Document Detail


A mixture model for longitudinal data with application to assessment of noncompliance.
MedLine Citation:
PMID:  10877305     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In clinical trials of a self-administered drug, repeated measures of a laboratory marker, which is affected by study medication and collected in all treatment arms, can provide valuable information on population and individual summaries of compliance. In this paper, we introduce a general finite mixture of nonlinear hierarchical models that allows estimates of component membership probabilities and random effect distributions for longitudinal data arising from multiple subpopulations, such as from noncomplying and complying subgroups in clinical trials. We outline a sampling strategy for fitting these models, which consists of a sequence of Gibbs, Metropolis-Hastings, and reversible jump steps, where the latter is required for switching between component models of different dimensions. Our model is applied to identify noncomplying subjects in the placebo arm of a clinical trial assessing the effectiveness of zidovudine (AZT) in the treatment of patients with HIV, where noncompliance was defined as initiation of AZT during the trial without the investigators' knowledge. We fit a hierarchical nonlinear change-point model for increases in the marker MCV (mean corpuscular volume of erythrocytes) for subjects who noncomply and a constant mean random effects model for those who comply. As part of our fully Bayesian analysis, we assess the sensitivity of conclusions to prior and modeling assumptions and demonstrate how external information and covariates can be incorporated to distinguish subgroups.
Authors:
D K Pauler; N M Laird
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Biometrics     Volume:  56     ISSN:  0006-341X     ISO Abbreviation:  Biometrics     Publication Date:  2000 Jun 
Date Detail:
Created Date:  2000-10-10     Completed Date:  2000-10-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0370625     Medline TA:  Biometrics     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  464-72     Citation Subset:  IM; X    
Affiliation:
Biostatistics Center, Massachusetts General Hospital, Boston 02114, USA. donna@newton.mgh.harvard.edu
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MeSH Terms
Descriptor/Qualifier:
Anti-HIV Agents / therapeutic use
Biometry / methods*
Clinical Trials as Topic / methods
HIV Infections / drug therapy,  psychology
Humans
Longitudinal Studies*
Markov Chains
Models, Statistical
Monte Carlo Method
Motivation
Patient Compliance
Treatment Refusal*
Zidovudine / therapeutic use
Chemical
Reg. No./Substance:
0/Anti-HIV Agents; 30516-87-1/Zidovudine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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