318052
Climate-driven longitudinal trends in pasture-borne helminth infections of dairy cattle.

PubMed

Charlier, Johannes; Ghebretinsae, Aklilu H; Levecke, Bruno; Ducheyne, Els; Claerebout, Edwin; Vercruysse, Jozef

2016-12-01

Helminth parasites of grazing ruminants are highly prevalent globally and impact negatively on animal productivity and food security. There is a growing concern that climate change increases helminth disease frequency and intensity. In Europe, these concerns stem from case reports and theoretical life cycle models assessing the effects of climate change scenarios on helminth epidemiology. We believe this study is the first to investigate climate-driven trends in helminth infections of cattle on a cohort of randomly selected farms. One thousand, six hundred and eighty dairy farms were monitored over an 8year period for the two major helminth infections in temperate climate regions and climate-driven trends were investigated by multivariable linear mixed models. The general levels of exposure to Fasciola hepatica decreased over the study period while those to Ostertagia ostertagi increased, and this could at least be partially explained by meteorological factors (i.e. the number of rainy (precipitation >1mm) and warm days (average daily temperature >10°C) in a year). The longitudinal trends varied according to the altitude and the agricultural region of the farm. This study shows that longitudinal epidemiological data from sentinel farms combined with meteorological datasets can significantly contribute to understanding the effects of climate on infectious disease dynamics. When local environmental conditions are taken into account, the effects of climate change on disease dynamics can also be understood at more local scales. We recommend setting up a longitudinal sampling strategy across Europe in order to monitor climate-driven changes in helminth disease risk to inform adaptation strategies to promote animal health and productivity. Copyright Â© 2016 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.
Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification.

PubMed

Módis, László Jr; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile.
Longitudinal Change in Telomere Length and the Chronic Stress Response in a Randomized Pilot Biobehavioral Clinical Study: Implications for Cancer Prevention

PubMed Central

Biegler, Kelly A.; Anderson, Amanda K. L.; Wenzel, Lari B.; Osann, Kathryn; Nelson, Edward L.

2015-01-01

Shortened telomere length is associated with increased cancer incidence and mortality. Populations experiencing chronic stress have accelerated telomere shortening. In this exploratory study, we examined associations between longitudinal changes in patient reported outcomes (PRO) of psychologic distress and peripheral blood mononuclear cell (PBMC) telomere length to test the hypothesis that modulation of the chronic stress response would also modulate telomere dynamics. Archived PBMC specimens (N = 22) were analyzed from a completed and reported randomized, longitudinal trial that showed a psychosocial telephone counseling intervention improved quality of life (QOL) and modulated stress-associated biomarkers in cervical cancer survivors. PROs and biospecimens were collected at baseline and 4 months postenrollment. Telomere length of archived PBMCs was evaluated using the flow-FISH assay. Longitudinal changes in psychologic distress, measured by the Brief Symptom Inventory-18, were significantly associated with increased telomere length within the CD14+ (monocyte) population (r = 0.46, P = 0.043); a similar trend was observed for the CD14− population. Longitudinal changes in telomere length of the CD14− subset, primarily T lymphocytes, were associated with longitudinal increases in the naive T-cell population (r = 0.49, P = 0.052). Alterations in the chronic stress response were associated with modulation of telomere length in PBMCs, with evidence for mobilization of “younger” cells from progenitor populations. These data provide preliminary support for the (i) capacity to modulate the chronic stress response and the associated accelerated telomere shortening, (ii) inclusion of telomere length in the biobehavioral paradigm, and (iii) potential link between the chronic stress response and biologic mechanisms responsible for genomic integrity and carcinogenesis. PMID:22827974

Predicting declines in perceived relationship continuity using practice deprivation scores: a longitudinal study in primary care.

PubMed

Levene, Louis S; Baker, Richard; Walker, Nicola; Williams, Christopher; Wilson, Andrew; Bankart, John

2018-06-01

Increased relationship continuity in primary care is associated with better health outcomes, greater patient satisfaction, and fewer hospital admissions. Greater socioeconomic deprivation is associated with lower levels of continuity, as well as poorer health outcomes. To investigate whether deprivation scores predicted variations in the decline over time of patient-perceived relationship continuity of care, after adjustment for practice organisational and population factors. An observational study in 6243 primary care practices with more than one GP, in England, using a longitudinal multilevel linear model, 2012-2017 inclusive. Patient-perceived relationship continuity was calculated using two questions from the GP Patient Survey. The effect of deprivation on the linear slope of continuity over time was modelled, adjusting for nine confounding variables (practice population and organisational factors). Clustering of measurements within general practices was adjusted for by using a random intercepts and random slopes model. Descriptive statistics and univariable analyses were also undertaken. Relationship continuity declined by 27.5% between 2012 and 2017, and at all deprivation levels. Deprivation scores from 2012 did not predict variations in the decline of relationship continuity at practice level, after accounting for the effects of organisational and population confounding variables, which themselves did not predict, or weakly predicted with very small effect sizes, the decline of continuity. Cross-sectionally, continuity and deprivation were negatively correlated within each year. The decline in relationship continuity of care has been marked and widespread. Measures to maximise continuity will need to be feasible for individual practices with diverse population and organisational characteristics. © British Journal of General Practice 2018.
Fractional Brownian motion and multivariate-t models for longitudinal biomedical data, with application to CD4 counts in HIV-positive patients.

PubMed

Stirrup, Oliver T; Babiker, Abdel G; Carpenter, James R; Copas, Andrew J

2016-04-30

Longitudinal data are widely analysed using linear mixed models, with 'random slopes' models particularly common. However, when modelling, for example, longitudinal pre-treatment CD4 cell counts in HIV-positive patients, the incorporation of non-stationary stochastic processes such as Brownian motion has been shown to lead to a more biologically plausible model and a substantial improvement in model fit. In this article, we propose two further extensions. Firstly, we propose the addition of a fractional Brownian motion component, and secondly, we generalise the model to follow a multivariate-t distribution. These extensions are biologically plausible, and each demonstrated substantially improved fit on application to example data from the Concerted Action on SeroConversion to AIDS and Death in Europe study. We also propose novel procedures for residual diagnostic plots that allow such models to be assessed. Cohorts of patients were simulated from the previously reported and newly developed models in order to evaluate differences in predictions made for the timing of treatment initiation under different clinical management strategies. A further simulation study was performed to demonstrate the substantial biases in parameter estimates of the mean slope of CD4 decline with time that can occur when random slopes models are applied in the presence of censoring because of treatment initiation, with the degree of bias found to depend strongly on the treatment initiation rule applied. Our findings indicate that researchers should consider more complex and flexible models for the analysis of longitudinal biomarker data, particularly when there are substantial missing data, and that the parameter estimates from random slopes models must be interpreted with caution. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.
Effects of vibration therapy on hormone response and stress in severely disabled patients: a double-blind randomized placebo-controlled clinical trial.

PubMed

Seco, J; Rodríguez-Pérez, V; López-Rodríguez, A F; Torres-Unda, J; Echevarria, E; Díez-Alegre, M I; Ortega, A; Morán, P; Mendoza-Laíz, N; Abecia Inchaurregui, L C

2015-01-01

To assess the effects of vibration therapy (VT) on quality of life and hormone response in severely disabled patients compared with placebo. A longitudinal prospective, double-blind, randomized placebo-controlled trial, with pre and postintervention assessments. A total of 20 severely disabled individuals were recruited from a National Reference Centre in Spain: 13 (65%) men and 7 (35%) women, 45.5 ± 9.32 years of age (range 41: 22-63). We evaluated their physical stress and state anxiety. No statistically significant changes were found in the socio-psychological variables studied, while in the experimental group state anxiety decreased significantly with p < 0.01 (Z = 2.38; one-tailed p = .009) and, among the biological variables, the level of cortisol fell (p = 0.03). Short periods of exposure to low-frequency and low-amplitude local vibration are a safe and effective mechanical stimulus that can have a positive effect in terms of hormone response. VT can be considered to have an anti-stress effect. © 2013 Association of Rehabilitation Nurses.
MIXREG: a computer program for mixed-effects regression analysis with autocorrelated errors.

PubMed

Hedeker, D; Gibbons, R D

1996-05-01

MIXREG is a program that provides estimates for a mixed-effects regression model (MRM) for normally-distributed response data including autocorrelated errors. This model can be used for analysis of unbalanced longitudinal data, where individuals may be measured at a different number of timepoints, or even at different timepoints. Autocorrelated errors of a general form or following an AR(1), MA(1), or ARMA(1,1) form are allowable. This model can also be used for analysis of clustered data, where the mixed-effects model assumes data within clusters are dependent. The degree of dependency is estimated jointly with estimates of the usual model parameters, thus adjusting for clustering. MIXREG uses maximum marginal likelihood estimation, utilizing both the EM algorithm and a Fisher-scoring solution. For the scoring solution, the covariance matrix of the random effects is expressed in its Gaussian decomposition, and the diagonal matrix reparameterized using the exponential transformation. Estimation of the individual random effects is accomplished using an empirical Bayes approach. Examples illustrating usage and features of MIXREG are provided.
Altering school climate through school-wide Positive Behavioral Interventions and Supports: findings from a group-randomized effectiveness trial.

PubMed

Bradshaw, Catherine P; Koth, Christine W; Thornton, Leslie A; Leaf, Philip J

2009-06-01

Positive Behavioral Interventions and Supports (PBIS) is a universal, school-wide prevention strategy that is currently implemented in over 7,500 schools to reduce disruptive behavior problems. The present study examines the impact of PBIS on staff reports of school organizational health using data from a group-randomized controlled effectiveness trial of PBIS conducted in 37 elementary schools. Longitudinal multilevel analyses on data from 2,596 staff revealed a significant effect of PBIS on the schools' overall organizational health, resource influence, staff affiliation, and academic emphasis over the 5-year trial; the effects on collegial leadership and institutional integrity were significant when implementation fidelity was included in the model. Trained schools that adopted PBIS the fastest tended to have higher levels of organizational health at baseline, but the later-implementing schools tended to experience the greatest improvements in organizational health after implementing PBIS. This study indicated that changes in school organizational health are important consequences of the PBIS whole-school prevention model, and may in turn be a potential contextual mediator of the effect of PBIS on student performance.
Changing friend selection in middle school: A social network analysis of a randomized intervention study designed to prevent adolescent problem behavior

PubMed Central

DeLay, Dawn; Ha, Thao; Van Ryzin, Mark; Winter, Charlotte; Dishion, Thomas J.

2015-01-01

Adolescent friendships that promote problem behavior are often chosen in middle school. The current study examines the unintended impact of a randomized school based intervention on the selection of friends in middle school, as well as on observations of deviant talk with friends five years later. Participants included 998 middle school students (526 boys and 472 girls) recruited at the onset of middle school (age 11-12 years) from three public middle schools participating in the Family Check-up model intervention. The current study focuses only on the effects of the SHAPe curriculum—one level of the Family Check-up model—on friendship choices. Participants nominated friends and completed measures of deviant peer affiliation. Approximately half of the sample (n=500) was randomly assigned to the intervention and the other half (n=498) comprised the control group within each school. The results indicate that the SHAPe curriculum affected friend selection within School 1, but not within Schools 2 or 3. The effects of friend selection in School 1 translated into reductions in observed deviancy training five years later (age 16-17 years). By coupling longitudinal social network analysis with a randomized intervention study the current findings provide initial evidence that a randomized public middle school intervention can disrupt the formation of deviant peer groups and diminish levels of adolescent deviance five years later. PMID:26377235
Longitudinal impact of the Cyber Friendly Schools program on adolescents' cyberbullying behavior.

PubMed

Cross, Donna; Shaw, Thérèse; Hadwen, Kate; Cardoso, Patricia; Slee, Phillip; Roberts, Clare; Thomas, Laura; Barnes, Amy

2016-01-01

Cyberbullying is a major public health problem associated with serious mental, social, and academic consequences for young people. To date, few programs addressing cyberbullying have been developed and empirically tested. The Cyber Friendly Schools (CFS) group-randomized controlled trial measured the longitudinal impact of a whole-school online cyberbullying prevention and intervention program, developed in partnership with young people. Non-government secondary schools in Perth, Western Australia, (N = 35; 3,000+ students) were randomized to an intervention (n = 19) or usual practice control group (n = 16 schools). Students completed online questionnaires in 2010, 2011, and at 1-year follow-up in 2012, measuring their cyberbullying experiences during the previous school term. The intervention group received the program in Grades 8 and 9 (aged 13-14 years). Program effects were tested using two-part growth models. The program was associated with significantly greater declines in the odds of involvement in cyber-victimization and perpetration from pre- to the first post-test, but no other differences were evident between the study conditions. However, teachers implemented only one third of the program content. More work is needed to build teacher capacity and self-efficacy to effectively implement cyberbullying programs. Whole-school cyberbullying interventions implemented in conjunction with other bullying prevention programs may reduce cyber-victimization more than traditional school-based bullying prevention programs alone. Aggr. Behav. 42:166-180, 2016. © 2015 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
Cancer-related fatigue: Mechanisms, risk factors, and treatments

PubMed Central

Bower, Julienne E.

2015-01-01

Fatigue is one of the most common and distressing side effects of cancer and its treatment, and may persist for years after treatment completion in otherwise healthy survivors. Cancer-related fatigue causes disruption in all aspects of quality of life and may be a risk factor for reduced survival. The prevalence and course of fatigue in cancer patients has been well characterized, and there is growing understanding of underlying biological mechanisms. Inflammation has emerged as a key biological pathway for cancer-related fatigue, with studies documenting links between markers of inflammation and fatigue before, during, and particularly after treatment. There is considerable variability in the experience of cancer-related fatigue that is not explained by disease- or treatment-related characteristics, suggesting that host factors may play an important role in the development and persistence of this symptom. Indeed, longitudinal studies have begun to identify genetic, biological, psychosocial, and behavioral risk factors for cancer-related fatigue. Given the multi-factorial nature of cancer-related fatigue, a variety of intervention approaches have been examined in randomized controlled trials, including physical activity, psychosocial, mind-body, and pharmacological treatments. Although there is currently no gold standard for treating fatigue, several of these approaches have shown beneficial effects and can be recommended to patients. This report provides a state of the science review of mechanisms, risk factors, and interventions for cancer-related fatigue, with a focus on recent longitudinal studies and randomized trials that have targeted fatigued patients. PMID:25113839
Social relationships and longitudinal changes in body mass index and waist circumference: the coronary artery risk development in young adults study.

PubMed

Kershaw, Kiarri N; Hankinson, Arlene L; Liu, Kiang; Reis, Jared P; Lewis, Cora E; Loria, Catherine M; Carnethon, Mercedes R

2014-03-01

Few studies have examined longitudinal associations between close social relationships and weight change. Using data from 3,074 participants in the Coronary Artery Risk Development in Young Adults Study who were examined in 2000, 2005, and 2010 (at ages 33-45 years in 2000), we estimated separate logistic regression random-effects models to assess whether patterns of exposure to supportive and negative relationships were associated with 10% or greater increases in body mass index (BMI) (weight (kg)/height (m)(2)) and waist circumference. Linear regression random-effects modeling was used to examine associations of social relationships with mean changes in BMI and waist circumference. Participants with persistently high supportive relationships were significantly less likely to increase their BMI values and waist circumference by 10% or greater compared with those with persistently low supportive relationships after adjustment for sociodemographic characteristics, baseline BMI/waist circumference, depressive symptoms, and health behaviors. Persistently high negative relationships were associated with higher likelihood of 10% or greater increases in waist circumference (odds ratio = 1.62, 95% confidence interval: 1.15, 2.29) and marginally higher BMI increases (odds ratio = 1.50, 95% confidence interval: 1.00, 2.24) compared with participants with persistently low negative relationships. Increasingly negative relationships were associated with increases in waist circumference only. These findings suggest that supportive relationships may minimize weight gain, and that adverse relationships may contribute to weight gain, particularly via central fat accumulation.
Social Relationships and Longitudinal Changes in Body Mass Index and Waist Circumference: The Coronary Artery Risk Development in Young Adults Study

PubMed Central

Kershaw, Kiarri N.; Hankinson, Arlene L.; Liu, Kiang; Reis, Jared P.; Lewis, Cora E.; Loria, Catherine M.; Carnethon, Mercedes R.

2014-01-01

Few studies have examined longitudinal associations between close social relationships and weight change. Using data from 3,074 participants in the Coronary Artery Risk Development in Young Adults Study who were examined in 2000, 2005, and 2010 (at ages 33–45 years in 2000), we estimated separate logistic regression random-effects models to assess whether patterns of exposure to supportive and negative relationships were associated with 10% or greater increases in body mass index (BMI) (weight (kg)/height (m)2) and waist circumference. Linear regression random-effects modeling was used to examine associations of social relationships with mean changes in BMI and waist circumference. Participants with persistently high supportive relationships were significantly less likely to increase their BMI values and waist circumference by 10% or greater compared with those with persistently low supportive relationships after adjustment for sociodemographic characteristics, baseline BMI/waist circumference, depressive symptoms, and health behaviors. Persistently high negative relationships were associated with higher likelihood of 10% or greater increases in waist circumference (odds ratio = 1.62, 95% confidence interval: 1.15, 2.29) and marginally higher BMI increases (odds ratio = 1.50, 95% confidence interval: 1.00, 2.24) compared with participants with persistently low negative relationships. Increasingly negative relationships were associated with increases in waist circumference only. These findings suggest that supportive relationships may minimize weight gain, and that adverse relationships may contribute to weight gain, particularly via central fat accumulation. PMID:24389018
Enhancement of mechanical properties of polymers by thin flake addition and apparatus for producing such thin flakes

DOEpatents

Bunnell, Sr., Lee R.

1991-01-01

Compositions in accordance with the invention comprise a polymer and flake reinforcing material distributed throughout the polymer in an effective amount to structurally reinforce the polymer. Individual flakes of the flake material (a) are less than or equal to 1,000 Angstroms in thickness, (b) have an aspect ratio greater than or equal to 100, and (c) are preferably significantly randomly oriented throughout the polymer. A novel apparatus for shear grinding a platy solid material into such individual flakes comprises a cylindrical shearing drum and a shear grinder received therein. The shearing drum has a longitudinal axis and an internal surface formed about a first predetermined radius of curvature. The cylindrical drum is supported for rotation about its longitudinal axis. The shear grinder has an external surface formed about a second predetermined radius of curvature. The second radius of curvature is slightly less than the first radius of curvature.
Enhancement of the mechanical properties by graphite flake addition

DOEpatents

Bunnell, Sr., Lee R.

1991-01-01

Compositions in accordance with the invention comprise a polymer and flake reinforcing material distributed throughout the polymer in an effective amount to structurally reinforce the polymer. Individual flakes of the flake material (a) are less than or equal to 1,000 Angstroms in thickness, (b) have an aspect ratio greater than or equal to 100, and (c) are preferably significantly randomly oriented throughout the polymer. A novel apparatus for shear grinding a platy solid material into such individual flakes comprises a cylindrical shearing drum and a shear grinder received therein. The shearing drum has a longitudinal axis and an internal surface formed about a first predetermined radius of curvature. The cylindrical drum is supported for rotation about its longitudinal axis. The shear grinder has an external surface formed about a second predetermined radius of curvature. The second radius of curvature is slightly less than the first radius of curvature.
Apparatus for producing thin flakes

DOEpatents

Bunnell, Sr., Lee R.

1991-01-01

Compositions in accordance with the invention comprise a polymer and flake reinforcing material distributed throughout the polymer in an effective amount to structurally reinforce the polymer. Individual flakes of the flake material a) are less than or equal to 1,000 Angstroms in thickness, b) have an aspect ratio greater than or equal to 100, and c) are preferably significantly randomly oriented throughout the polymer. A novel apparatus for shear grinding a platy solid material into such individual flakes comprises a cylindrical shearing drum and a shear grinder received therein. The shearing drum has a longitudinal axis and an internal surface formed about a first predetermined radius of curvature. The cylindrical drum is supported for rotation about its longitudinal axis. The shear grinder has an external surface formed about a second predetermined radius of curvature. The second radius of curvature is slightly less than the first radius of curvature.
A Randomized Longitudinal Factorial Design to Assess Malaria Vector Control and Disease Management Interventions in Rural Tanzania

PubMed Central

Kramer, Randall A.; Mboera, Leonard E. G.; Senkoro, Kesheni; Lesser, Adriane; Shayo, Elizabeth H.; Paul, Christopher J.; Miranda, Marie Lynn

2014-01-01

The optimization of malaria control strategies is complicated by constraints posed by local health systems, infrastructure, limited resources, and the complex interactions between infection, disease, and treatment. The purpose of this paper is to describe the protocol of a randomized factorial study designed to address this research gap. This project will evaluate two malaria control interventions in Mvomero District, Tanzania: (1) a disease management strategy involving early detection and treatment by community health workers using rapid diagnostic technology; and (2) vector control through community-supported larviciding. Six study villages were assigned to each of four groups (control, early detection and treatment, larviciding, and early detection and treatment plus larviciding). The primary endpoint of interest was change in malaria infection prevalence across the intervention groups measured during annual longitudinal cross-sectional surveys. Recurring entomological surveying, household surveying, and focus group discussions will provide additional valuable insights. At baseline, 962 households across all 24 villages participated in a household survey; 2,884 members from 720 of these households participated in subsequent malariometric surveying. The study design will allow us to estimate the effect sizes of different intervention mixtures. Careful documentation of our study protocol may also serve other researchers designing field-based intervention trials. PMID:24840349
A randomized longitudinal factorial design to assess malaria vector control and disease management interventions in rural Tanzania.

PubMed

Kramer, Randall A; Mboera, Leonard E G; Senkoro, Kesheni; Lesser, Adriane; Shayo, Elizabeth H; Paul, Christopher J; Miranda, Marie Lynn

2014-05-16

The optimization of malaria control strategies is complicated by constraints posed by local health systems, infrastructure, limited resources, and the complex interactions between infection, disease, and treatment. The purpose of this paper is to describe the protocol of a randomized factorial study designed to address this research gap. This project will evaluate two malaria control interventions in Mvomero District, Tanzania: (1) a disease management strategy involving early detection and treatment by community health workers using rapid diagnostic technology; and (2) vector control through community-supported larviciding. Six study villages were assigned to each of four groups (control, early detection and treatment, larviciding, and early detection and treatment plus larviciding). The primary endpoint of interest was change in malaria infection prevalence across the intervention groups measured during annual longitudinal cross-sectional surveys. Recurring entomological surveying, household surveying, and focus group discussions will provide additional valuable insights. At baseline, 962 households across all 24 villages participated in a household survey; 2,884 members from 720 of these households participated in subsequent malariometric surveying. The study design will allow us to estimate the effect sizes of different intervention mixtures. Careful documentation of our study protocol may also serve other researchers designing field-based intervention trials.
Statistical Reviewers Improve Reporting in Biomedical Articles: A Randomized Trial

PubMed Central

Cobo, Erik; Selva-O'Callagham, Albert; Ribera, Josep-Maria; Cardellach, Francesc; Dominguez, Ruth; Vilardell, Miquel

2007-01-01

Background Although peer review is widely considered to be the most credible way of selecting manuscripts and improving the quality of accepted papers in scientific journals, there is little evidence to support its use. Our aim was to estimate the effects on manuscript quality of either adding a statistical peer reviewer or suggesting the use of checklists such as CONSORT or STARD to clinical reviewers or both. Methodology and Principal Findings Interventions were defined as 1) the addition of a statistical reviewer to the clinical peer review process, and 2) suggesting reporting guidelines to reviewers; with “no statistical expert” and “no checklist” as controls. The two interventions were crossed in a 2×2 balanced factorial design including original research articles consecutively selected, between May 2004 and March 2005, by the Medicina Clinica (Barc) editorial committee. We randomized manuscripts to minimize differences in terms of baseline quality and type of study (intervention, longitudinal, cross-sectional, others). Sample-size calculations indicated that 100 papers provide an 80% power to test a 55% standardized difference. We specified the main outcome as the increment in quality of papers as measured on the Goodman Scale. Two blinded evaluators rated the quality of manuscripts at initial submission and final post peer review version. Of the 327 manuscripts submitted to the journal, 131 were accepted for further review, and 129 were randomized. Of those, 14 that were lost to follow-up showed no differences in initial quality to the followed-up papers. Hence, 115 were included in the main analysis, with 16 rejected for publication after peer review. 21 (18.3%) of the 115 included papers were interventions, 46 (40.0%) were longitudinal designs, 28 (24.3%) cross-sectional and 20 (17.4%) others. The 16 (13.9%) rejected papers had a significantly lower initial score on the overall Goodman scale than accepted papers (difference 15.0, 95% CI: 4.6–24.4). The effect of suggesting a guideline to the reviewers had no effect on change in overall quality as measured by the Goodman scale (0.9, 95% CI: −0.3–+2.1). The estimated effect of adding a statistical reviewer was 5.5 (95% CI: 4.3–6.7), showing a significant improvement in quality. Conclusions and Significance This prospective randomized study shows the positive effect of adding a statistical reviewer to the field-expert peers in improving manuscript quality. We did not find a statistically significant positive effect by suggesting reviewers use reporting guidelines. PMID:17389922
Normative changes in interests from adolescence to adulthood: A meta-analysis of longitudinal studies.

PubMed

Hoff, Kevin A; Briley, Daniel A; Wee, Colin J M; Rounds, James

2018-04-01

Vocational interests predict a variety of important outcomes and are among the most widely applied individual difference constructs in psychology and education. Despite over 90 years of research, little is known about the longitudinal development of interests. In this meta-analysis, the authors investigate normative changes in interests through adolescence and young adulthood. Effect sizes were aggregated from 49 longitudinal studies reporting mean-level changes in vocational interests, containing 98 total samples and 20,639 participants. Random effects meta-analytic regression models were used to assess age-related changes and gender differences across Holland's (1959, 1997) RIASEC categories and composite dimensions (people, things, data, and ideas). Results showed that mean-level interest scores generally increase with age, but effect sizes varied across interest categories and developmental periods. Adolescence was defined by two broad patterns of change: interest scores generally decreased during early adolescence, but then increased during late adolescence. During young adulthood, the most striking changes were found across the people and things orientations. Interests involving people tended to increase (artistic, social, and enterprising), whereas interests involving things either decreased (conventional) or remained constant (realistic and investigative). Gender differences associated with occupational stereotypes reached a lifetime peak during early adolescence, then tended to decrease in all subsequent age periods. Overall findings suggest there are normative changes in vocational interests from adolescence to adulthood, with important implications for developmental theories and the applied use of interests. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
Effects of ignoring baseline on modeling transitions from intact cognition to dementia.

PubMed

Yu, Lei; Tyas, Suzanne L; Snowdon, David A; Kryscio, Richard J

2009-07-01

This paper evaluates the effect of ignoring baseline when modeling transitions from intact cognition to dementia with mild cognitive impairment (MCI) and global impairment (GI) as intervening cognitive states. Transitions among states are modeled by a discrete-time Markov chain having three transient (intact cognition, MCI, and GI) and two competing absorbing states (death and dementia). Transition probabilities depend on two covariates, age and the presence/absence of an apolipoprotein E-epsilon4 allele, through a multinomial logistic model with shared random effects. Results are illustrated with an application to the Nun Study, a cohort of 678 participants 75+ years of age at baseline and followed longitudinally with up to ten cognitive assessments per nun.
Isoflurane reduces the ischemia reperfusion injury surge: a longitudinal study with MRI.

PubMed

Taheri, Saeid; Shunmugavel, Anandakumar; Clark, Danielle; Shi, Honglian

2014-10-24

Recent studies show neuroprotective benefits of isoflurane (ISO) administered during cerebral ischemia. However, the available studies evaluated cerebral injury only at a single time point following the intervention and thus the longitudinal effect of ISO on ischemic tissues remains to be investigated. The objective of the present study was to investigate the longitudinal effect of ISO treatment in counteracting the deleterious effect of ischemia by evoking the transcription factor, hypoxia inducible factor-1 (HIF-1), and vascular endothelial growth factor (VEGF). Focal cerebral ischemia was induced in 70 rats by filament medial cerebral artery occlusion (MCAo) method. MCAo rats were randomly assigned to control (90 min ischemia) and MCAo+ISO (90 min ischemia+2% ISO) groups. Infarct volume, edema, intracerebral hemorrhage (ICH), and regional cerebral blood flow (rCBF) were measured in eight in vivo sequential MR imaging sessions for 3 weeks. Western blot analysis and immunofluorescence were used to determine the expression level of HIF-1α (the regulatable subunit of HIF-1) and VEGF proteins. ISO inhalation during ischemia significantly decreased the surge of infarct volume, edema, ICH, and reduced the mortality rate (p<0.01). ISO transiently altered the rCBF, significantly enhanced the expression of HIF-1α and VEGF, and decreased the immune cell infiltration. Locomotor dysfunction was ameliorated at a significantly faster pace, and the benefit was seen to persist up to three weeks. Treatment with ISO during ischemia limits the deadly surge in the dynamics of ischemia reperfusion injury with no observed long-term inverse effect. Copyright © 2014 Elsevier B.V. All rights reserved.
A suicide education programme for nurses to educate the family caregivers of suicidal individuals: a longitudinal study.

PubMed

Sun, Fan-Ko; Chiang, Chun-Ying; Yu, Pei-Jane; Lin, Ching-Hsing

2013-10-01

Family members lack the ability to care for suicidal relatives. Nurses have a responsibility to improve family members' ability to care for their suicidal relatives. The aims of this study were to design a suicide education programme for nurses to educate family caregivers and to evaluate the longitudinal (12 months after the educational programme) effects of a suicide care education programme on the ability of families to care for suicidal relatives. A randomised controlled trial was conducted. The study population (n=61) was composed of the family caregivers of suicidal individuals. Several caregivers (n=26) were randomly allocated to an experimental group who attended a two-hour suicide care education programme, and the other caregivers (n=35) represented a control group who did not attend the education programme. All of the participants were given a questionnaire at baseline, 3 months, and 12 months during the period from 2009 to 2011. The results of the longitudinal effects of the suicide care education programme demonstrated that there were statistically significant differences after the educational programme as compared to before the programme with regard to "seeking assistance from resources" and the ability to care for those who were once suicidal. The longitudinal results of both groups showed that there was a significant difference in terms of "caring ability" at 12 months. The results of a multiple linear regression analysis indicated that evaluations performed at the three-month time point were able to effectively predict success in "seeking assistance from resources", "caring ability"; caring ability was also significantly improved among those who engaged in the educational programme at the 12-month time point. The suicide care education programme had long-term effects for family caregivers caring for their suicidal relatives. Nurses could employ this suicide care education programme to improve the ability of family caregivers to care for their suicidal relatives. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Oil Extraction and Indigenous Livelihoods in the Northern Ecuadorian Amazon

PubMed Central

Bozigar, Matthew; Gray, Clark L.; Bilsborrow, Richard E.

2015-01-01

Globally, the extraction of minerals and fossil fuels is increasingly penetrating into isolated regions inhabited by indigenous peoples, potentially undermining their livelihoods and well-being. To provide new insight to this issue, we draw on a unique longitudinal dataset collected in the Ecuadorian Amazon over an 11-year period from 484 indigenous households with varying degrees of exposure to oil extraction. Fixed and random effects regression models of the consequences of oil activities for livelihood outcomes reveal mixed and multidimensional effects. These results challenge common assumptions about these processes and are only partly consistent with hypotheses drawn from the Dutch disease literature. PMID:26543302
Effectiveness of Circle of Life, an HIV-Preventive Intervention for American Indian Middle School Youths: A Group Randomized Trial in a Northern Plains Tribe

PubMed Central

Whitesell, Nancy Rumbaugh; Keane, Ellen M.; Desserich, Jennifer A.; Giago, Cindy; Sam, Angela; Mitchell, Christina M.

2014-01-01

Objectives. We assessed the effectiveness of Circle of Life (COL), an HIV-preventive intervention developed specifically for American Indian and Alaska Native (AI/AN) middle school youths. Methods. By partnering with a tribal community, we conducted a longitudinal wait-listed group randomized trial with 635 seventh and eighth graders in 13 schools of a Northern Plains tribe. We surveyed participants at baseline, 3 months, and 12 months from 2006 to 2007. Results. COL was found to increase HIV knowledge in the short term, but had no effect on sexual activity compared with those who did not receive it. However, COL was found to be effective for delaying the onset of sexual activity, with the greatest reduction in risk occurring for those receiving COL at early ages. Conclusions. Community partnership was key to successful project design, implementation, and analysis. The project confirmed the importance of the timing of interventions in early adolescence. COL may be a key resource for reducing sexual risk among AI/AN youths. PMID:24754555
Evaluation of interlayer interfacial stiffness and layer wave velocity of multilayered structures by ultrasonic spectroscopy.

PubMed

Ishii, Yosuke; Biwa, Shiro

2014-07-01

An ultrasonic evaluation procedure for the interlayer interfacial normal stiffness and the intralayer longitudinal wave velocity of multilayered plate-like structures is proposed. Based on the characteristics of the amplitude reflection spectrum of ultrasonic wave at normal incidence to a layered structure with spring-type interlayer interfaces, it is shown that the interfacial normal stiffness and the longitudinal wave velocity in the layers can be simultaneously evaluated from the frequencies of local maxima and minima of the spectrum provided that all interfaces and layers have the same properties. The effectiveness of the proposed procedure is investigated from the perspective of the sensitivity of local extremal frequencies of the reflection spectrum. The feasibility of the proposed procedure is also investigated when the stiffness of each interface is subjected to small random fluctuations about a certain average value. The proposed procedure is applied to a 16-layered cross-ply carbon-fiber-reinforced composite laminate. The normal stiffness of resin-rich interfaces and the longitudinal wave velocity of plies in the thickness direction evaluated from the experimental reflection spectrum are shown to be consistent with simple theoretical estimations.
Prevention of adolescent problem behavior: longitudinal impact of the Project P.A.T.H.S. in Hong Kong.

PubMed

Shek, Daniel T L; Yu, Lu

2011-03-07

The present study attempts to examine the longitudinal impact of a curriculum-based positive youth development program, entitled the Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes), on adolescent problem behavior in Hong Kong. Using a longitudinal randomized group design, six waves of data were collected from 19 experimental schools (n = 3,797 at Wave 1) in which students participated in the Project P.A.T.H.S. and 24 control schools (n = 4,049 at Wave 1). At each wave, students responded to questions asking about their current problem behaviors, including delinquency and use of different types of drugs, and their intentions of engaging in such behaviors in the future. Results based on individual growth curve modeling generally showed that the participants displayed lower levels of substance abuse and delinquent behavior than did the control students. Participants who regarded the program to be helpful also showed lower levels of problem behavior than did the control students. The present findings suggest that the Project P.A.T.H.S. is effective in preventing adolescent problem behavior in the junior secondary school years.
Corneal endothelial morphology and function after torsional and longitudinal ultrasound mode phacoemulsification

PubMed Central

Módis, László Jr.; Szalai, Eszter; Flaskó, Zsuzsa; Németh, Gábor

2016-01-01

Purpose. To study the endothelial cell morphology and corneal thickness changes after phacoemulsification by using the OZil torsional and longitudinal ultrasound techniques (Infiniti Vision System, Alcon Laboratories). Setting. Department of Ophthalmology, Clinical Center, University of Debrecen, Debrecen, Hungary. Methods. 52 patients with cataract were randomly assigned to longitudinal ultrasound and torsional mode group. All surgeries were performed through a 2.2 mm clear corneal incision, the method employed being divide and conquer. The endothelial morphometry such as cell density (ECD), mean cell area, coefficient of variation of cell area, and central corneal thickness were examined with specular microscopy (EM-1000, Tomey) preoperatively and 4, 8 weeks postoperatively. Results. ECD values decreased significantly in both surgical groups (P < .001, repeated- mesures ANOVA), the postoperative endothelial cell loss was higher in the longitudinal ultrasound mode group (3.5% and 6.5%, at 4 and 8 weeks after surgery) than in the torsional group (3.3% and 5.5%, at 4 and 8 weeks after surgery), the difference not being significant between the two groups (P = .164 and P = .479, at 4 and 8 weeks after surgery, Mann-Whitney test). There was no statistically significant difference in any of the assessed parameters between the two surgical groups (P > .05). No significant correlation was found between the endothelial cell loss and the nucleus density. Conclusions. Both phacoemulsification techniques were safe and effective. The torsional handpiece performs oscillatory movements and delivers less energy into the eye than the longitudinal ultrasound technique, therefore providing more favorable energy and thermal safety profile. PMID:29450332
An advanced stochastic model for threshold crossing studies of rotor blade vibrations.

NASA Technical Reports Server (NTRS)

Gaonkar, G. H.; Hohenemser, K. H.

1972-01-01

A stochastic model to analyze turbulence-excited rotor blade vibrations, previously described by Gaonkar et al. (1971), is generalized to include nonuniformity of the atmospheric turbulence velocity across the rotor disk in the longitudinal direction. The results of the presented analysis suggest that the nonuniformity of the vertical turbulence over the rotor disk is of little influence on the random blade flapping response, at least as far as longitudinal nonuniformity is concerned.
Local drinking water filters reduce diarrheal disease in Cambodia: a randomized, controlled trial of the ceramic water purifier.

PubMed

Brown, Joe; Sobsey, Mark D; Loomis, Dana

2008-09-01

A randomized, controlled intervention trial of two household-scale drinking water filters was conducted in a rural village in Cambodia. After collecting four weeks of baseline data on household water quality, diarrheal disease, and other data related to water use and handling practices, households were randomly assigned to one of three groups of 60 households: those receiving a ceramic water purifier (CWP), those receiving a second filter employing an iron-rich ceramic (CWP-Fe), and a control group receiving no intervention. Households were followed for 18 weeks post-baseline with biweekly follow-up. Households using either filter reported significantly less diarrheal disease during the study compared with a control group of households without filters as indicated by longitudinal prevalence ratios CWP: 0.51 (95% confidence interval [CI]: 0.41-0.63); CWP-Fe: 0.58 (95% CI: 0.47-0.71), an effect that was observed in all age groups and both sexes after controlling for clustering within households and within individuals over time.
Investigation of dynamic noise affecting geodynamics information in a tethered subsatellite

NASA Technical Reports Server (NTRS)

Gullahorn, G. E.

1985-01-01

Work performed as part of an investigation of noise affecting instrumentation in a tethered subsatellite, was studied. The following specific topics were addressed during the reporting period: a method for stabilizing the subsatellite against the rotational effects of atmospheric perturbation was developed; a variety of analytic studies of tether dynamics aimed at elucidating dynamic noise processes were performed; a novel mechanism for coupling longitudinal and latitudinal oscillations of the tether was discovered, and random vibration analysis for modeling the tethered subsatellite under atmospheric perturbation were studied.
Coherent electromagnetic waves in the presence of a half space of randomly distributed scatterers

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1988-01-01

The present investigation of coherent field propagation notes, upon solving the Foldy-Twersky integral equation for a half-space of small spherical scatterers illuminated by a plane wave at oblique incidence, that the coherent field for a horizontally-polarized incident wave exhibits reflectivity and transmissivity consistent with the Fresnel formula for an equivalent continuous effective medium. In the case of a vertically polarized incident wave, both the vertical and longitudinal waves obtained for the coherent field have reflectivities and transmissivities that do not agree with the Fresnel formula.
Body Weight, Marital Status, and Changes in Marital Status

PubMed Central

Teachman, Jay

2014-01-01

In this article, I use 20 years of data taken from the 1979 National Longitudinal Study of Youth to examine the relationship between body weight and both marital status and changes in marital status. I use a latent growth curve model that allows both fixed and random effects. The results show that living without a partner, either being divorced or never married, is associated with lower body weight. Cohabitors and married respondents tend to weigh more. Marital transitions also matter but only for divorce. Gender does not appear to moderate these results. PMID:26778872
Effects of Simulated Interventions to Improve School Entry Academic Skills on Socioeconomic Inequalities in Educational Achievement

PubMed Central

Chittleborough, Catherine R; Mittinty, Murthy N; Lawlor, Debbie A; Lynch, John W

2014-01-01

Randomized controlled trial evidence shows that interventions before age 5 can improve skills necessary for educational success; the effect of these interventions on socioeconomic inequalities is unknown. Using trial effect estimates, and marginal structural models with data from the Avon Longitudinal Study of Parents and Children (n = 11,764, imputed), simulated effects of plausible interventions to improve school entry academic skills on socioeconomic inequality in educational achievement at age 16 were examined. Progressive universal interventions (i.e., more intense intervention for those with greater need) to improve school entry academic skills could raise population levels of educational achievement by 5% and reduce absolute socioeconomic inequality in poor educational achievement by 15%. PMID:25327718
Experimental research on the stability and the multilongitudinal mode interference of bidirectional outputs of LD-pumped solid state ring laser

NASA Astrophysics Data System (ADS)

Wan, Shunping; Tian, Qian; Sun, Liqun; Yao, Minyan; Mao, Xianhui; Qiu, Hongyun

2004-05-01

This paper reports an experimental research on the stability of bidirectional outputs and multi-longitudinal mode interference of laser diode end-pumped Nd:YVO4 solid-state ring laser (DPSSL). The bidirectional, multi-longitudinal and TEM00 mode continuous wave outputs are obtained and the output powers are measured and their stabilities are analyzed respectively. The spectral characteristic of the outputs is measured. The interfering pattern of the bidirectional longitudinal mode outputs is obtained and analyzed in the condition of the ring cavity with rotation velocity. The movement of the interfering fringe of the multi-longitudinal modes is very sensitive to the deformation of the setup base and the fluctuation of the intracavity air, but is stationary or randomly dithers when the stage is rotating.
Classification of longitudinal data through a semiparametric mixed-effects model based on lasso-type estimators.

