A core outcome set for cranioplasty following stroke or traumatic brain injury - The COAST study

Introduction: There is substantial heterogeneity in the reporting of outcomes in the global cranioplasty literature. This study aimed to establish a core outcome set (COS) for cranioplasty after decompressive craniectomy for stroke or traumatic brain injury. Methodology: The scope was defined according to the criteria recommended by the Core Outcome Measures in Effectiveness Trials (COMET) Initiative. Phase 1 focused on outcome gathering through a systematic review and a qualitative study. Phase 2 focused on consolidation and consensus of outcomes through a two-round Delphi survey and consensus meeting. Participants from the four stakeholder groups (1. patients and/or relatives; 2. Surgeons, 3. physicians (non-surgeons), 4. Nurses, allied health professionals, and researchers) individually scored all outcomes on a 9-point Likert scale. Variables that did not reach the predefined consensus threshold for COS inclusion or exclusion were voted upon at the final consensus meeting. Results: In total, 208 verbatim outcomes were consolidated into 56 domains. A total of 153 participants completed round 1, with 45 additional outcomes suggested for inclusion. Following rationalisation, four were included in round 2. A total of 109/153 participants (71 %) from 16 countries completed Round 2 and re-scored all 60 outcomes (56 original + 4 additional). Nine outcomes were voted in, and 12 were excluded from the Delphi. The remaining 39 were discussed at a consensus meeting with 11 voted in. The final COS included 20 outcomes (12 + 8) across four domains: life impact, pathophysiological manifestations, resource use/economic impact, and mortality. Conclusion: COAST COS covers key cranioplasty outcomes, as assessed by international stakeholders, including surgical, medical, rehabilitation, and nursing professionals, as well as patients and their relatives. Future implementation will aid in the standardisation of outcomes and facilitate the development of cranioplasty-specific outcome measures, aiding between-study comparisons and improving the relevance of trial findings to healthcare professionals and patients.