Retrospective studies and failure time models

Abstract

The proportional hazards failure time model of Cox (1972) is adapted to the retrospective epidemiological study, in which cases and controls are sampled from a population in order to relate disease incidence rates to exposure to suspected risk factors. The method permits simultaneous study of several exposure variables, that may be discrete or continuous or a mixture of both, in the presence of additional explanatory variables and competing risks. The proportional hazards framework provides a fresh look at the concepts of matching, choice of controls, confounding and effect modification.