PubMed

Arribas-Gil, Ana; De la Cruz, Rolando; Lebarbier, Emilie; Meza, Cristian

2015-06-01

We propose a classification method for longitudinal data. The Bayes classifier is classically used to determine a classification rule where the underlying density in each class needs to be well modeled and estimated. This work is motivated by a real dataset of hormone levels measured at the early stages of pregnancy that can be used to predict normal versus abnormal pregnancy outcomes. The proposed model, which is a semiparametric linear mixed-effects model (SLMM), is a particular case of the semiparametric nonlinear mixed-effects class of models (SNMM) in which finite dimensional (fixed effects and variance components) and infinite dimensional (an unknown function) parameters have to be estimated. In SNMM's maximum likelihood estimation is performed iteratively alternating parametric and nonparametric procedures. However, if one can make the assumption that the random effects and the unknown function interact in a linear way, more efficient estimation methods can be used. Our contribution is the proposal of a unified estimation procedure based on a penalized EM-type algorithm. The Expectation and Maximization steps are explicit. In this latter step, the unknown function is estimated in a nonparametric fashion using a lasso-type procedure. A simulation study and an application on real data are performed. © 2015, The International Biometric Society.
Persistence of physical activity in middle age: a nonlinear dynamic panel approach.

PubMed

Kumagai, Narimasa; Ogura, Seiritsu

2014-09-01

No prior investigation has considered the effects of state dependence and unobserved heterogeneity on the relationship between regular physical activity (RPA) and latent health stock (LHS). Accounting for state dependence corrects the possible overestimation of the impact of socioeconomic factors. We estimated the degree of the state dependence of RPA and LHS among middle-aged Japanese workers. The 5 years' longitudinal data used in this study were taken from the Longitudinal Survey of Middle and Elderly Persons. Individual heterogeneity was found for both RPA and LHS, and the dynamic random-effects probit model provided the best specification. A smoking habit, low educational attainment, longer work hours, and longer commuting time had negative effects on RPA participation. RPA had positive effects on LHS, taking into consideration the possibility of confounding with other lifestyle variables. The degree of state dependence of LHS was positive and significant. Increasing the intensity of RPA had positive effects on LHS and caused individuals with RPA to exhibit greater persistence of LHS compared to individuals without RPA. This result implies that policy interventions that promote RPA, such as smoking cessation, have lasting consequences. We concluded that smoking cessation is an important health policy to increase both the participation in RPA and LHS.
Perceived control moderates the relationship between social capital and binge drinking: longitudinal findings from the Montreal Neighborhood Networks and Health Aging (MoNNET-HA) panel.

PubMed

Child, Stephanie; Stewart, Steven; Moore, Spencer

2017-02-01

Cross-sectional research suggests social capital has negative consequences for problem drinking behaviors. Previous studies have suggested psychosocial resources, including perceived control, may buffer this association. Little research has examined whether such relationships persist longitudinally. Random effects models examined between-person relationships among problem drinking, social capital, and perceived control, and whether perceived control moderated the relationship between social capital and drinking. Fixed effects models assessed whether social capital and perceived control were related to changes in problem drinking. Greater network capital and generalized trust predicted higher odds of binge drinking (RR = 1.08; 95% CI = 1.03-1.12 and RR = 1.23; 95% CI = 1.03-1.48, respectively). Perceived control moderated the positive association of network capital with binge drinking (RR = 0.91; 95% CI = 0.87-0.96). The present findings support previous notions about the complex role of social capital on health, and offer new insights on the role of perceived control on problem drinking. Copyright © 2016 Elsevier Inc. All rights reserved.
A method for fitting regression splines with varying polynomial order in the linear mixed model.

PubMed

Edwards, Lloyd J; Stewart, Paul W; MacDougall, James E; Helms, Ronald W

2006-02-15

The linear mixed model has become a widely used tool for longitudinal analysis of continuous variables. The use of regression splines in these models offers the analyst additional flexibility in the formulation of descriptive analyses, exploratory analyses and hypothesis-driven confirmatory analyses. We propose a method for fitting piecewise polynomial regression splines with varying polynomial order in the fixed effects and/or random effects of the linear mixed model. The polynomial segments are explicitly constrained by side conditions for continuity and some smoothness at the points where they join. By using a reparameterization of this explicitly constrained linear mixed model, an implicitly constrained linear mixed model is constructed that simplifies implementation of fixed-knot regression splines. The proposed approach is relatively simple, handles splines in one variable or multiple variables, and can be easily programmed using existing commercial software such as SAS or S-plus. The method is illustrated using two examples: an analysis of longitudinal viral load data from a study of subjects with acute HIV-1 infection and an analysis of 24-hour ambulatory blood pressure profiles.
Predictors of long-term change of a physical activity promotion programme in primary care.

PubMed

Sanchez, Alvaro; Grandes, Gonzalo; Ortega Sánchez-Pinilla, Ricardo; Torcal, Jesus; Montoya, Imanol

2014-02-04

Further research is needed to improve the evidence regarding determinants of physical activity (PA) as a crucial step to plan higher effective intervention strategies. The goal of the present study is to identify socio-demographic and clinical characteristics of primary care (PHC) insufficiently active patients that are associated with longitudinal changes in the level of physical activity. Longitudinal analysis of baseline socio-demographic and clinical predictors of physical activity change in insufficiently active PHC patients who participated in a PA-promoting multi-centre randomized clinical trial conducted from October 2003 through March 2006. The primary outcome measure was the self-reported physical activity assessed with the 7-day Physical Activity Recall (PAR), at baseline, 6, 12 and 24 months. Baseline covariates included sex, age, social class, anthropometric measures and other cardiovascular risk factors or associated diseases (Diabetes, HTA, tobacco use, etc.), and stage of readiness to change PA. Generalized linear mixed models were used to estimate longitudinal association of studied variables on PA change over the three follow-up measurements. A total of 3691 patients (85% of the 4317 recruited in the trial) with at least one follow-up measurement were included in the longitudinal analysis. At baseline, analysed patients (mean age: 50.6 years; 64.6% women) devoted 34.7 minutes and 2.36 metabolic equivalent hours per week (MET.h/week) to moderate and vigorous physical activity. Older age, male gender, higher social class, lower BMI, diagnosis of diabetes or hypertension, and measurement season were significant predictors of PA longitudinal change. The effect of baseline readiness to change on PA dose was modified by time, showing a positive gradient in favour of those with more readiness to change that increases significantly at 12 and 24 months (p-value interaction < .0001). Identified baseline characteristics such as readiness to change and risk factors can guide physicians to prioritize time and intervention efforts for maximizing their impact on insufficiently active PHC patients.
Multivariate-$t$ nonlinear mixed models with application to censored multi-outcome AIDS studies.

PubMed

Lin, Tsung-I; Wang, Wan-Lun

2017-10-01

In multivariate longitudinal HIV/AIDS studies, multi-outcome repeated measures on each patient over time may contain outliers, and the viral loads are often subject to a upper or lower limit of detection depending on the quantification assays. In this article, we consider an extension of the multivariate nonlinear mixed-effects model by adopting a joint multivariate-$t$ distribution for random effects and within-subject errors and taking the censoring information of multiple responses into account. The proposed model is called the multivariate-$t$ nonlinear mixed-effects model with censored responses (MtNLMMC), allowing for analyzing multi-outcome longitudinal data exhibiting nonlinear growth patterns with censorship and fat-tailed behavior. Utilizing the Taylor-series linearization method, a pseudo-data version of expectation conditional maximization either (ECME) algorithm is developed for iteratively carrying out maximum likelihood estimation. We illustrate our techniques with two data examples from HIV/AIDS studies. Experimental results signify that the MtNLMMC performs favorably compared to its Gaussian analogue and some existing approaches. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Use of Lipid-Based Nutrient Supplements by HIV-Infected Malawian Women during Lactation Has No Effect on Infant Growth from 0 to 24 Weeks1234

PubMed Central

Flax, Valerie L.; Bentley, Margaret E.; Chasela, Charles S.; Kayira, Dumbani; Hudgens, Michael G.; Knight, Rodney J.; Soko, Alice; Jamieson, Denise J.; van der Horst, Charles M.; Adair, Linda S.

2012-01-01

The Breastfeeding, Antiretrovirals, and Nutrition Study evaluated the effect of daily consumption of lipid-based nutrient supplements (LNS) by 2121 lactating, HIV-infected mothers on the growth of their exclusively breast-fed, HIV-uninfected infants from 0 to 24 wk. The study had a 2 × 3 factorial design. Malawian mothers with CD4+ ≥250 cells/mm3, hemoglobin ≥70 g/L, and BMI ≥17 kg/m2 were randomized within 36 h of delivery to receive either no LNS or 140 g/d of LNS to meet lactation energy and protein needs, and mother-infant pairs were assigned to maternal antiretroviral drugs (ARV), infant ARV, or no ARV. Sex-stratified, longitudinal, random effects models were used to estimate the effect of the 6 study arms on infant weight, length, and BMI. Logistic regression models were used to calculate the odds of growth faltering [decline in weight-for-age Z-score (WAZ) or length-for-age Z-score (LAZ) >0.67] using the control arm as the reference. Although some differences between study arms emerged with increasing infant age in boys, there were no consistent effects of the maternal supplement across the 3 growth outcomes in longitudinal models. At the ages where differences were observed, the effects on weight and BMI were quite small (≤200 g and ≤0.4 kg/m2) and unlikely to be of clinical importance. Overall, 21 and 34% of infants faltered in WAZ and LAZ, respectively. Maternal supplementation did not reduce the odds of infant weight or length faltering from 0 to 24 wk in any arm. These results indicate that blanket supplementation of HIV-infected lactating women may have little impact on infant growth. PMID:22649265
Mental skills training with basic combat training soldiers: A group-randomized trial.

PubMed

Adler, Amy B; Bliese, Paul D; Pickering, Michael A; Hammermeister, Jon; Williams, Jason; Harada, Coreen; Csoka, Louis; Holliday, Bernie; Ohlson, Carl

2015-11-01

Cognitive skills training has been linked to greater skills, self-efficacy, and performance. Although research in a variety of organizational settings has demonstrated training efficacy, few studies have assessed cognitive skills training using rigorous, longitudinal, randomized trials with active controls. The present study examined cognitive skills training in a high-risk occupation by randomizing 48 platoons (N = 2,432 soldiers) in basic combat training to either (a) mental skills training or (b) an active comparison condition (military history). Surveys were conducted at baseline and 3 times across the 10-week course. Multilevel mixed-effects models revealed that soldiers in the mental skills training condition reported greater use of a range of cognitive skills and increased confidence relative to those in the control condition. Soldiers in the mental skills training condition also performed better on obstacle course events, rappelling, physical fitness, and initial weapons qualification scores, although effects were generally moderated by gender and previous experience. Overall, effects were small; however, given the rigor of the design, the findings clearly contribute to the broader literature by providing supporting evidence that cognitive training skills can enhance performance in occupational and sports settings. Future research should address gender and experience to determine the need for targeting such training appropriately. (c) 2015 APA, all rights reserved).

The first clinical experience on efficacy of topical flutamide on melasma compared with topical hydroquinone: a randomized clinical trial.

PubMed

Adalatkhah, Hassan; Sadeghi-Bazargani, Homayoun

2015-01-01

Treatment of melasma is unsatisfactory most of the times. Hormonal role is shown to exist in pathogenesis of the melasma, and sex-hormone related drugs may have an effect on melasma. To investigate efficacy of 1% flutamide cream versus 4% hydroquinone cream on melasma. In a parallel randomized clinical trial, 74 women with melasma were allocated to receive a sunscreen along with 4% hydroquinone cream or 1% flutamide cream. Melasma Area and Severity Index (MASI), mexameter melanin assay, and patient satisfaction were investigated. Mean age of the participants was 33.8 years. Mean length of time suffering from Melasma was 96.3 months. The subjects reported in average 1.1 hours per day of exposure to sunlight. Mean standardized total patient satisfaction score was 28.8 (standard deviation [SD] 17.2) in flutamide group patients versus 18 (SD 15.5) in control group (P<0.01). Regardless of treatment group, the skin darkness assessed upon MASI scales was reduced over the treatment course (P<0.001). Using mixed effects, longitudinal modeling showed better treatment efficacy based on MASI scale for flutamide group compared to the hydroquinone group (P<0.05). However, longitudinal analysis of mexameter scores did not reveal any significant difference in melanin measurements between flutamide and hydroquinone. Topical flutamide appeared as effective as topical hydroquinone in treating melasma using mexameter assessment but with a better MASI improvement trend and higher patient satisfaction in flutamide treatment versus topical hydroquinone. As the present study is possibly the first clinical experience on efficacy of topical flutamide on melasma, it would be quite unreasonable to recommend clinical use of it before future studies replicate the results on its efficacy and safety.
The first clinical experience on efficacy of topical flutamide on melasma compared with topical hydroquinone: a randomized clinical trial

PubMed Central

Adalatkhah, Hassan; Sadeghi-Bazargani, Homayoun

2015-01-01

Background Treatment of melasma is unsatisfactory most of the times. Hormonal role is shown to exist in pathogenesis of the melasma, and sex-hormone related drugs may have an effect on melasma. Aim To investigate efficacy of 1% flutamide cream versus 4% hydroquinone cream on melasma. Methods In a parallel randomized clinical trial, 74 women with melasma were allocated to receive a sunscreen along with 4% hydroquinone cream or 1% flutamide cream. Melasma Area and Severity Index (MASI), mexameter melanin assay, and patient satisfaction were investigated. Results Mean age of the participants was 33.8 years. Mean length of time suffering from Melasma was 96.3 months. The subjects reported in average 1.1 hours per day of exposure to sunlight. Mean standardized total patient satisfaction score was 28.8 (standard deviation [SD] 17.2) in flutamide group patients versus 18 (SD 15.5) in control group (P<0.01). Regardless of treatment group, the skin darkness assessed upon MASI scales was reduced over the treatment course (P<0.001). Using mixed effects, longitudinal modeling showed better treatment efficacy based on MASI scale for flutamide group compared to the hydroquinone group (P<0.05). However, longitudinal analysis of mexameter scores did not reveal any significant difference in melanin measurements between flutamide and hydroquinone. Conclusion Topical flutamide appeared as effective as topical hydroquinone in treating melasma using mexameter assessment but with a better MASI improvement trend and higher patient satisfaction in flutamide treatment versus topical hydroquinone. As the present study is possibly the first clinical experience on efficacy of topical flutamide on melasma, it would be quite unreasonable to recommend clinical use of it before future studies replicate the results on its efficacy and safety. PMID:26345129
The combined effects of job demand and control, effort-reward imbalance and work-family conflicts on the risk of major depressive episode: a 4-year longitudinal study.

PubMed

Nigatu, Yeshambel T; Wang, JianLi

2018-01-01

Work-related psychosocial factors may precipitate the onset of depression. In occupational mental health research, there are three widely used theoretical models, namely, job demand and control (JD-C), effort-reward imbalance (ERI) and work-family conflicts (WFC). However, the interaction between these models and their combined effect on the risk of major depression in the workplace is largely unknown. The aim of this study is to examine the longitudinal combined effects of JD-C, ERI and WFC on the risk of major depression in the working population. Longitudinal data (2008-2013) were collected on randomly selected participants (n=4200) from the working population of the province of Alberta, Canada, at baseline and 1-, 2-, 3- and 4-year follow-up. Data about JD-C, ERI, WFC and major depression were collected by trained interviewers using a computer-assisted telephone interviewing method. Generalised estimating equations for longitudinal modelling were used. There was an independent association between high ERI and high WFC at t x and major depression at t x+1 (OR 1.56, 95% CI 1.25 to 1.96; OR 1.33, 95% CI 1.16 to 1.52), respectively. The combined effects of JD-C and ERI, ERI and WFC, and WFC and JD-C on the risk of major depression were as follows: OR 1.71, 95% CI 1.22 to 2.42, OR 2.47, 95% CI 1.99 to 3.49 and OR 2.21, 95% CI 1.48 to 3.30, respectively. The relative excess risks attributable to the interactions were statistically non-significant. Work-related psychosocial factors are associated with increased risk of major depression over time, but their combined effect is not synergistic. The effects of the factors depicted in the three occupational health models on the risk of major depression appear to be additive. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.
Benefit-Cost Analysis of a Randomized Evaluation of Communities That Care: Monetizing Intervention Effects on the Initiation of Delinquency and Substance Use Through Grade 12.

PubMed

Kuklinski, Margaret R; Fagan, Abigail A; Hawkins, J David; Briney, John S; Catalano, Richard F

2015-06-01

To determine whether the Communities That Care (CTC) prevention system is a cost-beneficial intervention. Data were from a longitudinal panel of 4,407 youth participating in a randomized controlled trial including 24 towns in 7 states, matched in pairs within state and randomly assigned to condition. Significant differences favoring intervention youth in sustained abstinence from delinquency, alcohol use, and tobacco use through Grade 12 were monetized and compared to economic investment in CTC. CTC was estimated to produce $4,477 in benefits per youth (discounted 2011 dollars). It cost $556 per youth to implement CTC for 5 years. The net present benefit was $3,920. The benefit-cost ratio was $8.22 per dollar invested. The internal rate of return was 21%. Risk that investment would exceed benefits was minimal. Investment was expected to be recouped within 9 years. Sensitivity analyses in which effects were halved yielded positive cost-beneficial results. CTC is a cost-beneficial, community-based approach to preventing initiation of delinquency, alcohol use, and tobacco use. CTC is estimated to generate economic benefits that exceed implementation costs when disseminated with fidelity in communities.
Job Strain and Tobacco Smoking: An Individual-Participant Data Meta-Analysis of 166 130 Adults in 15 European Studies

PubMed Central

Heikkilä, Katriina; Nyberg, Solja T.; Fransson, Eleonor I.; Alfredsson, Lars; De Bacquer, Dirk; Bjorner, Jakob B.; Bonenfant, Sébastien; Borritz, Marianne; Burr, Hermann; Clays, Els; Casini, Annalisa; Dragano, Nico; Erbel, Raimund; Geuskens, Goedele A.; Goldberg, Marcel; Hooftman, Wendela E.; Houtman, Irene L.; Joensuu, Matti; Jöckel, Karl-Heinz; Kittel, France; Knutsson, Anders; Koskenvuo, Markku; Koskinen, Aki; Kouvonen, Anne; Leineweber, Constanze; Lunau, Thorsten; Madsen, Ida E. H.; Hanson, Linda L. Magnusson; Marmot, Michael G.; Nielsen, Martin L.; Nordin, Maria; Pentti, Jaana; Salo, Paula; Rugulies, Reiner; Steptoe, Andrew; Siegrist, Johannes; Suominen, Sakari; Vahtera, Jussi; Virtanen, Marianna; Väänänen, Ari; Westerholm, Peter; Westerlund, Hugo; Zins, Marie; Theorell, Töres; Hamer, Mark; Ferrie, Jane E.; Singh-Manoux, Archana; Batty, G. David; Kivimäki, Mika

2012-01-01

Background Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job strain, is associated with tobacco smoking in working adults. Methodology and Principal Findings We analysed cross-sectional data from 15 European studies comprising 166 130 participants. Longitudinal data from six studies were used. Job strain and smoking were self-reported. Smoking was harmonised into three categories never, ex- and current. We modelled the cross-sectional associations using logistic regression and the results pooled in random effects meta-analyses. Mixed effects logistic regression was used to examine longitudinal associations. Of the 166 130 participants, 17% reported job strain, 42% were never smokers, 33% ex-smokers and 25% current smokers. In the analyses of the cross-sectional data, current smokers had higher odds of job strain than never-smokers (age, sex and socioeconomic position-adjusted odds ratio: 1.11, 95% confidence interval: 1.03, 1.18). Current smokers with job strain smoked, on average, three cigarettes per week more than current smokers without job strain. In the analyses of longitudinal data (1 to 9 years of follow-up), there was no clear evidence for longitudinal associations between job strain and taking up or quitting smoking. Conclusions Our findings show that smokers are slightly more likely than non-smokers to report work-related stress. In addition, smokers who reported work stress smoked, on average, slightly more cigarettes than stress-free smokers. PMID:22792154
Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models.

PubMed

Seeker, Luise A; Ilska, Joanna J; Psifidi, Androniki; Wilbourn, Rachael V; Underwood, Sarah L; Fairlie, Jennifer; Holland, Rebecca; Froy, Hannah; Bagnall, Ainsley; Whitelaw, Bruce; Coffey, Mike; Nussey, Daniel H; Banos, Georgios

2018-01-01

Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05-0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954).
Longitudinal changes in telomere length and associated genetic parameters in dairy cattle analysed using random regression models

PubMed Central

Ilska, Joanna J.; Psifidi, Androniki; Wilbourn, Rachael V.; Underwood, Sarah L.; Fairlie, Jennifer; Holland, Rebecca; Froy, Hannah; Bagnall, Ainsley; Whitelaw, Bruce; Coffey, Mike; Nussey, Daniel H.; Banos, Georgios

2018-01-01

Telomeres cap the ends of linear chromosomes and shorten with age in many organisms. In humans short telomeres have been linked to morbidity and mortality. With the accumulation of longitudinal datasets the focus shifts from investigating telomere length (TL) to exploring TL change within individuals over time. Some studies indicate that the speed of telomere attrition is predictive of future disease. The objectives of the present study were to 1) characterize the change in bovine relative leukocyte TL (RLTL) across the lifetime in Holstein Friesian dairy cattle, 2) estimate genetic parameters of RLTL over time and 3) investigate the association of differences in individual RLTL profiles with productive lifespan. RLTL measurements were analysed using Legendre polynomials in a random regression model to describe TL profiles and genetic variance over age. The analyses were based on 1,328 repeated RLTL measurements of 308 female Holstein Friesian dairy cattle. A quadratic Legendre polynomial was fitted to the fixed effect of age in months and to the random effect of the animal identity. Changes in RLTL, heritability and within-trait genetic correlation along the age trajectory were calculated and illustrated. At a population level, the relationship between RLTL and age was described by a positive quadratic function. Individuals varied significantly regarding the direction and amount of RLTL change over life. The heritability of RLTL ranged from 0.36 to 0.47 (SE = 0.05–0.08) and remained statistically unchanged over time. The genetic correlation of RLTL at birth with measurements later in life decreased with the time interval between samplings from near unity to 0.69, indicating that TL later in life might be regulated by different genes than TL early in life. Even though animals differed in their RLTL profiles significantly, those differences were not correlated with productive lifespan (p = 0.954). PMID:29438415
Just entertainment: effects of TV series about intrigue on young adults

PubMed Central

Wang, Fei; Lin, Shengdong; Ke, Xue

2015-01-01

The potential harmful effects of media violence have been studied systematically and extensively. However, very little attention has been devoted to the intrigue and struggles between people depicted in the mass media. A longitudinal randomized experimental group-control group, pretest–posttest design study was conducted to examine the potential effects of this type of TV series on young adults. A typical and popular TV series was select as a stimulus. By scrutinizing the outline of this TV series and inspired by studies of the effects of media violence, one behavioral observation and five scales were adopted as dependent measures. The study did not find any effect of the intrigue TV series on any of the six dependent variables. Finally, possible interference variables or moderators were discussed. PMID:26029127
Prospective randomized trial to assess effects of continuing hormone therapy on cerebral function in postmenopausal women at risk for dementia.

PubMed

Rasgon, Natalie L; Geist, Cheri L; Kenna, Heather A; Wroolie, Tonita E; Williams, Katherine E; Silverman, Daniel H S

2014-01-01

The objective of this study was to examine the effects of estrogen-based hormone therapy (HT) on regional cerebral metabolism in postmenopausal women (mean age = 58, SD = 5) at risk for development of dementia. The prospective clinical trial design included pre- and post-intervention neuroimaging of women randomized to continue (HT+) or discontinue (HT-) therapy following an average of 10 years of use. The primary outcome measure was change in brain metabolism during the subsequent two years, as assessed with fluorodeoxyglucose-18 positron emission tomography (FDG-PET). Longitudinal FDG-PET data were available for 45 study completers. Results showed that women randomized to continue HT experienced relative preservation of frontal and parietal cortical metabolism, compared with women randomized to discontinue HT. Women who discontinued 17-β estradiol (17βE)-based HT, as well as women who continued conjugated equine estrogen (CEE)-based HT, exhibited significant decline in metabolism of the precuneus/posterior cingulate cortical (PCC) area. Significant decline in PCC metabolism was additionally seen in women taking concurrent progestins (with either 17βE or CEE). Together, these findings suggest that among postmenopausal subjects at risk for developing dementia, regional cerebral cortical metabolism is relatively preserved for at least two years in women randomized to continue HT, compared with women randomized to discontinue HT. In addition, continuing unopposed 17βE therapy is associated specifically with preservation of metabolism in PCC, known to undergo the most significant decline in the earliest stages of Alzheimer's disease. ClinicalTrials.gov NCT00097058.
A Two-Stage Estimation Method for Random Coefficient Differential Equation Models with Application to Longitudinal HIV Dynamic Data.

PubMed

Fang, Yun; Wu, Hulin; Zhu, Li-Xing

2011-07-01

We propose a two-stage estimation method for random coefficient ordinary differential equation (ODE) models. A maximum pseudo-likelihood estimator (MPLE) is derived based on a mixed-effects modeling approach and its asymptotic properties for population parameters are established. The proposed method does not require repeatedly solving ODEs, and is computationally efficient although it does pay a price with the loss of some estimation efficiency. However, the method does offer an alternative approach when the exact likelihood approach fails due to model complexity and high-dimensional parameter space, and it can also serve as a method to obtain the starting estimates for more accurate estimation methods. In addition, the proposed method does not need to specify the initial values of state variables and preserves all the advantages of the mixed-effects modeling approach. The finite sample properties of the proposed estimator are studied via Monte Carlo simulations and the methodology is also illustrated with application to an AIDS clinical data set.
Feeling Thanks and Saying Thanks: A Randomized Controlled Trial Examining If and How Socially Oriented Gratitude Journals Work.

PubMed

O'Connell, Brenda H; O'Shea, Deirdre; Gallagher, Stephen

2017-10-01

This study examined the effect of a reflective interpersonal gratitude journal, a reflective-behavioral interpersonal gratitude journal and an active control journal, on primary qualities of well-being and depression. Participants (n = 192; 67.2% female) completed this 3-month longitudinal randomized controlled design. Participants in the reflective-behavioral condition experienced the greatest improvements in affect balance and reductions in depression at immediate posttest. Both gratitude interventions improved affect balance at 1 month, compared to the control. Changes in affect balance for those in the reflective-behavioral condition were mediated by the rate at which people expressed gratitude in their existing relationships. This effect was moderated by participant's baseline depressive status. Expressing felt gratitude to others appears to be a crucial step in deriving benefits, and these benefits may not be limited to the emotionally healthy. Given the applied popularity of gratitude interventions, understanding not only if but also how they work is essential. © 2017 Wiley Periodicals, Inc.
Smooth random change point models.

PubMed

van den Hout, Ardo; Muniz-Terrera, Graciela; Matthews, Fiona E

2011-03-15

Change point models are used to describe processes over time that show a change in direction. An example of such a process is cognitive ability, where a decline a few years before death is sometimes observed. A broken-stick model consists of two linear parts and a breakpoint where the two lines intersect. Alternatively, models can be formulated that imply a smooth change between the two linear parts. Change point models can be extended by adding random effects to account for variability between subjects. A new smooth change point model is introduced and examples are presented that show how change point models can be estimated using functions in R for mixed-effects models. The Bayesian inference using WinBUGS is also discussed. The methods are illustrated using data from a population-based longitudinal study of ageing, the Cambridge City over 75 Cohort Study. The aim is to identify how many years before death individuals experience a change in the rate of decline of their cognitive ability. Copyright © 2010 John Wiley & Sons, Ltd.
Changing Friend Selection in Middle School: A Social Network Analysis of a Randomized Intervention Study Designed to Prevent Adolescent Problem Behavior.

PubMed

DeLay, Dawn; Ha, Thao; Van Ryzin, Mark; Winter, Charlotte; Dishion, Thomas J

2016-04-01

Adolescent friendships that promote problem behavior are often chosen in middle school. The current study examines the unintended impact of a randomized school-based intervention on the selection of friends in middle school, as well as on observations of deviant talk with friends 5 years later. Participants included 998 middle school students (526 boys and 472 girls) recruited at the onset of middle school (age 11-12 years) from three public middle schools participating in the Family Check-up model intervention. The current study focuses only on the effects of the SHAPe curriculum-one level of the Family Check-up model-on friendship choices. Participants nominated friends and completed measures of deviant peer affiliation. Approximately half of the sample (n = 500) was randomly assigned to the intervention, and the other half (n = 498) comprised the control group within each school. The results indicate that the SHAPe curriculum affected friend selection within school 1 but not within schools 2 or 3. The effects of friend selection in school 1 translated into reductions in observed deviancy training 5 years later (age 16-17 years). By coupling longitudinal social network analysis with a randomized intervention study, the current findings provide initial evidence that a randomized public middle school intervention can disrupt the formation of deviant peer groups and diminish levels of adolescent deviance 5 years later.
Using Random Forest Models to Predict Organizational Violence

NASA Technical Reports Server (NTRS)

Levine, Burton; Bobashev, Georgly

2012-01-01

We present a methodology to access the proclivity of an organization to commit violence against nongovernment personnel. We fitted a Random Forest model using the Minority at Risk Organizational Behavior (MAROS) dataset. The MAROS data is longitudinal; so, individual observations are not independent. We propose a modification to the standard Random Forest methodology to account for the violation of the independence assumption. We present the results of the model fit, an example of predicting violence for an organization; and finally, we present a summary of the forest in a "meta-tree,"
Time Course of Atrophic Remodeling: Effects of Exercise on Cardiac Morpology and Function

NASA Technical Reports Server (NTRS)

Scott, J. M.; Martin, D.; Caine, T.; Matz, T.; Ploutz-Snyder, L. L.

2014-01-01

Early and consistent evaluation of cardiac morphology and function throughout an atrophic stimulus is critically important for the design and optimization of interventions. Exercise training is one intervention that has been shown to confer favorable improvements in LV mass and function during unloading. However, the format and intensity of exercise required to induce optimal cardiac improvements has not been investigated. PURPOSE: This randomized, controlled trial was designed to 1) comprehensively characterize the time course of unloading-induced morpho-functional remodeling, and 2) examine the effects of high intensity exercise training on cardiac structural and functional parameters during unloading. METHODS: Twenty six subjects completed 70 days of head down tilt bed rest (HDBR): 17 were randomized to exercise training (ExBR) and 9 remained sedentary. Exercise consisted of integrated high intensity, continuous, and resistance exercise. We assessed cardiac morphology (left ventricular mass; LVM) and function (speckle-tracking assessment of longitudinal, radial, and circumferential strain and twist) before (BR-2), during (BR7,21,31,70), and following (BR+0, +3) HDBR. Cardiorespiratory fitness (VO2max) was evaluated before (BR- 3), during (BR4,25,46,68) and following (BR+0) HDBR. RESULTS: Sedentary HDBR resulted in a progressive decline in LVM, longitudinal, radial, and circumferential strain, and an increase in twist. ExBR mitigated decreases in LVM and function. Change in twist was significantly related to change in VO2max (R=0.68, p<0.01). CONCLUSIONS: Alterations in cardiac morphology and function begin early during unloading. High-intensity exercise attenuates atrophic morphological and functional remodeling.
Influence assessment in censored mixed-effects models using the multivariate Student’s-t distribution

PubMed Central

Matos, Larissa A.; Bandyopadhyay, Dipankar; Castro, Luis M.; Lachos, Victor H.

2015-01-01

In biomedical studies on HIV RNA dynamics, viral loads generate repeated measures that are often subjected to upper and lower detection limits, and hence these responses are either left- or right-censored. Linear and non-linear mixed-effects censored (LMEC/NLMEC) models are routinely used to analyse these longitudinal data, with normality assumptions for the random effects and residual errors. However, the derived inference may not be robust when these underlying normality assumptions are questionable, especially the presence of outliers and thick-tails. Motivated by this, Matos et al. (2013b) recently proposed an exact EM-type algorithm for LMEC/NLMEC models using a multivariate Student’s-t distribution, with closed-form expressions at the E-step. In this paper, we develop influence diagnostics for LMEC/NLMEC models using the multivariate Student’s-t density, based on the conditional expectation of the complete data log-likelihood. This partially eliminates the complexity associated with the approach of Cook (1977, 1986) for censored mixed-effects models. The new methodology is illustrated via an application to a longitudinal HIV dataset. In addition, a simulation study explores the accuracy of the proposed measures in detecting possible influential observations for heavy-tailed censored data under different perturbation and censoring schemes. PMID:26190871
Effect of radioactive iodine-induced hypothyroidism on longitudinal bone growth during puberty in immature female rats.

PubMed

Choi, Hyeonhae; Ryu, Ki-Young; Roh, Jaesook; Bae, Jaeman

2018-05-22

Thyroid cancer in children, the most common endocrine malignancy, shows aggressive behavior and has a high recurrence rate after surgical ablation. Radioactive iodine (RAI) treatment is the most effective primary modality for medical ablation of juvenile thyroid cancer, and leads to intentional hypothyroidism. Although several negative impacts of hypothyroidism have been reported in children in response to other antithyroid agents, the combined effects of RAI exposure and hypothyroidism, on growing bones specifically, are unknown. In this study, we investigated the effect of RAI-induced hypothyroidism on the long bones during the pubertal growth spurt using immature female rats. Female Sprague-Dawley rats were randomly divided into a control group, and an RAI-treated group fed with RAI (0.37 MBq/g body weight) twice via gavage. After 4 weeks, we observed a significantly-reduced serum free thyroxine level in the RAI group. The latter group also displayed decreased body weight gain compared to the control. In addition, the lengths of long bones, such as the leg bones and vertebral column, as well as bone mineral content, were reduced in the RAI-treated animals. Our results confirm the negative impacts of RAI-induced thyroid deficiency during puberty on longitudinal bone growth and bone mineralization.
Anharmonic longitudinal motion of bases and dynamics of nonlinear excitation in DNA.

PubMed

Di Garbo, Angelo

2016-01-01

The dynamics of the transcription bubble in DNA is studied by using a nonlinear model in which torsional and longitudinal conformations of the biomolecule are coupled. In the absence of forcing and dissipation the torsional dynamics is described by a perturbed kink of the Sine-Gordon DNA model, while the longitudinal conformational energy propagate as phonons. It was found that for random initial conditions of the longitudinal conformational field the presence of the kink promotes the creation of phonons propagating along the chain axis. Moreover, the presence of forcing, describing the active role of RNA polymerase, determines in agreement to the experimental data a modulation of the velocity of the transcription bubble. Lastly, it was shown that the presence of dissipation impacts the dynamic of the phonon by reducing the amplitude of the corresponding conformational field. On the contrary, dissipation and forcing modulate the velocity of the transcription bubble alone.
Growth hormone combined with child-specific motor training improves motor development in infants with Prader-Willi syndrome: a randomized controlled trial.

PubMed

Reus, Linda; Pelzer, Ben J; Otten, Barto J; Siemensma, Elbrich P C; van Alfen-van der Velden, Janielle A A E M; Festen, Dederieke A M; Hokken-Koelega, Anita C S; Nijhuis-van der Sanden, Maria W G

2013-10-01

Although severe motor problems in infants with Prader-Willi syndrome (PWS) are striking, motor development has never been studied longitudinally and the results of growth hormone (GH) treatment on motor development are contradictory. The authors studied whether GH treatment can enhance the effect of physical training on motor development in infants with PWS. Twenty-two infants were followed for two years during a randomized controlled trial. The treatment and control groups began GH after baseline or following a control period, respectively. Both groups followed a child-specific physical training program. Motor performance was measured every three months. Multi-level regression analysis revealed that motor development differed significantly between infants (p<.001), and this could be partially explained by baseline motor developmental level (p<.01). GH treatment enhanced the effects of child-specific physical training on both motor developmental rate and motor developmental potential. Moreover, this effect was more pronounced when GH treatment was initiated at a younger age. Copyright © 2013 Elsevier Ltd. All rights reserved.
Gene–Environment Correlation: Difficulties and a Natural Experiment–Based Strategy

PubMed Central

Li, Jiang; Liu, Hexuan; Guo, Guang

2013-01-01

Objectives. We explored how gene–environment correlations can result in endogenous models, how natural experiments can protect against this threat, and if unbiased estimates from natural experiments are generalizable to other contexts. Methods. We compared a natural experiment, the College Roommate Study, which measured genes and behaviors of college students and their randomly assigned roommates in a southern public university, with observational data from the National Longitudinal Study of Adolescent Health in 2008. We predicted exposure to exercising peers using genetic markers and estimated environmental effects on alcohol consumption. A mixed-linear model estimated an alcohol consumption variance that was attributable to genetic markers and across peer environments. Results. Peer exercise environment was associated with respondent genotype in observational data, but not in the natural experiment. The effects of peer drinking and presence of a general gene–environment interaction were similar between data sets. Conclusions. Natural experiments, like random roommate assignment, could protect against potential bias introduced by gene–environment correlations. When combined with representative observational data, unbiased and generalizable causal effects could be estimated. PMID:23927502

Effects of ignoring baseline on modeling transitions from intact cognition to dementia

PubMed Central

Yu, Lei; Tyas, Suzanne L.; Snowdon, David A.; Kryscio, Richard J.

2009-01-01

This paper evaluates the effect of ignoring baseline when modeling transitions from intact cognition to dementia with mild cognitive impairment (MCI) and global impairment (GI) as intervening cognitive states. Transitions among states are modeled by a discrete-time Markov chain having three transient (intact cognition, MCI, and GI) and two competing absorbing states (death and dementia). Transition probabilities depend on two covariates, age and the presence/absence of an apolipoprotein E-ε4 allele, through a multinomial logistic model with shared random effects. Results are illustrated with an application to the Nun Study, a cohort of 678 participants 75+ years of age at baseline and followed longitudinally with up to ten cognitive assessments per nun. PMID:20161282
Longitudinal effects of integrated treatment on alcohol use for persons with serious mental illness and substance use disorders.

PubMed

Herman, S E; Frank, K A; Mowbray, C T; Ribisl, K M; Davidson, W S; BootsMiller, B; Jordan, L; Greenfield, A L; Loveland, D; Luke, D A

2000-08-01

A randomized experimental design was used to assign participants to an integrated mental health and substance use treatment program or to standard hospital treatment. A multilevel, nonlinear model was used to estimate hospital treatment effects on days of alcohol use for persons with serious mental illness and substance use disorders over 18 months. The integrated treatment program had a significant effect on the rate of alcohol use at 2 months postdischarge, reducing the rate of use by 54%. Motivation for sobriety at hospital discharge, posttreatment self-help attendance, and social support for sobriety were also found to reduce the rate of use during the follow-up period. Implications for mental health treatment and aftercare support are discussed.
[Azilsartan Medoxomil Capabilities in Arterial Hypertension and Obesity].

