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.