Calculating additive treatment effects from multiple randomized trials provides useful estimates of combination therapies

OBJECTIVE: Many clinicians and decision makers want to know the combined effects of treatments that have not been evaluated in combination. It is possible to determine such treatment effects by making assumptions about the additive effects. We discuss here the prerequisites and methods of applying additivity assumptions in synthesizing the evidence from randomized trials and multiple treatment meta-analyses. STUDY DESIGN AND SETTING: Using …