PubMed

Vasyuk, Y A; Shupenina, E Y; Nesvetov, V V; Nesterova, E A; Golubkova, E I

2016-12-01

Arterial hypertension (AH) is one of the most common cardiovascular disease. Angiotensin II (AT II), the hormone of renin-angiotensin-aldosterone system, realizes its negative effects through AT 1 receptors - application point of angiotensin receptor blockers (ARB). Due to different dissociation AT 1 receptors properties some ARBs are more effective than others. Multiply multicenter randomized and observational studies approve the effectiveness and safety of azilsartan medoxomil in patients with AH 1-2 grade. Several preclinical studies have shown the additional properties of azilsartan, including increase of insulin sensitivity, cardio- and nephron protection in obesity. In our clinical case we showed the positive influence of azilsartan medoxomil on clinic and ambulatory blood pressure, 24-hour aortic stiffness parameters, longitudinal left ventricular strain in patient with AH and obesity.
Antiretroviral treatment is associated with iron deficiency in HIV-infected Malawian women that is mitigated with supplementation, but is not associated with infant iron deficiency during 24 weeks of exclusive breastfeeding

PubMed Central

Widen, Elizabeth M; Bentley, Margaret E; Chasela, Charles S; Kayira, Dumbani; Flax, Valerie L; Kourtis, Athena P; Ellington, Sascha R; Kacheche, Zebrone; Tegha, Gerald; Jamieson, Denise J; van der Horst, Charles M; Allen, Lindsay H; Shahab-Ferdows, Setareh; Adair, Linda S

2015-01-01

Objective In resource-limited settings without safe alternatives to breastfeeding, the WHO recommends exclusive breastfeeding and antiretroviral (ARV) prophylaxis. Given the high prevalence of anemia among HIV-infected women, mothers and their infants (via fetal iron accretion) may be at risk of iron deficiency. We assessed the effects of maternal micronutrient-fortified lipid-based nutrient supplements (LNS) and maternal ARV treatment or infant ARV prophylaxis on maternal and infant iron status during exclusive breastfeeding from birth to 24 weeks. Methods The Breastfeeding, Antiretrovirals, and Nutrition Study was a randomized controlled trial conducted in Lilongwe, Malawi from 2004-2010. HIV-infected mothers (CD4>200 cells/ul) and their infants were randomly assigned to 28-week interventions: maternal-LNS/maternal-ARV (n=424), maternal-LNS/infant-ARV (n=426), maternal-LNS (n=334), maternal-ARV (n=425), infant-ARV (n=426), or control (n=334). Longitudinal models tested intervention effects on hemoglobin (Hb). In a subsample (n=537) with multiple iron indicators, intervention effects on Hb, transferrin receptors (TfR) and ferritin were tested with linear and Poisson regression. Results In longitudinal models, LNS effects on maternal and infant Hb were minimal. In subsample mothers, maternal ARVs were associated with tissue iron depletion (TfR>8.3 mg/L) (Risk ratio (RR): 3.1, p<0.01), but not in ARV-treated mothers receiving LNS (p=0.17). LNS without ARVs, was not associated with iron deficiency or anemia (p>0.1). In subsample infants, interventions were not associated with impaired iron status (all p-values>0.1). Conclusions Maternal ARV treatment with protease inhibitors is associated with maternal tissue iron depletion; but LNS mitigates adverse effects. ARVs do not appear to influence infant iron status; however, extended use needs to be evaluated. PMID:25723140
Clinical impact of negative-pressure wound therapy: a 1,126-patient observational prospective study.

PubMed

Téot, Luc; Guillot-Masanovic, Margot; Miquel, Pierre; Truchetet, François; Meaume, Sylvie; Dompmartin, Anne; Charles Kerihuel, Jean; Trial, Chloé; Faure, Christine

2014-01-01

Negative-pressure wound therapy (NPWT) was developed in the early 1990s and reported in 1997 by Argenta and Morykwas. Ignored at first, this technique progressively came to be considered as an outstanding advancement in reconstructive surgery. Several randomized controlled studies produced evidence for the effect of NPWT on promotion of granulation tissue formation and prevention of tissue damage and amputation. However, no important longitudinal study has yet produced clinical and economic data on the consequences of integrating NPWT into practice in multiple institutions. This prospective, comparative longitudinal study of NPWT as a clinical-practice innovation was conducted in 1,126 patients between March 2006 and June 2009 in 30 university and nonuniversity public and private hospitals in France. NPWT was proposed in a nonrandomized fashion for various clinical indications, and the patients were divided into two groups, one using NPWT, the second using standard care. Efficacy criteria were spontaneous closure, closure after surgical coverage using skin grafts or flaps, or achievement of 40% wound area regression. The results, observed in a pragmatic but not randomized study, are suggestive of a favorable impact of NPWT in multiple clinical situations. The significance of differences between surgical patients who underwent NPWT and those who did not was unclear, as NPWT had already been adopted by most of the surgical wards. © 2014 by the Wound Healing Society.
Reciprocal longitudinal relations between weight/shape concern and comorbid pathology among women at very high risk for eating disorder onset.

PubMed

Fitzsimmons-Craft, Ellen E; Eichen, Dawn M; Kass, Andrea E; Trockel, Mickey; Crosby, Ross D; Taylor, C Barr; Wilfley, Denise E

2017-12-28

Understanding how known eating disorder (ED) risk factors change in relating to one another over time may inform efficient intervention targets. We examined short-term (i.e., 1 month) reciprocal longitudinal relations between weight/shape concern and comorbid symptoms (i.e., depressed mood, anxiety) and behaviors (i.e., binge drinking) over the course of 24 months using cross-lagged panel models. Participants were 185 women aged 18-25 years at very high risk for ED onset, randomized to an online ED preventive intervention or waitlist control. We also tested whether relations differed based on intervention receipt. Weight/shape concern in 1 month significantly predicted depressed mood the following month; depressed mood in 1 month also predicted weight/shape concern the following month, but the effect size was smaller. Likewise, weight/shape concern in 1 month significantly predicted anxiety the following month, but the reverse was not true. Results showed no temporal relations between weight/shape concern and binge drinking in either direction. Relations between weight/shape concern, and comorbid symptoms and behaviors did not differ based on intervention receipt. Results support focusing intervention on reducing weight/shape concern over reducing comorbid constructs for efficient short-term change. Level I, evidence obtained from a properly designed randomized controlled trial.
Reducing diarrhoea in Guatemalan children: randomized controlled trial of flocculant-disinfectant for drinking-water.

PubMed

Chiller, Tom M; Mendoza, Carlos E; Lopez, M Beatriz; Alvarez, Maricruz; Hoekstra, Robert M; Keswick, Bruce H; Luby, Stephen P

2006-01-01

To examine the effect of a new point-of-use treatment for drinking-water, a commercially developed flocculant-disinfectant, on the prevalence of diarrhoea in children. We conducted a randomized controlled trial among 514 rural Guatemalan households, divided into 42 neighbourhood clusters, for 13 weeks, from 4 November 2002 through 31 January 2003. Clusters assigned to water treatment with the flocculant-disinfectant were compared with those using their usual water-handling practices. The longitudinal prevalence of diarrhoea was calculated as the proportion of total days with diarrhoea divided by the total number of days of observation. The prevalence of diarrhoea was compared using the Wilcoxon rank-sum test. The 1702 people in households receiving the disinfectant had a prevalence of diarrhoea that was 40% lower than that among the 1699 people using standard water-handling practices (0.9% versus 1.5%; P = 0.001). In households using the flocculant-disinfectant, children < 1 year of age had a 39% lower prevalence of diarrhoea than those in households using their standard practices (3.7% versus 6.0%; P = 0.005). In settings where families rarely treat drinking-water, we introduced a novel flocculant-disinfectant that reduced the longitudinal prevalence of diarrhoea, especially among children aged < 1 year, among whom diarrhoea has been strongly associated with mortality. Successful introduction and use of this product could contribute to preventing diarrhoeal disease globally.
Predicting the multi-domain progression of Parkinson's disease: a Bayesian multivariate generalized linear mixed-effect model.

PubMed

Wang, Ming; Li, Zheng; Lee, Eun Young; Lewis, Mechelle M; Zhang, Lijun; Sterling, Nicholas W; Wagner, Daymond; Eslinger, Paul; Du, Guangwei; Huang, Xuemei

2017-09-25

It is challenging for current statistical models to predict clinical progression of Parkinson's disease (PD) because of the involvement of multi-domains and longitudinal data. Past univariate longitudinal or multivariate analyses from cross-sectional trials have limited power to predict individual outcomes or a single moment. The multivariate generalized linear mixed-effect model (GLMM) under the Bayesian framework was proposed to study multi-domain longitudinal outcomes obtained at baseline, 18-, and 36-month. The outcomes included motor, non-motor, and postural instability scores from the MDS-UPDRS, and demographic and standardized clinical data were utilized as covariates. The dynamic prediction was performed for both internal and external subjects using the samples from the posterior distributions of the parameter estimates and random effects, and also the predictive accuracy was evaluated based on the root of mean square error (RMSE), absolute bias (AB) and the area under the receiver operating characteristic (ROC) curve. First, our prediction model identified clinical data that were differentially associated with motor, non-motor, and postural stability scores. Second, the predictive accuracy of our model for the training data was assessed, and improved prediction was gained in particularly for non-motor (RMSE and AB: 2.89 and 2.20) compared to univariate analysis (RMSE and AB: 3.04 and 2.35). Third, the individual-level predictions of longitudinal trajectories for the testing data were performed, with ~80% observed values falling within the 95% credible intervals. Multivariate general mixed models hold promise to predict clinical progression of individual outcomes in PD. The data was obtained from Dr. Xuemei Huang's NIH grant R01 NS060722 , part of NINDS PD Biomarker Program (PDBP). All data was entered within 24 h of collection to the Data Management Repository (DMR), which is publically available ( https://pdbp.ninds.nih.gov/data-management ).
A Longitudinal Analysis of the Effects of Socioeconomic Factors, Foreign Media, and Attitude toward Appearance on General and Central Adiposity in Chinese Adolescents.

PubMed

Felicitas, Jamie Q; Tanenbaum, Hilary C; Li, Yawen; Chou, Chih-Ping; Palmer, Paula H; Spruijt-Metz, Donna; Reynolds, Kim D; Johnson, C Anderson; Xie, Bin

This paper explores the longitudinal effects of socioeconomic factors (i.e., parent education and family income level), foreign media, and attitude toward appearance on general and central adiposity among Chinese adolescents. A longitudinal analysis was performed using data from the China Seven Cities Study, a health promotion and smoking prevention study conducted in seven cities across Mainland China between 2002 and 2005. Participants included 5,020 middle and high school students and their parents. Explanatory variables included foreign media exposure, attitude toward appearance, parent education, and family income. Three-level, random-effect models were used to predict general adiposity (i.e., body mass index) and central adiposity (i.e., waist circumference). The Generalized Estimating Equation approach was utilized to determine the effect of explanatory variables on overweight status. Among girls, foreign media exposure was significantly negatively associated with general adiposity over time (β=-0.06, p=0.01 for middle school girls; β=-0.06, p=0.03 for high school girls). Attitude toward appearance was associated with lesser odds of being overweight, particularly among high school girls (OR=0.86, p<0.01). Among boys, parental education was significantly positively associated with general adiposity (β=0.62, p<0.01 for middle school boys; β=0.37, p=0.02 for high school boys) and associated with greater odds of being overweight (OR=1.55, p<0.01 for middle school boys; OR=1.26, p=0.04 for high school boys). Across all gender and grade levels, family income was significantly negatively associated with central adiposity over time. Interventions addressing Chinese adolescent overweight/obesity should consider these factors as potential focus areas.
Methods for a longitudinal quantitative outcome with a multivariate Gaussian distribution multi-dimensionally censored by therapeutic intervention.

PubMed

Sun, Wanjie; Larsen, Michael D; Lachin, John M

2014-04-15

In longitudinal studies, a quantitative outcome (such as blood pressure) may be altered during follow-up by the administration of a non-randomized, non-trial intervention (such as anti-hypertensive medication) that may seriously bias the study results. Current methods mainly address this issue for cross-sectional studies. For longitudinal data, the current methods are either restricted to a specific longitudinal data structure or are valid only under special circumstances. We propose two new methods for estimation of covariate effects on the underlying (untreated) general longitudinal outcomes: a single imputation method employing a modified expectation-maximization (EM)-type algorithm and a multiple imputation (MI) method utilizing a modified Monte Carlo EM-MI algorithm. Each method can be implemented as one-step, two-step, and full-iteration algorithms. They combine the advantages of the current statistical methods while reducing their restrictive assumptions and generalizing them to realistic scenarios. The proposed methods replace intractable numerical integration of a multi-dimensionally censored MVN posterior distribution with a simplified, sufficiently accurate approximation. It is particularly attractive when outcomes reach a plateau after intervention due to various reasons. Methods are studied via simulation and applied to data from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications study of treatment for type 1 diabetes. Methods proved to be robust to high dimensions, large amounts of censored data, low within-subject correlation, and when subjects receive non-trial intervention to treat the underlying condition only (with high Y), or for treatment in the majority of subjects (with high Y) in combination with prevention for a small fraction of subjects (with normal Y). Copyright © 2013 John Wiley & Sons, Ltd.
Comparison of a theory-based (AIDS Risk Reduction Model) cognitive behavioral intervention versus enhanced counseling for abused ethnic minority adolescent women on infection with sexually transmitted infection: results of a randomized controlled trial.

PubMed

Champion, Jane Dimmitt; Collins, Jennifer L

2012-02-01

Ethnic minority adolescent women with a history of sexual or physical abuse and sexually transmitted infections represent a vulnerable population at risk for HIV. Community-based interventions for behavior modification and subsequent risk reduction have not been effective among these women. To evaluate the effects of a theory-based (AIDS Risk Reduction Model) cognitive behavioral intervention model versus enhanced counseling for abused ethnic minority adolescent women on infection with sexually transmitted infection at 6 and 12 months follow-up. Controlled randomized trial with longitudinal follow-up. Southwestern United States, Metropolitan community-based clinic. Mexican-and-African American adolescent women aged 14-18 years with a history of abuse or sexually transmitted infection seeking sexual health care. Extensive preliminary study for intervention development was conducted including individual interviews, focus groups, secondary data analysis, pre-testing and feasibility testing for modification of an evidence-based intervention prior to testing in the randomized controlled trial. Following informed consents for participation in the trial, detailed interviews concerning demographics, abuse history, sexual risk behavior, sexual health and physical exams were obtained. Randomization into either control or intervention groups was conducted. Intervention participants received workshop, support group and individual counseling sessions. Control participants received abuse and enhanced clinical counseling. Follow-up including detailed interview and physical exam was conducted at 6 and 12 months following study entry to assess for infection. Intention to treat analysis was conducted to assess intervention effects using chi-square and multiple regression models. 409 Mexican-(n=342) and African-(n=67) American adolescent women with abuse and sexually transmitted infection histories were enrolled; 90% intervention group attendance; longitudinal follow-up at 6 (93%) and 12 (94%) months. Intervention (n=199) versus control (n=210) group participants experienced fewer infections at 0-6 (0% versus 6.6%, p=.001), 6-12 (3.6% versus 7.8%, p=.005, CI 95% lower-upper .001-.386) and 0-12 (4.8% versus 13.2%, p=.002, CI 95% lower-upper, .002-.531) month intervals. A cognitive behavioral intervention specifically designed for ethnic minority adolescent women with a history of abuse and sexually transmitted infection was effective for prevention of infection. These results provide evidence for development of evidence-based interventions for sexually transmitted infection/HIV. Implications include translation to community-clinic-based settings for prevention of adverse outcomes regarding sexual health of adolescent women. Copyright © 2011 Elsevier Ltd. All rights reserved.
Kidney function changes with aging in adults: comparison between cross-sectional and longitudinal data analyses in renal function assessment.

PubMed

Chung, Sang M; Lee, David J; Hand, Austin; Young, Philip; Vaidyanathan, Jayabharathi; Sahajwalla, Chandrahas

2015-12-01

The study evaluated whether the renal function decline rate per year with age in adults varies based on two primary statistical analyses: cross-section (CS), using one observation per subject, and longitudinal (LT), using multiple observations per subject over time. A total of 16628 records (3946 subjects; age range 30-92 years) of creatinine clearance and relevant demographic data were used. On average, four samples per subject were collected for up to 2364 days (mean: 793 days). A simple linear regression and random coefficient models were selected for CS and LT analyses, respectively. The renal function decline rates per year were 1.33 and 0.95 ml/min/year for CS and LT analyses, respectively, and were slower when the repeated individual measurements were considered. The study confirms that rates are different based on statistical analyses, and that a statistically robust longitudinal model with a proper sampling design provides reliable individual as well as population estimates of the renal function decline rates per year with age in adults. In conclusion, our findings indicated that one should be cautious in interpreting the renal function decline rate with aging information because its estimation was highly dependent on the statistical analyses. From our analyses, a population longitudinal analysis (e.g. random coefficient model) is recommended if individualization is critical, such as a dose adjustment based on renal function during a chronic therapy. Copyright © 2015 John Wiley & Sons, Ltd.
A randomized controlled trial of an online, modular, active learning training program for behavioral activation for depression.

PubMed

Puspitasari, Ajeng J; Kanter, Jonathan W; Busch, Andrew M; Leonard, Rachel; Dunsiger, Shira; Cahill, Shawn; Martell, Christopher; Koerner, Kelly

2017-08-01

This randomized-controlled trial assessed the efficacy of a trainer-led, active-learning, modular, online behavioral activation (BA) training program compared with a self-paced online BA training with the same modular content. Seventy-seven graduate students (M = 30.3 years, SD = 6.09; 76.6% female) in mental health training programs were randomly assigned to receive either the trainer-led or self-paced BA training. Both trainings consisted of 4 weekly sessions covering 4 core BA strategies. Primary outcomes were changes in BA skills as measured by an objective role-play assessment and self-reported use of BA strategies. Assessments were conducted at pre-, post-, and 6-weeks after training. A series of longitudinal mixed effect models assessed changes in BA skills and a longitudinal model implemented with generalized estimating equations assessed BA use over time. Significantly greater increases in total BA skills were found in the trainer-led training condition. The trainer-led training condition also showed greater increases in all core BA skills either at posttraining, follow-up, or both. Reported use of BA strategies with actual clients increased significantly from pre- to posttraining and maintained at follow-up in both training conditions. This trial adds to the literature on the efficacy of online training as a method to disseminate BA. Online training with an active learning, modular approach may be a promising and accessible implementation strategy. Additional strategies may need to be paired with the online BA training to assure the long-term implementation and sustainability of BA in clinical practice. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
A longitudinal multilevel CFA-MTMM model for interchangeable and structurally different methods

PubMed Central

Koch, Tobias; Schultze, Martin; Eid, Michael; Geiser, Christian

2014-01-01

One of the key interests in the social sciences is the investigation of change and stability of a given attribute. Although numerous models have been proposed in the past for analyzing longitudinal data including multilevel and/or latent variable modeling approaches, only few modeling approaches have been developed for studying the construct validity in longitudinal multitrait-multimethod (MTMM) measurement designs. The aim of the present study was to extend the spectrum of current longitudinal modeling approaches for MTMM analysis. Specifically, a new longitudinal multilevel CFA-MTMM model for measurement designs with structurally different and interchangeable methods (called Latent-State-Combination-Of-Methods model, LS-COM) is presented. Interchangeable methods are methods that are randomly sampled from a set of equivalent methods (e.g., multiple student ratings for teaching quality), whereas structurally different methods are methods that cannot be easily replaced by one another (e.g., teacher, self-ratings, principle ratings). Results of a simulation study indicate that the parameters and standard errors in the LS-COM model are well recovered even in conditions with only five observations per estimated model parameter. The advantages and limitations of the LS-COM model relative to other longitudinal MTMM modeling approaches are discussed. PMID:24860515
Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Insomnia: an Update of the Literature.

PubMed

Wynchank, Dora; Bijlenga, Denise; Beekman, Aartjan T; Kooij, J J Sandra; Penninx, Brenda W

2017-10-30

Insomnia is diagnosed when there is dissatisfaction with sleep quantity or quality. It has a prevalence in the general population ranging from 31 to 56%. Insomnia has previously been associated with adult attention-deficit/hyperactivity disorder (ADHD). In this review, we address three topics: (1) the cross-sectional relationship between ADHD and insomnia in adulthood, (2) the longitudinal relationship between ADHD and insomnia, and (3) insomnia as a side effect of pharmacological treatments for adult ADHD. Three cross-sectional, clinical, and population studies report a prevalence of insomnia in ADHD adults ranging from 43 to 80%. Longitudinal evidence for a link between childhood-onset ADHD and insomnia at later age is mixed, with one study confirming and another study not supporting such a longitudinal association. In randomized, placebo-controlled trials, insomnia is reported significantly more often in the treatment arm than in the placebo arm. In varying percentages of trial participants, insomnia is a treatment-emergent adverse effect in triple-bead mixed amphetamine salts (40-45%), dasotraline (35-45%), lisdexamfetamine (10-19%), and extended-release methylphenidate (11%). Ten to seventeen percent of subjects in placebo-controlled trials of atomoxetine report insomnia, possibly related to poor metabolizer status. The mechanisms explaining the relationship between ADHD and sleep problems are incompletely understood, but both genetic and non-shared environmental influences may be involved. Adults with ADHD should be assessed for insomnia, which is frequently comorbid, and both conditions should be treated.
Causal Effect of Self-esteem on Cigarette Smoking Stages in Adolescents: Coarsened Exact Matching in a Longitudinal Study.

PubMed

Khosravi, Ahmad; Mohammadpoorasl, Asghar; Holakouie-Naieni, Kourosh; Mahmoodi, Mahmood; Pouyan, Ali Akbar; Mansournia, Mohammad Ali

2016-12-01

Identification of the causal impact of self-esteem on smoking stages faces seemingly insurmountable problems in observational data, where self-esteem is not manipulable by the researcher and cannot be assigned randomly. The aim of this study was to find out if weaker self-esteem in adolescence is a risk factor of cigarette smoking in a longitudinal study in Iran. In this longitudinal study, 4,853 students (14-18 years) completed a self-administered multiple-choice anonym questionnaire. The students were evaluated twice, 12 months apart. Students were matched based on coarsened exact matching on pretreatment variables, including age, gender, smoking stages at the first wave of study, socioeconomic status, general risk-taking behavior, having a smoker in the family, having a smoker friend, attitude toward smoking, and self-injury, to ensure statistically equivalent comparison groups. Self-esteem was measured using the Rosenberg 10-item questionnaire and were classified using a latent class analysis. After matching, the effect of self-esteem was evaluated using a multinomial logistic model. In the causal fitted model, for adolescents with weaker self-esteem relative to those with stronger self-esteem, the relative risk for experimenters and regular smokers relative to nonsmokers would be expected to increase by a factor of 2.2 (1.9-2.6) and 2.0 (1.5-2.6), respectively. Using a causal approach, our study indicates that low self-esteem is consistently associated with progression in cigarette smoking stages.
The experience of electroconvulsive therapy and its impact on associated stigma: A meta-analysis.

PubMed

Aoki, Yuta; Yamaguchi, Sosei; Ando, Shuntaro; Sasaki, Natsuki; Bernick, Peter J; Akiyama, Tsuyoshi

2016-12-01

Despite its efficacy and safety, electroconvulsive therapy (ECT) is underutilized, in part due to stigma associated with the treatment. The aim of this study was to test the hypothesis that experiencing ECT has an impact on associated stigma, as measured by patient and family knowledge of and attitudes toward ECT. A comprehensive literature search was conducted using MEDLINE, EMBASE and PsycINFO. Studies with cross-sectional and/or longitudinal designs were identified. Studies were further categorized into subcategories based on participant type (patients or patient family members) and outcome domain (knowledge or attitudes). Effect size (Cohen's d) was calculated for each study and then integrated into each subcategory (participant type by outcome domain) using a random effect model. Eight studies were identified as being eligible for analysis. Two studies were cross-sectional, five were longitudinal and one incorporated both designs. Analysis of the longitudinal studies indicated that experiencing ECT both increased knowledge of and improved attitudes toward ECT in patients; in family members of patients, analysis showed significant positive change in knowledge of ECT, but no significant change in attitudes toward ECT. Experience with ECT may have a positive impact on knowledge of and attitudes toward ECT. However, the quality of evidence of included studies was low; further research is required in order to clarify the relationship and to identify information of use to individuals considering ECT as a treatment option. © The Author(s) 2016.
Do Older Drivers At-Risk for Crashes Modify Their Driving Over Time?

PubMed Central

Clay, Olivio J.; Edwards, Jerri D.; Ball, Karlene K.; Wadley, Virginia G.; Vance, David E.; Cissell, Gayla M.; Roenker, Daniel L.; Joyce, John J.

2009-01-01

Five-year driving habit trajectories among older adults (n = 645) at-risk for crashes were examined. Performance measures included Useful Field of View (UFOV). Motor-Free Visual Perception Test, Rapid Walk, and Foot Tap. Self-report measures included demographics and the Driving Habits Questionnaire. Longitudinal random-effects models revealed that drivers at-risk for subsequent crashes, based upon UFOV, regulated their driving more than the lower-risk participants. Restricted driving was present at baseline for the at-risk group and was observed in longitudinal trajectories that controlled for baseline differences. Results indicate that persons at-risk for subsequent crashes increasingly limit their driving over time. Despite this self-regulation, a larger sample of such older drivers was twice as likely to incur subsequent at-fault crashes. Results suggest that self-regulation among older drivers at-risk for crashes is an insufficient compensatory approach to eliminating increased crash risk. UFOV is a registered trademark of Visual Awareness, Inc. PMID:19196692
Using Exponential Random Graph Models to Analyze the Character of Peer Relationship Networks and Their Effects on the Subjective Well-being of Adolescents.

PubMed

Jiao, Can; Wang, Ting; Liu, Jianxin; Wu, Huanjie; Cui, Fang; Peng, Xiaozhe

2017-01-01

The influences of peer relationships on adolescent subjective well-being were investigated within the framework of social network analysis, using exponential random graph models as a methodological tool. The participants in the study were 1,279 students (678 boys and 601 girls) from nine junior middle schools in Shenzhen, China. The initial stage of the research used a peer nomination questionnaire and a subjective well-being scale (used in previous studies) to collect data on the peer relationship networks and the subjective well-being of the students. Exponential random graph models were then used to explore the relationships between students with the aim of clarifying the character of the peer relationship networks and the influence of peer relationships on subjective well being. The results showed that all the adolescent peer relationship networks in our investigation had positive reciprocal effects, positive transitivity effects and negative expansiveness effects. However, none of the relationship networks had obvious receiver effects or leaders. The adolescents in partial peer relationship networks presented similar levels of subjective well-being on three dimensions (satisfaction with life, positive affects and negative affects) though not all network friends presented these similarities. The study shows that peer networks can affect an individual's subjective well-being. However, whether similarities among adolescents are the result of social influences or social choices needs further exploration, including longitudinal studies that investigate the potential processes of subjective well-being similarities among adolescents.
Using Exponential Random Graph Models to Analyze the Character of Peer Relationship Networks and Their Effects on the Subjective Well-being of Adolescents

PubMed Central

Jiao, Can; Wang, Ting; Liu, Jianxin; Wu, Huanjie; Cui, Fang; Peng, Xiaozhe

2017-01-01

The influences of peer relationships on adolescent subjective well-being were investigated within the framework of social network analysis, using exponential random graph models as a methodological tool. The participants in the study were 1,279 students (678 boys and 601 girls) from nine junior middle schools in Shenzhen, China. The initial stage of the research used a peer nomination questionnaire and a subjective well-being scale (used in previous studies) to collect data on the peer relationship networks and the subjective well-being of the students. Exponential random graph models were then used to explore the relationships between students with the aim of clarifying the character of the peer relationship networks and the influence of peer relationships on subjective well being. The results showed that all the adolescent peer relationship networks in our investigation had positive reciprocal effects, positive transitivity effects and negative expansiveness effects. However, none of the relationship networks had obvious receiver effects or leaders. The adolescents in partial peer relationship networks presented similar levels of subjective well-being on three dimensions (satisfaction with life, positive affects and negative affects) though not all network friends presented these similarities. The study shows that peer networks can affect an individual’s subjective well-being. However, whether similarities among adolescents are the result of social influences or social choices needs further exploration, including longitudinal studies that investigate the potential processes of subjective well-being similarities among adolescents. PMID:28450845

Analysis of longitudinal laboratory data in the presence of common selection mechanisms: a view toward greater emphasis on pre-marketing pharmaceutical safety.

PubMed

Schildcrout, Jonathan S; Jenkins, Cathy A; Ostroff, Jack H; Gillen, Daniel L; Harrell, Frank E; Trost, Donald C

2008-05-30

Pharmaceutical safety has received substantial attention in the recent past; however, longitudinal clinical laboratory data routinely collected during clinical trials to derive safety profiles are often used ineffectively. For example, these data are frequently summarized by comparing proportions (between treatment arms) of participants who cross pre-specified threshold values at some time during follow-up. This research is intended, in part, to encourage more effective utilization of these data by avoiding unnecessary dichotomization of continuous data, acknowledging and making use of the longitudinal follow-up, and combining data from multiple clinical trials. However, appropriate analyses require careful consideration of a number of challenges (e.g. selection, comparability of study populations, etc.). We discuss estimation strategies based on estimating equations and maximum likelihood for analyses in the presence of three response history-dependent selection mechanisms: dropout, follow-up frequency, and treatment discontinuation. In addition, because clinical trials' participants usually represent non-random samples from target populations, we describe two sensitivity analysis approaches. All discussions are motivated by an analysis that aims to characterize the dynamic relationship between concentrations of a liver enzyme (alanine aminotransferase) and three distinct doses (no drug, low dose, and high dose) of an nk-1 antagonist across four Phase II clinical trials.
Music training improves speech-in-noise perception: Longitudinal evidence from a community-based music program.

PubMed

Slater, Jessica; Skoe, Erika; Strait, Dana L; O'Connell, Samantha; Thompson, Elaine; Kraus, Nina

2015-09-15

Music training may strengthen auditory skills that help children not only in musical performance but in everyday communication. Comparisons of musicians and non-musicians across the lifespan have provided some evidence for a "musician advantage" in understanding speech in noise, although reports have been mixed. Controlled longitudinal studies are essential to disentangle effects of training from pre-existing differences, and to determine how much music training is necessary to confer benefits. We followed a cohort of elementary school children for 2 years, assessing their ability to perceive speech in noise before and after musical training. After the initial assessment, participants were randomly assigned to one of two groups: one group began music training right away and completed 2 years of training, while the second group waited a year and then received 1 year of music training. Outcomes provide the first longitudinal evidence that speech-in-noise perception improves after 2 years of group music training. The children were enrolled in an established and successful community-based music program and followed the standard curriculum, therefore these findings provide an important link between laboratory-based research and real-world assessment of the impact of music training on everyday communication skills. Copyright © 2015 Elsevier B.V. All rights reserved.
Effectiveness of a School- and Community-based Academic Asthma Health Education Program on Use of Effective Asthma Self-care Behaviors in Older School-age Students

PubMed Central

Kintner, Eileen K.; Cook, Gwendolyn; Marti, C. Nathan; Allen, April; Stoddard, Debbie; Harmon, Phyllis; Gomes, Melissa; Meeder, Linda; Van Egeren, Laurie A.

2014-01-01

Purpose The purpose was to evaluate the effectiveness of SHARP, an academic asthma health education and counseling program, on fostering use of effective asthma self-care behaviors. Design and Methods This was a phase III, two-group, cluster randomized, single-blinded, longitudinal design guided the study. Caregivers of 205 fourth- and fifth-grade students completed the asthma health behaviors survey at pre-intervention and 1, 12, and 24 months post-intervention. Analysis involved multilevel modeling. Results All students demonstrated improvement in episode management, risk-reduction/prevention, and health promotion behaviors; SHARP students demonstrated increased improvement in episode management and risk-reduction/prevention behaviors. Practice Implications Working with schoolteachers, nurses can improve use of effective asthma self-care behaviors. PMID:25443867
Learning Bayesian Networks from Correlated Data

NASA Astrophysics Data System (ADS)

Bae, Harold; Monti, Stefano; Montano, Monty; Steinberg, Martin H.; Perls, Thomas T.; Sebastiani, Paola

2016-05-01

Bayesian networks are probabilistic models that represent complex distributions in a modular way and have become very popular in many fields. There are many methods to build Bayesian networks from a random sample of independent and identically distributed observations. However, many observational studies are designed using some form of clustered sampling that introduces correlations between observations within the same cluster and ignoring this correlation typically inflates the rate of false positive associations. We describe a novel parameterization of Bayesian networks that uses random effects to model the correlation within sample units and can be used for structure and parameter learning from correlated data without inflating the Type I error rate. We compare different learning metrics using simulations and illustrate the method in two real examples: an analysis of genetic and non-genetic factors associated with human longevity from a family-based study, and an example of risk factors for complications of sickle cell anemia from a longitudinal study with repeated measures.
What You Don't Know Can Hurt You: Missing Data and Partial Credit Model Estimates

PubMed Central

Thomas, Sarah L.; Schmidt, Karen M.; Erbacher, Monica K.; Bergeman, Cindy S.

2017-01-01

The authors investigated the effect of Missing Completely at Random (MCAR) item responses on partial credit model (PCM) parameter estimates in a longitudinal study of Positive Affect. Participants were 307 adults from the older cohort of the Notre Dame Study of Health and Well-Being (Bergeman and Deboeck, 2014) who completed questionnaires including Positive Affect items for 56 days. Additional missing responses were introduced to the data, randomly replacing 20%, 50%, and 70% of the responses on each item and each day with missing values, in addition to the existing missing data. Results indicated that item locations and person trait level measures diverged from the original estimates as the level of degradation from induced missing data increased. In addition, standard errors of these estimates increased with the level of degradation. Thus, MCAR data does damage the quality and precision of PCM estimates. PMID:26784376
Effectiveness and sustainability of the ViSC Social Competence Program to prevent cyberbullying and cyber-victimization: Class and individual level moderators.

PubMed

Gradinger, Petra; Yanagida, Takuya; Strohmeier, Dagmar; Spiel, Christiane

2016-01-01

We investigated whether the general anti-bullying program ViSC sustainably prevents cyberbullying and cyber-victimization. A longitudinal randomized control group design was used to examine (i) program effectiveness immediately after a 1 year implementation phase and (ii) sustainable program effects 6 months later taking several moderators on the class level (class climate and ethnic diversity) and on the individual level (gender, age, internet usage, traditional bullying/victimization) into account. Effectiveness (e.g., the change between waves 2 and 1) was examined in 2,042 students (47.6% girls), aged 11.7 years (SD = 0.88) enrolled in 18 schools and 103 classes. Sustainability (e.g., the change between waves 3 and 2) was examined in a sub-sample of 6 schools and 35 classes comprising 659 students. The self-assessment multiple-item scales showed longitudinal and multiple group invariance. Factor scores were extracted to compute difference scores for effectiveness (Posttest minus Pretest) and sustainability (Follow-up test minus Posttest) for cyberbullying and cyber-victimization. Multilevel Modeling was applied to examine (i) the effectiveness and (ii) the sustainability of the ViSC intervention controlling for several individual and class level variables. Controlling for covariates, it was demonstrated that the ViSC program is effective in preventing cyberbullying and cyber-victimization and that the effects are sustainable after 6 months. The consequences for cyberbullying prevention are discussed. © 2016 Wiley Periodicals, Inc.
Residential self-selection bias in the estimation of built environment effects on physical activity between adolescence and young adulthood.

PubMed

Boone-Heinonen, Janne; Guilkey, David K; Evenson, Kelly R; Gordon-Larsen, Penny

2010-10-04

Built environment research is dominated by cross-sectional designs, which are particularly vulnerable to residential self-selection bias resulting from health-related attitudes, neighborhood preferences, or other unmeasured characteristics related to both neighborhood choice and health-related outcomes. We used cohort data from the National Longitudinal Study of Adolescent Health (United States; Wave I, 1994-95; Wave III, 2001-02; n = 12,701) and a time-varying geographic information system. Longitudinal relationships between moderate to vigorous physical activity (MVPA) bouts and built and socioeconomic environment measures (landcover diversity, pay and public physical activity facilities per 10,000 population, street connectivity, median household income, and crime rate) from adolescence to young adulthood were estimated using random effects models (biased by unmeasured confounders) and fixed effects models (within-person estimator, which adjusts for unmeasured confounders that are stable over time). Random effects models yielded null associations except for negative crime-MVPA associations [coefficient (95% CI): -0.056 (-0.083, -0.029) in males, -0.061 (-0.090, -0.033) in females]. After controlling for measured and time invariant unmeasured characteristics using within-person estimators, MVPA was higher with greater physical activity pay facilities in males [coefficient (95% CI): 0.024 (0.006, 0.042)], and lower with higher crime rates in males [coefficient (95% CI): -0.107 (-0.140, -0.075)] and females [coefficient (95% CI): -0.046 (-0.083, -0.009)]. Other associations were null or in the counter-intuitive direction. Comparison of within-person estimates to estimates unadjusted for unmeasured characteristics suggest that residential self-selection can bias associations toward the null, as opposed to its typical characterization as a positive confounder. Differential environment-MVPA associations by residential relocation suggest that studies examining changes following residential relocation may be vulnerable to selection bias. The authors discuss complexities of adjusting for residential self-selection and residential relocation, particularly during the adolescent to young adult transition.
Longitudinal relationships between gratitude, deliberate rumination, and posttraumatic growth in adolescents following the Wenchuan earthquake in China.

PubMed

Zhou, Xiao; Wu, Xinchun

2015-10-01

To examine the longitudinal relationship between gratitude, deliberate rumination and posttraumatic growth (PTG) in the adolescent survivors after the Wenchuan earthquake, 217 adolescent survivors were randomly selected from several primary and secondary schools in the county of Wenchuan, and were assessed by questionnaires at three and a half years (T1), four and a half years (T2), five and a half years (T3) after the Wenchuan earthquake, respectively. The results found that there was a one-way predictive relationship of gratitude onto PTG from T1 to T3, and gratitude predicted deliberate rumination from T1 to T2 but not T2 to T3. Deliberate rumination only had a significant positive effect on PTG from T2 to T3, and PTG only predicted deliberate rumination from T1 to T2. These results indicated that gratitude could be a stable predictive factor for the development of PTG, and gratitude could also affect PTG by deliberate rumination. In addition, the predictive effect between deliberate rumination and PTG is unstable with time change. © 2015 Scandinavian Psychological Associations and John Wiley & Sons Ltd.
Collateral benefits of the Family Check-Up on early childhood school readiness: indirect effects of parents' positive behavior support.

PubMed

Lunkenheimer, Erika S; Dishion, Thomas J; Shaw, Daniel S; Connell, Arin M; Gardner, Frances; Wilson, Melvin N; Skuban, Emily M

2008-11-01

The authors examined the longitudinal effects of the Family Check-Up (FCU) on parents' positive behavior support and children's school readiness competencies in early childhood. It was hypothesized that the FCU would promote language skills and inhibitory control in children at risk for behavior problems as an indirect outcome associated with targeted improvements in parents' positive behavior support. High-risk families in the Women, Infants, and Children Nutrition Program participated in a multisite preventive intervention study (N = 731) with 3 yearly assessments beginning at child age 2 years. Positive behavior support was measured using 4 indicators derived from at-home observations of parent-child interaction during semistructured tasks. Longitudinal structural equation models revealed that parents in families randomly assigned to the FCU showed improvements in positive behavior support from child age 2 to 3, which in turn promoted children's inhibitory control and language development from age 3 to 4, accounting for child gender, ethnicity, and parental education. Findings suggest that a brief, ecological preventive intervention supporting positive parenting practices can indirectly foster key facets of school readiness in children at risk.
Application of zero-inflated poisson mixed models in prognostic factors of hepatitis C.

PubMed

Akbarzadeh Baghban, Alireza; Pourhoseingholi, Asma; Zayeri, Farid; Jafari, Ali Akbar; Alavian, Seyed Moayed

2013-01-01

In recent years, hepatitis C virus (HCV) infection represents a major public health problem. Evaluation of risk factors is one of the solutions which help protect people from the infection. This study aims to employ zero-inflated Poisson mixed models to evaluate prognostic factors of hepatitis C. The data was collected from a longitudinal study during 2005-2010. First, mixed Poisson regression (PR) model was fitted to the data. Then, a mixed zero-inflated Poisson model was fitted with compound Poisson random effects. For evaluating the performance of the proposed mixed model, standard errors of estimators were compared. The results obtained from mixed PR showed that genotype 3 and treatment protocol were statistically significant. Results of zero-inflated Poisson mixed model showed that age, sex, genotypes 2 and 3, the treatment protocol, and having risk factors had significant effects on viral load of HCV patients. Of these two models, the estimators of zero-inflated Poisson mixed model had the minimum standard errors. The results showed that a mixed zero-inflated Poisson model was the almost best fit. The proposed model can capture serial dependence, additional overdispersion, and excess zeros in the longitudinal count data.
Idea density measured in late life predicts subsequent cognitive trajectories: implications for the measurement of cognitive reserve.

