Article
Semiparametric regression analysis of longitudinal data with informative drop-outs
Source: Biostatistics, Volume 4, Number 3, 1 July 2003 , pp. 385-398(14)
Publisher: Oxford University Press
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Abstract:
Informative drop-out arises in longitudinal studies when the subject's follow-up time depends on the unobserved values of the response variable. We specify a semiparametric linear regression model for the repeatedly measured response variable and an accelerated failure time model for the time to informative drop-out. The error terms from the two models are assumed to have a common, but completely arbitrary joint distribution. Using a rank-based estimator for the accelerated failure time model and an artificial censoring device, we construct an asymptotically unbiased estimating function for the linear regression model. The resultant estimator is shown to be consistent and asymptotically normal. A resampling scheme is developed to estimate the limiting covariance matrix. Extensive simulation studies demonstrate that the proposed methods are suitable for practical use. Illustrations with data taken from two AIDS clinical trials are provided.
Keywords: Artificial censoring; Counting process; Dependent censoring; Linear regression; Missing data; Repeated measures
Document Type: Original article
Affiliations: 1: Department of Biostatistics, University of North Carolina, CB#7420 McGavran-Greenberg, Chapel Hill, NC 27599-7420, USA lin@bios.unc.edu 2: Department of Statistics, 618 Mathematics, Columbia University, New York, NY 10027, USA zying@stat.columbia.edu
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