A Consumer's Guide to Subgroup Analyses

doi:10.1059/0003-4819-116-1-78

A Consumer's Guide to Subgroup Analyses

Andrew D. Oxman, MD; and
Gordon H. Guyatt, MD

Abstract

▪ The extent to which a clinician should believe and act on the results of subgroup analyses of data from randomized trials or meta-analyses is controversial. Guidelines are provided in this paper for making these decisions. The strength of inference regarding a proposed difference in treatment effect among subgroups is dependent on the magnitude of the difference, the statistical significance of the difference, whether the hypothesis preceded or followed the analysis, whether the subgroup analysis was one of a small number of hypotheses tested, whether the difference was suggested by comparisons within or between studies, the consistency of the difference, and the existence of indirect evidence that supports the difference. Application of these guidelines will assist clinicians in making decisions regarding whether to base a treatment decision on overall results or on the results of a subgroup analysis.

Article and Author Information

From McMaster University Health Sciences Centre, Hamilton, Ontario. For current author addresses, see end of text.
Grant Support: In part by the Ontario Ministry of Health. Dr. Guyatt is a career scientist of the Ontario Ministry of Health.
Requests for Reprints: Andy Oxman, MD, Department of Family Medicine, McMaster University, Health Sciences Centre, Room 2V10, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5.
Current Author Addresses: Dr. Oxman: Department of Family Medicine, McMaster University, Health Sciences Centre, Room 2V10, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5.

Dr. Guyatt: Department of Clinical Epidemiology and Biostatistics, McMaster University, Health Sciences Centre, Room 2C12, 1200 Main Street West, Hamilton, Ontario, L8N 3Z5.