PubMed

Farias, Sarah Tomaszewski; Chand, Vineeta; Bonnici, Lisa; Baynes, Kathleen; Harvey, Danielle; Mungas, Dan; Simon, Christa; Reed, Bruce

2012-11-01

The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change. ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial abilities, and executive function) were examined as outcomes. Separate random effects models tested the effect of ID on longitudinal change in outcomes, adjusted for age and education. Lower ID was associated with greater subsequent decline in global cognition, semantic memory, episodic memory, and spatial abilities. When analysis was restricted to only participants without dementia at the time ID was collected, results were similar. Linguistic ability in young adulthood, as measured by ID, has been previously proposed as an index of neurocognitive development and/or cognitive reserve. The present study provides evidence that even when ID is measured in old age, it continues to be associated with subsequent cognitive decline and as such may continue to provide a marker of cognitive reserve.
Collateral Benefits of the Family Check-Up on Early Childhood School Readiness: Indirect Effects of Parents’ Positive Behavior Support

PubMed Central

Lunkenheimer, Erika S.; Dishion, Thomas J.; Shaw, Daniel S.; Connell, Arin M.; Gardner, Frances; Wilson, Melvin N.; Skuban, Emily M.

2009-01-01

The authors examined the longitudinal effects of the Family Check-Up (FCU) on parents’ positive behavior support and children’s school readiness competencies in early childhood. It was hypothesized that the FCU would promote language skills and inhibitory control in children at risk for behavior problems as an indirect outcome associated with targeted improvements in parents’ positive behavior support. High-risk families in the Women, Infants, and Children Nutrition Program participated in a multisite preventive intervention study (N = 731) with 3 yearly assessments beginning at child age 2 years. Positive behavior support was measured using 4 indicators derived from at-home observations of parent–child interaction during semistructured tasks. Longitudinal structural equation models revealed that parents in families randomly assigned to the FCU showed improvements in positive behavior support from child age 2 to 3, which in turn promoted children’s inhibitory control and language development from age 3 to 4, accounting for child gender, ethnicity, and parental education. Findings suggest that a brief, ecological preventive intervention supporting positive parenting practices can indirectly foster key facets of school readiness in children at risk. PMID:18999335
Longitudinal changes in everyday life after home modifications for people aging with disabilities.

PubMed

Petersson, Ingela; Kottorp, Anders; Bergström, Jakob; Lilja, Margareta

2009-05-01

To investigate longitudinal impacts of home modifications on the difficulty of performing everyday life tasks for people aging with disabilities, and to investigate whether other factors had any additional impacts on difficulty in everyday life tasks for people receiving home modifications. The sample consisted of 103 persons aging with disabilities and in need of home modifications, divided into an intervention group and a comparison group. The data were first subjected to Rasch analysis and a random coefficient model was used. Participants in the intervention group reported a significantly lower level of difficulty in everyday life tasks compared with those in the comparison group. One confounding factor, number of months waiting for home modification, had an impact on difficulty in everyday life. Home modifications are effective in decreasing difficulty in performing everyday life tasks up to six months after the installation. Furthermore, to be effective home modifications need to be installed in a timely fashion. For each consecutive month the person waited for their home modification the difficulty of performing everyday life tasks increased. Therefore, it is important that home modifications be installed as soon as possible after the need has been identified.
Industrial water pollution, water environment treatment, and health risks in China.

PubMed

Wang, Qing; Yang, Zhiming

2016-11-01

The negative health effects of water pollution remain a major source of morbidity and mortality in China. The Chinese government is making great efforts to strengthen water environment treatment; however, no studies have evaluated the effects of water treatment on human health by water pollution in China. This study evaluated the association between water pollution and health outcomes, and determined the extent to which environmental regulations on water pollution may lead to health benefits. Data were extracted from the 2011 and 2013 China Health and Retirement Longitudinal Study (CHARLS). Random effects model and random effects Logit model were applied to study the relationship between health and water pollution, while a Mediator model was used to estimate the effects of environmental water treatment on health outcomes by the intensity of water pollution. Unsurprisingly, water pollution was negatively associated with health outcomes, and the common pollutants in industrial wastewater had differential impacts on health outcomes. The effects were stronger for low-income respondents. Water environment treatment led to improved health outcomes among Chinese people. Reduced water pollution mediated the associations between water environment treatment and health outcomes. The results of this study offer compelling evidence to support treatment of water pollution in China. Copyright © 2016 Elsevier Ltd. All rights reserved.
Effects of prenatal yoga on women's stress and immune function across pregnancy: A randomized controlled trial.

PubMed

Chen, Pao-Ju; Yang, Luke; Chou, Cheng-Chen; Li, Chia-Chi; Chang, Yu-Cune; Liaw, Jen-Jiuan

2017-04-01

The effects of prenatal yoga on biological indicators have not been widely studied. Thus, we compared changes in stress and immunity salivary biomarkers from 16 to 36 weeks' gestation between women receiving prenatal yoga and those receiving routine prenatal care. For this longitudinal, prospective, randomized controlled trial, we recruited 94 healthy pregnant women at 16 weeks' gestation through convenience sampling from a prenatal clinic in Taipei. Participants were randomly assigned to intervention (n=48) or control (n=46) groups using Clinstat block randomization. The 20-week intervention comprised two weekly 70-min yoga sessions led by a midwife certified as a yoga instructor; the control group received only routine prenatal care. In both groups, participants' salivary cortisol and immunoglobulin A levels were collected before and after yoga every 4 weeks from 16 to 36 weeks' gestation. The intervention group had lower salivary cortisol (p<0.001) and higher immunoglobulin A (p<0.001) levels immediately after yoga than the control group. Specifically, the intervention group had significantly higher long-term salivary immunoglobulin A levels than the control group (p=0.018), and infants born to women in the intervention group weighed more than those born to the control group (p<0.001). Prenatal yoga significantly reduced pregnant women's stress and enhanced their immune function. Clinicians should learn the mechanisms of yoga and its effects on pregnant women. Our findings can guide clinicians to help pregnant women alleviate their stress and enhance their immune function. Copyright © 2017. Published by Elsevier Ltd.
Benefit-Cost Analysis of a Randomized Evaluation of Communities That Care: Monetizing Intervention Effects on the Initiation of Delinquency and Substance Use Through Grade 12

PubMed Central

Kuklinski, Margaret R.; Fagan, Abigail A.; Hawkins, J. David; Briney, John S.; Catalano, Richard F.

2015-01-01

Objective To determine whether the Communities That Care (CTC) prevention system is a cost-beneficial intervention. Methods Data were from a longitudinal panel of 4,407 youth participating in a randomized controlled trial including 24 towns in 7 states, matched in pairs within state and randomly assigned to condition. Significant differences favoring intervention youth in sustained abstinence from delinquency, alcohol use, and tobacco use through Grade 12 were monetized and compared to economic investment in CTC. Results CTC was estimated to produce $4,477 in benefits per youth (discounted 2011 dollars). It cost $556 per youth to implement CTC for 5 years. The net present benefit was $3,920. The benefit-cost ratio was $8.22 per dollar invested. The internal rate of return was 21%. Risk that investment would exceed benefits was minimal. Investment was expected to be recouped within 9 years. Sensitivity analyses in which effects were halved yielded positive cost-beneficial results. Conclusions CTC is a cost-beneficial, community-based approach to preventing initiation of delinquency, alcohol use, and tobacco use. CTC is estimated to generate economic benefits that exceed implementation costs when disseminated with fidelity in communities. PMID:26213527
Metabolic Profiling of Adiponectin Levels in Adults: Mendelian Randomization Analysis.

PubMed

Borges, Maria Carolina; Barros, Aluísio J D; Ferreira, Diana L Santos; Casas, Juan Pablo; Horta, Bernardo Lessa; Kivimaki, Mika; Kumari, Meena; Menon, Usha; Gaunt, Tom R; Ben-Shlomo, Yoav; Freitas, Deise F; Oliveira, Isabel O; Gentry-Maharaj, Aleksandra; Fourkala, Evangelia; Lawlor, Debbie A; Hingorani, Aroon D

2017-12-01

Adiponectin, a circulating adipocyte-derived protein, has insulin-sensitizing, anti-inflammatory, antiatherogenic, and cardiomyocyte-protective properties in animal models. However, the systemic effects of adiponectin in humans are unknown. Our aims were to define the metabolic profile associated with higher blood adiponectin concentration and investigate whether variation in adiponectin concentration affects the systemic metabolic profile. We applied multivariable regression in ≤5909 adults and Mendelian randomization (using cis -acting genetic variants in the vicinity of the adiponectin gene as instrumental variables) for analyzing the causal effect of adiponectin in the metabolic profile of ≤37 545 adults. Participants were largely European from 6 longitudinal studies and 1 genome-wide association consortium. In the multivariable regression analyses, higher circulating adiponectin was associated with higher high-density lipoprotein lipids and lower very-low-density lipoprotein lipids, glucose levels, branched-chain amino acids, and inflammatory markers. However, these findings were not supported by Mendelian randomization analyses for most metabolites. Findings were consistent between sexes and after excluding high-risk groups (defined by age and occurrence of previous cardiovascular event) and 1 study with admixed population. Our findings indicate that blood adiponectin concentration is more likely to be an epiphenomenon in the context of metabolic disease than a key determinant. © 2017 The Authors.
A randomized controlled trial of home visits by neighborhood mentor mothers to improve children's nutrition in South Africa

PubMed Central

le Roux, Ingrid M.; le Roux, Karl; Mbeutu, Kwanie; Comulada, W. Scott; Desmond, Katherine A.; Rotheram-Borus, Mary Jane

2011-01-01

Malnourished children and babies with birth weights under 2500 g are at high risk for negative outcomes over their lifespans. Philani, a paraprofessional home visiting program, was developed to improve nutritional outcomes for young children in South Africa. One “mentor mother” was recruited from each of 37 neighborhoods in Cape Town, South Africa. Mentor mothers were trained to conduct home visits to weigh children under six years old and to support mothers to problem-solve life challenges, especially around nutrition. Households with underweight children were assigned randomly on a 2:1 ratio to the Philani program (n = 500) or to a standard care condition (n = 179); selection effects occurred and children in the intervention households weighed less at recruitment. Children were evaluated over a one-year period (n = 679 at recruitment and n = 638 with at least one follow-up; 94%). Longitudinal random effects models indicated that, over 12 months, the children in the intervention condition gained significantly more weight than children in the control condition. Mentor mothers who are positive peer deviants may be a viable strategy that is efficacious and can build community, and the use of mentor mothers for other problems in South Africa is discussed. PMID:22299019
Using a shared parameter mixture model to estimate change during treatment when termination is related to recovery speed.

PubMed

Gottfredson, Nisha C; Bauer, Daniel J; Baldwin, Scott A; Okiishi, John C

2014-10-01

This study demonstrates how to use a shared parameter mixture model (SPMM) in longitudinal psychotherapy studies to accommodate missingness that is due to a correlation between rate of improvement and termination of therapy. Traditional growth models assume that such a relationship does not exist (i.e., assume that data are missing at random) and produce biased results if this assumption is incorrect. We used longitudinal data from 4,676 patients enrolled in a naturalistic study of psychotherapy to compare results from a latent growth model and an SPMM. In this data set, estimates of the rate of improvement during therapy differed by 6.50%-6.66% across the two models, indicating that participants with steeper trajectories left psychotherapy earliest, thereby potentially biasing inference for the slope in the latent growth model. We conclude that reported estimates of change during therapy may be underestimated in naturalistic studies of therapy in which participants and their therapists determine the end of treatment. Because non-randomly missing data can also occur in randomized controlled trials or in observational studies of development, the utility of the SPMM extends beyond naturalistic psychotherapy data. PsycINFO Database Record (c) 2014 APA, all rights reserved.
Chondron curvature mapping in growth plate cartilage under compressive loading.

PubMed

Vendra, Bhavya B; Roan, Esra; Williams, John L

2018-05-18

The physis, or growth plate, is a layer of cartilage responsible for long bone growth. It is organized into reserve, proliferative and hypertrophic zones. Unlike the reserve zone where chondrocytes are randomly arranged, either singly or in pairs, the proliferative and hypertrophic chondrocytes are arranged within tubular structures called chondrons. In previous studies, the strain patterns within the compressed growth plate have been reported to be nonuniform and inhomogeneous, with an apparent random pattern in compressive strains and a localized appearance of tensile strains. In this study we measured structural deformations along the entire lengths of chondrons when the physis was subjected to physiological (20%) and hyper-physiological (30% and 40%) levels of compression. This provided a means to interpret the apparent random strain patterns seen in texture correlation maps in terms of bending deformations of chondron structures and provided a physical explanation for the inhomogeneous and nonuniform strain patterns reported in previous studies. We observed relatively large bending deformations (kinking) of the chondron structures at the interface of the reserve and proliferative zones during compression. Bending in this region may induce dividing cells to align longitudinally to maintain column formation and drive longitudinal growth. Copyright © 2018 Elsevier Ltd. All rights reserved.

Family-focused preventive interventions: evaluating parental risk moderation of substance use trajectories.

PubMed

Guyll, Max; Spoth, Richard L; Chao, Wei; Wickrama, K A S; Russell, Daniel

2004-06-01

Four years of longitudinal data from 373 families participating in a randomized intervention-control clinical trial were used to examine whether intervention effects on adolescent alcohol and tobacco use trajectories were moderated by family risk, as defined by parental social emotional maladjustment. Consistent with earlier outcome evaluations based on analyses of covariance, analyses confirmed that both the Preparing for the Drug Free Years program and the Iowa Strengthening Families Program favorably influenced alcohol use index trajectories across the time frame of the study; only the latter program, however, evidenced positive effects on a tobacco use index. Concerning the primary research question, analyses provided no support for family risk moderation of any intervention effect. Findings indicate the feasibility of developing universal preventive interventions that offer comparable benefits to all families.
Estimating onset time from longitudinal and cross-sectional data with an application to estimating gestational age from longitudinal maternal anthropometry during pregnancy and neonatal anthropometry at birth.

PubMed

Ortega-Villa, Ana Maria; Grantz, Katherine L; Albert, Paul S

2018-06-01

Determining the date of conception is important for estimating gestational age and monitoring whether the fetus and mother are on track in their development and pregnancy. Various methods based on ultrasound have been proposed for dating a pregnancy in high resource countries. However, such techniques may not be available in under-resourced countries. We develop a shared random parameter model for estimating the date of conception using longitudinal assessment of multiple maternal anthropometry and cross-sectional neonatal anthropometry. The methodology is evaluated with a training-test set paradigm as well as with simulations to examine the robustness of the method to model misspecification. We illustrate this new methodology with data from the NICHD Fetal Growth Studies.
Modeling Longitudinal Changes in Older Adults’ Memory for Spoken Discourse: Findings from the ACTIVE Cohort

PubMed Central

Payne, Brennan R.; Gross, Alden L.; Parisi, Jeanine M.; Sisco, Shannon M.; Stine-Morrow, Elizabeth A. L.; Marsiske, Michael; Rebok, George W.

2014-01-01

Episodic memory shows substantial declines with advancing age, but research on longitudinal trajectories of spoken discourse memory (SDM) in older adulthood is limited. Using parallel process latent growth curve models, we examined 10 years of longitudinal data from the no-contact control group (N = 698) of the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) randomized controlled trial in order to test (a) the degree to which SDM declines with advancing age, (b) predictors of these age-related declines, and (c) the within-person relationship between longitudinal changes in SDM and longitudinal changes in fluid reasoning and verbal ability over 10 years, independent of age. Individuals who were younger, White, had more years of formal education, were male, and had better global cognitive function and episodic memory performance at baseline demonstrated greater levels of SDM on average. However, only age at baseline uniquely predicted longitudinal changes in SDM, such that declines accelerated with greater age. Independent of age, within-person decline in reasoning ability over the 10-year study period was substantially correlated with decline in SDM (r = .87). An analogous association with SDM did not hold for verbal ability. The findings suggest that longitudinal declines in fluid cognition are associated with reduced spoken language comprehension. Unlike findings from memory for written prose, preserved verbal ability may not protect against developmental declines in memory for speech. PMID:24304364
Building better bones in childhood: a randomized controlled study to test the efficacy of a dietary intervention program to increase calcium intake.

PubMed

Weber, D R; Stark, L J; Ittenbach, R F; Stallings, V A; Zemel, B S

2017-06-01

Many children do not consume the recommended daily allowance of calcium. Inadequate calcium intake in childhood may limit bone accrual. The objective of this study was to determine if a behavioral modification and nutritional education (BM-NE) intervention improved dietary calcium intake and bone accrual in children. 139 (86 female) healthy children, 7-10 years of age, were enrolled in this randomized controlled trial conducted over 36 months. Participants randomized to the BM-NE intervention attended five sessions over a 6-week period designed to increase calcium intake to 1500 mg/day. Participants randomized to the usual care (UC) group received a single nutritional counseling session. The Calcium Counts Food Frequency Questionnaire was used to assess calcium intake; dual energy X-ray absorptiometry was used to assess areal bone mineral density (aBMD) and bone mineral content (BMC). Longitudinal mixed effects models were used to assess for an effect of the intervention on calcium intake, BMC and aBMD. BM-NE participants had greater increases in calcium intake that persisted for 12 months following the intervention compared with UC. The intervention had no effect on BMC or aBMD accrual. Secondary analyses found a negative association between calcium intake and adiposity such that greater calcium intake was associated with lesser gains in body mass index and fat mass index. A family-centered BM-NE intervention program in healthy children was successful in increasing calcium intake for up to 12 months but had no effect on bone accrual. A beneficial relationship between calcium intake and adiposity was observed and warrants future study.
Jump starting skeletal health: a 4-year longitudinal study assessing the effects of jumping on skeletal development in pre and circum pubertal children.

PubMed

Gunter, Katherine; Baxter-Jones, Adam D G; Mirwald, Robert L; Almstedt, Hawley; Fuller, Arwen; Durski, Shantel; Snow, Christine

2008-04-01

Evidence suggests bone mineral increases attributable to exercise training prior to puberty may confer a significant advantage into adulthood. However, there is a dearth of supportive prospective longitudinal data. The purpose of this study was to assess bone mineral content (BMC) of the whole body (WB), total hip (TH), femoral neck (FN) and lumbar spine (LS) over four years in pre-pubertal boys and girls following a 7-month jumping intervention. The study population included 107 girls and 98 boys aged 8.6+/-0.88 years at baseline. Participating schools were randomly assigned as either intervention or control school. Children at the intervention school (n=101) participated in a jumping intervention embedded within the standard PE curriculum. The control school children (n=104) had similar exposure to PE without the jumping intervention. BMC was assessed by DXA at baseline, at 7-month post intervention, and annually thereafter for three years totaling 5 measurement opportunities. Multi-level random effects models were constructed and used to predict change from study entry in BMC parameters at each measurement occasion. A significant intervention effect was found at all bone sites. The effect was greatest immediately following the intervention (at 7 months) but still significant three years after the intervention. At 7 months, intervention participants had BMC values that were 7.9%, 8.4%, 7.7% and 7.3% greater than the controls at the LS, TH, FN and WB, respectively (p<0.05), when the confounders of age, maturity and tissue mass were controlled. Three years after the intervention had concluded the intervention group had 2.3%, 3.2%, 4.4% and 2.9% greater BMC than controls at the LS, TH, FN and WB respectively (p<0.05), when the confounders of age, maturity and tissue mass were controlled. This provides evidence that short-term high impact exercise in pre-puberty has a persistent effect over and above the effects of normal growth and development. If the benefits are sustained until BMC plateaus in early adulthood, this could have substantial effects on fracture risk.
Activation and Self-Efficacy in a Randomized Trial of a Depression Self-Care Intervention.

PubMed

McCusker, Jane; Lambert, Sylvie D; Cole, Martin G; Ciampi, Antonio; Strumpf, Erin; Freeman, Ellen E; Belzile, Eric

2016-12-01

In a sample of primary care participants with chronic physical conditions and comorbid depressive symptoms: to describe the cross-sectional and longitudinal associations of activation and self-efficacy with demographic, physical and mental health status, health behaviors, depression self-care, health care utilization, and use of self-care tools; and to examine the effects of a depression self-care coaching intervention on these two outcomes. Design/Study Setting. A secondary analysis of activation and self-efficacy data collected as part of a randomized trial to compare the effects of a telephone-based coached depression self-care intervention with a noncoached intervention. Activation (Patient Activation Measure) was measured at baseline and 6 months. Depression self-care self-efficacy was assessed at baseline, at 3 months, and at 6 months. In multivariable cross-sectional analyses (n = 215), activation and/or self-efficacy were associated with language, birthplace, better physical and mental health, individual exercise, specialist visits, and antidepressant nonuse. In longitudinal analyses (n = 158), an increase in activation was associated with increased medication adherence; an increase in self-efficacy was associated with use of cognitive self-care strategies and increases in social and solitary activities. There were significant improvements from baseline to 6 months in activation and self-efficacy scores both among coached and noncoached groups. The self-care coaching intervention did not affect 6-month activation or self-efficacy but was associated with quicker improvement in self-efficacy. Overall, the results for activation and self-efficacy were similar, although self-efficacy correlated more consistently than activation with depression-specific behaviors and was responsive to a depression self-care coaching intervention. © 2016 Society for Public Health Education.
Pediatric advance care planning (pACP) for teens with cancer and their families: Design of a dyadic, longitudinal RCCT.

PubMed

Curtin, Katherine B; Watson, Anne E; Wang, Jichuan; Okonkwo, Obianuju C; Lyon, Maureen E

2017-11-01

Cancer is the leading cause of disease-related death for adolescents and young adults (AYAs) in the United States. Parents of AYAs with life-threatening illnesses have expressed the desire to talk to their children about end of life (EOL) care, yet, like caregivers of adult patients, struggle to initiate this conversation. Building Evidence for Effective Palliative/End of Life Care for Teens with Cancer is a longitudinal, randomized, controlled, single-blinded clinical trial aimed at evaluating the efficacy of FAmily CEntered disease-specific advance care planning (ACP) for teens with cancer (FACE-TC). A total of 130 dyads (260 subjects) composed of AYAs 14-20years old with cancer and their family decision maker (≥18years old) will be recruited from pediatric oncology programs at Akron Children's Hospital and St. Jude Children's Research Hospital. Dyads will be randomized to either the FACE-TC intervention or Treatment as Usual (TAU) control. FACE-TC intervention dyads will complete three 60-minute ACP sessions held at weekly intervals. Follow-up data will be collected at 3, 6, 12, and 18months post-intervention by a blinded research assistant (RA). The effects of FACE-TC on patient-family congruence in treatment preferences, quality of life (QOL), and advance directive completion will be analyzed. FACE-TC is an evidenced-based and patient-centered intervention that considers QOL and EOL care according to the AYA's representation of illness. The family is involved in the ACP process to facilitate shared decision making, increase understanding of the AYA's preferences, and make a commitment to honor the AYA's wishes. Copyright © 2017 Elsevier Inc. All rights reserved.
Behavior in children with Prader-Willi syndrome before and during growth hormone treatment: a randomized controlled trial and 8-year longitudinal study.

PubMed

Lo, Sin T; Siemensma, Elbrich P C; Festen, Dederieke A M; Collin, Philippe J L; Hokken-Koelega, Anita C S

2015-09-01

Information on behavior of children with Prader-Willi syndrome (PWS) and the effect of growth hormone (GH) treatment is scarce. Parents report less problem behavior during GH treatment. Forty-two pre-pubertal children, aged 3.5-14 years were studied in a randomized controlled GH trial (RCT) during 2 years, followed by a longitudinal study during 8 years of GH treatment. Behavior was measured annually by the Developmental Behavior Checklist for children with intellectual disability (DBC) and a Dutch questionnaire to evaluate social behavioral problems in children, the Children's Social Behavior Questionnaire (CSBQ). Problem behavior measured by the DBC in children with PWS was similar compared to peers with comparable intellectual disability. Scores on 'Social disabilities' subscale were however significantly higher compared to the DBC total score (p < 0.01). A lower IQ was associated with more self-absorbed behavior, more communication problems and more problem behavior in general. Problem behavior measured by the CSBQ was similar compared to peers with a comparable intellectual disability, but children with PWS scored significantly higher on the 'Not tuned', 'Understanding', and 'Stereotyped' subscales than the CSBQ total score (p < 0.05 for all subscales and p = 0.001 for the 'Not tuned'-subscale). There were no significant effects of GH treatment during the RCT and 8 years of GH treatment. Children with PWS showed similar problem behavior as a reference population with a comparable intellectual disability. Social problems were the most pronounced within-problem behavior in PWS. In contrast to our expectations and parents reports, our study shows no improvement but also no deterioration of behavioral problems in children with PWS during long-term GH treatment.
Escitalopram is Associated with Reductions in Pain Severity and Pain Interference in Opioid Dependent Patients with Depressive Symptoms

PubMed Central

Tsui, Judith I.; Herman, Debra S.; Kettavong, Malyna; Anderson, Bradley J.; Stein, Michael D.

2011-01-01

Pain is common among opioid dependent patients, yet pharmacologic strategies are limited. The aim of this study was to explore whether escitalopram, a selective serotonin reuptake inhibitor, was associated with reductions in pain. The study used longitudinal data from a randomized, controlled trial that evaluated the effects of escitalopram on treatment retention in patients with depressive symptoms who were initiating buprenorphine/naloxone for treatment of opioid dependence. Participants were randomized to take escitalopram 10mg or placebo daily. Changes in pain severity, pain interference and depression were assessed at 1, 2 and 3 months visits using the Visual Analog Scale, Brief Pain Inventory and the Beck Depression Inventory II, respectively. Fixed-effects estimator for panel regression models were used to assess the effects of intervention on changes in outcomes over time. Additional models were estimated to explore whether the intervention effect was mediated by within-person changes in depression. In this sample of 147 adults, we found that participants randomized to escitalopram had significantly larger reductions on both pain severity (b = −14.34, t = −2.66, p < .01) and pain interference (b = −1.20, t = −2.23, p < .05) between baseline and follow-up. After adjusting for within-subject changes in depression, the estimated effects of escitalopram on pain severity and pain interference were virtually identical to the unadjusted effects. In summary, this study of opioid-dependent patients with depressive symptoms found that treatment with escitalopram was associated with clinically meaningful reductions in pain severity and pain interference during the first three months of therapy. PMID:21924552
Longitudinal Study of New and Prevalent Use of Self-Monitoring of Blood Glucose

PubMed Central

Karter, Andrew J.; Parker, Melissa M.; Moffet, Howard H.; Spence, Michele M.; Chan, James; Ettner, Susan L.; Selby, Joe V.

2008-01-01

OBJECTIVE We sought to assess longitudinal association between self-monitoring of blood glucose (SMBG) and glycemic control in diabetic patients from an integrated health plan (Kaiser Permanente Northern California). RESEARCH DESIGN AND METHODS Longitudinal analyses of glycemic control among 1) 16,091 patients initiating SMBG (new-user cohort) and 2) 15,347 ongoing users of SMBG (prevalent-user cohort). SMBG frequency was based on pharmacy use (number of blood glucose test strips dispensed), and glycemic control was based on HbA1c (A1C). In the new-user cohort, ANCOVA models (pre- and posttest design) were used to assess the effect of initiating SMBG. In the prevalent-user cohort, repeated-measure, mixed-effects models with random-intercept and time-dependent covariates were used to assess changes in SMBG and A1C. All models were stratified by therapy (no medications, oral agents only, or insulin) and adjusted for baseline A1C, sociodemographics, insulin injection frequency, comorbidity index, medication adherence, smoking status, health care use, and provider specialty. RESULTS Greater SMBG practice frequency among new users was associated with a graded decrease in A1C (relative to nonusers) regardless of diabetes therapy (P < 0.0001). Changes in SMBG frequency among prevalent users were associated with an inverse graded change in A1C only among pharmacologically treated patients (P < 0.0001). CONCLUSIONS These observational findings are consistent with short-term benefits of initiating SMBG practice for all patients but continuing benefits only for pharmacologically treated patients. Differences in effectiveness between new versus prevalent users of SMBG have implications for guideline development and interpretation of observational outcomes data. PMID:16873776
Flow and axial dispersion in a sinusoidal-walled tube: Effects of inertial and unsteady flows

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

Richmond, Marshall C.; Perkins, William A.; Scheibe, Timothy D.

2013-12-01

Dispersion in porous media flows has been the subject of much experimental, theoretical and numerical study. Here we consider a wavy-walled tube (a three-dimensional tube with sinusoidally-varying diameter) as a simplified conceptualization of flow in porous media, where constrictions represent pore throats and expansions pore bodies. A theoretical model for effective (macroscopic) longitudinal dispersion in this system has been developed by volume averaging the microscale velocity field. Direct numerical simulation using computational fluid dynamics (CFD) methods was used to compute velocity fields by solving the Navier-Stokes equations, and also to numerically solve the volume averaging closure problem, for a rangemore » of Reynolds numbers (Re) spanning the low-Re to inertial flow regimes, including one simulation at Re = 449 for which unsteady flow was observed. Dispersion values were computed using both the volume averaging solution and a random walk particle tracking method, and results of the two methods were shown to be consistent. Our results are compared to experimental measurements of dispersion in porous media and to previous theoretical results for the low-Re, Stokes flow regime. In the steady inertial regime we observe an power-law increase in effective longitudinal dispersion (DL) with Re, consistent with previous results. This rapid rate of increase is caused by trapping of solute in expansions due to flow separation (eddies). For the unsteady case (Re = 449), the rate of increase of DL with Re was smaller than that observed at lower Re. Velocity fluctuations in this regime lead to increased rates of solute mass transfer between the core flow and separated flow regions, thus diminishing the amount of tailing caused by solute trapping in eddies and thereby reducing longitudinal dispersion.« less
Social disadvantage and individual vulnerability: a longitudinal investigation of welfare receipt and mental health in Australia.

PubMed

Kiely, Kim M; Butterworth, Peter

2013-07-01

To examine longitudinal associations between mental health and welfare receipt among working-age Australians. We analysed 9 years of data from 11,701 respondents (49% men) from the Household, Income and Labour Dynamics in Australia (HILDA) Survey. Mental health was assessed by the mental health subscale from the Short Form 36 questionnaire. Linear mixed models were used to examine the longitudinal associations between mental health and income support adjusting for the effects of demographic and socio-economic factors, physical health, lifestyle behaviours and financial stress. Within-person variation in welfare receipt over time was differentiated from between-person propensity to receive welfare payments. Random effect models tested the effects of income support transitions. Socio-demographic and financial variables explained the association between mental health and income support for those receiving student and parenting payments. Overall, recipients of disability, unemployment and mature age payments had poorer mental health regardless of their personal, social and financial circumstances. In addition, those receiving unemployment and disability payments had even poorer mental health at the times that they were receiving income support relative to the times when they were not. The greatest reductions in mental health were associated with transitions to disability payments and parenting payments for single parents. The poor mental health of welfare recipients may limit their opportunities to gain work and participate in community life. In part, this seems to reflect their adverse social and personal circumstances. However, there remains evidence of a direct link between welfare receipt and poor mental health that could be due to factors such as welfare stigma or other adverse life events coinciding with welfare receipt for those receiving unemployment or disability payments. Understanding these factors is critical to inform the next stage of welfare reform.
Centrifugal Expansion of Fundus Autofluorescence Patterns in Stargardt Disease Over Time

PubMed Central

Cukras, Catherine A.; Wong, Wai T.; Caruso, Rafael; Cunningham, Denise; Zein, Wadih; Sieving, Paul

2012-01-01

Objective Changing lipofuscin and melanin content in RPE cells has been hypothesized to contribute to Stargardt disease pathogenesis. Longitudinal study of autofluorescence in Stargardt disease which reflect changing fluorophore compositions can reveal aspects of disease progression not previously evident. Method We examined the temporal-spatial patterns of fundus autofluorescence with excitation at both 488 nm (standard fundus autofluorescence, FAF) and 795nm (near infrared autofluorescence, NIA) in a longitudinal case series involving 8 eyes of 4 patients (range of follow-up = 11 to 57 months; mean = 39 months). Image processing was performed to analyze spatial and temporal cross-modality associations. Results Longitudinal FAF imaging of fleck lesions revealed hyperautofluorescent lesions that extended in a centrifugal direction from the fovea with time. Patterns of spread were non-random and followed a radial path that leaves behind a trail of diminishing autofluorescence. Longitudinal NIA imaging also demonstrated centrifugal lesion spread, but with fewer hyperautofluorescent lesions, suggestive of more transient hyperautofluorescence and more rapid decay at longer wavelengths. FAF and NIA abnormalities were spatially correlated to each other, and together reflect systematic progressions in fleck distribution and fluorophore composition occurring during the natural history of the disease. Conclusion Stargardt disease fleck lesions do not evolve randomly in location but instead follow consistent patterns of radial expansion and a systematic decay of autofluorescence that reflect changing lipofuscin and melanin compositions in RPE cells. These progressive foveal-to-peripheral changes are helpful in elucidating molecular and cellular mechanisms underlying Stargardt disease and may constitute potential outcome measures in clinical trials. PMID:21987580
Anthropometric Differences between HIV-Infected Individuals Prior to Antiretroviral Treatment and the General Population from 1998–2007: The AIDS Clinical Trials Group Longitudinal Linked Randomized Trials (ALLRT) Cohort and NHANES

PubMed Central

Atkinson, Benjamin E.; Krishnan, Supriya; Cox, Gary; Hulgan, Todd; Collier, Ann C.

2013-01-01

Objective To assess differences in body circumferences and body mass index (BMI, kg/m2) between antiretroviral treatment (ART) naïve HIV-infected and HIV-uninfected persons. Methods Waist, arm, and thigh circumferences and BMI were measured within the ALLRT and NHANES cohorts between 1998 and 2007. ALLRT is a prospective, longitudinal study of U.S. participants enrolled in randomized HIV treatment studies conducted by the AIDS Clinical Trials Group (ACTG). NHANES is a representative group of the US population. The cohorts were analyzed in two time periods, to account for trends towards increased adiposity. Anthropometrics were displayed in percentiles by age and sex. Multiple linear regression models examined differences between cohorts. Results ALLRT had more males (82% versus 48%, p<0.0001), more black participants (32% versus 23%, p<0.0001), and less Hispanics (21% versus 30%, p<0.0001) than NHANES. Mean BMI was smaller in ALLRT males and females compared to NHANES by 1.6–2.4 kg/m2 (p<0.0001). Mean waist and arm circumferences in both sexes and time periods were significantly smaller in ALLRT than in NHANES (p<0.0001). Mean thigh circumference in ALLRT was also smaller than NHANES among males (p<0.0001 in both time periods) and females (p = 0.01 in the early time period). Conclusions Differences in anthropometrics existed prior to ART initiation, in this large national cohort of HIV-infected individuals, compared to a representative HIV-uninfected cohort, indicating that HIV and its complications have important effects on body shape. Further longitudinal examination of anthropometrics in this HIV-infected cohort may provide additional insight into disease risk. Trial Registration NCT00001137 at www.clinicaltrials.gov. PMID:23755215
Favorable longitudinal change of lung function in patients with asthma-COPD overlap from a COPD cohort.

PubMed

Park, Hye Yun; Lee, Suh-Young; Kang, Danbee; Cho, Juhee; Lee, Hyun; Lim, Seong Yong; Yoon, Ho Il; Ra, Seung Won; Kim, Ki Uk; Oh, Yeon-Mok; Sin, Don D; Lee, Sang-Do; Park, Yong Bum

2018-03-02

The recognition of asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) as a distinct phenotype of COPD or asthma has increased. Although ACO has worse clinical features than non-ACO COPD, limited information is available on long-term outcomes of lung function decline for ACO and non-ACO COPD. COPD patients with at least 3 years of follow-up were selected from the Korean Obstructive Lung Disease cohort. ACO was defined based on 3 major criteria: 1) airflow limitation in individuals 40 years of age and older, 2) ≥10 pack-years of smoking history, and 3) a history of asthma or bronchodilator response of > 400 mL in forced expiratory volume in 1 s (FEV 1 ) at baseline; and at least 1 minor criterion: 1) history of atopy or allergic rhinitis, 2) two separated bronchodilator responses of ≥12% and 200 mL in FEV 1 , or 3) peripheral blood eosinophils ≥300 cells/μL. Lung function decline was compared using a linear mixed effects model for longitudinal data with random intercept and random slope. Among 239 patients, 47 were diagnosed with ACO (19.7%). During the follow-up period, change in smoking status, use of inhaled corticosteroids (ICS) and long-acting β2-agonists or ICS and at least 2 exacerbations per year were similar between patients with non-ACO COPD and ACO. Over a median follow-up duration of 5.8 years, patients with non-ACO COPD experienced a faster annual decline in pre-bronchodilator FEV 1 than patients with ACO (- 29.3 ml/year vs. -13.9 ml/year, P = 0.042), which was persistent after adjustment for confounders affecting lung function decline. Patients with ACO showed favorable longitudinal changes in lung function compared to COPD patients over a median follow-up of 5.8 years.
Predictors of long-term change of a physical activity promotion programme in primary care

PubMed Central

2014-01-01

Background Further research is needed to improve the evidence regarding determinants of physical activity (PA) as a crucial step to plan higher effective intervention strategies. The goal of the present study is to identify socio-demographic and clinical characteristics of primary care (PHC) insufficiently active patients that are associated with longitudinal changes in the level of physical activity. Methods Longitudinal analysis of baseline socio-demographic and clinical predictors of physical activity change in insufficiently active PHC patients who participated in a PA-promoting multi-centre randomized clinical trial conducted from October 2003 through March 2006. The primary outcome measure was the self-reported physical activity assessed with the 7-day Physical Activity Recall (PAR), at baseline, 6, 12 and 24 months. Baseline covariates included sex, age, social class, anthropometric measures and other cardiovascular risk factors or associated diseases (Diabetes, HTA, tobacco use, etc.), and stage of readiness to change PA. Generalized linear mixed models were used to estimate longitudinal association of studied variables on PA change over the three follow-up measurements. Results A total of 3691 patients (85% of the 4317 recruited in the trial) with at least one follow-up measurement were included in the longitudinal analysis. At baseline, analysed patients (mean age: 50.6 years; 64.6% women) devoted 34.7 minutes and 2.36 metabolic equivalent hours per week (MET.h/week) to moderate and vigorous physical activity. Older age, male gender, higher social class, lower BMI, diagnosis of diabetes or hypertension, and measurement season were significant predictors of PA longitudinal change. The effect of baseline readiness to change on PA dose was modified by time, showing a positive gradient in favour of those with more readiness to change that increases significantly at 12 and 24 months (p-value interaction < .0001). Conclusions Identified baseline characteristics such as readiness to change and risk factors can guide physicians to prioritize time and intervention efforts for maximizing their impact on insufficiently active PHC patients. PMID:24491081
A multicohort, longitudinal study of cerebellar development in attention deficit hyperactivity disorder.

PubMed

Shaw, Philip; Ishii-Takahashi, Ayaka; Park, Min Tae; Devenyi, Gabriel A; Zibman, Chava; Kasparek, Steven; Sudre, Gustavo; Mangalmurti, Aman; Hoogman, Martine; Tiemeier, Henning; von Polier, Georg; Shook, Devon; Muetzel, Ryan; Chakravarty, M Mallar; Konrad, Kerstin; Durston, Sarah; White, Tonya

2018-04-25

The cerebellum supports many cognitive functions disrupted in attention deficit hyperactivity disorder (ADHD). Prior neuroanatomic studies have been often limited by small sample sizes, inconsistent findings, and a reliance on cross-sectional data, limiting inferences about cerebellar development. Here, we conduct a multicohort study using longitudinal data, to characterize cerebellar development. Growth trajectories of the cerebellar vermis, hemispheres and white matter were estimated using piecewise linear regression from 1,656 youth; of whom 63% had longitudinal data, totaling 2,914 scans. Four cohorts participated, all contained childhood data (age 4-12 years); two had adolescent data (12-25 years). Growth parameters were combined using random-effects meta-analysis. Diagnostic differences in growth were confined to the corpus medullare (cerebellar white matter). Here, the ADHD group showed slower growth in early childhood compared to the typically developing group (left corpus medullare z = 2.49, p = .01; right z = 2.03, p = .04). This reversed in late childhood, with faster growth in ADHD in the left corpus medullare (z = 2.06, p = .04). Findings held when gender, intelligence, comorbidity, and psychostimulant medication were considered. Across four independent cohorts, containing predominately longitudinal data, we found diagnostic differences in the growth of cerebellar white matter. In ADHD, slower white matter growth in early childhood was followed by faster growth in late childhood. The findings are consistent with the concept of ADHD as a disorder of the brain's structural connections, formed partly by developing cortico-cerebellar white matter tracts. © 2018 Association for Child and Adolescent Mental Health.
Using Rasch motor FIM individual growth curves to inform clinical decisions for persons with paraplegia.

