Validity of Composite Outcomes in Meta-Analyses of Stroke Prevention Trials: The Case of Aspirin

BACKGROUND: Aspirin has been reported to be less effective for secondary vascular prevention in patients with ischaemic stroke, compared with other high-risk populations. This contention is largely based on results of meta-analyses that used a composite outcome of vascular death, myocardial infarction and stroke, reporting a 13% relative risk reduction. In this study, we explore whether the summary relative risk reduction for this composite …