Adverse events are considered but not always explicitly selected as core outcomes in research: an updated systematic review

Objectives

The annual systematic review update of published core outcome sets (COSs) by the Core Outcome Measures in Effectiveness Trials Initiative allows assessment of adherence to development standards. The objectives of this study were to assess the quality of COS development and the approach to the inclusion of adverse event outcomes.

Study Design and Setting

Studies reporting the development of a COS, published or indexed in 2022 and 2023, were identified using systematic review methods previously applied. Adherence to internationally agreed consensus-based standards for COS development was assessed. An existing outcome taxonomy was used to classify the core outcomes from all studies. The approach to consideration and inclusion of adverse event outcomes was examined.

Results

Fifty-eight COS development studies were included in the 2022 update and a further 40 studies in the 2023 update. Scope specification standards were fully met in all studies. Stakeholder inclusion standards were fully met in 38 (66%) and 34 (85%) of the 2022 and 2023 studies, respectively; the proportion meeting all four standards for the consensus process was lower, 13 (22%) and 13 (33%), respectively. The consideration of adverse events in the COS development process varied. Around half (54, 49%) of 2022–2023 COS included either the adverse events domain or specifically named adverse events as core outcomes.

Conclusion

Continued improvement in adherence to recognized standards, including patient participation, is evident; however, further improvement is needed in relation to the consensus process standards. COS developers should be explicit about and explain the rationale for their approach to consideration of adverse events.