Diagnosing Crohn's Disease in Presumed Cryptoglandular Perianal Fistulas: An Expert Delphi Consensus on Early Identification of Patients at Risk of Crohn's Disease in Perianal Fistulas (PREFAB)

Background: The aim of this Delphi study was to reach consensus on a new clinical decision tool to help identify or exclude Crohn's disease (CD) in patients with perianal fistula(s) (PAF).

Methods: A panel of international experts in the field of proctology/Inflammatory Bowel Disease (IBD) were invited to participate. In the first round (electronic survey), participants were asked to anonymously provide their opinion probing 1) the relevance and use of clinical characteristics suggestive of underlying CD, 2) the use of faecal calprotectin (FCP) for screening for CD and 3) on the diagnostic work-up for CD in PAF patients with raised clinical suspicion. In the second/third round (virtual consensus meetings), statements were paired/revised and presented in final sets of statements. Consensus was predefined as ≥70% (dis)agreement.

Results: Final consensus was reached on twelve statements, including screening of all PAF patients (regardless of the complexity, biological behaviour and co-existent perianal symptoms) and referral of PAF patients for a colonoscopy in case of elevated FCP levels (≥150mcg/g) and/or in case of one clinical major criterion (defined as: unintentional weight loss, unexplained diarrhea, PSC, UC, >1 internal fistula openings, fistula involving other organs (vagina/bladder), recurrent fistulation (after initial healing), proctitis and anal stenosis). Also, clinical (fistula-)characteristics that warrant raised suspicion for CD and an algorithm on the diagnostic work-/follow-up of patients with raised suspicion were defined.

Conclusion: International consensus was reached on a new, clinical decision tool, including a practical and relevant algorithm for finding/excluding CD in PAF patients.