Abstract Background Pouch anal and vaginal fistulae (PAVF) are complications of ileoanal pouch surgery that occur in 5 % of cases and result in significant morbidity. Progress in research is limited by heterogeneity in outcome reporting. The Pouch Anal and Vaginal Fistula Core Outcome Set (PAVFCOS) initiative established what to measure (Figure 1); this study aimed to develop a core outcome measurement set (PAVFCOMS) to standardize how and when outcomes should be measured. Methods This study followed COSMIN methodology. First, a systematic review identified outcome measurement instruments (OMIs) used in PAVF research (3). Next, a two-round international Delphi consensus process was undertaken, followed by a stakeholder meeting. Participants included patients with PAVF, colorectal surgeons, gastroenterologists, radiologists, and IBD nurses. An a priori consensus threshold of ≥ 70% agreement was required for OMI selection (4). Results Of 142 participants who took part in Round 1, 139 (98%) completed both Delphi rounds. The final stakeholder meeting agreed that fistula healing should be assessed clinically (at 3, 6, and 12 months), and radiologically (at 6 and 12 months) using the TOpClass definition (4). A minimum of 3 months was required to declare clinical improvement and 12 months for fistula healing. New fistulae or abscesses should be assessed clinically and/or radiologically as appropriate. Major and minor rescue interventions should be recorded continuously during follow-up. Continence should be measured using the Vaizey Incontinence Score, while fistula-related pain, impact of discharge, and global quality of life should be assessed using the disease-specific PAVF-QoL scale at 3, 6, and 12 months post-intervention. Conclusion PAVFCOMS is the first internationally agreed COMS for pouch-related anal and vaginal fistulae. It defines standardized OMIs and recommended timepoints (3, 6, and 12 months) for use in clinical research, as well as identifying gaps where adequate OMIs do not currently exist. Its adoption will improve outcome reporting consistency and comparability across PAVF research. Future work includes validation of PAVF-QoL and development of a fistula-specific continence scale. References: (1) Reza L, Bapir L, Iqbal N, Sackitey C, Hughes S, Babbar M, et al. PAVFCOS: The development of a core outcome set for pouch anal and vaginal fistula. Colorectal Disease. 2025;27(8): e70184. https://doi.org/10.1111/codi.70184. (2) Anand E, Joshi S, Reza L, Sahnan K, Lung P, Hart A, et al. A systematic review of outcome measurement instruments used in pouch anal and vaginal fistulae: a COSMIN-based analysis. Quality of Life Research: An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation. 2025; https://doi.org/10.1007/s11136-025-03911-4. (3) Anand E, Joshi S, Reza L, Sahnan K, Lung P, Hart A, et al. Study protocol for the development of a pouch anal and vaginal fistula core outcome measurement set (PAVFCOMS). Journal of Surgical Protocols and Research Methodologies. 2025;2025: snae017. https://doi.org/10.1093/jsprm/snae017. (4) Anand E, Devi J, Ballard DH, Joshi S, Tozer P, Hart A, et al. Defining radiological healing in perianal fistulising Crohn’s Disease: a TOpClass global expert Delphi consensus. Clinical Gastroenterology and Hepatology. 2025; S1542356525002484. https://doi.org/10.1016/j.cgh.2025.02.009. Conflict of interest: Mr. Anand, Easan: No conflict of interest Joshi, Shivani: No conflict of interest Pelly, Theo: No conflict of interest Ghersin, Itai: No conflict of interest Reza, Lillian: No conflict of interest Gallinari, Rita: No conflict of interest Davies, David: No conflict of interest Alexander, James: No conflict of interest Sahnan, Kapil: No conflict of interest Hart, Ailsa: No conflict of interest Lung, Phillip FC: No conflict of interest Tozer, Philip: No conflict of interest
Anand et al. (Thu,) studied this question.