The core outcome set for studies on feminizing genital gender-affirming surgery: findings from the GenderCOS project

Feminizing genital gender-affirming surgery (gGAS) comprises various surgical procedures and techniques. Comprehensive knowledge of the outcomes of all procedures and techniques is fundamental for informed decision-making. However, in current research on feminizing gGAS there is significant heterogeneity in reported outcomes. Standardization of outcome measurement is therefore urgently required. This study aimed to develop a Core Outcome Set (COS) for feminizing gGAS.

A multidisciplinary, international study steering group comprising 16 panellists from Europe, the United Kingdom, North America, and South America-including health care professionals and transgender individuals-was appointed to guide the development of a COS. The steering group convened on 16 June 2022, 28 September 2023, 2 May 2024, and 29 August 2024. The study involved three phases: (i) relevant outcomes were identified through a literature review and focus groups with transgender and gender-diverse people; (ii) stakeholders were invited to participate in an international Delphi study to reach consensus on the key outcomes; (iii) a consensus meeting was held to reach a final consensus on the COS.

Initial data collection yielded 2621 unique outcomes. This number was reduced to 39 potential outcomes for the Delphi process through a structured selection process. The Delphi rounds encompassed February, May and July 2024 respectively. Following the consensus meeting in September 2024, a final list of 11 outcomes was agreed, of which six are patient-reported outcomes. Seven outcomes apply to all feminizing gGAS procedures and four are specific to vaginoplasty procedures involving the creation of a vaginal canal.

Adoption of the COS for feminizing gGAS could ensure that the most relevant outcomes in clinical research are measured and reported in a standardized way. Future studies adopting these suggested outcome measures could reduce the heterogeneity of reported outcomes across studies and working to improve the quality of research and care.

None received.