Are component endpoints equal? A preference study into the practice of composite endpoints in clinical trials.

OBJECTIVES: To examine patients' perspectives regarding composite endpoints and the utility patients put on possible adverse outcomes of revascularization procedures.

DESIGN: In the PRECORE study, a stated preference elicitation method Best-Worst Scaling (BWS) was used to determine patient preference for 8 component endpoints (CEs): need for redo percutaneous coronary intervention (PCI) within 1 year, minor stroke with symptoms <24 hours, minor myocardial infarction (MI) with symptoms <3 months, recurrent angina pectoris, need for redo coronary artery bypass grafting (CABG) within 1 year, major MI causing permanent disability, major stroke causing permanent disability and death within 24 hours.

SETTING: A tertiary PCI/CABG centre.

PARTICIPANTS: One hundred and sixty patients with coronary artery disease who underwent PCI or CABG.

MAIN OUTCOME MEASURES: Importance weights (IWs).

RESULTS: Patients considered need for redo PCI within 1 year (IW: 0.008), minor stroke with symptoms <24 hours (IW: 0.017), minor MI with symptoms <3 months (IW: 0.027), need for redo CABG within 1 year (IW: 0.119), recurrent angina pectoris (IW: 0.300) and major MI causing permanent disability (IW: 0.726) less severe than death within 24 hours (IW: 1.000). Major stroke causing permanent disability was considered worse than death within 24 hours (IW: 1.209). Ranking of CEs and the relative values attributed to the CEs differed among subgroups based on gender, age and educational level.

CONCLUSION: Patients attribute different weight to individual CEs. This has significant implications for the interpretation of clinical trial data.