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

Background
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.
Methods
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.
Findings
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.
Interpretation
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.

Contributors

Marleen S. Vallinga, Philippine J. Roijera, Thomas E. Pidgeon, Matteo Angelini, Aline Ceulemans, Alex Bakker, Brenda Carrière, Tina Rashid, James Bellringer, Javier Belinky, Marlon Buncamper, Shane D. Morrison, Walter P. Bouman, Tim C. van de Grift, Mark-Bram Bouman, Margriet G. Mullender

Publication

Journal: eClinicalMedicine
Volume: 85
Issue:
Pages: -
Year: 2025
DOI: 10.1016/j.eclinm.2025.103323

Further Study Information

Current Stage: Completed
Date: June 2021 - December 2025
Funding source(s): No funding sources


Health Area

Disease Category: Other

Disease Name: N/A

Target Population

Age Range: 18 - 120

Sex: Either

Nature of Intervention: Surgery

Stakeholders Involved

- Clinical experts
- Consumers (patients)
- Researchers

Study Type

- COS for clinical trials or clinical research

Method(s)

- Consensus meeting
- Delphi process
- Focus group(s)
- Interview
- Systematic review

The guidelines by the Core Outcome Measures in Effectiveness Trails (COMET) initiative will be followed during this project. The phases of development are; i) a systematic review to identify all outcomes measured and reported in previous research; ii) Identify outcomes suggested by patients during focus groups and interviews; iii) To combine and structure the clinician reported outcomes and patient reported outcomes in a preliminary outcome list for the COS, which will be iv) distributed as e-Delphi surveys among stakeholders (i.e. professionals in transgender healthcare and transgender- and gender divers individuals) in which all potential outcomes will be rated on importance; v) an online consensus meeting to decide on the final COS.