Composite endpoints and competing risks analysis [Statistical primer]

Composite end-points are common primary outcomes in clinical trials. Their main benefit of utilizing a composite outcome is increasing the number of primary outcome events meaning fewer participants are required to deliver an adequately powered trial. By combining multiple important end-points in the primary outcome rather than having to select only one, composite end-points potentially make clinically meaningful benefits easier to detect and avoid ranking outcomes hierarchically. However there are a number of important considerations when designing and interpreting clinical trials that utilize composite end-points. In this Statistical Primer, issues with composite end-points such as competing events, halo effect, risk of bias, time to event limitations and the win ratio are discussed in the context of real world clinical trials.