Title
Flexible longitudinal linear mixed models for multiple censored responses data
Date Issued
15 March 2019
Access level
open access
Resource Type
journal article
Author(s)
Pontificia Universidad Católica de Chile
Publisher(s)
John Wiley and Sons Ltd
Abstract
In biomedical studies and clinical trials, repeated measures are often subject to some upper and/or lower limits of detection. Hence, the responses are either left or right censored. A complication arises when more than one series of responses is repeatedly collected on each subject at irregular intervals over a period of time and the data exhibit tails heavier than the normal distribution. The multivariate censored linear mixed effect (MLMEC) model is a frequently used tool for a joint analysis of more than one series of longitudinal data. In this context, we develop a robust generalization of the MLMEC based on the scale mixtures of normal distributions. To take into account the autocorrelation existing among irregularly observed measures, a damped exponential correlation structure is considered. For this complex longitudinal structure, we propose an exact estimation procedure to obtain the maximum-likelihood estimates of the fixed effects and variance components using a stochastic approximation of the EM algorithm. This approach allows us to estimate the parameters of interest easily and quickly as well as to obtain the standard errors of the fixed effects, the predictions of unobservable values of the responses, and the log-likelihood function as a byproduct. The proposed method is applied to analyze a set of AIDS data and is examined via a simulation study.
Start page
1074
End page
1102
Volume
38
Issue
6
Language
English
OCDE Knowledge area
VirologÃa
EstadÃsticas, Probabilidad
Subjects
DOI
Scopus EID
2-s2.0-85056334746
PubMed ID
Source
Statistics in Medicine
ISSN of the container
02776715
Sponsor(s)
We are grateful to two anonymous referees and the associate editor for very useful comments and suggestions, which greatly improved this paper. L. Matos acknowledges support from FAPESP-Brazil (grants 2016/05420-6 and 2018/05013-7). V.H. Lachos acknowledges the support from FAPESP-Brazil (grant 2018/05013-7). Dr. M.-H. Chen's research was partially supported by NIH grants #GM 70335 and #P01 CA142538. L.M. Castro acknowledges support from grant FONDECYT 1170258 from the Chilean government and Iniciativa CientÃfica Milenio - Minecon Núcleo Milenio MiDaS.
Sources of information:
Directorio de Producción CientÃfica
Scopus