Clinical Trials

■■❚❙❘Chapter 23Subgroup AnalysisAmeet Bakhai, Zoe Fox, and Duolao WangSubgroup analyses in a clinical trial explore whether there isa relationship between the specific characteristics of subjectsand their responses to treatments. Although subgroup analysesare reported in most clinical trials, considerable controversyexists about the best means of performing these investigations.Statisticians are wary of performing multiple subgroup analyses –‘data dredging’ – since this increases the risk of finding a falsepositiveresult (a Type I error). Meanwhile, clinicians try to justify‘torturing the data’ with the notion that such analyses mightidentify the patients who benefit the most from specific treatmentstrategies. In this chapter, we discuss appropriate uses andcommon abuses of subgroup analyses, and how to interpretthe results generated by them.265