PubMed

Pretz, C R; Kozlowski, A J; Charlifue, S; Chen, Y; Heinemann, A W

2014-09-01

A longitudinal retrospective study. To better understand individual-level temporal change in functional status for participants with paraplegia in the National Spinal Cord Injury Database (NSCID), as measured by Rasch Transformed Motor Functional Indepedence Measure (FIM) scores. Multicenter/Multistate longitudinal study across the United States. Non-linear random effects modeling, that is, individual growth curve analysis of retrospective data obtained from the National Institute on Disability and Rehabilitation Research (NIDRR) NSCID. We generated non-linear individual level trajectories of recovery for Rasch Transformed Motor FIM scores that rise rapidly from inpatient rehabilitation admission to a plateau. Trajectories are based on relationships between growth parameters and patient and injury factors: race, gender, level of education at admission, age at injury, neurological level at discharge, American Spinal Injury Association Impairment Scale (AIS) at discharge, days from injury to first system inpatient rehabilitation admission, rehabilitation length of stay, marital status and etiology. On the basis of study results, an interactive tool was developed to represent individual level longitudinal outcomes as trajectories based upon an individual's given baseline characteristics, that is, information supplied by the covariates and provides a robust description of temporal change for those with paraplegia within the NSCID. This methodology allows researchers and clinicians to generate and better understand patient-specific trajectories through the use of an automated interactive tool where a nearly countless number of longitudinal paths of recovery can be explored. Projected trajectories holds promise in facilitating planning for inpatient and outpatient services, which could positively impact long term outcomes.
Regression calibration for models with two predictor variables measured with error and their interaction, using instrumental variables and longitudinal data.

PubMed

Strand, Matthew; Sillau, Stefan; Grunwald, Gary K; Rabinovitch, Nathan

2014-02-10

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured-with-error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) - outdoor fine particulate matter and cigarette smoke - and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE 4 , outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory. Copyright © 2013 John Wiley & Sons, Ltd.
DNA Methylation and BMI: Investigating Identified Methylation Sites at HIF3A in a Causal Framework

PubMed Central

Richmond, Rebecca C.; Ward, Mary E.; Fraser, Abigail; Lyttleton, Oliver; McArdle, Wendy L.; Ring, Susan M.; Gaunt, Tom R.; Lawlor, Debbie A.; Davey Smith, George; Relton, Caroline L.

2016-01-01

Multiple differentially methylated sites and regions associated with adiposity have now been identified in large-scale cross-sectional studies. We tested for replication of associations between previously identified CpG sites at HIF3A and adiposity in ∼1,000 mother-offspring pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC). Availability of methylation and adiposity measures at multiple time points, as well as genetic data, allowed us to assess the temporal associations between adiposity and methylation and to make inferences regarding causality and directionality. Overall, our results were discordant with those expected if HIF3A methylation has a causal effect on BMI and provided more evidence for causality in the reverse direction (i.e., an effect of BMI on HIF3A methylation). These results are based on robust evidence from longitudinal analyses and were also partially supported by Mendelian randomization analysis, although this latter analysis was underpowered to detect a causal effect of BMI on HIF3A methylation. Our results also highlight an apparent long-lasting intergenerational influence of maternal BMI on offspring methylation at this locus, which may confound associations between own adiposity and HIF3A methylation. Further work is required to replicate and uncover the mechanisms underlying the direct and intergenerational effect of adiposity on DNA methylation. PMID:26861784

Reducing diarrhoea in Guatemalan children: randomized controlled trial of flocculant-disinfectant for drinking-water.

PubMed Central

Chiller, Tom M.; Mendoza, Carlos E.; Lopez, M. Beatriz; Alvarez, Maricruz; Hoekstra, Robert M.; Keswick, Bruce H.; Luby, Stephen P.

2006-01-01

OBJECTIVE: To examine the effect of a new point-of-use treatment for drinking-water, a commercially developed flocculant-disinfectant, on the prevalence of diarrhoea in children. METHODS: We conducted a randomized controlled trial among 514 rural Guatemalan households, divided into 42 neighbourhood clusters, for 13 weeks, from 4 November 2002 through 31 January 2003. Clusters assigned to water treatment with the flocculant-disinfectant were compared with those using their usual water-handling practices. The longitudinal prevalence of diarrhoea was calculated as the proportion of total days with diarrhoea divided by the total number of days of observation. The prevalence of diarrhoea was compared using the Wilcoxon rank-sum test. FINDINGS: The 1702 people in households receiving the disinfectant had a prevalence of diarrhoea that was 40% lower than that among the 1699 people using standard water-handling practices (0.9% versus 1.5%; P = 0.001). In households using the flocculant-disinfectant, children < 1 year of age had a 39% lower prevalence of diarrhoea than those in households using their standard practices (3.7% versus 6.0%; P = 0.005). CONCLUSION: In settings where families rarely treat drinking-water, we introduced a novel flocculant-disinfectant that reduced the longitudinal prevalence of diarrhoea, especially among children aged < 1 year, among whom diarrhoea has been strongly associated with mortality. Successful introduction and use of this product could contribute to preventing diarrhoeal disease globally. PMID:16501712
Attrition Bias Related to Missing Outcome Data: A Longitudinal Simulation Study.

PubMed

Lewin, Antoine; Brondeel, Ruben; Benmarhnia, Tarik; Thomas, Frédérique; Chaix, Basile

2018-01-01

Most longitudinal studies do not address potential selection biases due to selective attrition. Using empirical data and simulating additional attrition, we investigated the effectiveness of common approaches to handle missing outcome data from attrition in the association between individual education level and change in body mass index (BMI). Using data from the two waves of the French RECORD Cohort Study (N = 7,172), we first examined how inverse probability weighting (IPW) and multiple imputation handled missing outcome data from attrition in the observed data (stage 1). Second, simulating additional missing data in BMI at follow-up under various missing-at-random scenarios, we quantified the impact of attrition and assessed how multiple imputation performed compared to complete case analysis and to a perfectly specified IPW model as a gold standard (stage 2). With the observed data in stage 1, we found an inverse association between individual education and change in BMI, with complete case analysis, as well as with IPW and multiple imputation. When we simulated additional attrition under a missing-at-random pattern (stage 2), the bias increased with the magnitude of selective attrition, and multiple imputation was useless to address it. Our simulations revealed that selective attrition in the outcome heavily biased the association of interest. The present article contributes to raising awareness that for missing outcome data, multiple imputation does not do better than complete case analysis. More effort is thus needed during the design phase to understand attrition mechanisms by collecting information on the reasons for dropout.
A comparison of multiple imputation methods for handling missing values in longitudinal data in the presence of a time-varying covariate with a non-linear association with time: a simulation study.

PubMed

De Silva, Anurika Priyanjali; Moreno-Betancur, Margarita; De Livera, Alysha Madhu; Lee, Katherine Jane; Simpson, Julie Anne

2017-07-25

Missing data is a common problem in epidemiological studies, and is particularly prominent in longitudinal data, which involve multiple waves of data collection. Traditional multiple imputation (MI) methods (fully conditional specification (FCS) and multivariate normal imputation (MVNI)) treat repeated measurements of the same time-dependent variable as just another 'distinct' variable for imputation and therefore do not make the most of the longitudinal structure of the data. Only a few studies have explored extensions to the standard approaches to account for the temporal structure of longitudinal data. One suggestion is the two-fold fully conditional specification (two-fold FCS) algorithm, which restricts the imputation of a time-dependent variable to time blocks where the imputation model includes measurements taken at the specified and adjacent times. To date, no study has investigated the performance of two-fold FCS and standard MI methods for handling missing data in a time-varying covariate with a non-linear trajectory over time - a commonly encountered scenario in epidemiological studies. We simulated 1000 datasets of 5000 individuals based on the Longitudinal Study of Australian Children (LSAC). Three missing data mechanisms: missing completely at random (MCAR), and a weak and a strong missing at random (MAR) scenarios were used to impose missingness on body mass index (BMI) for age z-scores; a continuous time-varying exposure variable with a non-linear trajectory over time. We evaluated the performance of FCS, MVNI, and two-fold FCS for handling up to 50% of missing data when assessing the association between childhood obesity and sleep problems. The standard two-fold FCS produced slightly more biased and less precise estimates than FCS and MVNI. We observed slight improvements in bias and precision when using a time window width of two for the two-fold FCS algorithm compared to the standard width of one. We recommend the use of FCS or MVNI in a similar longitudinal setting, and when encountering convergence issues due to a large number of time points or variables with missing values, the two-fold FCS with exploration of a suitable time window.
Short-term effects of social encouragement on exercise behavior: insights from China's Wanbu network.

PubMed

Wang, Liuan; Guo, Xitong; Wu, Tianshi; Lv, Lucheng; Zhang, Zhiwei

2017-07-01

The objective is to explore the short-term effects of social encouragement on exercise behavior in China. A longitudinal observational study. We collected longitudinal data on exercise and social interactions through public access to the Wanbu network, a large Chinese social network designed to encourage people to walk more. Our data set consisted of 5010 subjects who participated in the network between March 14, 2014, and September 4, 2015, and had at least one social interaction recorded. The data were analyzed using linear regression models relating the number of steps (NS) walked per day to the number of comments (NC), number of thumbs-up (NT), and number of posts (NP) received on the previous day, while adjusting for day of week, quarter of year, and a fixed or random subject effect, with or without a lag term (NS on the previous day) to account for serial correlation. We found that all three social interactions have positive effects on the next day's exercise level. The estimated effect sizes can be ordered as NT > NC > NP for each of the four models considered. The results also indicate that the participants walked less in the first quarter than in the other three quarters and more on weekdays than on weekends, with Monday being the most active day of a week. Social encouragement has positive short-term effects on exercise behavior. Copyright © 2017 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
The effect of Early Head Start on child welfare system involvement: A first look at longitudinal child maltreatment outcomes☆

PubMed Central

Green, Beth L.; Ayoub, Catherine; Bartlett, Jessica Dym; Von Ende, Adam; Furrer, Carrie; Chazan-Cohen, Rachel; Vallotton, Claire; Klevens, Joanne

2015-01-01

The high societal and personal costs of child maltreatment make identification of effective early prevention programs a high research priority. Early Head Start (EHS), a dual generational program serving low-income families with children prenatally through age three years, is one of the largest federally funded programs for infants and toddlers in the United States. A national randomized trial found EHS to be effective in improving parent and child outcomes, but its effectiveness in reducing child maltreatment was not assessed. The current study used administrative data from state child welfare agencies to examine the impact of EHS on documented abuse and neglect among children from seven of the original seventeen programs in the national EHS randomized controlled trial. Results indicated that children in EHS had significantly fewer child welfare encounters between the ages of five and nine years than did children in the control group, and that EHS slowed the rate of subsequent encounters. Additionally, compared to children in the control group, children in EHS were less likely to have a substantiated report of physical or sexual abuse, but more likely to have a substantiated report of neglect. These findings suggest that EHS may be effective in reducing child maltreatment among low-income children, in particular, physical and sexual abuse. PMID:26744550
Extending cluster Lot Quality Assurance Sampling designs for surveillance programs

PubMed Central

Hund, Lauren; Pagano, Marcello

2014-01-01

Lot quality assurance sampling (LQAS) has a long history of applications in industrial quality control. LQAS is frequently used for rapid surveillance in global health settings, with areas classified as poor or acceptable performance based on the binary classification of an indicator. Historically, LQAS surveys have relied on simple random samples from the population; however, implementing two-stage cluster designs for surveillance sampling is often more cost-effective than simple random sampling. By applying survey sampling results to the binary classification procedure, we develop a simple and flexible non-parametric procedure to incorporate clustering effects into the LQAS sample design to appropriately inflate the sample size, accommodating finite numbers of clusters in the population when relevant. We use this framework to then discuss principled selection of survey design parameters in longitudinal surveillance programs. We apply this framework to design surveys to detect rises in malnutrition prevalence in nutrition surveillance programs in Kenya and South Sudan, accounting for clustering within villages. By combining historical information with data from previous surveys, we design surveys to detect spikes in the childhood malnutrition rate. PMID:24633656
Random acoustic metamaterial with a subwavelength dipolar resonance.

PubMed

Duranteau, Mickaël; Valier-Brasier, Tony; Conoir, Jean-Marc; Wunenburger, Régis

2016-06-01

The effective velocity and attenuation of longitudinal waves through random dispersions of rigid, tungsten-carbide beads in an elastic matrix made of epoxy resin in the range of beads volume fraction 2%-10% are determined experimentally. The multiple scattering model proposed by Luppé, Conoir, and Norris [J. Acoust. Soc. Am. 131(2), 1113-1120 (2012)], which fully takes into account the elastic nature of the matrix and the associated mode conversions, accurately describes the measurements. Theoretical calculations show that the rigid particles display a local, dipolar resonance which shares several features with Minnaert resonance of bubbly liquids and with the dipolar resonance of core-shell particles. Moreover, for the samples under study, the main cause of smoothing of the dipolar resonance of the scatterers and the associated variations of the effective mass density of the dispersions is elastic relaxation, i.e., the finite time required for the shear stresses associated to the translational motion of the scatterers to propagate through the matrix. It is shown that its influence is governed solely by the value of the particle to matrix mass density contrast.
Longitudinal follow-up comparison of educational interventions: multimedia textbook, traditional lecture, and printed textbook.

PubMed

D'Alessandro, D M; Kreiter, C D; Erkonen, W E; Winter, R J; Knapp, H R

1997-11-01

The goal of this prospective, interinstitutional study was to compare the long-term instructional effectiveness of a pediatric multimedia textbook (MMTB) to that of a standard lecture and a printed textbook. A randomized cohort of 89 3rd-year medical students from two institutions were initially evaluated from June 1992 to June 1993 and reevaluated in May 1994. Students were randomly assigned to one of four instructional groups: computer-aided instruction by means of MMTBs (n = 21), traditional lecture (n = 23), printed textbook (n = 19), and a control group (n = 26). After instruction, all groups were tested by means of a multiple choice test at the end of their pediatric clerkship; they were given this same test 11-22 months later. The long-term instructional effectiveness of the MMTB, printed textbook, and lecture were the same as that in the control group, as determined by analysis of variance of mean test scores. The educational advantage of MMTBs observed immediately after instruction was not detected 1 year later. Because attrition reduced statistical power, further research is necessary to determine how educational fading affects these instructional formats.
Extending cluster lot quality assurance sampling designs for surveillance programs.

PubMed

Hund, Lauren; Pagano, Marcello

2014-07-20

Lot quality assurance sampling (LQAS) has a long history of applications in industrial quality control. LQAS is frequently used for rapid surveillance in global health settings, with areas classified as poor or acceptable performance on the basis of the binary classification of an indicator. Historically, LQAS surveys have relied on simple random samples from the population; however, implementing two-stage cluster designs for surveillance sampling is often more cost-effective than simple random sampling. By applying survey sampling results to the binary classification procedure, we develop a simple and flexible nonparametric procedure to incorporate clustering effects into the LQAS sample design to appropriately inflate the sample size, accommodating finite numbers of clusters in the population when relevant. We use this framework to then discuss principled selection of survey design parameters in longitudinal surveillance programs. We apply this framework to design surveys to detect rises in malnutrition prevalence in nutrition surveillance programs in Kenya and South Sudan, accounting for clustering within villages. By combining historical information with data from previous surveys, we design surveys to detect spikes in the childhood malnutrition rate. Copyright © 2014 John Wiley & Sons, Ltd.
Bayesian model selection techniques as decision support for shaping a statistical analysis plan of a clinical trial: An example from a vertigo phase III study with longitudinal count data as primary endpoint

PubMed Central

2012-01-01

Background A statistical analysis plan (SAP) is a critical link between how a clinical trial is conducted and the clinical study report. To secure objective study results, regulatory bodies expect that the SAP will meet requirements in pre-specifying inferential analyses and other important statistical techniques. To write a good SAP for model-based sensitivity and ancillary analyses involves non-trivial decisions on and justification of many aspects of the chosen setting. In particular, trials with longitudinal count data as primary endpoints pose challenges for model choice and model validation. In the random effects setting, frequentist strategies for model assessment and model diagnosis are complex and not easily implemented and have several limitations. Therefore, it is of interest to explore Bayesian alternatives which provide the needed decision support to finalize a SAP. Methods We focus on generalized linear mixed models (GLMMs) for the analysis of longitudinal count data. A series of distributions with over- and under-dispersion is considered. Additionally, the structure of the variance components is modified. We perform a simulation study to investigate the discriminatory power of Bayesian tools for model criticism in different scenarios derived from the model setting. We apply the findings to the data from an open clinical trial on vertigo attacks. These data are seen as pilot data for an ongoing phase III trial. To fit GLMMs we use a novel Bayesian computational approach based on integrated nested Laplace approximations (INLAs). The INLA methodology enables the direct computation of leave-one-out predictive distributions. These distributions are crucial for Bayesian model assessment. We evaluate competing GLMMs for longitudinal count data according to the deviance information criterion (DIC) or probability integral transform (PIT), and by using proper scoring rules (e.g. the logarithmic score). Results The instruments under study provide excellent tools for preparing decisions within the SAP in a transparent way when structuring the primary analysis, sensitivity or ancillary analyses, and specific analyses for secondary endpoints. The mean logarithmic score and DIC discriminate well between different model scenarios. It becomes obvious that the naive choice of a conventional random effects Poisson model is often inappropriate for real-life count data. The findings are used to specify an appropriate mixed model employed in the sensitivity analyses of an ongoing phase III trial. Conclusions The proposed Bayesian methods are not only appealing for inference but notably provide a sophisticated insight into different aspects of model performance, such as forecast verification or calibration checks, and can be applied within the model selection process. The mean of the logarithmic score is a robust tool for model ranking and is not sensitive to sample size. Therefore, these Bayesian model selection techniques offer helpful decision support for shaping sensitivity and ancillary analyses in a statistical analysis plan of a clinical trial with longitudinal count data as the primary endpoint. PMID:22962944
Bayesian model selection techniques as decision support for shaping a statistical analysis plan of a clinical trial: an example from a vertigo phase III study with longitudinal count data as primary endpoint.

PubMed

Adrion, Christine; Mansmann, Ulrich

2012-09-10

A statistical analysis plan (SAP) is a critical link between how a clinical trial is conducted and the clinical study report. To secure objective study results, regulatory bodies expect that the SAP will meet requirements in pre-specifying inferential analyses and other important statistical techniques. To write a good SAP for model-based sensitivity and ancillary analyses involves non-trivial decisions on and justification of many aspects of the chosen setting. In particular, trials with longitudinal count data as primary endpoints pose challenges for model choice and model validation. In the random effects setting, frequentist strategies for model assessment and model diagnosis are complex and not easily implemented and have several limitations. Therefore, it is of interest to explore Bayesian alternatives which provide the needed decision support to finalize a SAP. We focus on generalized linear mixed models (GLMMs) for the analysis of longitudinal count data. A series of distributions with over- and under-dispersion is considered. Additionally, the structure of the variance components is modified. We perform a simulation study to investigate the discriminatory power of Bayesian tools for model criticism in different scenarios derived from the model setting. We apply the findings to the data from an open clinical trial on vertigo attacks. These data are seen as pilot data for an ongoing phase III trial. To fit GLMMs we use a novel Bayesian computational approach based on integrated nested Laplace approximations (INLAs). The INLA methodology enables the direct computation of leave-one-out predictive distributions. These distributions are crucial for Bayesian model assessment. We evaluate competing GLMMs for longitudinal count data according to the deviance information criterion (DIC) or probability integral transform (PIT), and by using proper scoring rules (e.g. the logarithmic score). The instruments under study provide excellent tools for preparing decisions within the SAP in a transparent way when structuring the primary analysis, sensitivity or ancillary analyses, and specific analyses for secondary endpoints. The mean logarithmic score and DIC discriminate well between different model scenarios. It becomes obvious that the naive choice of a conventional random effects Poisson model is often inappropriate for real-life count data. The findings are used to specify an appropriate mixed model employed in the sensitivity analyses of an ongoing phase III trial. The proposed Bayesian methods are not only appealing for inference but notably provide a sophisticated insight into different aspects of model performance, such as forecast verification or calibration checks, and can be applied within the model selection process. The mean of the logarithmic score is a robust tool for model ranking and is not sensitive to sample size. Therefore, these Bayesian model selection techniques offer helpful decision support for shaping sensitivity and ancillary analyses in a statistical analysis plan of a clinical trial with longitudinal count data as the primary endpoint.
Longitudinal association of suicidal ideation and physical dating violence among high school students.

PubMed

Nahapetyan, Lusine; Orpinas, Pamela; Song, Xiao; Holland, Kristin

2014-04-01

Two salient problems in adolescent development are dating violence and suicidal ideation. Theory and empirical research have supported their association in primarily cross-sectional studies. The purpose of this study is to examine the longitudinal association between physical dating violence and suicidal ideation (thoughts or plans) in a cohort of students evaluated annually from Grades 9 to 12. The sample consisted of 556 random-selected students (50.2 % males; 47.5 % White, 37.8 % Black, 11.2 % Latino) who reported dating at least once during the four assessments. Self-reported frequency of suicidal ideation, dating, and physical dating violence perpetration and victimization were assessed each spring from ninth to twelfth grade. We used generalized estimating equations modeling to predict the effects of sex, race, school grade, and physical dating perpetration and victimization on suicidal ideation. Cumulatively, one-fourth of the sample reported suicidal ideation at least once by the end of Grade 12, and approximately half reported physical dating violence. Female gender (OR = 1.7, p = 0.02), physical dating perpetration (OR = 1.54, p = 0.048), physical dating victimization (OR = 2.03, p < 0.001), and being in grades 9-11 versus 12 in high school (OR = 1.83, p = 0.004) were significant predictors of suicidal ideation. Race was not a significant predictor among adolescents in this sample. This longitudinal study highlights the detrimental emotional effect of physical dating violence perpetration and victimization among high school students. It is important that suicide prevention programs incorporate physical dating violence education and prevention strategies starting early in high school.
Dynamic Indices of Methamphetamine Dependence and HIV Infection Predict Fluctuations in Affective Distress: A Five-year Longitudinal Analysis

PubMed Central

Montoya, Jessica L.; Umlauf, Anya; Abramson, Ian; Badiee, Jayraan; Woods, Steven Paul; Atkinson, J. Hampton; Grant, Igor; Moore, David J.

2013-01-01

Background Methamphetamine (METH) use and human immunodeficiency virus (HIV) infection are highly comorbid, and both are associated with increased prevalence of affective distress. Delineating the trajectory of affective distress in the context of METH dependence and HIV infection is important given the implications for everyday functional impairment, adverse health behaviors, and increased risk for adverse health outcomes. Methods We conducted a five-year longitudinal investigation involving 133 METH-dependent (74 HIV seropositive) and 163 non-METH-dependent (90 HIV seropositive) persons to examine both long-standing patterns and transient changes in affective distress. Mixed-effect regression models with random subject-specific slopes and intercepts evaluated the effect of METH dependence, HIV serostatus, and related variables on affective distress, as measured by the Profile of Mood States. Results Transient changes in affective distress were found to be greater among those with a diagnosis of current MDD, briefer durations of abstinence from METH, and higher quantity of METH consumed. Weak associations were observed among static (time-independent predictors) covariates and long-standing patterns in affective distress. Limitations Study lacked data pertaining to the participants’ involvement in METH treatment and relied on respondent-driven sampling. Conclusions Our longitudinal investigation of the trajectory of affective distress indicated that specific and dynamic indices of current METH use were associated with greater transient changes in mood. In the evaluation and treatment of affective distress, recency and quantity of current METH use are important to consider given their association with heightened affective distress and mood instability over time. PMID:24012068
Dynamic indices of methamphetamine dependence and HIV infection predict fluctuations in affective distress: a five-year longitudinal analysis.

PubMed

Montoya, Jessica L; Umlauf, Anya; Abramson, Ian; Badiee, Jayraan; Woods, Steven Paul; Atkinson, J Hampton; Grant, Igor; Moore, David J

2013-11-01

Methamphetamine (METH) use and human immunodeficiency virus (HIV) infection are highly comorbid, and both are associated with increased prevalence of affective distress. Delineating the trajectory of affective distress in the context of METH dependence and HIV infection is important given the implications for everyday functional impairment, adverse health behaviors, and increased risk for adverse health outcomes. We conducted a five-year longitudinal investigation involving 133 METH-dependent (74 HIV seropositive) and 163 non-METH-dependent (90 HIV seropositive) persons to examine both long-standing patterns and transient changes in affective distress. Mixed-effect regression models with random subject-specific slopes and intercepts evaluated the effect of METH dependence, HIV serostatus, and related variables on affective distress, as measured by the Profile of Mood States. Transient changes in affective distress were found to be greater among those with a diagnosis of current MDD, briefer durations of abstinence from METH, and higher quantity of METH consumed. Weak associations were observed among static (time-independent predictors) covariates and long-standing patterns in affective distress. Study lacked data pertaining to the participants' involvement in METH treatment and relied on respondent-driven sampling. Our longitudinal investigation of the trajectory of affective distress indicated that specific and dynamic indices of current METH use were associated with greater transient changes in mood. In the evaluation and treatment of affective distress, recency and quantity of current METH use are important to consider given their association with heightened affective distress and mood instability over time. © 2013 Elsevier B.V. All rights reserved.
Patient-reported outcomes in a phase iii study of everolimus versus placebo in patients with metastatic carcinoma of the kidney that has progressed on vascular endothelial growth factor receptor tyrosine kinase inhibitor therapy.

PubMed

Beaumont, Jennifer L; Butt, Zeeshan; Baladi, Jeanfrancois; Motzer, Robert J; Haas, Tomas; Hollaender, Norbert; Kay, Andrea; Cella, David

2011-01-01

A phase III, randomized, double-blind, placebo-controlled trial was conducted in patients with metastatic renal cell carcinoma. The focus of this paper is to evaluate the patient-reported outcomes. Patients were randomly assigned (2:1) to receive oral everolimus 10 mg once daily or placebo. The Functional Assessment of Cancer Therapy Kidney Symptom Index-Disease-Related Symptoms (FKSI-DRS) and European Organization for the Research and Treatment of Cancer (EORTC) QLQ-C30 were administered before randomization and on day 1 of each cycle. The FKSI-DRS and the EORTC QLQ-C30 Physical Functioning and Global Quality of Life scores were the primary endpoints examined. Longitudinal models were used to compare treatment arms. Sensitivity analyses were conducted to explore the impact of missing data assumptions. Longitudinal trends for FKSI-DRS scores did not differ by treatment arm. Taking nonignorable missing data into account, there were significant differences between treatment arms in the trend over time for physical functioning and global quality of life, with the everolimus arm exhibiting greater decreases. All three of these measures of health-related quality of life were significantly related to progression-free survival. There was no evidence of a difference between everolimus and placebo in longitudinal patterns of disease-related symptoms, and little difference between the arms in physical functioning or global quality of life trends. This supports the conclusion that delay in tumor progression demonstrated by everolimus is associated with minimal impact on symptoms, physical functioning, or quality of life, as reported by patients.
Patient-Reported Outcomes in a Phase III Study of Everolimus Versus Placebo in Patients with Metastatic Carcinoma of the Kidney That Has Progressed on Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitor Therapy

PubMed Central

Butt, Zeeshan; Baladi, Jeanfrancois; Motzer, Robert J.; Haas, Tomas; Hollaender, Norbert; Kay, Andrea; Cella, David

2011-01-01

Purpose. A phase III, randomized, double-blind, placebo-controlled trial was conducted in patients with metastatic renal cell carcinoma. The focus of this paper is to evaluate the patient-reported outcomes. Methods. Patients were randomly assigned (2:1) to receive oral everolimus 10 mg once daily or placebo. The Functional Assessment of Cancer Therapy Kidney Symptom Index—Disease-Related Symptoms (FKSI-DRS) and European Organization for the Research and Treatment of Cancer (EORTC) QLQ-C30 were administered before randomization and on day 1 of each cycle. The FKSI-DRS and the EORTC QLQ-C30 Physical Functioning and Global Quality of Life scores were the primary endpoints examined. Longitudinal models were used to compare treatment arms. Sensitivity analyses were conducted to explore the impact of missing data assumptions. Results. Longitudinal trends for FKSI-DRS scores did not differ by treatment arm. Taking nonignorable missing data into account, there were significant differences between treatment arms in the trend over time for physical functioning and global quality of life, with the everolimus arm exhibiting greater decreases. All three of these measures of health-related quality of life were significantly related to progression-free survival. Conclusions. There was no evidence of a difference between everolimus and placebo in longitudinal patterns of disease-related symptoms, and little difference between the arms in physical functioning or global quality of life trends. This supports the conclusion that delay in tumor progression demonstrated by everolimus is associated with minimal impact on symptoms, physical functioning, or quality of life, as reported by patients. PMID:21459902
Impact of Workplace Exposure and Stress on Neck Pain and Disabilities in Women-A Longitudinal Follow-up After a Rehabilitation Intervention.

PubMed

Svedmark, Åsa; Björklund, Martin; Häger, Charlotte K; Sommar, Johan Nilsson; Wahlström, Jens

2018-05-28

The aim was to evaluate if pain, disability, and work productivity are influenced by physical and psychosocial work exposures as well as by stress, up to 1 year after a randomized controlled trial treatment intervention, and to determine whether any such association differed between treatment and control groups. Ninety-seven working women suffering non-specific neck pain (n = 67 treatment group, n = 30 control group) were followed from end of treatment intervention and at 9- and 15-month follow-ups, respectively. Physical and psychosocial exposures, as well as perceived stress, were assessed after the treatment intervention. Pain, neck disability, and work productivity were assessed at baseline, after intervention 3 months later and at 9- and 15-month follow-ups. Longitudinal assessment was conducted using the exposure level at 3 months as predictor of pain, disability, and work productivity at 3, 9, and 15 months, respectively. Mixed models were used to estimate longitudinal associations, accounting for within-individual correlation of repeated outcome measures by incorporation of a random intercept. Age and duration of neck pain were adjusted for in all models. To evaluate group differences, interactions between exposures and treatment groups were estimated. High perceived stress was associated with more neck pain, more neck disability, and decreased work productivity in both cross-sectional and longitudinal analyses. High 'control of decision' was associated with less neck pain, less neck disability, and higher work productivity in cross-sectional analyses but only to less disability and higher productivity in longitudinal analyses. Shoulder/arm load was the only physical exposure variable that was significantly associated with work productivity in the univariate analyses. Only small differences were observed between treatment and control groups. High perceived stress and low 'control of decision' were associated with more neck pain, increased neck disability, and decreased work productivity. Treatment interventions for individuals with neck pain should take into account psychosocial workplace exposures and stress to improve intermediate and long-term results.
Lensless digital holography with diffuse illumination through a pseudo-random phase mask.

PubMed

Bernet, Stefan; Harm, Walter; Jesacher, Alexander; Ritsch-Marte, Monika

2011-12-05

Microscopic imaging with a setup consisting of a pseudo-random phase mask, and an open CMOS camera, without an imaging objective, is demonstrated. The pseudo random phase mask acts as a diffuser for an incoming laser beam, scattering a speckle pattern to a CMOS chip, which is recorded once as a reference. A sample which is afterwards inserted somewhere in the optical beam path changes the speckle pattern. A single (non-iterative) image processing step, comparing the modified speckle pattern with the previously recorded one, generates a sharp image of the sample. After a first calibration the method works in real-time and allows quantitative imaging of complex (amplitude and phase) samples in an extended three-dimensional volume. Since no lenses are used, the method is free from lens abberations. Compared to standard inline holography the diffuse sample illumination improves the axial sectioning capability by increasing the effective numerical aperture in the illumination path, and it suppresses the undesired so-called twin images. For demonstration, a high resolution spatial light modulator (SLM) is programmed to act as the pseudo-random phase mask. We show experimental results, imaging microscopic biological samples, e.g. insects, within an extended volume at a distance of 15 cm with a transverse and longitudinal resolution of about 60 μm and 400 μm, respectively.
The PX-EM algorithm for fast stable fitting of Henderson's mixed model

PubMed Central

Foulley, Jean-Louis; Van Dyk, David A

2000-01-01

This paper presents procedures for implementing the PX-EM algorithm of Liu, Rubin and Wu to compute REML estimates of variance covariance components in Henderson's linear mixed models. The class of models considered encompasses several correlated random factors having the same vector length e.g., as in random regression models for longitudinal data analysis and in sire-maternal grandsire models for genetic evaluation. Numerical examples are presented to illustrate the procedures. Much better results in terms of convergence characteristics (number of iterations and time required for convergence) are obtained for PX-EM relative to the basic EM algorithm in the random regression. PMID:14736399
Design of a digital ride quality augmentation system for commuter aircraft

NASA Technical Reports Server (NTRS)

Hammond, T. A.; Amin, S. P.; Paduano, J. D.; Downing, D. R.

1984-01-01

Commuter aircraft typically have low wing loadings, and fly at low altitudes, and so they are susceptible to undesirable accelerations caused by random atmospheric turbulence. Larger commercial aircraft typically have higher wing loadings and fly at altitudes where the turbulence level is lower, and so they provide smoother rides. This project was initiated based on the goal of making the ride of the commuter aircraft as smooth as the ride experienced on the major commercial airliners. The objectives of this project were to design a digital, longitudinal mode ride quality augmentation system (RQAS) for a commuter aircraft, and to investigate the effect of selected parameters on those designs.

Association between economic fluctuations and road mortality in OECD countries.

PubMed

Chen, Gang

2014-08-01

Using longitudinal data from 32 Organization for Economic Co-operation and Development (OECD) countries (1970-2010), this article investigates association between annual variations in road mortality and the economic fluctuations. Two regression models (fixed-effects and random-coefficients) were adopted for estimation. The cross-country data analyses suggested that road mortality is pro-cyclical and that the cyclicality is symmetric. Based on data from 32 OECD countries, an increase of on average 1% in economic growth is associated with a 1.1% increase in road mortality, and vice versa. © The Author 2014. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.
Effects on Subclinical Heart Failure in Type 2 Diabetic Subjects on Liraglutide Treatment vs. Glimepiride Both in Combination with Metformin: A Randomized Open Parallel-Group Study.

PubMed

Nyström, Thomas; Padro Santos, Irene; Hedberg, Fredric; Wardell, Johan; Witt, Nils; Cao, Yang; Bojö, Leif; Nilsson, Bo; Jendle, Johan

2017-01-01

We aimed to investigate the effect of liraglutide treatment on heart function in type 2 diabetes (T2D) patients with subclinical heart failure. Randomized open parallel-group trial. 62 T2D patients (45 male) with subclinical heart failure were randomized to either once daily liraglutide 1.8 mg, or glimepiride 4 mg, both add on to metformin 1 g twice a day. Mitral annular systolic (s') and early diastolic (e') velocities were measured at rest and during bicycle ergometer exercise, using tissue Doppler echocardiography. The primary endpoint was 18-week treatment changes in longitudinal functional reserve index (LFRI diastolic/systolic ). Clinical characteristics between groups (liraglutide = 33 vs. glimepiride = 29) were well matched. At baseline left ventricle ejection fraction (53.7 vs. 53.6%) and global longitudinal strain (-15.3 vs. -16.5%) did not differ between groups. There were no significant differences in mitral flow velocities between groups. For the primary endpoint, there was no treatment change [95% confidence interval] for: LFRI diastolic (-0.18 vs. -0.53 [-0.28, 2.59; p = 0.19]), or LFRI systolic (-0.10 vs. -0.18 [-1.0, 1.7; p = 0.54]); for the secondary endpoints, there was a significant treatment change in respect of body weight (-3.7 vs. -0.2 kg [-5.5, -1.4; p = 0.001]), waist circumference (-3.1 vs. -0.8 cm [-4.2, -0.4; p = 0.019]), and heart rate (HR) (6.3 vs. -2.3 bpm [-3.0, 14.2; p = 0.003]), with no such treatment change in hemoglobin A1c levels (-11.0 vs. -9.2 mmol/mol [-7.0, 2.6; p = 0.37]), between groups. 18-week treatment of liraglutide compared with glimepiride did not improve LFRI diastolic/systolic , but however increased HR. There was a significant treatment change in body weight reduction in favor for liraglutide treatment.
MicroFilament Analyzer identifies actin network organizations in epidermal cells of Arabidopsis thaliana roots

PubMed Central

Jacques, Eveline; Lewandowski, Michal; Buytaert, Jan; Fierens, Yves; Verbelen, Jean-Pierre; Vissenberg, Kris

2013-01-01

The plant cytoskeleton plays a crucial role in the cells’ growth and development during different developmental stages and it undergoes many rearrangements. In order to describe the arrangements of the F-actin cytoskeleton in root epidermal cells of Arabidopsis thaliana, the recently developed software MicroFilament Analyzer (MFA) was exploited. This software enables high-throughput identification and quantification of the orientation of filamentous structures on digital images in a highly standardized and fast way. Using confocal microscopy and transgenic GFP-FABD2-GFP plants the actin cytoskeleton was visualized in the root epidermis. MFA analysis revealed that during the early stages of cell development F-actin is organized in a mainly random pattern. As the cells grow, they preferentially adopt a longitudinal organization, a pattern that is also preserved in the largest cells. In the evolution from young to old cells, an approximately even distribution of transverse, oblique or combined orientations is always present besides the switch from random to a longitudinal oriented actin cytoskeleton. PMID:23656865
Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities

PubMed Central

Saez, M; Figueiras, A; Ballester, F; Perez-Hoyos, S; Ocana, R; Tobias, A

2001-01-01

STUDY OBJECTIVE—The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches. DESIGN—The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992-1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models. MAIN RESULTS—The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 µg/m3 and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10 µg/m3 of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables. CONCLUSIONS—Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.   Keywords: air pollution; mortality; longitudinal studies PMID:11351001
Longitudinal evaluation of the impact of dental caries treatment on oral health-related quality of life among schoolchildren.

PubMed

de Paula, Janice S; Sarracini, Karin L M; Meneghim, Marcelo C; Pereira, Antônio C; Ortega, Edwin M M; Martins, Natália S; Mialhe, Fábio L

2015-06-01

This study aimed to evaluate the impact of dental caries treatment on oral health-related quality of life (OHRQoL) among schoolchildren and the responsiveness of the Child Perceptions Questionnaire (CPQ8-10 ) instrument. Brazilian schoolchildren, 8-10 yr of age, were randomly selected and assigned to two groups--dental caries treatment (DCT) and caries-free (CF)--according to their caries experience [decayed, missing, or filled primary teeth (dmft) and decayed, missing or filled secondary teeth (DMFT) values of ≥ 0]. The CPQ8-10 instrument was administered at baseline and at 4 wk of follow-up (i.e. 4 wk after completion of dental treatment). In the DCT group, increases in CPQ8-10 scores were observed between the baseline and follow-up results. However, longitudinal evaluation of the CF group demonstrated no statistically significant difference in CPQ8-10 scores. Responsiveness of the CPQ8-10 instrument (magnitude of change in CPQ8-10 scores) in the DCT group was greater (effect size >0.7) than in the CF group. The findings of this study show that dental caries treatment has an important impact on OHRQoL of children. The CPQ8-10 was considered an acceptable instrument for longitudinal measurement of changes in OHRQoL. © 2015 Eur J Oral Sci.
Longitudinal trends in gasoline price and physical activity: The CARDIA study

PubMed Central

Hou, Ningqi; Popkin, Barry M; Jacobs, David R; Song, Yan; Guilkey, David K; He, Ka; Lewis, Cora E.; Gordon-Larsen, Penny

2011-01-01

Objective To investigate longitudinal associations between community-level gasoline price and physical activity (PA). Method In the Coronary Artery Risk Development in Young Adults study, 5,115 black and white participants aged 18–30 at baseline 1985–86 were recruited from four U.S. cities (Birmingham, Chicago, Minneapolis and Oakland) and followed over time. We used data from 3 follow-up exams: 1992–93, 1995–96, and 2000–01, when the participants were located across 48 states. From questionnaire data, a total PA score was summarized in exercise units (EU) based on intensity and frequency of 13 PA categories. Using Geographic Information Systems, participants’ residential locations were linked to county-level inflation-adjusted gasoline price data collected by the Council for Community & Economic Research. We used a random-effect longitudinal regression model to examine associations between time-varying gasoline price and time-varying PA, controlling for age, race, gender, baseline study center, and time-varying education, marital status, household income, county cost of living, county bus fare, census block-group poverty, and urbanicity. Results Holding all control variables constant, a 25-cent increase in inflation-adjusted gasoline price was significantly associated with an increase of 9.9 EU in total PA (95%CI: 0.8–19.1). Conclusion Rising prices of gasoline may be associated with an unintended increase in leisure PA. PMID:21338621
The longitudinal association between social functioning and theory of mind in first-episode psychosis.

