The Challenge of Subgroup Analyses — Reporting without Distorting

Subgroup analyses are an important part of the analysis of a comparative clinical trial. However, they are commonly overinterpreted14 and can lead to further research that is misguided or, worse, to suboptimal patient care.Consider a randomized, clinical trial designed to determine whether a new treatment is more effective than an established treatment and assessed with a test, based on all randomized patients, of the null hypothesis that the treatments have equal efficacy, as measured in terms of the primary end point. Then, subgroup analyses are conducted to assess whether different types of patients respond differently to the new . . .