@article{ref1,
title="Time-dependent covariates in the Cox proportional hazards model. Theory and practice",
journal="Revue d'epidemiologie et de sante publique",
year="2005",
author="Desquilbet, L. and Meyer, L.",
volume="53",
number="1",
pages="51-68",
abstract="In survival analysis, exposure that appears or changes during the follow-up of subjects must be taken into account as a time-dependent covariate in the Cox proportional hazards model. Two types of time-dependent covariates are defined: covariates with unique change, and covariates with multiple changes. The way of taking into account such changes in the exposure is presented in theory and illustrated from a small sample of 5 subjects enrolled in a French HIV cohort. The problems raised by missing data as well as alternative but more sophisticated solutions are also evocated. Annexes include programs for SAS software, and results from the &quot;Log&quot; and &quot;Results&quot; windows.<p /><p>Language: fr</p>",
language="fr",
issn="0398-7620",
doi="",
url="http://dx.doi.org/"
}