Assessing exchangeability in indirect and mixed treatment comparisons

Demissie AlemayehuPfizer, Inc, Statistics Department, New York, USAAbstract: In comparative effectiveness research (CER), investigators often resort to methods of indirect and mixed treatment comparisons, due to the unavailability of head-to-head comparative data from randomized clinical trials for competing treatment options. However, implicit in the available indirect comparison techniques is an assumption of exchangeability, which in practice cannot be conclusively verified. This paper discusses the implications of violations of this assumption, and describes approaches to evaluate its validity and steps that may be taken to minimize the impact on conclusions drawn from such studies.Keywords: network meta-analysis, heterogeneity, comparative effectiveness research, systematic review