Composite End Points in Clinical Research: A Time for Reappraisal

Advances in cardiovascular medicine fueled by innovative clinical trials have dramatically improved the lives of patients worldwide. Commensurate with this progress has been a decline in morbid and mortal events. Accordingly, an increased propensity to collate patient outcomes in clinical trials has emerged that combines death and nonfatal complications into a single composite event. Despite the acknowledged benefits in trial efficiency from such an approach, this method assumes uniform directionality of each component, does not distinguish the relative clinical significance of each, and counts only the first occurrence of any event in the final tally within a conventional time to first event analysis. In this article, we evaluate the criticisms that have been leveled at this approach and provide an overview of recently published phase III cardiovascular trials using primary composite end points. We then explore what to anticipate from the large cohort of as-yet unpublished clinical trials in this arena. Last, we propose a variety of novel approaches that use composite end points and suggest a path forward to enhancing their use in future clinical trials.