Estimation of multiple relative risk functions in matched case-control studies.

A linear logistic model used to estimate multiple risk functions in both cohort and case-control studies is adapted for sampling plans wherein each case is matched with R controls. The resulting methodology substantially liberalizes current practice by permitting simultaneous analysis of multiple discrete and continuous risk factors. Interactions among risk factors, and between risk factors and matching variables, may be explored. Data from two studies of oesophageal cancer, one conducted among Singapore Chinese and the other on the Caspian littoral of Iran, illustrate the methods.