PubMed

Sullivan, Sarah; Lewis, Glyn; Mohr, Christine; Herzig, Daniela; Corcoran, Rhiannon; Drake, Richard; Evans, Jonathan

2014-01-01

There is some cross-sectional evidence that theory of mind ability is associated with social functioning in those with psychosis but the direction of this relationship is unknown. This study investigates the longitudinal association between both theory of mind and psychotic symptoms and social functioning outcome in first-episode psychosis. Fifty-four people with first-episode psychosis were followed up at 6 and 12 months. Random effects regression models were used to estimate the stability of theory of mind over time and the association between baseline theory of mind and psychotic symptoms and social functioning outcome. Neither baseline theory of mind ability (regression coefficients: Hinting test 1.07 95% CI -0.74, 2.88; Visual Cartoon test -2.91 95% CI -7.32, 1.51) nor baseline symptoms (regression coefficients: positive symptoms -0.04 95% CI -1.24, 1.16; selected negative symptoms -0.15 95% CI -2.63, 2.32) were associated with social functioning outcome. There was evidence that theory of mind ability was stable over time, (regression coefficients: Hinting test 5.92 95% CI -6.66, 8.92; Visual Cartoon test score 0.13 95% CI -0.17, 0.44). Neither baseline theory of mind ability nor psychotic symptoms are associated with social functioning outcome. Further longitudinal work is needed to understand the origin of social functioning deficits in psychosis.
Nonlinear dual-axis biodynamic response of the semi-supine human body during longitudinal horizontal whole-body vibration

NASA Astrophysics Data System (ADS)

Huang, Ya; Griffin, Michael J.

2008-04-01

The resonance frequencies in frequency response functions of the human body (e.g. apparent mass and transmissibility) decrease with increasing vibration magnitude. This nonlinear biodynamic response is found with various sitting and standing postures requiring postural control. The present study measured the apparent mass of the body in a relaxed semi-supine posture with two types of longitudinal horizontal vibration (in the z-axis of the semi-supine body): (i) continuous random excitation (0.25-20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75 and 1.0 ms -2 rms); (ii) intermittent random excitation (0.25-20 Hz) alternately at 0.25 and 1.0 ms -2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 3.7 to 2.4 Hz as the vibration magnitude increased from 0.125 to 1.0 ms -2 rms. A nonlinear response was apparent in both the horizontal ( z-axis) apparent mass and the vertical ( x-axis) cross-axis apparent mass. With intermittent random vibration, as the vibration magnitude increased from 0.25 to 1.0 ms -2 rms, the median resonance frequency of the apparent mass decreased from 3.2 to 2.5 Hz whereas, with continuous random vibration over the same range of magnitudes, the resonance frequency decreased from 3.4 to 2.4 Hz. The median change in the resonance frequency (between 0.25 and 1.0 ms -2 rms) was 0.6 Hz with the intermittent random vibration and 0.9 Hz with the continuous random vibration. With intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration at the same magnitudes. The responses were consistent with passive thixotropy being a primary cause of nonlinear biodynamic responses to whole-body vibration, although reflex activity of the muscles may also have an influence.
Children's executive function and high-calorie, low-nutrient food intake: mediating effects of child-perceived adult fast food intake.

PubMed

Tate, Eleanor B; Unger, Jennifer B; Chou, Chih-Ping; Spruijt-Metz, Donna; Pentz, Mary Ann; Riggs, Nathaniel R

2015-04-01

This study tested the relationships among child executive function (EF), child-perceived parent fast food intake, and child self-reported subsequent consumption of high-calorie, low-nutrient (HCLN) food. One year and 6-month longitudinal observation from a larger randomized controlled trial. Southern California elementary schools. Fourth- and fifth-grade children (N = 1,005) participating in the Pathways to Health obesity prevention program. Child EF problems were associated with higher concurrent HCLN intake (B = 0.29, SE = 0.10, p < .001) and had a significant indirect effect through higher perceived frequency of parent fast food intake (indirect effect = 0.17, 95% confidence interval [CI] = [0.11, 0.25], p < .001). Longitudinally, child EF problems did not significantly predict higher HCLN intake a year and a half later (B = 0.01, SE = 0.10, p = .92, n = 848) but did have a significant indirect effect through higher perceived parent fast food intake (indirect effect = 0.05, 95% CI = [0.02, 0.10], p < .001). Children's EF difficulties may increase their perception of parent concurrent fast food intake, contributing to their own unhealthy food intake. However, EF problems may not directly affect HCLN intake across time, except when problems are associated with child perception of more frequent parent consumption of convenience foods. Future research is needed to investigate the possibility that helping children perceive and understand role models' convenience food consumption may improve child dietary consumption patterns. © 2014 Society for Public Health Education.
Direct and maternal genetic effects for preweaning growth in Retinta cattle estimated by a longitudinal approach throughout the calving trajectory of the cow.

PubMed

Morales, R; Menéndez-Buxadera, A; Avilés, C; Molina, A

2013-12-01

The direct and maternal genetic effects were estimated for the preweaning growth of Retinta calves with a multitrait model across parities, using a longitudinal approach with random regression models (RRM). The 120 (P120) and 180 days (P180) weights (5972 calves) were considered as different traits in each calving. The heritability of direct effect across parities was on average 0.37 for P120 and 0.58 for P180, slightly higher than the estimates by univariate (0.30 and 0.56) and bivariate models (0.30 and 0.51, respectively). The heritability for maternal effects was 0.16 for P120 and 0.26 for P180 and very similar by uni- (0.16 and 0.23) and multivariate model (0.16 and 0.22, respectively). The correlation between direct and maternal effects by RRM showed a pronounced antagonism -0.64 for P120 and -0.78 for P180), likewise uni- (-0.62 and -0.72) and multivariate case (-0.64 and -0.74, respectively). The preweaning weights should be considered as different traits across parities, because the genetic correlations were different from unity. The RRM also allowed us to estimate all the parameters throughout the calving trajectory of the cow. The use of multiple traits RRM across parities can provide very useful information for the breeding programmes. © 2013 Blackwell Verlag GmbH.
Clinical Health Outcomes Initiative in Comparative Effectiveness for Bipolar Disorder (Bipolar CHOICE): A Pragmatic Trial of Complex Treatment for a Complex Disorder

PubMed Central

Nierenberg, Andrew A.; Sylvia, Louisa G.; Leon, Andrew C.; Reilly-Harrington, Noreen; Shesler, Leah W.; McElroy, Susan L.; Friedman, Edward S.; Thase, Michael E.; Shelton, Richard C.; Bowden, Charles; Tohen, Mauricio; Singh, Vivek; Deckersbach, Thilo; Ketter, Terence; Kocsis, James; McInnis, Melvin G.; Schoenfeld, David; Bobo, William V.; Calabrese, Joseph R.

2015-01-01

Background Classic and second generation antipsychotic mood stabilizers are recommended for treatment of bipolar disorder, yet there are no randomized comparative effectiveness studies that have examined the “real-world” advantages and disadvantages of these medications Purpose We describe the strategic decisions in the design of the Clinical and Health Outcomes Initiative in Comparative Effectiveness for Bipolar Disorder (Bipolar CHOICE). This paper outlines the key issues and solutions the investigators faced in designing a clinical trial that would maximize generalizability and inform real-world clinical treatment of bipolar disorder. Methods Bipolar CHOICE was a 6-month, multi-site, prospective, randomized clinical trial of outpatients with bipolar disorder. This study compares the effectiveness of quetiapine versus lithium, each with adjunctive personalized treatments. The co-primary outcomes selected are the overall benefits and harms of the study medications (as measured by the Clinical Global Impression-Efficacy Index) and the Necessary Clinical Adjustments (a measure of the number of medication changes). Secondary outcomes are continuous measures of mood, the Framingham General Cardiovascular Risk Score and the Longitudinal Interval Follow up Evaluation Range of Impaired Functioning Tool. Results The final study design consisted of a single-blind, randomized comparative effectiveness trial of quetiapine versus lithium, plus adjunctive personalized treatment (APT), across ten sites. Other important study considerations included limited exclusion criteria to maximize generalizability, flexible dosing of APT medications to mimic real-world treatment, and an intent-to-treat analysis plan. 482 participants were randomized to the study and 364 completed. Limitations The potential limitations of the study include the heterogeneity of APT, selection of study medications, lack of a placebo-control group, and participants’ ability to pay for study medications. Conclusion We expect that this study will inform our understanding of the benefits and harms of lithium, a classic mood stabilizer, compared to quetiapine, a second generation antipsychotic with broad-spectrum activity in bipolar disorder and will provide an example of a well-designed and well-conducted randomized comparative effectiveness clinical trial. PMID:24346608
Clinical and Health Outcomes Initiative in Comparative Effectiveness for Bipolar Disorder (Bipolar CHOICE): a pragmatic trial of complex treatment for a complex disorder.

PubMed

Nierenberg, Andrew A; Sylvia, Louisa G; Leon, Andrew C; Reilly-Harrington, Noreen A; Shesler, Leah W; McElroy, Susan L; Friedman, Edward S; Thase, Michael E; Shelton, Richard C; Bowden, Charles L; Tohen, Mauricio; Singh, Vivek; Deckersbach, Thilo; Ketter, Terence A; Kocsis, James H; McInnis, Melvin G; Schoenfeld, David; Bobo, William V; Calabrese, Joseph R

2014-02-01

Classic and second-generation antipsychotic mood stabilizers are recommended for treatment of bipolar disorder, yet there are no randomized comparative effectiveness studies that have examined the 'real-world' advantages and disadvantages of these medications. We describe the strategic decisions in the design of the Clinical and Health Outcomes Initiative in Comparative Effectiveness for Bipolar Disorder (Bipolar CHOICE). This article outlines the key issues and solutions the investigators faced in designing a clinical trial that would maximize generalizability and inform real-world clinical treatment of bipolar disorder. Bipolar CHOICE was a 6-month, multi-site, prospective, randomized clinical trial of outpatients with bipolar disorder. This study compares the effectiveness of quetiapine versus lithium, each with adjunctive personalized treatments (APTs). The co-primary outcomes selected are the overall benefits and harms of the study medications (as measured by the Clinical Global Impression-Efficacy Index) and the Necessary Clinical Adjustments (a measure of the number of medication changes). Secondary outcomes are continuous measures of mood, the Framingham General Cardiovascular Risk Score, and the Longitudinal Interval Follow up Evaluation Range of Impaired Functioning Tool (LIFE-RIFT). The final study design consisted of a single-blind, randomized comparative effectiveness trial of quetiapine versus lithium, plus APT, across 10 sites. Other important study considerations included limited exclusion criteria to maximize generalizability, flexible dosing of APT medications to mimic real-world treatment, and an intent-to-treat analysis plan. In all, 482 participants were randomized to the study, and 364 completed the study. The potential limitations of the study include the heterogeneity of APT, selection of study medications, lack of a placebo-control group, and participants' ability to pay for study medications. We expect that this study will inform our understanding of the benefits and harms of lithium, a classic mood stabilizer, compared to quetiapine, a second-generation antipsychotic with broad-spectrum activity in bipolar disorder, and will provide an example of a well-designed and well-conducted randomized comparative effectiveness clinical trial.
Genetic parameters for growth characteristics of free-range chickens under univariate random regression models.

PubMed

Rovadoscki, Gregori A; Petrini, Juliana; Ramirez-Diaz, Johanna; Pertile, Simone F N; Pertille, Fábio; Salvian, Mayara; Iung, Laiza H S; Rodriguez, Mary Ana P; Zampar, Aline; Gaya, Leila G; Carvalho, Rachel S B; Coelho, Antonio A D; Savino, Vicente J M; Coutinho, Luiz L; Mourão, Gerson B

2016-09-01

Repeated measures from the same individual have been analyzed by using repeatability and finite dimension models under univariate or multivariate analyses. However, in the last decade, the use of random regression models for genetic studies with longitudinal data have become more common. Thus, the aim of this research was to estimate genetic parameters for body weight of four experimental chicken lines by using univariate random regression models. Body weight data from hatching to 84 days of age (n = 34,730) from four experimental free-range chicken lines (7P, Caipirão da ESALQ, Caipirinha da ESALQ and Carijó Barbado) were used. The analysis model included the fixed effects of contemporary group (gender and rearing system), fixed regression coefficients for age at measurement, and random regression coefficients for permanent environmental effects and additive genetic effects. Heterogeneous variances for residual effects were considered, and one residual variance was assigned for each of six subclasses of age at measurement. Random regression curves were modeled by using Legendre polynomials of the second and third orders, with the best model chosen based on the Akaike Information Criterion, Bayesian Information Criterion, and restricted maximum likelihood. Multivariate analyses under the same animal mixed model were also performed for the validation of the random regression models. The Legendre polynomials of second order were better for describing the growth curves of the lines studied. Moderate to high heritabilities (h(2) = 0.15 to 0.98) were estimated for body weight between one and 84 days of age, suggesting that selection for body weight at all ages can be used as a selection criteria. Genetic correlations among body weight records obtained through multivariate analyses ranged from 0.18 to 0.96, 0.12 to 0.89, 0.06 to 0.96, and 0.28 to 0.96 in 7P, Caipirão da ESALQ, Caipirinha da ESALQ, and Carijó Barbado chicken lines, respectively. Results indicate that genetic gain for body weight can be achieved by selection. Also, selection for body weight at 42 days of age can be maintained as a selection criterion. © 2016 Poultry Science Association Inc.
Does low self-esteem predict depression and anxiety? A meta-analysis of longitudinal studies.

PubMed

Sowislo, Julia Friederike; Orth, Ulrich

2013-01-01

Low self-esteem and depression are strongly related, but there is not yet consistent evidence on the nature of the relation. Whereas the vulnerability model states that low self-esteem contributes to depression, the scar model states that depression erodes self-esteem. Furthermore, it is unknown whether the models are specific for depression or whether they are also valid for anxiety. We evaluated the vulnerability and scar models of low self-esteem and depression, and low self-esteem and anxiety, by meta-analyzing the available longitudinal data (covering 77 studies on depression and 18 studies on anxiety). The mean age of the samples ranged from childhood to old age. In the analyses, we used a random-effects model and examined prospective effects between the variables, controlling for prior levels of the predicted variables. For depression, the findings supported the vulnerability model: The effect of self-esteem on depression (β = -.16) was significantly stronger than the effect of depression on self-esteem (β = -.08). In contrast, the effects between low self-esteem and anxiety were relatively balanced: Self-esteem predicted anxiety with β = -.10, and anxiety predicted self-esteem with β = -.08. Moderator analyses were conducted for the effect of low self-esteem on depression; these suggested that the effect is not significantly influenced by gender, age, measures of self-esteem and depression, or time lag between assessments. If future research supports the hypothesized causality of the vulnerability effect of low self-esteem on depression, interventions aimed at increasing self-esteem might be useful in reducing the risk of depression.
Analyzing Multiple Outcomes in Clinical Research Using Multivariate Multilevel Models

PubMed Central

Baldwin, Scott A.; Imel, Zac E.; Braithwaite, Scott R.; Atkins, David C.

2014-01-01

Objective Multilevel models have become a standard data analysis approach in intervention research. Although the vast majority of intervention studies involve multiple outcome measures, few studies use multivariate analysis methods. The authors discuss multivariate extensions to the multilevel model that can be used by psychotherapy researchers. Method and Results Using simulated longitudinal treatment data, the authors show how multivariate models extend common univariate growth models and how the multivariate model can be used to examine multivariate hypotheses involving fixed effects (e.g., does the size of the treatment effect differ across outcomes?) and random effects (e.g., is change in one outcome related to change in the other?). An online supplemental appendix provides annotated computer code and simulated example data for implementing a multivariate model. Conclusions Multivariate multilevel models are flexible, powerful models that can enhance clinical research. PMID:24491071
Effectiveness of a School-based Academic Asthma Health Education and Counseling Program on Fostering Acceptance of Asthma in Older School-age Students with Asthma

PubMed Central

Kintner, Eileen K.; Cook, Gwendolyn; Marti, C. Nathan; Gomes, Melissa; Meeder, Linda; Van Egeren, Laurie A.

2014-01-01

Purpose The purpose was to evaluate the effectiveness of the academic asthma education and counseling SHARP program on fostering psychosocial acceptance of asthma. Design and Methods This was a phase III, two-group, cluster randomized, single-blinded, longitudinal study. Students from grades 4 and 5 (N = 205) with asthma and their caregivers completed surveys at pre-intervention and at 1, 12, and 24 months post-intervention. Analysis involved multilevel modeling. Results All students demonstrated significant improvement in aspects of acceptance; students in SHARP demonstrated significant improvement in openness to sharing and connectedness with teachers over students in the control condition. Practice Implications The SHARP program offers a well-tested, effective program for psychosocial acceptance of asthma, which is welcomed by schools. PMID:25443593
Disentangling the Relative Influence of Schools and Neighborhoods on Adolescents’ Risk for Depressive Symptoms

PubMed Central

Milliren, Carly E.; Evans, Clare R.; Subramanian, S. V.; Richmond, Tracy K.

2015-01-01

Objectives. Although schools and neighborhoods influence health, little is known about their relative importance, or the influence of one context after the influence of the other has been taken into account. We simultaneously examined the influence of each setting on depression among adolescents. Methods. Analyzing data from wave 1 (1994–1995) of the National Longitudinal Study of Adolescent Health, we used cross-classified multilevel modeling to examine between-level variation and individual-, school-, and neighborhood-level predictors of adolescent depressive symptoms. Also, we compared the results of our cross-classified multilevel models (CCMMs) with those of a multilevel model wherein either school or neighborhood was excluded. Results. In CCMMs, the school-level random effect was significant and more than 3 times the neighborhood-level random effect, even after individual-level characteristics had been taken into account. Individual-level indicators (e.g., race/ethnicity, socioeconomic status) were associated with depressive symptoms, but there was no association with either school- or neighborhood-level fixed effects. The between-level variance in depressive symptoms was driven largely by schools as opposed to neighborhoods. Conclusions. Schools appear to be more salient than neighborhoods in explaining variation in depressive symptoms. Future work incorporating cross-classified multilevel modeling is needed to understand the relative effects of schools and neighborhoods. PMID:25713969
Acute and Chronic Effects of Endurance Running on Inflammatory Markers: A Systematic Review

PubMed Central

Barros, Edilberto S.; Nascimento, Dahan C.; Prestes, Jonato; Nóbrega, Otávio T.; Córdova, Claúdio; Sousa, Fernando; Boullosa, Daniel A.

2017-01-01

In order to understand the effect of endurance running on inflammation, it is necessary to quantify the extent to which acute and chronic running affects inflammatory mediators. The aim of this study was to summarize the literature on the effects of endurance running on inflammation mediators. Electronic searches were conducted on PubMED and Science Direct with no limits of date and language of publication. Randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs) investigating the acute and chronic effects of running on inflammation markers in runners were reviewed by two researchers for eligibility. The modified Downs and Black checklist for the assesssments of the methodological quality of studies was subsequently used. Fifty-one studies were finally included. There were no studies with elite athletes. Only two studies were chronic interventions. Results revealed that acute and chronic endurance running may affect anti- and pro-inflammatory markers but methodological differences between studies do not allow comparisons or generalization of the results. The information provided in this systematic review would help practitioners for better designing further studies while providing reference values for a better understanding of inflammatory responses after different running events. Further longitudinal studies are needed to identify the influence of training load parameters on inflammatory markers in runners of different levels and training background. PMID:29089897
Antisocial personality disorder as a predictor of criminal behaviour in a longitudinal study of a cohort of abusers of several classes of drugs: relation to type of substance and type of crime.

PubMed

Fridell, Mats; Hesse, Morten; Jaeger, Mads Meier; Kühlhorn, Eckart

2008-06-01

Mixed findings have been made with regard to the long-term predictive validity of antisocial personality disorder (ASPD) on criminal behaviour in samples of substance abusers. A longitudinal record-linkage study of a cohort of 1052 drug abusers admitted 1977-1995 was undertaken. Subjects were recruited from a detoxification and short-term rehabilitation unit in Lund, Sweden, and followed through criminal justice registers from their first treatment episode to death or to the year 2004. In a ML multinomial random effects regression, subjects diagnosed with antisocial personality disorders were 2.16 times more likely to be charged with theft only (p<0.001), and 2.44 times more likely to be charged committing multiple types of crime during an observation year (p<0.001). The findings of the current study support the predictive validity of the DSM-III-R diagnosis of ASPD. ASPD should be taken seriously in drug abusers, and be targeted in treatment to prevent crime in society.
Impact of Project P.A.T.H.S. on adolescent developmental outcomes in Hong Kong: findings based on seven waves of data.

PubMed

Shek, Daniel T L; Ma, Cecilia M S

2012-01-18

The present study examined the longitudinal impact of Project P.A.T.H.S. (Positive Adolescent Training through Holistic Social Programmes) on adolescent developmental outcomes in Hong Kong. Using a longitudinal randomized group design, seven waves of data were collected from 24 experimental schools (n=4049 at wave 1) in which students participated in the Tier 1 Program of Project P.A.T.H.S. and 24 control schools (n=3797 at wave 1). Results based on individual growth curve modeling generally showed that, relative to the control participants, participants in the experimental group had: (a) a higher level of positive development; (b) a lower level of substance abuse; and (c) a lower level of delinquent behavior. Participants who regarded the program to be beneficial also showed higher levels of positive development and lower levels of problem behavior than did the control school students. The present findings suggest that Project P.A.T.H.S. is effective in promoting positive development and preventing adolescent problem behavior in Chinese adolescents in Hong Kong.

Redesigning a large school-based clinical trial in response to changes in community practice

PubMed Central

Gerald, Lynn B; Gerald, Joe K; McClure, Leslie A; Harrington, Kathy; Erwin, Sue; Bailey, William C

2011-01-01

Background Asthma exacerbations are seasonal with the greatest risk in elementary-age students occurring shortly after returning to school following summer break. Recent research suggests that this seasonality in children is primarily related to viral respiratory tract infections. Regular hand washing is the most effective method to prevent the spread of viral respiratory infections; unfortunately, achieving hand washing recommendations in schools is difficult. Therefore, we designed a study to evaluate the effect of hand sanitizer use in elementary schools on exacerbations among children with asthma. Purpose To describe the process of redesigning the trial in response to changes in the safety profile of the hand sanitizer as well as changes in hand hygiene practice in the schools. Methods The original trial was a randomized, longitudinal, subject-blinded, placebo-controlled, community-based crossover trial. The primary aim was to evaluate the incremental effectiveness of hand sanitizer use in addition to usual hand hygiene practices to decrease asthma exacerbations in elementary-age children. Three events occurred that required major modifications to the original study protocol: (1) safety concerns arose regarding the hand sanitizer’s active ingredient; (2) no substitute placebo hand sanitizer was available; and (3) community preferences changed regarding hand hygiene practices in the schools. Results The revised protocol is a randomized, longitudinal, community-based crossover trial. The primary aim is to evaluate the incremental effectiveness of a two-step hand hygiene process (hand hygiene education plus institutionally provided alcohol-based hand sanitizer) versus usual care to decrease asthma exacerbations. Enrollment was completed in May 2009 with 527 students from 30 schools. The intervention began in August 2009 and will continue through May 2011. Study results should be available at the end of 2011. Limitations The changed design does not allow us to directly measure the effectiveness of hand sanitizer use as a supplement to traditional hand washing practices. Conclusions The need to balance a rigorous study design with one that is acceptable to the community requires investigators to be actively involved with community collaborators and able to adapt study protocols to fit changing community practices. PMID:21730079
Redesigning a large school-based clinical trial in response to changes in community practice.

PubMed

Gerald, Lynn B; Gerald, Joe K; McClure, Leslie A; Harrington, Kathy; Erwin, Sue; Bailey, William C

2011-06-01

Asthma exacerbations are seasonal with the greatest risk in elementary-age students occurring shortly after returning to school following summer break. Recent research suggests that this seasonality in children is primarily related to viral respiratory tract infections. Regular hand washing is the most effective method to prevent the spread of viral respiratory infections; unfortunately, achieving hand washing recommendations in schools is difficult. Therefore, we designed a study to evaluate the effect of hand sanitizer use in elementary schools on exacerbations among children with asthma. To describe the process of redesigning the trial in response to changes in the safety profile of the hand sanitizer as well as changes in hand hygiene practice in the schools. The original trial was a randomized, longitudinal, subject-blinded, placebo-controlled, community-based crossover trial. The primary aim was to evaluate the incremental effectiveness of hand sanitizer use in addition to usual hand hygiene practices to decrease asthma exacerbations in elementary-age children. Three events occurred that required major modifications to the original study protocol: (1) safety concerns arose regarding the hand sanitizer's active ingredient; (2) no substitute placebo hand sanitizer was available; and (3) community preferences changed regarding hand hygiene practices in the schools. The revised protocol is a randomized, longitudinal, community-based crossover trial. The primary aim is to evaluate the incremental effectiveness of a two-step hand hygiene process (hand hygiene education plus institutionally provided alcohol-based hand sanitizer) versus usual care to decrease asthma exacerbations. Enrollment was completed in May 2009 with 527 students from 30 schools. The intervention began in August 2009 and will continue through May 2011. Study results should be available at the end of 2011. The changed design does not allow us to directly measure the effectiveness of hand sanitizer use as a supplement to traditional hand washing practices. The need to balance a rigorous study design with one that is acceptable to the community requires investigators to be actively involved with community collaborators and able to adapt study protocols to fit changing community practices.
Small individual loans and mental health: a randomized controlled trial among South African adults

PubMed Central

Fernald, Lia CH; Hamad, Rita; Karlan, Dean; Ozer, Emily J; Zinman, Jonathan

2008-01-01

Background In the developing world, access to small, individual loans has been variously hailed as a poverty-alleviation tool – in the context of "microcredit" – but has also been criticized as "usury" and harmful to vulnerable borrowers. Prior studies have assessed effects of access to credit on traditional economic outcomes for poor borrowers, but effects on mental health have been largely ignored. Methods Applicants who had previously been rejected (n = 257) for a loan (200% annual percentage rate – APR) from a lender in South Africa were randomly assigned to a "second-look" that encouraged loan officers to approve their applications. This randomized encouragement resulted in 53% of applicants receiving a loan they otherwise would not have received. All subjects were assessed 6–12 months later with questions about demographics, socio-economic status, and two indicators of mental health: the Center for Epidemiologic Studies – Depression Scale (CES-D) and Cohen's Perceived Stress scale. Intent-to-treat analyses were calculated using multinomial probit regressions. Results Randomization into receiving a "second look" for access to credit increased perceived stress in the combined sample of women and men; the findings were stronger among men. Credit access was associated with reduced depressive symptoms in men, but not women. Conclusion Our findings suggest that a mechanism used to reduce the economic stress of extremely poor individuals can have mixed effects on their experiences of psychological stress and depressive symptomatology. Our data support the notion that mental health should be included as a measure of success (or failure) when examining potential tools for poverty alleviation. Further longitudinal research is needed in South Africa and other settings to understand how borrowing at high interest rates affects gender roles and daily life activities. CCT: ISRCTN 10734925 PMID:19087316
Small individual loans and mental health: a randomized controlled trial among South African adults.

PubMed

Fernald, Lia C H; Hamad, Rita; Karlan, Dean; Ozer, Emily J; Zinman, Jonathan

2008-12-16

In the developing world, access to small, individual loans has been variously hailed as a poverty-alleviation tool - in the context of "microcredit" - but has also been criticized as "usury" and harmful to vulnerable borrowers. Prior studies have assessed effects of access to credit on traditional economic outcomes for poor borrowers, but effects on mental health have been largely ignored. Applicants who had previously been rejected (n = 257) for a loan (200% annual percentage rate - APR) from a lender in South Africa were randomly assigned to a "second-look" that encouraged loan officers to approve their applications. This randomized encouragement resulted in 53% of applicants receiving a loan they otherwise would not have received. All subjects were assessed 6-12 months later with questions about demographics, socio-economic status, and two indicators of mental health: the Center for Epidemiologic Studies - Depression Scale (CES-D) and Cohen's Perceived Stress scale. Intent-to-treat analyses were calculated using multinomial probit regressions. Randomization into receiving a "second look" for access to credit increased perceived stress in the combined sample of women and men; the findings were stronger among men. Credit access was associated with reduced depressive symptoms in men, but not women. Our findings suggest that a mechanism used to reduce the economic stress of extremely poor individuals can have mixed effects on their experiences of psychological stress and depressive symptomatology. Our data support the notion that mental health should be included as a measure of success (or failure) when examining potential tools for poverty alleviation. Further longitudinal research is needed in South Africa and other settings to understand how borrowing at high interest rates affects gender roles and daily life activities. CCT: ISRCTN 10734925.
Bayesian analysis of zero inflated spatiotemporal HIV/TB child mortality data through the INLA and SPDE approaches: Applied to data observed between 1992 and 2010 in rural North East South Africa

NASA Astrophysics Data System (ADS)

Musenge, Eustasius; Chirwa, Tobias Freeman; Kahn, Kathleen; Vounatsou, Penelope

2013-06-01

Longitudinal mortality data with few deaths usually have problems of zero-inflation. This paper presents and applies two Bayesian models which cater for zero-inflation, spatial and temporal random effects. To reduce the computational burden experienced when a large number of geo-locations are treated as a Gaussian field (GF) we transformed the field to a Gaussian Markov Random Fields (GMRF) by triangulation. We then modelled the spatial random effects using the Stochastic Partial Differential Equations (SPDEs). Inference was done using a computationally efficient alternative to Markov chain Monte Carlo (MCMC) called Integrated Nested Laplace Approximation (INLA) suited for GMRF. The models were applied to data from 71,057 children aged 0 to under 10 years from rural north-east South Africa living in 15,703 households over the years 1992-2010. We found protective effects on HIV/TB mortality due to greater birth weight, older age and more antenatal clinic visits during pregnancy (adjusted RR (95% CI)): 0.73(0.53;0.99), 0.18(0.14;0.22) and 0.96(0.94;0.97) respectively. Therefore childhood HIV/TB mortality could be reduced if mothers are better catered for during pregnancy as this can reduce mother-to-child transmissions and contribute to improved birth weights. The INLA and SPDE approaches are computationally good alternatives in modelling large multilevel spatiotemporal GMRF data structures.
Cross-section and panel estimates of peer effects in early adolescent cannabis use: With a little help from my 'friends once removed'.

PubMed

Moriarty, John; McVicar, Duncan; Higgins, Kathryn

2016-08-01

Peer effects in adolescent cannabis are difficult to estimate, due in part to the lack of appropriate data on behaviour and social ties. This paper exploits survey data that have many desirable properties and have not previously been used for this purpose. The data set, collected from teenagers in three annual waves from 2002 to 2004 contains longitudinal information about friendship networks within schools (N = 5020). We exploit these data on network structure to estimate peer effects on adolescents from their nominated friends within school using two alternative approaches to identification. First, we present a cross-sectional instrumental variable (IV) estimate of peer effects that exploits network structure at the second degree, i.e. using information on friends of friends who are not themselves ego's friends to instrument for the cannabis use of friends. Second, we present an individual fixed effects estimate of peer effects using the full longitudinal structure of the data. Both innovations allow a greater degree of control for correlated effects than is commonly the case in the substance-use peer effects literature, improving our chances of obtaining estimates of peer effects than can be plausibly interpreted as causal. Both estimates suggest positive peer effects of non-trivial magnitude, although the IV estimate is imprecise. Furthermore, when we specify identical models with behaviour and characteristics of randomly selected school peers in place of friends', we find effectively zero effect from these 'placebo' peers, lending credence to our main estimates. We conclude that cross-sectional data can be used to estimate plausible positive peer effects on cannabis use where network structure information is available and appropriately exploited. Copyright © 2016 Elsevier Ltd. All rights reserved.
Maternal employment and the health of low-income young children.

PubMed

Gennetian, Lisa A; Hill, Heather D; London, Andrew S; Lopoo, Leonard M

2010-05-01

This study examines whether maternal employment affects the health status of low-income, elementary-school-aged children using instrumental variables estimation and experimental data from a welfare-to-work program implemented in the early 1990s. Maternal report of child health status is predicted as a function of exogenous variation in maternal employment associated with random assignment to the experimental group. IV estimates show a modest adverse effect of maternal employment on children's health. Making use of data from another welfare-to-work program we propose that any adverse effect on child health may be tempered by increased family income and access to public health insurance coverage, findings with direct relevance to a number of current policy discussions. In a secondary analysis using fixed effects techniques on longitudinal survey data collected in 1998 and 2001, we find a comparable adverse effect of maternal employment on child health that supports the external validity of our primary result.
Training the elderly on the ability factors of spatial orientation and inductive reasoning.

PubMed

Willis, S L; Schaie, K W

1986-09-01

We examined the effects of cognitive training with elderly participants from the Seattle Longitudinal Study. Subjects were classified as having remained stable or having declined over the previous 14-year interval on each of two primary abilities, spatial orientation and inductive reasoning. Subjects who had declined on one of these abilities received training on that ability; subjects who had declined on both abilities or who had remained stable on both were randomly assigned to the spatial orientation or inductive reasoning training programs. Training outcomes were examined within an ability-measurement framework with empirically determined factorial structure. Significant training effects, at the level of the latent ability constructs, occurred for both spatial orientation and inductive reasoning. These effects were general, in that no significant interactions with decline status or gender were found. Thus, training interventions were effective both in remediating cognitive decline on the target abilities and in improving the performance of stable subjects.
Associations of Renin-Angiotensin-Aldosterone System Genes With Blood Pressure Changes and Hypertension Incidence.

PubMed

He, William J; Li, Changwei; Rao, Dabeeru C; Hixson, James E; Huang, Jianfeng; Cao, Jie; Rice, Treva K; Shimmin, Lawrence C; Gu, Dongfeng; Kelly, Tanika N

2015-11-01

The renin-angiotensin-aldosterone system (RAAS) plays an important role in blood pressure (BP) regulation. The current study uses single-marker and gene-based analyses to examine the association between RAAS genes and longitudinal BP phenotypes in a Han Chinese population. A total of 1,768 participants from the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) follow-up study were included in the current study. Twenty-seven BP measurements were taken using random-zero sphygmomanometers at baseline and 2 follow-up visits. Mixed-effect models were used to assess the additive associations of 106 single-nucleotide polymorphisms (SNPs) in 10 RAAS genes with longitudinal BP changes and hypertension incidence. Gene-based analyses were conducted using the truncated product method. Attempts were made to replicate significant findings among Asian participants of the Multi-ethnic Study of Atherosclerosis (MESA). False discovery rate procedures were used to adjust for multiple testing. During an average of 7.2 years of follow-up, average systolic and diastolic BP increased, and 32.1% (512) of participants free from hypertension at baseline developed hypertension. NR3C2 SNPs rs7694064 and rs6856803 were significantly associated with longitudinal changes in systolic BP (P interaction = 6.9×10(-5) and 8.2×10(-4), respectively). Through gene-based analysis, NR3C2 was found to be significantly associated with longitudinal systolic BP change (P value of 1.00×10(-7)), even after removal of significant markers rs7694064 and rs6856803 from the analysis. The association between NR3C2 and longitudinal systolic BP change was replicated in Asian MESA participants (P value of 1.00×10(-4)). These findings indicate that NR3C2 may play an important role in BP progression and development of hypertension. © American Journal of Hypertension, Ltd 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Using a Shared Parameter Mixture Model to Estimate Change during Treatment when Termination is Related to Recovery Speed

PubMed Central

Gottfredson, Nisha C.; Bauer, Daniel J.; Baldwin, Scott A.; Okiishi, John C.

2014-01-01

Objective This study demonstrates how to use a shared parameter mixture model (SPMM) in longitudinal psychotherapy studies to accommodate missing that are due to a correlation between rate of improvement and termination of therapy. Traditional growth models assume that such a relationship does not exist (i.e., assume that data are missing at random) and will produce biased results if this assumption is incorrect. Method We use longitudinal data from 4,676 patients enrolled in a naturalistic study of psychotherapy to compare results from a latent growth model and a shared parameter mixture model (SPMM). Results In this dataset, estimates of the rate of improvement during therapy differ by 6.50 – 6.66% across the two models, indicating that participants with steeper trajectories left psychotherapy earliest, thereby potentially biasing inference for the slope in the latent growth model. Conclusion We conclude that reported estimates of change during therapy may be underestimated in naturalistic studies of therapy in which participants and their therapists determine the end of treatment. Because non-randomly missing data can also occur in randomized controlled trials or in observational studies of development, the utility of the SPMM extends beyond naturalistic psychotherapy data. PMID:24274626
Multivariate generalized hidden Markov regression models with random covariates: Physical exercise in an elderly population.

PubMed

Punzo, Antonio; Ingrassia, Salvatore; Maruotti, Antonello

2018-04-22

A time-varying latent variable model is proposed to jointly analyze multivariate mixed-support longitudinal data. The proposal can be viewed as an extension of hidden Markov regression models with fixed covariates (HMRMFCs), which is the state of the art for modelling longitudinal data, with a special focus on the underlying clustering structure. HMRMFCs are inadequate for applications in which a clustering structure can be identified in the distribution of the covariates, as the clustering is independent from the covariates distribution. Here, hidden Markov regression models with random covariates are introduced by explicitly specifying state-specific distributions for the covariates, with the aim of improving the recovering of the clusters in the data with respect to a fixed covariates paradigm. The hidden Markov regression models with random covariates class is defined focusing on the exponential family, in a generalized linear model framework. Model identifiability conditions are sketched, an expectation-maximization algorithm is outlined for parameter estimation, and various implementation and operational issues are discussed. Properties of the estimators of the regression coefficients, as well as of the hidden path parameters, are evaluated through simulation experiments and compared with those of HMRMFCs. The method is applied to physical activity data. Copyright © 2018 John Wiley & Sons, Ltd.
A Systematic Review and Meta-Analysis of The Effect of Low Vitamin D on Cognition.

PubMed

Goodwill, Alicia M; Szoeke, Cassandra

2017-10-01

With an aging population and no cure for dementia on the horizon, risk factor modification prior to disease onset is an urgent health priority. Therefore, this review examined the effect of low vitamin D status or vitamin D supplementation on cognition in midlife and older adults without a diagnosis of dementia. Systematic review and random effect meta-analysis. Observational (cross-sectional and longitudinal cohort) studies comparing low and high vitamin D status and interventions comparing vitamin D supplementation with a control group were included in the review and meta-analysis. Studies including adults and older adults without a dementia diagnosis were included. Medline (PubMed), AMED, Psych INFO, and Cochrane Central databases were searched for articles until August 2016. The Newcastle-Ottawa Scale and Physiotherapy Evidence Database assessed methodological quality of all studies. Twenty-six observational and three intervention studies (n = 19-9,556) were included in the meta-analysis. Low vitamin D was associated with worse cognitive performance (OR = 1.24, CI = 1.14-1.35) and cognitive decline (OR = 1.26, CI = 1.09-1.23); with cross-sectional yielding a stronger effect compared to longitudinal studies. Vitamin D supplementation showed no significant benefit on cognition compared with control (SMD = 0.21, CI = -0.05 to 0.46). Observational evidence demonstrates low vitamin D is related to poorer cognition; however, interventional studies are yet to show a clear benefit from vitamin D supplementation. From the evidence to date, there is likely a therapeutic age window relevant to the development of disease and therefore vitamin D therapy. Longitudinal lifespan studies are necessary to depict the optimal timing and duration in which repletion of vitamin D may protect against cognitive decline and dementia in aging, to better inform trials and practice towards a successful therapy. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.
A longitudinal analysis of the effects of socioeconomic factors, foreign media, and attitude toward appearance on general and central adiposity in Chinese adolescents

PubMed Central

Felicitas, Jamie Q.; Tanenbaum, Hilary C.; Li, Yawen; Chou, Chih-Ping; Palmer, Paula H.; Spruijt-Metz, Donna; Reynolds, Kim D.; Johnson, C. Anderson; Xie, Bin

2015-01-01

This paper explores the longitudinal effects of socioeconomic factors (i.e., parent education and family income level), foreign media, and attitude toward appearance on general and central adiposity among Chinese adolescents. A longitudinal analysis was performed using data from the China Seven Cities Study, a health promotion and smoking prevention study conducted in seven cities across Mainland China between 2002 and 2005. Participants included 5,020 middle and high school students and their parents. Explanatory variables included foreign media exposure, attitude toward appearance, parent education, and family income. Three-level, random-effect models were used to predict general adiposity (i.e., body mass index) and central adiposity (i.e., waist circumference). The Generalized Estimating Equation approach was utilized to determine the effect of explanatory variables on overweight status. Among girls, foreign media exposure was significantly negatively associated with general adiposity over time (β = − 0.06, p = 0.01 for middle school girls; β = − 0.06, p = 0.03 for high school girls). Attitude toward appearance was associated with lesser odds of being overweight, particularly among high school girls (OR = 0.86, p < 0.01). Among boys, parental education was significantly positively associated with general adiposity (β = 0.62, p < 0.01 for middle school boys; β = 0.37, p = 0.02 for high school boys) and associated with greater odds of being overweight (OR = 1.55, p < 0.01 for middle school boys; OR = 1.26, p = 0.04 for high school boys). Across all gender and grade levels, family income was significantly negatively associated with central adiposity over time. Interventions addressing Chinese adolescent overweight/obesity should consider these factors as potential focus areas. PMID:26279973
A cognitive behavioral group approach to enhance adherence to hemodialysis fluid restrictions: a randomized controlled trial.

