[Dictionary] Composite Endpoint

A composite endpoint is a single clinical trial outcome built by combining two or more distinct individual outcome events into one measure, counted as a single event at the time of whichever qualifying component occurs first (time-to-first-event analysis). Trials use composites mainly to raise the total event rate, which increases statistical power and can shorten follow-up or reduce required sample size compared with powering each component outcome separately. A defensible composite requires components of similar clinical importance, a treatment effect that is directionally consistent across components, and individual component results reported alongside the combined figure -- not just the top-line composite result.