Analysis of a two-stage case-control study with cluster sampling of controls: application to nonmelanoma skin cancer.

We present a pseudolikelihood approach for analyzing a two-stage population-based case-control study with cluster sampling of controls. These methods were developed to analyze data from a study of nonmelanoma skin cancer (NMSC). This study was designed to evaluate the role of ultraviolet radiation (UVB) on NMSC risk while adjusting for age group, which is known for all subjects, and for other individual-level factors, such as susceptibility to sunburn, which are known only for participants in the case-control study. The methods presented yield estimates of relative and absolute risk, with standard errors, while accounting naturally for the two-stage sampling of the cohort and cluster sampling of controls.