PubMed

Sharp, John; Wild, Matt R; Gumley, Andrew I; Deighan, Christopher J

2005-06-01

Adhering to fluid restrictions represents one of the most difficult aspects of the hemodialysis treatment regimen. This report describes a randomized controlled trial of a group-based cognitive behavioral intervention aimed at improving fluid-restriction adherence in patients receiving hemodialysis. It was hypothesized that the intervention would improve adherence, measured by means of interdialytic weight gain (IWG), without impacting negatively on psychosocial functioning. Fifty-six participants receiving hemodialysis from 4 renal outpatient settings were randomly assigned to an immediate-treatment group (ITG; n = 29) or deferred-treatment group (DTG; n = 27). Participants were assessed at baseline, posttreatment, and follow-up stages. Treatment consisted of a 4-week intervention using educational, cognitive, and behavioral strategies to enhance effective self-management of fluid consumption. No significant difference in mean IWGs was found between the ITG and DTG during the acute-phase analysis (F(1,54) = 0.03; P > 0.05). However, in longitudinal analysis, there was a significant main effect for mean IWG (F(1.76,96.80) = 9.10; P < 0.001) and a significant difference between baseline and follow-up IWG values (t55 = 3.85; P < 0.001), reflecting improved adherence over time. No adverse effects of treatment were indicated through measures of psychosocial functioning. Some significant changes were evidenced in cognitions thought to be important in mediating behavioral change. The current study provides evidence for the feasibility and effectiveness of applying group-based cognitive behavior therapy to enhance adherence to hemodialysis fluid restrictions. Results are discussed in the context of the study's methodological limitations.
Effects of a 12 week self-managed stretching program among Korean-Chinese female migrant workers in Korea: a randomized trial.

PubMed

Lee, Hyeonkyeong; Chae, Duckhee; Wilbur, JoEllen; Miller, Arlene; Lee, Kyongeun; Jin, Hwaeun

2014-04-01

The purpose of this study was to assess the efficacy of a 12 week, self-managed, community-based stretching program on musculoskeletal fitness, musculoskeletal symptoms, and acculturative stress, in Korean-Chinese female migrant workers in Korea. This was a randomized controlled trial with random assignment of eligible full-time Korean-Chinese female migrant workers to a stretching exercise intervention (n=40) or an enhanced stretching exercise intervention (n=40) condition. Both conditions received a 6 min stretching exercise program that included an orientation and three work-related musculoskeletal disorder (WMSD) educational classes. Between educational classes, the enhanced stretching exercise condition also received mobile phone text messaging and telephone counseling to increase self-efficacy (confidence in overcoming barriers) and provide social support. Flexibility, muscle strength, musculoskeletal symptoms, and acculturative stress were assessed at baseline and 12 weeks. Significant increase in flexibility was noted for both conditions, but acculturative stress was significantly reduced only in the standard intervention condition. Muscle strength and WMSD symptoms had no significant changes at the 12 week follow up in both conditions. The 12 week, self-managed, community-based, stretching exercise program was effective to increase flexibility. The standard stretching intervention without any enhancements may be a more cost-effective way to increase flexibility. Longitudinal studies, however, are needed to see if the long-term effects are greater in the enhanced intervention for the migrant worker population. © 2013 The Authors. Japan Journal of Nursing Science © 2013 Japan Academy of Nursing Science.
Help yourself: the mechanisms through which a self-leadership intervention influences strain.

PubMed

Unsworth, Kerrie L; Mason, Claire M

2012-04-01

This research reports on two field studies which demonstrate that self-leadership training decreases strain via increases in self-efficacy and positive affect. The first, an experimental study, found that strain was reduced in the randomly assigned training group, but not in the control group. The second was a longitudinal study and supported the hypotheses that self-efficacy and positive affect mediated the effect of self-leadership training on strain. Our findings extend both self-leadership and stress management literatures by providing a theoretical framework within which the effects of self-leadership on strain can be understood. Practically speaking, our findings suggest that self-leadership training offers an individual-level preventive approach to stress management. PsycINFO Database Record (c) 2012 APA, all rights reserved.
GWAS with longitudinal phenotypes: performance of approximate procedures

PubMed Central

Sikorska, Karolina; Montazeri, Nahid Mostafavi; Uitterlinden, André; Rivadeneira, Fernando; Eilers, Paul HC; Lesaffre, Emmanuel

2015-01-01

Analysis of genome-wide association studies with longitudinal data using standard procedures, such as linear mixed model (LMM) fitting, leads to discouragingly long computation times. There is a need to speed up the computations significantly. In our previous work (Sikorska et al: Fast linear mixed model computations for genome-wide association studies with longitudinal data. Stat Med 2012; 32.1: 165–180), we proposed the conditional two-step (CTS) approach as a fast method providing an approximation to the P-value for the longitudinal single-nucleotide polymorphism (SNP) effect. In the first step a reduced conditional LMM is fit, omitting all the SNP terms. In the second step, the estimated random slopes are regressed on SNPs. The CTS has been applied to the bone mineral density data from the Rotterdam Study and proved to work very well even in unbalanced situations. In another article (Sikorska et al: GWAS on your notebook: fast semi-parallel linear and logistic regression for genome-wide association studies. BMC Bioinformatics 2013; 14: 166), we suggested semi-parallel computations, greatly speeding up fitting many linear regressions. Combining CTS with fast linear regression reduces the computation time from several weeks to a few minutes on a single computer. Here, we explore further the properties of the CTS both analytically and by simulations. We investigate the performance of our proposal in comparison with a related but different approach, the two-step procedure. It is analytically shown that for the balanced case, under mild assumptions, the P-value provided by the CTS is the same as from the LMM. For unbalanced data and in realistic situations, simulations show that the CTS method does not inflate the type I error rate and implies only a minimal loss of power. PMID:25712081
Effect of music care on depression and behavioral problems in elderly people with dementia in Taiwan: a quasi-experimental, longitudinal study.

PubMed

Wang, Su-Chin; Yu, Ching-Len; Chang, Su-Hsien

2017-02-01

The purpose was to examine the effectiveness of music care on cognitive function, depression, and behavioral problems among elderly people with dementia in long-term care facilities in Taiwan. The study had a quasi-experimental, longitudinal research design and used two groups of subjects. Subjects were not randomly assigned to experimental group (n = 90) or comparison group (n = 56). Based on Bandura's social cognition theory, subjects in the experimental group received Kagayashiki music care (KMC) twice per week for 24 weeks. Subjects in the comparison group were provided with activities as usual. Results found, using the control score of the Clifton Assessment Procedures for the Elderly Behavior Rating Scale (baseline) and time of attending KMC activities as a covariate, the two groups of subjects had statistically significant differences in the mini-mental state examination (MMSE). Results also showed that, using the control score of the Cornell Scale for Depression in Dementia (baseline) and MMSE (baseline) as a covariate, the two groups of subjects had statistically significant differences in the Clifton Assessment Procedures for the Elderly Behavior Rating Scale. These findings provide information for staff caregivers in long-term care facilities to develop a non-invasive care model for elderly people with dementia to deal with depression, anxiety, and behavioral problems.
Longitudinal analysis of physical activity, fluid intake, and graft function among kidney transplant recipients

PubMed Central

Gordon, Elisa J.; Prohaska, Thomas R.; Gallant, Mary P.; Sehgal, Ashwini R.; Strogatz, David; Yucel, Recai; Conti, David; Siminoff, Laura A.

2010-01-01

Summary Self-care is recommended to kidney transplant recipients as a vital component to maintain long-term graft function. However, little is known about the effects of physical activity, fluid intake, and smoking history on graft function. This longitudinal study examined the relationship between self-care practices on graft function among 88 new kidney transplant recipients in Chicago, IL and Albany, NY between 2005 and 2008. Participants were interviewed, completed surveys, and medical charts were abstracted. Physical activity, fluid intake, and smoking history at baseline were compared with changes in estimated glomerular filtration rate (eGFR) (every 6 months up to 1 year) using bivariate and multivariate regression analysis, while controlling for sociodemographic and clinical transplant variables. Multivariate analyses revealed that greater physical activity was significantly (P < 0.05) associated with improvement in GFR at 6 months; while greater physical activity, absence of smoking history, and nonwhite ethnicity were significant (P < 0.05) predictors of improvement in GFR at 12 months. These results suggest that increasing physical activity levels in kidney recipients may be an effective behavioral measure to help ensure graft functioning. Our findings suggest the need for a randomized controlled trial of exercise, fluid intake, and smoking history on GFR beyond 12 months. PMID:19619168
Longitudinal analysis of physical activity, fluid intake, and graft function among kidney transplant recipients.

PubMed

Gordon, Elisa J; Prohaska, Thomas R; Gallant, Mary P; Sehgal, Ashwini R; Strogatz, David; Yucel, Recai; Conti, David; Siminoff, Laura A

2009-10-01

Self-care is recommended to kidney transplant recipients as a vital component to maintain long-term graft function. However, little is known about the effects of physical activity, fluid intake, and smoking history on graft function. This longitudinal study examined the relationship between self-care practices on graft function among 88 new kidney transplant recipients in Chicago, IL and Albany, NY between 2005 and 2008. Participants were interviewed, completed surveys, and medical charts were abstracted. Physical activity, fluid intake, and smoking history at baseline were compared with changes in estimated glomerular filtration rate (eGFR) (every 6 months up to 1 year) using bivariate and multivariate regression analysis, while controlling for sociodemographic and clinical transplant variables. Multivariate analyses revealed that greater physical activity was significantly (P < 0.05) associated with improvement in GFR at 6 months; while greater physical activity, absence of smoking history, and nonwhite ethnicity were significant (P < 0.05) predictors of improvement in GFR at 12 months. These results suggest that increasing physical activity levels in kidney recipients may be an effective behavioral measure to help ensure graft functioning. Our findings suggest the need for a randomized controlled trial of exercise, fluid intake, and smoking history on GFR beyond 12 months.

Analysis of longitudinal multivariate outcome data from couples cohort studies: application to HPV transmission dynamics

PubMed Central

Kong, Xiangrong; Wang, Mei-Cheng; Gray, Ronald

2014-01-01

We consider a specific situation of correlated data where multiple outcomes are repeatedly measured on each member of a couple. Such multivariate longitudinal data from couples may exhibit multi-faceted correlations which can be further complicated if there are polygamous partnerships. An example is data from cohort studies on human papillomavirus (HPV) transmission dynamics in heterosexual couples. HPV is a common sexually transmitted disease with 14 known oncogenic types causing anogenital cancers. The binary outcomes on the multiple types measured in couples over time may introduce inter-type, intra-couple, and temporal correlations. Simple analysis using generalized estimating equations or random effects models lacks interpretability and cannot fully utilize the available information. We developed a hybrid modeling strategy using Markov transition models together with pairwise composite likelihood for analyzing such data. The method can be used to identify risk factors associated with HPV transmission and persistence, estimate difference in risks between male-to-female and female-to-male HPV transmission, compare type-specific transmission risks within couples, and characterize the inter-type and intra-couple associations. Applying the method to HPV couple data collected in a Ugandan male circumcision (MC) trial, we assessed the effect of MC and the role of gender on risks of HPV transmission and persistence. PMID:26195849
Early Parturition: Is Young Maternal Age at First Birth Associated with Obesity?

PubMed

Patchen, Loral; Leoutsakos, Jeannie-Marie; Astone, Nan M

2017-10-01

Examine the association of age at first birth with body mass index (BMI), and explore the role of young maternal age and subsequent obesity. This study analyzed data from the Panel Study of Income Dynamics, a nationally representative longitudinal study of US families. Analyses were conducted using a mixed effects longitudinal linear regression with a random intercept to examine the effect of aging, age at first birth, and minority status using nested data. Study criteria yielded a final sample of 146 women with 707 observations. BMI. Age at first birth exhibited a significant association with BMI. The association of age at first birth with BMI was greatest for women age 21 and younger. Overall, women who experienced their first birth at age 21 or younger had a BMI 5 units greater than women who delayed childbearing until at least age 30 (point estimate, 5.02; P = .02; 95% confidence interval, 0.65-9.40). Young maternal age at first birth might be associated with increased BMI. Minority women also experience their first birth at younger ages compared with white women, suggesting possible linkages between the timing of reproductive events and obesity disparities. Copyright © 2016 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.
Do self-efficacy and depression predict oral impacts on daily performances across time? A 2-yr follow-up of students in Tanzania.

PubMed

Åstrøm, Anne N; Lie, Stein A; Mbawalla, Hawa

2016-08-01

This study aimed to assess the longitudinal validity of the oral impacts on daily performance (OIDP) and to identify psychosocial determinants, in terms of self-efficacy and depressive symptoms, of the OIDP across time. Following conceptual frameworks of oral health, it was hypothesized that sociodemographic, clinical, and psychosocial factors predict oral impacts across time at both population- averaged and person-specific levels. Whether the effects of sociodemographic and clinical factors were accounted for, totally or in part, by psychosocial factors were also investigated. Self administered questionnaires and oral clinical examinations at baseline (2009) and follow-up (2011) were completed by 1,714 and 727 secondary school students, respectively. Generalized equalized equations and a random intercept model were used to account for the dependency in repeated observations. Mean OIDP change scores were negative (worsened) among those who reported worsened self-reported oral health. Psychosocial, clinical, and sociodemographic factors were independently associated with oral impacts at the population-averaged and person-specific levels. Mediation of sociodemographic and clinical variables according to psychosocial variables was not observed. Satisfactory longitudinal evaluative properties of the OIDP, and independent effects of psychosocial factors on oral impacts across time, were confirmed among secondary school students in Tanzania. © 2016 Eur J Oral Sci.
Idea Density Measured in Late Life Predicts Subsequent Cognitive Trajectories: Implications for the Measurement of Cognitive Reserve

PubMed Central

Chand, Vineeta; Bonnici, Lisa; Baynes, Kathleen; Harvey, Danielle; Mungas, Dan; Simon, Christa; Reed, Bruce

2012-01-01

Objective. The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change. Method. ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial abilities, and executive function) were examined as outcomes. Separate random effects models tested the effect of ID on longitudinal change in outcomes, adjusted for age and education. Results. Lower ID was associated with greater subsequent decline in global cognition, semantic memory, episodic memory, and spatial abilities. When analysis was restricted to only participants without dementia at the time ID was collected, results were similar. Discussion. Linguistic ability in young adulthood, as measured by ID, has been previously proposed as an index of neurocognitive development and/or cognitive reserve. The present study provides evidence that even when ID is measured in old age, it continues to be associated with subsequent cognitive decline and as such may continue to provide a marker of cognitive reserve. PMID:22357642
Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines.

PubMed

Grajeda, Laura M; Ivanescu, Andrada; Saito, Mayuko; Crainiceanu, Ciprian; Jaganath, Devan; Gilman, Robert H; Crabtree, Jean E; Kelleher, Dermott; Cabrera, Lilia; Cama, Vitaliano; Checkley, William

2016-01-01

Childhood growth is a cornerstone of pediatric research. Statistical models need to consider individual trajectories to adequately describe growth outcomes. Specifically, well-defined longitudinal models are essential to characterize both population and subject-specific growth. Linear mixed-effect models with cubic regression splines can account for the nonlinearity of growth curves and provide reasonable estimators of population and subject-specific growth, velocity and acceleration. We provide a stepwise approach that builds from simple to complex models, and account for the intrinsic complexity of the data. We start with standard cubic splines regression models and build up to a model that includes subject-specific random intercepts and slopes and residual autocorrelation. We then compared cubic regression splines vis-à-vis linear piecewise splines, and with varying number of knots and positions. Statistical code is provided to ensure reproducibility and improve dissemination of methods. Models are applied to longitudinal height measurements in a cohort of 215 Peruvian children followed from birth until their fourth year of life. Unexplained variability, as measured by the variance of the regression model, was reduced from 7.34 when using ordinary least squares to 0.81 (p < 0.001) when using a linear mixed-effect models with random slopes and a first order continuous autoregressive error term. There was substantial heterogeneity in both the intercept (p < 0.001) and slopes (p < 0.001) of the individual growth trajectories. We also identified important serial correlation within the structure of the data (ρ = 0.66; 95 % CI 0.64 to 0.68; p < 0.001), which we modeled with a first order continuous autoregressive error term as evidenced by the variogram of the residuals and by a lack of association among residuals. The final model provides a parametric linear regression equation for both estimation and prediction of population- and individual-level growth in height. We show that cubic regression splines are superior to linear regression splines for the case of a small number of knots in both estimation and prediction with the full linear mixed effect model (AIC 19,352 vs. 19,598, respectively). While the regression parameters are more complex to interpret in the former, we argue that inference for any problem depends more on the estimated curve or differences in curves rather than the coefficients. Moreover, use of cubic regression splines provides biological meaningful growth velocity and acceleration curves despite increased complexity in coefficient interpretation. Through this stepwise approach, we provide a set of tools to model longitudinal childhood data for non-statisticians using linear mixed-effect models.
Coping with Memory Effect and Serial Correlation when Estimating Reliability in a Longitudinal Framework

ERIC Educational Resources Information Center

Laenen, Annouschka; Alonso, Ariel; Molenberghs, Geert; Vangeneugden, Tony; Mallinckrodt, Craig H.

2010-01-01

Longitudinal studies are permeating clinical trials in psychiatry. Therefore, it is of utmost importance to study the psychometric properties of rating scales, frequently used in these trials, within a longitudinal framework. However, intrasubject serial correlation and memory effects are problematic issues often encountered in longitudinal data.…
De qeurvian tenosynovitis: clinical outcomes of surgical treatment with longitudinal and transverse incision.

PubMed

Abrisham, Syyed Jalil; Karbasi, Mohammad Hosein Akhavan; Zare, Jalil; Behnamfar, Zahra; Tafti, Arefah Dehghani; Shishesaz, Behzad

2011-03-01

De Quervain disease is a mechanical tenosynovitis due to inadequacy volume between abductor pollicis longus, extensor pollicis brevis and their tunnel. Treatment methods include immobilization, steroid injections, and operation. For the first time Fritz De Quervain described surgical treatment of this disease. Since then, various ways of treatment have been reported. The purpose of this study is to compare the clinical outcomes of a longitudinal incision with a transverse incision in De Quervain disease. This was a randomized controlled clinical trial conducted in three hospitals in Iran, Yazd from March 2003 to September 2008. One hundred-twenty patients with De Quervain disease who did not respond to conservative treatment were operated with two different incisions. The patients were followed for three months to compare the surgical outcomes. During a three month follow-up, a significant difference was shown between the two methods (p=0.03). Results of surgical treatment with longitudinal incision were excellent (only 5 hypertrophic scars), but there were 13 postoperative complaints with transverse incision. According to our findings, longitudinal incision in surgical treatment of De Quervain disease is better than transverse incision.
Associations between ankle-brachial index and cognitive function: results from the Lifestyle Interventions and Independence for Elders trial

USDA-ARS?s Scientific Manuscript database

OBJECTIVE: The objective of this study was to evaluate cross-sectional and longitudinal associations between ankle-brachial index (ABI) and indicators of cognitive function. DESIGN: Randomized clinical trial (Lifestyle Interventions and Independence for Elders Trial). SETTING: Eight US academic ce...
Intergenerational Benefits of Family-Based HIV Interventions

ERIC Educational Resources Information Center

Rotheram-Borus, Mary Jane; Lester, Patricia; Song, Juwon; Lin, Ying-Ying; Leonard, Noelle R.; Beckwith, Leila; Ward, Mary J.; Sigman, Marian; Lord,Lynwood

2006-01-01

The longitudinal impact of a family-based intervention on grandchildren of parents with HIV (PWH) is evaluated. Because PWH and their daughters demonstrated gains over 6 years when randomized to a coping skills intervention compared with a control condition, the adjustment of the PWH's grandchildren was also compared across conditions.…
76 FR 1621 - Proposed Collection; Comment Request; NIH Toolbox for Assessment of Neurological and Behavioral...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-11

..., emotional, motor and sensory) for use in large longitudinal or epidemiological studies where functioning is... of establishing comparative norms. Existing recruitment databases will be randomly sampled and... * Adult study participants, single assessment..... 3,150 1 3 9,450 Adult study participants, two...
Compressive response and helix formation of a semiflexible polymer confined in a nanochannel

NASA Astrophysics Data System (ADS)

Hayase, Yumino; Sakaue, Takahiro; Nakanishi, Hiizu

2017-05-01

Configurations of a single semiflexible polymer is studied when it is pushed into a nanochannel in the case where the polymer persistence length lp is much longer than the channel diameter D :lp/D ≫1 . Using numerical simulations, we show that the polymer undergoes a sequence of recurring structural transitions upon longitudinal compression: random deflection along the channel, a helix going around the channel wall, double-fold random deflection, double-fold helix, etc. We find that the helix transition can be understood as buckling of deflection segments, and the initial helix formation takes place at very small compression with no appreciable weak compression regime of the random deflection polymer.
Spousal interrelations in happiness in the Seattle Longitudinal Study: considerable similarities in levels and change over time.

PubMed

Hoppmann, Christiane A; Gerstorf, Denis; Willis, Sherry L; Schaie, K Warner

2011-01-01

Development does not take place in isolation and is often interrelated with close others such as marital partners. To examine interrelations in spousal happiness across midlife and old age, we used 35-year longitudinal data from both members of 178 married couples in the Seattle Longitudinal Study. Latent growth curve models revealed sizeable spousal similarities not only in levels of happiness but also in how happiness changed over time. These spousal interrelations were considerably larger in size than those found among random pairs of women and men from the same sample. Results are in line with life-span theories emphasizing an interactive minds perspective by showing that adult happiness waxes and wanes in close association with the respective spouse. Our findings also complement previous individual-level work on age-related changes in well-being by pointing to the importance of using the couple as the unit of analysis.
The impact of victim-focused outreach on criminal legal system outcomes following police-reported intimate partner abuse.

PubMed

DePrince, Anne P; Belknap, Joanne; Labus, Jennifer S; Buckingham, Susan E; Gover, Angela R

2012-08-01

Randomized control designs have been used in the public health and psychological literatures to examine the relationship between victim outreach following intimate partner abuse (IPA) and various outcomes. These studies have largely relied on samples drawn from health providers and shelters to examine outcomes outside the criminal legal system. Based on the positive findings from this body of research, we expected that a victim-focused, community-coordinated outreach intervention would improve criminal legal system outcomes. The current study used a randomized, longitudinal design to recruit 236 ethnically diverse women with police-reported IPA to compare treatment-as-usual with an innovative community-coordinated, victim-focused outreach program. Findings indicated that the outreach program was effective in increasing women's engagement with prosecution tasks as well as likelihood of taking part in prosecution of their abusers. Results were particularly robust among women marginalized by ethnicity and class, and those still living with their abusers after the target incident.
Safety and efficacy of antihypertensive prescription at emergency department discharge.

PubMed

Brody, Aaron; Rahman, Tahsin; Reed, Brian; Millis, Scott; Ference, Brian; Flack, John M; Levy, Phillip D

2015-05-01

Poor blood pressure (BP) control is a primary risk factor for target organ damage in the heart, brain, and kidney. Uncontrolled hypertension is common among emergency department (ED) patients, particularly in underresourced settings, but it is unclear what role ED providers should play in the management of chronic antihypertensive therapy. The objective was to evaluate the safety and efficacy of prescribing antihypertensive therapy from the ED. This was a retrospective study of data pooled from two prospective, longitudinal, randomized controlled trials, both of which enrolled ED patients with asymptomatic hypertension. Antihypertensives were prescribed at emergency physician discretion, and this was not related to randomization arm. Demographic data, BP at screening and randomization visit, and data on adverse effects potentially related to antihypertensive therapy were compiled. Means were compared using Student's t-tests, and proportions were compared using chi-square tests. The effect of antihypertensive therapy on BP control was further analyzed using multivariable regression modeling controlling for age, race, sex, hypertension history, study cohort, and ED BP. Data were abstracted for 217 subjects. The median interval from ED visit to randomization was 12 days. Seventy-six subjects (35%) received one or more prescriptions for antihypertensive therapy. Age, sex, race, hypertension history, and mean duration of hypertension were equivalent between groups. Although mean ED BP was higher among those who received prescriptions, the mean systolic BP (sBP) reduction from ED to randomization was significantly greater (difference = 19 mm Hg, 95% confidence interval = 12 to 26 mm Hg). No patient in either group had an sBP less than 100 mm Hg at randomization. On multiple regression modeling, randomization sBP reduction was independently associated with antihypertensive prescription (p = 0.001). The incidence of adverse effects was equivalent and low in both groups. No new neurological deficits, ischemic events, or life-threatening anaphylactic reactions were reported in either group. Prescription of antihypertensive medication from the ED is associated with significantly lower sBP at short-term outpatient follow-up. Antihypertensive therapy was not associated with an increased incidence of adverse events, and BP reduction did not exceed potentially harmful levels. Initiation of chronic antihypertensive therapy in the ED is safe and effective and may be a reasonable consideration for at-risk populations. © 2015 by the Society for Academic Emergency Medicine.
Immigrant family skills-building to prevent tobacco use in Latino youth: study protocol for a community-based participatory randomized controlled trial

PubMed Central

2012-01-01

Background Despite declines over recent years, youth tobacco and other substance use rates remain high. Latino youth are at equal or increased risk for lifetime tobacco, alcohol, marijuana, and other illicit drug use compared with their white peers. Family plays an important and influential role in the lives of youth, and longitudinal research suggests that improving parenting skills may reduce youth substance use. However, few interventions are oriented towards immigrant Latino families, and none have been developed and evaluated using a community-based participatory research (CBPR) process that may increase the effectiveness and sustainability of such projects. Therefore, using CBPR principles, we developed a randomized clinical trial to assess the efficacy of a family-skills training intervention to prevent tobacco and other substance use intentions in Latino youth. Methods/Design In collaboration with seven Latino community-serving agencies, we will recruit and randomize 336 immigrant families, into intervention or delayed treatment conditions. The primary outcome is youth intention to smoke 6 months post intervention. The intervention consists of eight parent and four youth sessions targeting parenting skills and parent–youth relational factors associated with lower smoking and other substance use in youth. Discussion We present the study protocol for a family intervention using a CBPR randomized clinical trial to prevent smoking among Latino youth. The results of this trial will contribute to the limited information on effective and sustainable primary prevention programs for tobacco and other substance use directed at the growing US Latino communities. Trial registration ClinicalTrials.gov: NCT01442753 PMID:23253201
Perceived somatic and affective barriers for self-efficacy and physical activity.

PubMed

Warner, Lisa M; Wolff, Julia K; Spuling, Svenja M; Wurm, Susanne

2017-05-01

According to Bandura's social-cognitive theory, perceptions of somatic and affective barriers are sources of self-efficacy. This longitudinal study compares general indicators of health barriers with measures of perceived somatic and affective barriers to predict self-efficacy and accelerometer-assessed physical activity in a subsample of n = 153 (selected at random from N = 310) community-dwelling German older adults. Perceived somatic and affective barriers longitudinally predicted physical activity mediated by self-efficacy, whereas general health barriers did not. Perceived health barriers to physical activity might be more important than more objective health barriers for older adults' physical activity levels.
Combined effect of education and reproductive history on weight trajectories of young Australian women: A longitudinal study.

PubMed

Holowko, Natalie; Jones, Mark; Koupil, Ilona; Tooth, Leigh; Mishra, Gita

2016-10-01

To investigate the combined effect of education and reproductive history on weight trajectory. The association of education with weight trajectory (1996-2012) in relation to reproductive history was analyzed among 9,336 women (born 1973-1978) from the Australian Longitudinal Study on Women's Health using random effects models. Compared with women with a university degree/higher, lower-educated women were 2 kg heavier at baseline and gained an additional 0.24 kg/year. Giving birth was associated with an increase in weight which was more pronounced among women having their first birth <26 years of age (2.1 kg, 95% CI: 1.5-2.7), compared with 26 to 32 years or >32 years. While younger first-time mothers had a steeper weight trajectory (∼+0.16 kg/year, 95% CI: 0.1-0.3), this was less steep among lower-educated women. High-educated women with a second birth between 26 and 32 years had 0.9 kg decreased weight after this birth, while low-educated women gained 0.9 kg. While the effect of having children on weight in young adulthood was minimal, women having their first birth <26 years of age had increased risk of weight gain, particularly primiparous women. Educational differences in weight persisted after accounting for reproductive history, suggesting a need to explore alternative mechanisms through which social differences in weight are generated. © 2016 The Obesity Society.
Exploring longitudinal course and treatment-baseline severity interactions in secondary outcomes of smoking cessation treatment in individuals with attention-deficit hyperactivity disorder.

PubMed

Luo, Sean X; Wall, Melanie; Covey, Lirio; Hu, Mei-Chen; Scodes, Jennifer M; Levin, Frances R; Nunes, Edward V; Winhusen, Theresa

2018-01-25

A double blind, placebo-controlled randomized trial (NCT00253747) evaluating osmotic-release oral system methylphenidate (OROS-MPH) for smoking-cessation revealed a significant interaction effect in which participants with higher baseline ADHD severity had better abstinence outcomes with OROS-MPH while participants with lower baseline ADHD severity had worse outcomes. This current report examines secondary outcomes that might bear on the mechanism for this differential treatment effect. Longitudinal analyses were conducted to evaluate the effect of OROS-MPH on three secondary outcomes (ADHD symptom severity, nicotine craving, and withdrawal) in the total sample (N = 255, 56% Male), and in the high (N = 134) and low (N = 121) baseline ADHD severity groups. OROS-MPH significantly improved ADHD symptoms and nicotine withdrawal symptoms in the total sample, and exploratory analyses showed that in both higher and lower baseline severity groups, OROS-MPH statistically significantly improved these two outcomes. No effect on craving overall was detected, though exploratory analyses showed statistically significantly decreased craving in the high ADHD severity participants on OROS-MPH. No treatment by ADHD baseline severity interaction was detected for the outcomes. Methylphenidate improved secondary outcomes during smoking cessation independent of baseline ADHD severity, with no evident treatment-baseline severity interaction. Our results suggest divergent responses to smoking cessation treatment in the higher and lower severity groups cannot be explained by concordant divergence in craving, withdrawal and ADHD symptom severity, and alternative hypotheses may need to be identified.
Sibship size and educational attainment. A joint test of the Confluence Model and the Resource Dilution Hypothesis

PubMed Central

Jæger, Mads Meier

2012-01-01

Studies on family background often explain the negative effect of sibship size on educational attainment by one of two theories: the Confluence Model (CM) or the Resource Dilution Hypothesis (RDH). However, as both theories – for substantively different reasons – predict that sibship size should have a negative effect on educational attainment most studies cannot distinguish empirically between the CM and the RDH. In this paper, I use the different theoretical predictions in the CM and RDH on the role of cognitive ability as a partial or complete mediator of the effect of sibship size to distinguish the two theories and to identify a unique RDH effect on educational attainment. Using sibling data from the Wisconsin Longitudinal Study (WLS) and a random effect Instrumental Variable model I find that, in addition to a negative effect on cognitive ability, sibship size also has a strong negative effect on educational attainment which is uniquely explained by the RDH. PMID:22468016
Comparing meta-analysis and ecological-longitudinal analysis in time-series studies. A case study of the effects of air pollution on mortality in three Spanish cities.

PubMed

Saez, M; Figueiras, A; Ballester, F; Pérez-Hoyos, S; Ocaña, R; Tobías, A

2001-06-01

The objective of this paper is to introduce a different approach, called the ecological-longitudinal, to carrying out pooled analysis in time series ecological studies. Because it gives a larger number of data points and, hence, increases the statistical power of the analysis, this approach, unlike conventional ones, allows the complementation of aspects such as accommodation of random effect models, of lags, of interaction between pollutants and between pollutants and meteorological variables, that are hardly implemented in conventional approaches. The approach is illustrated by providing quantitative estimates of the short-term effects of air pollution on mortality in three Spanish cities, Barcelona, Valencia and Vigo, for the period 1992-1994. Because the dependent variable was a count, a Poisson generalised linear model was first specified. Several modelling issues are worth mentioning. Firstly, because the relations between mortality and explanatory variables were non-linear, cubic splines were used for covariate control, leading to a generalised additive model, GAM. Secondly, the effects of the predictors on the response were allowed to occur with some lag. Thirdly, the residual autocorrelation, because of imperfect control, was controlled for by means of an autoregressive Poisson GAM. Finally, the longitudinal design demanded the consideration of the existence of individual heterogeneity, requiring the consideration of mixed models. The estimates of the relative risks obtained from the individual analyses varied across cities, particularly those associated with sulphur dioxide. The highest relative risks corresponded to black smoke in Valencia. These estimates were higher than those obtained from the ecological-longitudinal analysis. Relative risks estimated from this latter analysis were practically identical across cities, 1.00638 (95% confidence intervals 1.0002, 1.0011) for a black smoke increase of 10 microg/m(3) and 1.00415 (95% CI 1.0001, 1.0007) for a increase of 10 microg/m(3) of sulphur dioxide. Because the statistical power is higher than in the individual analysis more interactions were statistically significant, especially those among air pollutants and meteorological variables. Air pollutant levels were related to mortality in the three cities of the study, Barcelona, Valencia and Vigo. These results were consistent with similar studies in other cities, with other multicentric studies and coherent with both, previous individual, for each city, and multicentric studies for all three cities.

COMPUTERIZED EXPERT SYSTEM FOR EVALUATION OF AUTOMATED VISUAL FIELDS FROM THE ISCHEMIC OPTIC NEUROPATHY DECOMPRESSION TRIAL: METHODS, BASELINE FIELDS, AND SIX-MONTH LONGITUDINAL FOLLOW-UP

PubMed Central

Feldon, Steven E

2004-01-01

ABSTRACT Purpose To validate a computerized expert system evaluating visual fields in a prospective clinical trial, the Ischemic Optic Neuropathy Decompression Trial (IONDT). To identify the pattern and within-pattern severity of field defects for study eyes at baseline and 6-month follow-up. Design Humphrey visual field (HVF) change was used as the outcome measure for a prospective, randomized, multi-center trial to test the null hypothesis that optic nerve sheath decompression was ineffective in treating nonarteritic anterior ischemic optic neuropathy and to ascertain the natural history of the disease. Methods An expert panel established criteria for the type and severity of visual field defects. Using these criteria, a rule-based computerized expert system interpreted HVF from baseline and 6-month visits for patients randomized to surgery or careful follow-up and for patients who were not randomized. Results A computerized expert system was devised and validated. The system was then used to analyze HVFs. The pattern of defects found at baseline for patients randomized to surgery did not differ from that of patients randomized to careful follow-up. The most common pattern of defect was a superior and inferior arcuate with central scotoma for randomized eyes (19.2%) and a superior and inferior arcuate for nonrandomized eyes (30.6%). Field patterns at 6 months and baseline were not different. For randomized study eyes, the superior altitudinal defects improved (P = .03), as did the inferior altitudinal defects (P = .01). For nonrandomized study eyes, only the inferior altitudinal defects improved (P = .02). No treatment effect was noted. Conclusions A novel rule-based expert system successfully interpreted visual field defects at baseline of eyes enrolled in the IONDT. PMID:15747764
Investigation of mode partition noise in Fabry-Perot laser diode

NASA Astrophysics Data System (ADS)

Guo, Qingyi; Deng, Lanxin; Mu, Jianwei; Li, Xun; Huang, Wei-Ping

2014-09-01

Passive optical network (PON) is considered as the most appealing access network architecture in terms of cost-effectiveness, bandwidth management flexibility, scalability and durability. And to further reduce the cost per subscriber, a Fabry-Perot (FP) laser diode is preferred as the transmitter at the optical network units (ONUs) because of its lower cost compared to distributed feedback (DFB) laser diode. However, the mode partition noise (MPN) associated with the multi-longitudinal-mode FP laser diode becomes the limiting factor in the network. This paper studies the MPN characteristics of the FP laser diode using the time-domain simulation of noise-driven multi-mode laser rate equation. The probability density functions are calculated for each longitudinal mode. The paper focuses on the investigation of the k-factor, which is a simple yet important measure of the noise power, but is usually taken as a fitted or assumed value in the penalty calculations. In this paper, the sources of the k-factor are studied with simulation, including the intrinsic source of the laser Langevin noise, and the extrinsic source of the bit pattern. The photon waveforms are shown under four simulation conditions for regular or random bit pattern, and with or without Langevin noise. The k-factors contributed by those sources are studied with a variety of bias current and modulation current. Simulation results are illustrated in figures, and show that the contribution of Langevin noise to the k-factor is larger than that of the random bit pattern, and is more dominant at lower bias current or higher modulation current.
Stimulus control and affect in dietary behaviours. An intensive longitudinal study.

PubMed

Schüz, Benjamin; Bower, Jodie; Ferguson, Stuart G

2015-04-01

Dietary behaviours are substantially influenced by environmental and internal stimuli, such as mood, social situation, and food availability. However, little is known about the role of stimulus control for eating in non-clinical populations, and no studies so far have looked at eating and drinking behaviour simultaneously. 53 individuals from the general population took part in an intensive longitudinal study with repeated, real-time assessments of eating and drinking using Ecological Momentary Assessment. Eating was assessed as main meals and snacks, drinks assessments were separated along alcoholic and non-alcoholic drinks. Situational and internal stimuli were assessed during both eating and drinking events, and during randomly selected non-eating occasions. Hierarchical multinomial logistic random effects models were used to analyse data, comparing dietary events to non-eating occasions. Several situational and affective antecedents of dietary behaviours could be identified. Meals were significantly associated with having food available and observing others eat. Snacking was associated with negative affect, having food available, and observing others eat. Engaging in activities and being with others decreased the likelihood of eating behaviours. Non-alcoholic drinks were associated with observing others eat, and less activities and company. Alcoholic drinks were associated with less negative affect and arousal, and with observing others eat. RESULTS support the role of stimulus control in dietary behaviours, with support for both internal and external, in particular availability and social stimuli. The findings for negative affect support the idea of comfort eating, and results point to the formation of eating habits via cue-behaviour associations. Copyright © 2015 Elsevier Ltd. All rights reserved.
Relation between social network and psychological distress among middle-aged adults in Japan: Evidence from a national longitudinal survey.

PubMed

Fu, Rong; Noguchi, Harkuo; Tachikawa, Hirokazu; Aiba, Miyuki; Nakamine, Shin; Kawamura, Akira; Takahashi, Hideto; Tamiya, Nanako

2017-02-01

It is widely documented that psychological distress is negatively associated with social networks involvement. However, despite the theoretical postulations that social networks are crucial for alleviating psychological distress, no study has yet empirically confirmed the causality of this relationship. Thus, we used the random-effects generalized least squares method to investigate the effect of one- and two-year lagged values for involvement in social networks on psychological distress. Nine years of longitudinal data were extracted from a nationally representative survey in Japan ("The Longitudinal Survey of Middle-aged and Older Persons"). We utilized the Kessler 6 (K6) score to measure psychological distress among 15,242 respondents aged 50-59 years in the baseline year (2005), and stratified participants into three layers of social networks: inner (well-established friendship ties and participating in hobby activates), intermediary (neighborly ties), and outer (involvement in community activities). We found highly significant and negative associations between all three layers and K6 scores, with the strongest association being for the inner layer. We further observed that one-year lagged involvement in the inner and intermediary layers led to significantly lower K6 scores. However, the protective influences of social networks generally diminished over time. In addition, the protective influences of social network involvement on psychological distress were stronger for women than for men. Furthermore, involvement in social networks was especially important for improving mental health among people with psychological distress. These findings would be important for policymaking to prevent mental health deterioration among middle-aged adults in Japan. Copyright © 2017 Elsevier Ltd. All rights reserved.
Longitudinal Effects of Acculturation on Alcohol Use among Vietnamese and Cambodian Immigrant Women in the USA.

