Identifying a core outcome set for cardiac arrest effectiveness trials

Cardiac arrest research seeks to improve survival rates and the quality of patient survival, but the comparability of research is limited by heterogeneous outcome reporting. The Core Outcome Set for Cardiac Arrest effectiveness trials (COSCA) study sought to identify the most important outcome domains that should be reported as minimum across all cardiac arrest effectiveness trials as part of a core outcome set (COS). Multiple perspectives were sought across COS development to ensure relevance. Potential outcome domains for COS inclusion were identified in: a systematic review of outcomes reported in published randomised controlled trials (RCTs) and interviews with survivors of cardiac arrest and their partners to understand the health outcomes that really matter. Consensus on the most important outcome domains was achieved in: an international modified Delphi survey and an international consensus meeting. Great heterogeneity (164 outcomes) was reported across current RCTs, failing to capture a number of outcomes important to cardiac arrest survivors identified in interviews. Across 2 rounds of ranking and rating exercise 48 outcome domains (18 health domains across 5 time points) were scored on their importance in the modified Delphi survey. Subsequently, 30 outcome domains were further discussed at a face to face consensus meeting. Three core outcome domains were defined: survival to hospital discharge/30 days, neurological outcome at hospital discharge/30 days and health related quality of life (HRQoL) within 1 year. Preliminary guidance on appropriate assessment tools were made but further evidence and understanding of the most appropriate measurement tools is required. Implementation of the defined COS has the potential to improve outcome reporting across cardiac arrest effectiveness trials, aiding the comparison of findings through homogeneous outcome reporting and ensuring the most important outcome domains to key stakeholders are reported.