Subgroup Analysis: A View from Industry

Subgroup analysis in clinical trials for regulatory and reimbursement purposes can be confirmatory or exploratory in nature. Confirmatory subgroup analysis requires pre-specification of the proposed analysis and appropriate control of the type I error rate. Exploratory subgroup analysis is a feature of Phase III clinical trials. Examination of the results by sex, age and race is required by FDA and submissions for regulatory approval typically involve numerous further analyses by baseline characteristics such as disease severity. For efficacy these exploratory analyses are often directed at providing reassurance that the overall estimated treatment effect translates into benefit for each of the subgroups and for safety to investigate the existence of signals in more vulnerable subgroups. For reimbursement purposes, extensive analysis is required to try to identify those groups experiencing most benefit and for whom the medicine is therefore most cost-effective.