PubMed

Kane, Jeremy C; Johnson, Renee M; Robinson, Courtland; Jernigan, David H; Harachi, Tracy W; Bass, Judith K

2016-11-01

Recent studies indicate that alcohol use is increasing among Asian American populations and that acculturation impacts alcohol use among immigrants in the USA. We investigated the longitudinal relationship between three domains of acculturation (traditionalism, biculturalism, assimilation) and alcohol use among 302 Vietnamese and Cambodian women in Washington State. Data were obtained from the Cross Cultural Families Project (CCF), a 5-year longitudinal investigation of a random sample of Vietnamese and Cambodian immigrant families living in Washington State. Alcohol use was measured with a three item scale assessing frequency and quantity of use, and binge drinking. Acculturation was measured with the Suinn-Lew Asian Self-Identity Acculturation Scale. Linear mixed effects regression models were estimated to assess the impact of acculturation on alcohol use among the overall sample and among a sub-sample of only women who consumed any alcohol. A majority of the sample, 73.2%, reported no alcohol use. In the overall sample, none of the three acculturation domains were significantly associated with drinking. Among a sub-sample of only those who reported any alcohol use, however, a greater degree of traditional cultural identification (β = -0.94, SE= 0.44, P= 0.03) and a greater degree of biculturalism (β = -1.33, SE= 0.53, P =0.01) were associated with lower levels of use. Our findings suggest that acculturation did not impact alcohol use prevalence but that it did affect the drinking pattern among alcohol consumers. Clinicians should be cognizant that certain aspects of cultural identification are important contributors to drinking behavior among alcohol consumers in these populations. © The Author 2016. Medical Council on Alcohol and Oxford University Press. All rights reserved.
Longitudinal changes in active transportation to school in Canadian youth aged 6 through 16 years.

PubMed

Pabayo, Roman; Gauvin, Lise; Barnett, Tracie A

2011-08-01

Concern has been raised regarding the increased prevalence of physical inactivity among children. Active transportation, such as walking and cycling to school, is an opportunity for children to be physically active. To identify the sociodemographic predictors of active transportation to schools across time among school-aged children participating in the Canadian National Longitudinal Survey of Children and Youth (NLSCY). The sample included 7690 school-aged children attending public schools who were drawn from cycle 2 (1996 and 1997) of the Canadian NLSCY. Data were collected through interviews with the person most knowledgeable about the child. Parents were asked how their child usually gets to school. Responses were dichotomized into active (walking or bicycling) or inactive (school bus, public transit, is driven, or multiple) modes. Using 3 waves of data from the Canadian NLSCY (1996-2001), we estimated the effect of sociodemographic factors on the likelihood of active transportation to school across time using random-effects models. Longitudinal analyses indicated that as children aged, the likelihood of using active transportation to school increased, peaked at the age of 10 years, and then decreased. Urban settings (odds ratio [OR]: 3.66 [95% confidence interval (CI): 3.23-4.15]), households with inadequate income (OR: 1.21 [95% CI: 1.06-1.38]), living with 1 parent (OR: 1.46 [95% CI: 1.29-1.65]), and having an older sibling living at home (OR: 1.14 [95% CI: 1.04-1.25]) were significant predictors of active transportation to school at baseline and carried through across time. Understanding the factors that influence active transportation may support its adoption by children, which in turn may contribute to meeting physical activity guidelines.
Developmental Changes in Isometric Strength: Longitudinal Study in Adolescent Soccer Players.

PubMed

Duarte, Joao P; Valente-Dos-Santos, João; Coelho-E-Silva, Manuel J; Malina, R M; Deprez, Dieter; Philippaerts, Renaat; Lenoir, Matthieu; Vaeyens, Roel

2018-06-20

This study aimed to examine longitudinal changes in isometric strength of the knee extensors (ImKE) and knee flexors (ImKF) at 30° and 60°. The sample was composed of 67 players aged 11.0-13.9 years at baseline over five years. Stature, body mass, skinfolds, and isometric strength (ImKE30°, ImKF30°, ImKE60° and ImKF60°) were measured. Fat mass and fat-free mass (FFM) were derived from skinfolds. Skeletal age was obtained using TW2 RUS. Multilevel random effects regression analyses extracted developmental polynomial models. An annual increment on chronological age (CA) corresponded to 5.6 N (ImKE30°: ), 2.7 N (ImKF30°: ), 4.6 N (ImKE60°: ) and 1.5 N (ImKF60°). An increment of 1 kg in FFM predicted isometric strength as follows: 1.2 N (ImKE30°), 2.1 N (ImKF30°), 3.1 N (ImKE60°) and 2.0 N (ImKF60°). The following equations were obtained: ImKE30°=5.759×CA+1.163×FFM; ImKF30°=-19.369+2.691×CA+0.693×CA 2 +2.108×FFM; ImKE60°=4.553×CA+3.134×FFM; and, ImKF60°=-19.669+1.544×CA+2.033×FFM. Although skeletal maturity had a negligible effect on dependent variables, age and body size, based on FFM, were relevant longitudinal predictors. During adolescence, systematic assessment of knee extensors and knee flexors are strongly recommended to prevent impairment of knee muscle groups. © Georg Thieme Verlag KG Stuttgart · New York.
The Myth of Blunted Gamers: No Evidence for Desensitization in Empathy for Pain after a Violent Video Game Intervention in a Longitudinal fMRI Study on Non-Gamers.

PubMed

Kühn, Simone; Kugler, Dimitrij; Schmalen, Katharina; Weichenberger, Markus; Witt, Charlotte; Gallinat, Jürgen

2018-01-31

It is a common concern in the research field and the community that habitual violent video gaming reduces empathy for pain in its players. However, previous fMRI studies have only compared habitual game players against control participants cross-sectionally. However the observed pattern of results may be due to a priori differences in people who become gamers and who not. In order to derive the causal conclusion that violent video game play causes desensitisation, longitudinal studies are needed. Therefore we conducted a longitudinal fMRI intervention study over 16 weeks. Participants were randomly assigned to 1) play a violent video game (Grand Theft Auto 5), 2) perform a social life simulation game (The Sims 3) 30 min/day for 8 weeks, 3) serve as passive control. To assess empathy processing, participants were exposed to painful and non-painful stimuli (e.g. someone cutting a cucumber with or without hurting herself) either as real photographs or video-game like depictions in a 3T MRI scanner before and after the training intervention as well as two months after training. We did not find any evidence for desensitization in the empathy network for pain in the violent video game group at any time point. The present results provide strong evidence against the frequently proclaimed negative effects of playing violent video games and will therefore help to communicate a more realistic scientific perspective of the effects of violent video gaming in real life. © 2018 The Author(s). Published by S. Karger AG, Basel.
Quantitative genetic analysis of cellular adhesion molecules: the Fels Longitudinal Study.

PubMed

Lee, Miryoung; Czerwinski, Stefan A; Choh, Audrey C; Demerath, Ellen W; Sun, Shumei S; Chumlea, Wm C; Towne, Bradford; Siervogel, Roger M

2006-03-01

Circulating concentrations of inflammatory markers predict cardiovascular disease (CVD) risk and are closely associated with obesity. However, little is known concerning genetic influences on serum levels of inflammatory markers. In this study, we estimated the heritability (h2) of soluble cellular adhesion molecule (sCAM) concentrations and examined the correlational architecture between different sCAMs. The study population included 234 men and 270 women aged 18-76 years, belonging to 121 families participating in the Fels Longitudinal Study. Serum levels of soluble intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sESEL-1) and P-selectin (sPSEL-1) were assayed using commercially available kits. A variance components-based maximum likelihood method was used to estimate the h2 of the different serum inflammatory markers while simultaneously adjusting for the effects of known CVD risk factors, such as age and smoking. Additionally, we used bivariate extensions of these methods to estimate genetic and random environmental correlations among sCAMs. Levels of sCAMs were significantly heritable: h2=0.24+/-0.10 for sICAM-1, h2=0.22+/-0.10 for sVCAM-1, h2=0.50+/-0.11 for sESEL-1, and h2=0.46+/-0.10 for sPSEL-1. In addition, a significant genetic correlation (rho(G)=0.63) was found between sICAM-1 and sVCAM-1 indicating some degree of shared genetic control. In the Fels Longitudinal Study, the levels of four sCAMs are significantly influenced by genetic effects, and sICAM-1 shares a common genetic background with sVCAM-1.
A pilot randomized controlled trial of time-intensive cognitive-behaviour therapy for postpartum obsessive-compulsive disorder: effects on maternal symptoms, mother-infant interactions and attachment.

PubMed

Challacombe, F L; Salkovskis, P M; Woolgar, M; Wilkinson, E L; Read, J; Acheson, R

2017-06-01

There is increasing recognition that perinatal anxiety disorders are both common and potentially serious for mother and child. Obsessive-compulsive disorder (OCD) can be triggered or exacerbated in the postpartum period, with mothers reporting significant effects on parenting tasks. However, there is little evidence concerning their effective treatment or the impact of successful treatment on parenting. A total of 34 mothers with OCD and a baby of 6 months old were randomized into either time-intensive cognitive-behaviour therapy (iCBT) or treatment as usual (TAU). iCBT took place after randomization at 6 months postpartum and was completed by 9 months. Maternal symptomatology, sensitivity in mother-infant interactions and parenting were assessed at baseline and reassessed at 12 months postpartum. At 12 months attachment was also assessed using Ainsworth's Strange Situation Procedure. A healthy control group of mothers and infants (n = 37) underwent the same assessments as a benchmark. iCBT was successful in ameliorating maternal symptoms of OCD (controlled effect size = 1.31-1.90). However, mother-infant interactions were unchanged by treatment and remained less sensitive in both OCD groups than a healthy control group. The distribution of attachment categories was similar across both clinical groups and healthy controls with approximately 72% classified as secure in each group. iCBT is an effective intervention for postpartum OCD. Sensitive parenting interactions are affected by the presence of postpartum OCD and this is not improved by successful treatment of OCD symptoms. However, the overall attachment bond appears to be unaffected. Longitudinal studies are needed to explore the impact of postpartum OCD as the child develops.
Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial

PubMed Central

Jokinen, Tarja S.; Syrjä, Pernilla; Junnila, Jouni; Hielm-Björkman, Anna; Laitinen-Vapaavuori, Outi

2018-01-01

Objective To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection. Methods A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed. Results Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin. Conclusion Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low. PMID:29320549
Assessing adverse effects of intra-articular botulinum toxin A in healthy Beagle dogs: A placebo-controlled, blinded, randomized trial.

PubMed

Heikkilä, Helka M; Jokinen, Tarja S; Syrjä, Pernilla; Junnila, Jouni; Hielm-Björkman, Anna; Laitinen-Vapaavuori, Outi

2018-01-01

To investigate the clinical, cytological, and histopathological adverse effects of intra-articularly injected botulinum toxin A in dogs and to study whether the toxin spreads from the joint after the injection. A longitudinal, placebo-controlled, randomized clinical trial was conducted with six healthy laboratory Beagle dogs. Stifle joints were randomized to receive either 30 IU of onabotulinum toxin A or placebo in a 1:1 ratio. Adverse effects and spread of the toxin were examined by evaluating dynamic and static weight-bearing of the injected limbs, by assessing painless range of motion and pain on palpation of joints, and by performing synovial fluid analysis, neurological examination, and electrophysiological recordings at different examination time-points in a 12-week period after the injections. The dogs were then euthanized and autopsy and histopathological examination of joint structures and adjacent muscles and nerves were performed. Intra-articular botulinum toxin A did not cause local weakness or injection site pain. Instead, static weight-bearing and painless range of motion of stifle joints decreased in the placebo limbs. No clinically significant abnormalities associated with intra-articular botulinum toxin A were detected in the neurological examinations. Electrophysiological recordings showed low compound muscle action potentials in two dogs in the botulinum toxin A-injected limb. No significant changes were detected in the synovial fluid. Autopsy and histopathological examination of the joint and adjacent muscles and nerves did not reveal histopathological adverse effects of the toxin. Intra-articular botulinum toxin A does not produce significant clinical, cytological, or histopathological adverse effects in healthy dogs. Based on the electrophysiological recordings, the toxin may spread from the joint, but its clinical impact seems to be low.
Two-Year Longitudinal Analysis of a Cluster Randomized Trial of Physical Activity Promotion by General Practitioners

PubMed Central

Grandes, Gonzalo; Sanchez, Alvaro; Montoya, Imanol; Ortega Sanchez-Pinilla, Ricardo; Torcal, Jesús

2011-01-01

Background We evaluate the effectiveness of a physical activity promotion programme carried out by general practitioners with inactive patients in routine care. Methods and Findings Pragmatic, cluster randomised clinical trial conducted in eleven public primary care centres in Spain. Fifty-six general practitioners (GPs) were randomly assigned to intervention (29) or standard care (27) groups. They assessed the physical activity level of a systematic sample of patients in routine practice and recruited 4317 individuals (2248 intervention and 2069 control) who did not meet minimum physical activity recommendations. Intervention GPs provided advice to all patients and a physical activity prescription to the subgroup attending an additional appointment (30%). A third of these prescriptions were opportunistically repeated. Control GPs provided standard care. Primary outcome measure was the change in self-reported physical activity from baseline to six, 12 and 24 months. Secondary outcomes included cardiorespiratory fitness and health-related quality of life. A total of 3691 patients (85%) were included in the longitudinal analysis and overall trends over the whole 24 month follow-up were significantly better in the intervention group (p<0.01). The greatest differences with the control group were observed at six months (adjusted difference 1.7 MET*hr/wk [95% CI, 0.8 to 2.6], 25 min/wk [95% CI, 11.3 to 38.4], and a 5.3% higher percentage of patients meeting minimum recommendations [95% CI: 2.1% to 8.8%] NNT = 19). These differences were not statistically significant at 12 and 24 months. No differences were found in secondary outcomes. A significant difference was maintained until 24 months in the proportion of patients achieving minimum recommendation in the subgroup that received a repeat prescription (adjusted difference 10.2%, 95% CI 1.5% to 19.4%). Conclusions General practitioners are effective at increasing the level of physical activity among their inactive patients during the initial six-months of an intervention but this effect wears off at 12 and 24 months. Only in the subgroup of patients receiving repeat prescriptions of physical activity is the effect maintained in long-term. Trial Registration clinicaltrials.gov NCT00131079 PMID:21479243
Results of an independent evaluation of Project ALERT delivered in schools by Cooperative Extension.

PubMed

St Pierre, Tena L; Osgood, D Wayne; Mincemoyer, Claudia C; Kaltreider, D Lynne; Kauh, Tina J

2005-12-01

Reported are results of an independent effectiveness study of the Project ALERT drug prevention program implemented in eight Pennsylvania middle schools by outside program leaders employed by Cooperative Extension. In this randomized, 2-cohort longitudinal evaluation, 1,649 seventh-grade students completed a pretest and four waves of posttests over the 2-year program and 1-year follow-up. Project ALERT's effectiveness was tested through a 3-level hierarchical linear model. Analyses failed to yield any positive effects for substance use or mediators for use in the adult or teen-assisted delivery of the curriculum. An extensive set of additional analyses detected no differential program effects by student risk level, gender, school, or level of implementation quality. Potential explanations for outcomes relative to Project ALERT's original effectiveness trial are discussed, as well as implications for future research, including the need to conduct independent effectiveness studies of previously validated programs in a variety of contexts.
Designing clinical trials to test disease-modifying agents: application to the treatment trials of Alzheimer's disease.

PubMed

Xiong, Chengjie; van Belle, Gerald; Miller, J Philip; Morris, John C

2011-02-01

Therapeutic trials of disease-modifying agents on Alzheimer's disease (AD) require novel designs and analyses involving switch of treatments for at least a portion of subjects enrolled. Randomized start and randomized withdrawal designs are two examples of such designs. Crucial design parameters such as sample size and the time of treatment switch are important to understand in designing such clinical trials. The purpose of this article is to provide methods to determine sample sizes and time of treatment switch as well as optimum statistical tests of treatment efficacy for clinical trials of disease-modifying agents on AD. A general linear mixed effects model is proposed to test the disease-modifying efficacy of novel therapeutic agents on AD. This model links the longitudinal growth from both the placebo arm and the treatment arm at the time of treatment switch for these in the delayed treatment arm or early withdrawal arm and incorporates the potential correlation on the rate of cognitive change before and after the treatment switch. Sample sizes and the optimum time for treatment switch of such trials as well as optimum test statistic for the treatment efficacy are determined according to the model. Assuming an evenly spaced longitudinal design over a fixed duration, the optimum treatment switching time in a randomized start or a randomized withdrawal trial is half way through the trial. With the optimum test statistic for the treatment efficacy and over a wide spectrum of model parameters, the optimum sample size allocations are fairly close to the simplest design with a sample size ratio of 1:1:1 among the treatment arm, the delayed treatment or early withdrawal arm, and the placebo arm. The application of the proposed methodology to AD provides evidence that much larger sample sizes are required to adequately power disease-modifying trials when compared with those for symptomatic agents, even when the treatment switch time and efficacy test are optimally chosen. The proposed method assumes that the only and immediate effect of treatment switch is on the rate of cognitive change. Crucial design parameters for the clinical trials of disease-modifying agents on AD can be optimally chosen. Government and industry officials as well as academia researchers should consider the optimum use of the clinical trials design for disease-modifying agents on AD in their effort to search for the treatments with the potential to modify the underlying pathophysiology of AD.
Seasonal variation of strongylosis in working donkeys of Ethiopia: a cross-sectional and longitudinal studies.

PubMed

Dibaba, Motuma Debelo; Getachew, A M; Assefa, Zerihun; Fanta, Alemayehu; Etana, Manyahilishal; Firew, Seyoum; Goshu, Lemessa; Burden, F

2017-07-01

Helminths are one of the major health problems of working donkeys, often with heavy worm burden and contributing to their early demise and/or reduction in their work output. Cross-sectional and longitudinal studies were conducted to investigate the current infection prevalence and level of strongyles infection donkeys would acquire through different seasons in the mid-lowland agro-ecological zones of Ethiopia. For this purpose, faecal samples from 206 (cross-sectional study) and 102 (longitudinal study) randomly selected donkeys were directly collected from the rectum and analysed. For the longitudinal study, the 102 donkeys dewormed at the end of main rainy season, beginning of October, were monitored for the level of strongyle infection they would acquire during subsequent dry and short rainy seasons. The cross-sectional study of 206 donkey has revealed an overall infection prevalence of 89.3% (95% confidence interval (CI) = 84.4, 92.9). Donkeys in the lowland zone showed a significantly higher strongyle infection prevalence (P = 0.0126) and mean eggs per gramme of faces (EPG) (P = 0.001; 2775 EPG) compared to donkeys in the midland zone (980.8 EPG). Age, sex and body condition did not have any significant effect on either the infection prevalence or level of infection (P > 0.05). The longitudinal study has shown a significantly lower strongyle infection prevalence (P = 0.003) and level of infection donkeys acquired (P = 0.001) in the subsequent dry and short rainy seasons compared to the main rainy season following October deworming. However, these values were not significantly different between the two agro-ecological zones (P > 0.05). This study clearly showed that parasitic infections are primarily acquired during the main rainy season when pasture/herbage coverage is relatively better, and the environment is conducive for parasites survival and development. On the other hand, the finding of majority of donkeys shedding low or no eggs during the dry and short rainy seasons showed that October deworming was effective, and donkeys acquire low or no parasitic infection during the subsequent dry and short rainy seasons. Therefore, the practice of anthelmintic treatment of donkeys at the end of short rain in May may not be necessary, and October deworming once a year is sufficient.
Improving numeracy through values affirmation enhances decision and STEM outcomes

PubMed Central

Peters, Ellen; Tompkins, Mary Kate; Schley, Dan; Meilleur, Louise; Sinayev, Aleksander; Tusler, Martin; Wagner, Laura; Crocker, Jennifer

2017-01-01

Greater numeracy has been correlated with better health and financial outcomes in past studies, but causal effects in adults are unknown. In a 9-week longitudinal study, undergraduate students, all taking a psychology statistics course, were randomly assigned to a control condition or a values-affirmation manipulation intended to improve numeracy. By the final week in the course, the numeracy intervention (statistics-course enrollment combined with values affirmation) enhanced objective numeracy, subjective numeracy, and two decision-related outcomes (financial literacy and health-related behaviors). It also showed positive indirect-only effects on financial outcomes and a series of STEM-related outcomes (course grades, intentions to take more math-intensive courses, later math-intensive courses taken based on academic transcripts). All decision and STEM-related outcome effects were mediated by the changes in objective and/or subjective numeracy and demonstrated similar and robust enhancements. Improvements to abstract numeric reasoning can improve everyday outcomes. PMID:28704410
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.
Improving homework performance among children with ADHD: A randomized clinical trial.

PubMed

Merrill, Brittany M; Morrow, Anne S; Altszuler, Amy R; Macphee, Fiona L; Gnagy, Elizabeth M; Greiner, Andrew R; Coles, Erika K; Raiker, Joseph S; Coxe, Stefany; Pelham, William E

2017-02-01

Evidence indicates that children with Attention Deficit Hyperactivity Disorder (ADHD) experience acute and prolonged academic impairment and underachievement including marked difficulty with completing homework. This study is the first to examine the effects of behavioral, psychostimulant, and combined treatments on homework problems, which have been shown to predict academic performance longitudinally. Children with ADHD (ages 5-12, N = 75, 71% male, 83% Hispanic/Latino) and their families were randomly assigned to either behavioral treatment (homework-focused parent training and a daily report card; BPT + DRC) or a waitlist control group. Children also participated in a concurrent psychostimulant crossover trial conducted in a summer treatment program. Children's objective homework completion and accuracy were measured as well as parent-reported child homework behaviors and parenting skills. BPT + DRC had large effects on objective measures of homework completion and accuracy (Cohen's ds from 1.40 to 2.21, ps < .001). Other findings, including unimodal medication and incremental combined treatment benefits, were not significant. Behavioral treatment focused on homework problems results in clear benefits for children's homework completion and accuracy (the difference between passing and failing, on average), whereas long-acting stimulant medication resulted in limited and largely nonsignificant acute effects on homework performance. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Improving Homework Performance Among Children with ADHD: A Randomized Clinical Trial

PubMed Central

Merrill, Brittany M.; Morrow, Anne S.; Altszuler, Amy R.; Macphee, Fiona L.; Gnagy, Elizabeth M.; Greiner, Andrew R.; Coles, Erika K.; Raiker, Joseph S.; Coxe, Stefany; Pelham, William E.

2016-01-01

Objective Evidence indicates that children with Attention Deficit Hyperactivity Disorder (ADHD) experience acute and prolonged academic impairment and underachievement including marked difficulty with completing homework. This study is the first to examine the effects of behavioral, psychostimulant, and combined treatments on homework problems, which have been shown to predict academic performance longitudinally. Method Children with ADHD (ages 5-12, N = 75, 71% male, 83% Hispanic/Latino) and their families were randomly assigned to either behavioral treatment (homework-focused parent training and a daily report card; BPT+DRC) or a waitlist control group. Children also participated in a concurrent psychostimulant crossover trial conducted in a summer treatment program. Children's objective homework completion and accuracy were measured as well as parent-reported child homework behaviors and parenting skills. Results BPT+DRC had large effects on objective measures of homework completion and accuracy (Cohen's ds from 1.40, to 2.21, ps < .001). Other findings, including unimodal medication and incremental combined treatment benefits, were not significant. Conclusions Behavioral treatment focused on homework problems results in clear benefits for children's homework completion and accuracy (the difference between passing failing, on average) whereas long-acting stimulant medication resulted in limited and largely non-significant acute effects on homework performance. PMID:27618639

Stochastic resonance training reduces musculoskeletal symptoms in metal manufacturing workers: a controlled preventive intervention study.

PubMed

Burger, Christian; Schade, Volker; Lindner, Christina; Radlinger, Lorenz; Elfering, Achim

2012-01-01

This study examined the effects of stochastic resonance whole-body vibration training on work-related musculoskeletal symptoms and accidents. Participants were white and blue-collar employees of a Swiss metal manufacturer (N=38), and participation was voluntary. The study was designed as a switching-replications longitudinal trial with randomized group allocation. The randomized controlled cross-over design consisted of two groups each given four weeks of exercise and no intervention during a second four-week period. Outcome was measured on a daily basis with questionnaires. Three components constituted musculoskeletal symptoms: musculoskeletal pain, related function limitations and musculoskeletal well-being. Accidents were assessed by ratings for balance and daily near-accidents. For statistical analysis, a mixed model was calculated. At the end of the training period musculoskeletal pain and related function limitation were significantly reduced, whereas musculoskeletal well-being had significantly increased. For function limitation and musculoskeletal well-being, change over time was linear. There was no effect on balance or near-accidents. Stochastic resonance whole-body vibration was found to be effective in the prevention of work-related musculoskeletal symptoms. It is well suited for the use in a work environment since it requires very little effort in terms of infrastructure, time and investment from participants.
Mediating processes in an effective life-review intervention.

PubMed

Korte, Jojanneke; Westerhof, Gerben J; Bohlmeijer, Ernst T

2012-12-01

Life review has been established as an evidence-based treatment for depression and anxiety. This paper addresses an important gap in the existing evidence of the working mechanisms of life review. We were able to longitudinally investigate possible mediators of a life-review intervention on depression and anxiety in the context of a large randomized controlled trial. A total of 202 older Dutch adults living in the community participated in this study. They were randomly assigned to either life review or care as usual. Participants were measured in terms of their depressive and anxiety symptoms, reminiscence functions, meaning in life, mastery and positive thoughts at study entry (t0), postintervention (t1; 3 months after study entry), and follow-up (t2; 3 months after the end of the intervention). Findings suggest that processes which have been theoretically and empirically proposed as important processes of change in life review therapy, that is, bitterness revival and boredom reduction reminiscence, mastery and positive thoughts, are indeed mediating the effects of life review on depression and anxiety. It is now recommended to measure these processes during the intervention in order to shed light on the exact process of change and direction of causality. 2013 APA, all rights reserved
Compassion meditation enhances empathic accuracy and related neural activity

PubMed Central

Mascaro, Jennifer S.; Rilling, James K.; Tenzin Negi, Lobsang; Raison, Charles L.

2013-01-01

The ability to accurately infer others’ mental states from facial expressions is important for optimal social functioning and is fundamentally impaired in social cognitive disorders such as autism. While pharmacologic interventions have shown promise for enhancing empathic accuracy, little is known about the effects of behavioral interventions on empathic accuracy and related brain activity. This study employed a randomized, controlled and longitudinal design to investigate the effect of a secularized analytical compassion meditation program, cognitive-based compassion training (CBCT), on empathic accuracy. Twenty-one healthy participants received functional MRI scans while completing an empathic accuracy task, the Reading the Mind in the Eyes Test (RMET), both prior to and after completion of either CBCT or a health discussion control group. Upon completion of the study interventions, participants randomized to CBCT and were significantly more likely than control subjects to have increased scores on the RMET and increased neural activity in the inferior frontal gyrus (IFG) and dorsomedial prefrontal cortex (dmPFC). Moreover, changes in dmPFC and IFG activity from baseline to the post-intervention assessment were associated with changes in empathic accuracy. These findings suggest that CBCT may hold promise as a behavioral intervention for enhancing empathic accuracy and the neurobiology supporting it. PMID:22956676
Randomly and Non-Randomly Missing Renal Function Data in the Strong Heart Study: A Comparison of Imputation Methods

PubMed Central

Shara, Nawar; Yassin, Sayf A.; Valaitis, Eduardas; Wang, Hong; Howard, Barbara V.; Wang, Wenyu; Lee, Elisa T.; Umans, Jason G.

2015-01-01

Kidney and cardiovascular disease are widespread among populations with high prevalence of diabetes, such as American Indians participating in the Strong Heart Study (SHS). Studying these conditions simultaneously in longitudinal studies is challenging, because the morbidity and mortality associated with these diseases result in missing data, and these data are likely not missing at random. When such data are merely excluded, study findings may be compromised. In this article, a subset of 2264 participants with complete renal function data from Strong Heart Exams 1 (1989–1991), 2 (1993–1995), and 3 (1998–1999) was used to examine the performance of five methods used to impute missing data: listwise deletion, mean of serial measures, adjacent value, multiple imputation, and pattern-mixture. Three missing at random models and one non-missing at random model were used to compare the performance of the imputation techniques on randomly and non-randomly missing data. The pattern-mixture method was found to perform best for imputing renal function data that were not missing at random. Determining whether data are missing at random or not can help in choosing the imputation method that will provide the most accurate results. PMID:26414328
Randomly and Non-Randomly Missing Renal Function Data in the Strong Heart Study: A Comparison of Imputation Methods.

PubMed

Shara, Nawar; Yassin, Sayf A; Valaitis, Eduardas; Wang, Hong; Howard, Barbara V; Wang, Wenyu; Lee, Elisa T; Umans, Jason G

2015-01-01

Kidney and cardiovascular disease are widespread among populations with high prevalence of diabetes, such as American Indians participating in the Strong Heart Study (SHS). Studying these conditions simultaneously in longitudinal studies is challenging, because the morbidity and mortality associated with these diseases result in missing data, and these data are likely not missing at random. When such data are merely excluded, study findings may be compromised. In this article, a subset of 2264 participants with complete renal function data from Strong Heart Exams 1 (1989-1991), 2 (1993-1995), and 3 (1998-1999) was used to examine the performance of five methods used to impute missing data: listwise deletion, mean of serial measures, adjacent value, multiple imputation, and pattern-mixture. Three missing at random models and one non-missing at random model were used to compare the performance of the imputation techniques on randomly and non-randomly missing data. The pattern-mixture method was found to perform best for imputing renal function data that were not missing at random. Determining whether data are missing at random or not can help in choosing the imputation method that will provide the most accurate results.
Early maternal depressive symptoms and child growth trajectories: a longitudinal analysis of a nationally representative US birth cohort

PubMed Central

2014-01-01

Background Maternal depressive symptoms are negatively associated with early child growth in developing countries; however, few studies have examined this relation in developed countries or used a longitudinal design with data past the second year of the child’s life. We investigated if and when early maternal depressive symptoms affect average growth in young children up to age 6 in a nationally representative sample of US children. Methods Using data from 6,550 singleton births from the Early Childhood Longitudinal Study -- Birth Cohort (ECLS-B), we fit growth trajectory models with random effects to examine the relation between maternal depressive symptoms at 9 months based on the twelve-item version of the Center for Epidemiologic Studies Depression Scale (CES-D) and child height and body mass index (BMI) to age 6 years. Results Mothers with moderate/severe depressive symptoms at 9 months postpartum had children with shorter stature at this same point in time [average 0.26 cm shorter; 95% CI: 5 cm, 48 cm] than mothers without depressive symptoms; children whose mothers reported postpartum depressive symptoms remained significantly shorter throughout the child’s first 6 years. Conclusions Results suggest that the first year postpartum is a critical window for addressing maternal depressive symptoms in order to optimize child growth. Future studies should investigate the role of caregiving and feeding practices as potential mechanisms linking maternal depressive symptoms and child growth trajectories. PMID:25047367
Vascular risk factors and neuropsychiatric symptoms in Alzheimer's disease: the Cache County Study.

PubMed

Steinberg, Martin; Hess, Kyle; Corcoran, Chris; Mielke, Michelle M; Norton, Maria; Breitner, John; Green, Robert; Leoutsakos, Jeannie; Welsh-Bohmer, Kathleen; Lyketsos, Constantine; Tschanz, Joann

2014-02-01

Knowledge of potentially modifiable risk factors for neuropsychiatric symptoms (NPS) in Alzheimer's disease (AD) is important. This study longitudinally explores modifiable vascular risk factors for NPS in AD. Participants enrolled in the Cache County Study on Memory in Aging with no dementia at baseline were subsequently assessed over three additional waves, and those with incident (new onset) dementia were invited to join the Dementia Progression Study for longitudinal follow-up. A total of 327 participants with incident AD were identified and assessed for the following vascular factors: atrial fibrillation, hypertension, diabetes mellitus, angina, coronary artery bypass surgery, myocardial infarction, cerebrovascular accident, and use of antihypertensive or diabetes medicines. A vascular index (VI) was also calculated. NPS were assessed over time using the Neuropsychiatric Inventory (NPI). Affective and Psychotic symptom clusters were assessed separately. The association between vascular factors and change in NPI total score was analyzed using linear mixed model and in symptom clusters using a random effects model. No individual vascular risk factors or the VI significantly predicted change in any individual NPS. The use of antihypertensive medications more than four times per week was associated with higher total NPI and Affective cluster scores. Use of antihypertensive medication was associated with higher total NPI and Affective cluster scores. The results of this study do not otherwise support vascular risk factors as modifiers of longitudinal change in NPS in AD. Copyright © 2013 John Wiley & Sons, Ltd.
Accounting for length-bias and selection effects in estimating the distribution of menstrual cycle length

PubMed Central

Lum, Kirsten J.; Sundaram, Rajeshwari; Louis, Thomas A.

2015-01-01

Prospective pregnancy studies are a valuable source of longitudinal data on menstrual cycle length. However, care is needed when making inferences of such renewal processes. For example, accounting for the sampling plan is necessary for unbiased estimation of the menstrual cycle length distribution for the study population. If couples can enroll when they learn of the study as opposed to waiting for the start of a new menstrual cycle, then due to length-bias, the enrollment cycle will be stochastically larger than the general run of cycles, a typical property of prevalent cohort studies. Furthermore, the probability of enrollment can depend on the length of time since a woman’s last menstrual period (a backward recurrence time), resulting in selection effects. We focus on accounting for length-bias and selection effects in the likelihood for enrollment menstrual cycle length, using a recursive two-stage approach wherein we first estimate the probability of enrollment as a function of the backward recurrence time and then use it in a likelihood with sampling weights that account for length-bias and selection effects. To broaden the applicability of our methods, we augment our model to incorporate a couple-specific random effect and time-independent covariate. A simulation study quantifies performance for two scenarios of enrollment probability when proper account is taken of sampling plan features. In addition, we estimate the probability of enrollment and the distribution of menstrual cycle length for the study population of the Longitudinal Investigation of Fertility and the Environment Study. PMID:25027273
Predictors of the Longitudinal Course of Postpartum Depression Following Interpersonal Psychotherapy

ERIC Educational Resources Information Center

Nylen, Kimberly J.; O'Hara, Michael W.; Brock, Rebecca; Moel, Joy; Gorman, Laura; Stuart, Scott

2010-01-01

Objective: We examined the course and predictors of postpartum depression in the 18 months following interpersonal psychotherapy (IPT). Method: We enrolled 120 community women with major depression in a 12-week randomized trial of individual IPT during the postpartum period (O'Hara, Stuart, Gorman, & Wenzel, 2000). At 6, 12, and 18 months…
Activation and Self-Efficacy in a Randomized Trial of a Depression Self-Care Intervention

ERIC Educational Resources Information Center

McCusker, Jane; Lambert, Sylvie D.; Cole, Martin G.; Ciampi, Antonio; Strumpf, Erin; Freeman, Ellen E.; Belzile, Eric

2016-01-01

Objectives: In a sample of primary care participants with chronic physical conditions and comorbid depressive symptoms: to describe the cross-sectional and longitudinal associations of activation and self-efficacy with demographic, physical and mental health status, health behaviors, depression self-care, health care utilization, and use of…
Reputation and Image: Some Connections to Resource Environments

ERIC Educational Resources Information Center

Hoagland, Steven R.

2012-01-01

The purpose of this paper is to extend knowledge about the external environment in which educational organizations operate and the patterns by which their resource flows translate into sources of uncertainty. Methods include examination of cross sectional and longitudinal data from secondary sources and a survey on a random sample of 80 public…
Change in Posttraumatic Stress Disorder Symptoms: Do Clinicians and Patients Agree?

ERIC Educational Resources Information Center

Monson, Candice M.; Gradus, Jaimie L.; Young-Xu, Yinong; Schnurr, Paula P.; Price, Jennifer L.; Schumm, Jeremiah A.

2008-01-01

This study assessed the longitudinal association between clinician and patient ratings of posttraumatic stress disorder (PTSD) symptoms over the course of 2 different randomized clinical trials of veterans with chronic PTSD. One trial, the Department of Veterans Affairs Cooperative Study 420 (CSP 420; N = 360) compared trauma-focused and…
Parent-Infant Vocalisations at 12 Months Predict Psychopathology at 7 Years

ERIC Educational Resources Information Center

Allely, C. S.; Purves, D.; McConnachie, A.; Marwick, H.; Johnson, P.; Doolin, O.; Puckering, C.; Golding, J.; Gillberg, C.; Wilson, P.

2013-01-01

This study investigated the utility of adult and infant vocalisation in the prediction of child psychopathology. Families were sampled from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. Vocalisation patterns were obtained from 180 videos (60 cases and 120 randomly selected sex-matched controls) of parent-infant…
Writing Week-Journals to Improve the Writing Quality of Fourth-Graders' Compositions

ERIC Educational Resources Information Center

Rosário, Pedro; Högemann, Julia; Núñez, José Carlos; Vallejo, Guillermo; Cunha, Jennifer; Oliveira, Vera; Fuentes, Sonia; Rodrigues, Celestino

2017-01-01

Students' writing problems are a global educational concern and is in need of particular attention. This study aims to examine the impact of providing extra writing opportunities (i.e., writing journals) on the quality of writing compositions. A longitudinal cluster-randomized controlled design using a multilevel modeling analysis with 182 fourth…
Power Analysis for Models of Change in Cluster Randomized Designs

ERIC Educational Resources Information Center

Li, Wei; Konstantopoulos, Spyros

2017-01-01

Field experiments in education frequently assign entire groups such as schools to treatment or control conditions. These experiments incorporate sometimes a longitudinal component where for example students are followed over time to assess differences in the average rate of linear change, or rate of acceleration. In this study, we provide methods…
Mechanisms in Psychosocial Interventions for Adults Living with Cancer: Opportunity for Integration of Theory, Research, and Practice

ERIC Educational Resources Information Center

Stanton, Annette L.; Luecken, Linda J.; MacKinnon, David P.; Thompson, Elizabeth H.

2013-01-01

Objective: The diagnosis and treatment of cancer are highly stressful experiences that can profoundly affect emotional and physical well-being. Hundreds of longitudinal investigations that identify risk and protective factors for psychological and physical adjustment in adults living with cancer and numerous randomized controlled psychosocial…
A Multidimensional Scaling Approach to Developmental Dimensions in Object Permanence and Tracking Stimuli.

ERIC Educational Resources Information Center

Townes-Rosenwein, Linda

This paper discusses a longitudinal, exploratory study of developmental dimensions related to object permanence theory and explains how multidimensional scaling techniques can be used to identify developmental dimensions. Eighty infants, randomly assigned to one of four experimental groups and one of four counterbalanced orders of stimuli, were…
Design, Baseline Results of Irbid Longitudinal, School-Based Smoking Study

ERIC Educational Resources Information Center

Mzayek, Fawaz; Khader, Yousef; Eissenberg, Thomas; Ward, Kenneth D.; Maziak, Wasim

2011-01-01

Objective: To compare patterns of water pipe and cigarette smoking in an eastern Mediterranean country. Methods: In 2008, 1781 out of 1877 seventh graders enrolled in 19 randomly selected schools in Irbid, Jordan, were surveyed. Results: Experimentation with and current water pipe smoking were more prevalent than cigarette smoking (boys: 38.7% vs…
How Central Is the Alliance in Psychotherapy? A Multilevel Longitudinal Meta-Analysis

ERIC Educational Resources Information Center

Fluckiger, Christoph; Del Re, A. C.; Wampold, Bruce E.; Symonds, Dianne; Horvath, Adam O.

2012-01-01

Prior meta-analyses have found a moderate but robust relationship between alliance and outcome across a broad spectrum of treatments, presenting concerns, contexts, and measurements. However, there continues to be a lively debate about the therapeutic role of the alliance, particularly in treatments that are tested using randomized clinical trial…
A Randomized Controlled Trial of a Multi-Dose Bystander Intervention Program Using Peer Education Theater

ERIC Educational Resources Information Center

McMahon, Sarah; Winter, Samantha C.; Palmer, Jane E.; Postmus, Judy L.; Peterson, N. Andrew; Zucker, Sharon; Koenick, RuthAnne

2015-01-01

This article reports findings from a longitudinal, experimental evaluation of a peer education theater program, Students Challenging Realities and Educating Against Myths (SCREAM) Theater. This study examines the impact of SCREAM Theater on a range of bystander-related outcomes (i.e. bystander intentions, bystander efficacy, perception of friend…

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