Abstract Background Perianal fistulising Crohn’s disease (pfCD) can have a devastating impact on an individual’s quality of life and ability to function within society. The need for a holistic evaluation is increasingly recognised however this is yet to be implemented within interventional studies. The advent of core outcome measurement sets represents a paradigm shift towards standardising outcome measurement and ensuring that measured outcomes truly matter to patients. A Core Outcome Set for pfCD (CAFCOS) has been developed1. This study aimed to undertake the next phase: a Core Outcome Measurement Set (CAFCOMS) to provide recommendations on outcome measurement instruments (OMIS), modalities and timepoints. Methods The study was conducted according to Core Outcome Measures in Effectiveness Trials (COMET) methodology. This involved two phases: a systematic review to identify existing OMIs and evaluate their psychometric properties, patient involvement in development and overall feasibility using the COSMIN checklist, and an international Delphi consensus involving patients and clinicians (gastroenterologists, colorectal surgeons, radiologists and IBD nurses). Consensus was defined as 70% agreement. Results A systematic review identified 29 OMIs and a further two OMIs were included following expert suggestion. These were evaluated and presented to the consensus group. Both rounds of the Delphi survey were completed by 135 participants. The final consensus meeting was attended by 29 participants (5 patients, 24 clinicians), during which the patient perspective was explored before each deciding vote. Consensus established OMI choice for quality of life (Crohn’s Anal Fistula Quality of Life Scale), incontinence (Vaizey score), perianal disease activity (Perianal Disease Activity Index) and an activity-based MRI score responsive to change (MAGNIFI-CD/TOpClass definition), although the latter three were deemed adequate but not optimal. Agreement was also reached for timepoints, modality, and outcome definitions. Conclusion The development of CAFCOMS represents a significant step towards acknowledging that the outcomes traditionally measured within studies do not always reflect the priorities of those living with the disease. Integrating this within fistula research will not only improve heterogeneity in outcome measurement, it will also enable clinicians to make meaningful, evidence-based decisions tailored to the individual. Reference: 1) Sahnan K, Tozer PJ, Adegbola SO, Lee MJ, Heywood N, McNair AGK, Hind D, Yassin N, Lobo AJ, Brown SR, Sebastian S, Phillips RKS, Lung PFC, Faiz OD, Crook K, Blackwell S, Verjee A, Hart AL, Fearnhead NS; ENiGMA collaborators. Developing a core outcome set for fistulising perianal Crohn’s disease. Gut. 2019 Feb;68(2):226-238. doi: 10.1136/gutjnl-2017-315503. Epub 2018 Feb 3. PMID: 29437911; PMCID: PMC6352412. Conflict of interest: Ms. Joshi, Shivani: Speaker Fees from Lilly Anand, Easan: Nil Antoniou, Anna: No conflict of interest Alexander, James: James has received speaker fees from Pfizer, Abbvie, Takeda and Janssen. He has received travel grants and support to attend meetings from Lilly, Tillotts Pharma, Takeda and Celltrion. Iqbal, Nusrat: No conflict of interest Lundby, Lilli: No conflict of interest Lung, Phillip FC: No conflict of interest McNair, Angus: No conflict of interest Sahnan, Kapil: Speaker fees from Takeda, JnJ, Intuitive Ad Board with Medtronic Stoker, Jaap: No conflict of interest Hart, Ailsa: Grant: Takeda Personal Fees: Abbvie, Amgen, Arena, AZ, Falk, Celltrion, Eli Lilly, Ferring, Genentech/ Roche, GSK, Pfizer, Takeda, Napp, Pharmacosmos, Janssen (J & J), Bristol-Myers Squibb, Gilead, Galapagos, Alfasigma Tozer, Philip: Personal Fees: Takeda - speakers fees, member of Inspire, and advisory boards Ferring - speakers fees Falk - speakers fees Tillott’s - speakers fees J & J - speakers fees Abbvie - speakers fees
Joshi et al. (2026) studied this question.