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)
Authors: Munster Liesbeth J , Hanna Luke N , Hart Ailsa L , Tozer Phil J , Buskens Christianne J , van der Bilt Jarmila D W ,   TOpCLASS perianal Crohn’s disease Consortium, the Dutch Initiative on Crohn and Colitis (ICC) and the Initiative on Crohn and Colitis - Surgery (ICC-S), Dige Anders , Lundby Lilli , Buskens Christianne J , Stoker Jaap , van der Bilt Jarmila D W , McGovern Dermot P B , Cohen Benjamin L , Holubar Stefan D , Powell Nick , Sebastian Shaji , Spinelli Antonino , Carvello Michele , Wong Serre-Yu , Colombel Jean-Frédéric , Catalán-Serra Ignacio , Connor Susan J , Anandabaskaran Sulak , Leblanc Jean-Frédéric , Lightner Amy L , Hart Ailsa L , Tozer Phil J , Sahnan Kapil , Lung Philip F C , Ding Nik S , Behrenbruch Corina , Winata Leon S , McCurdy Jeffrey D , Geldof Jeroen , De Looze Danny , De Kock Isabelle , Vermeire Séverine , Verstockt Bram , D’Hoore André , Bislenghi Gabriele , Rubin David T , McDonald Benjamin D , Deepak Parakkal , Ballard David H , Kotze Paulo G , Harmath Carla B , El Ouali Sara , Stassen Laurents P S , Hoogeboom Froukje J , Visschedijk Marijn C , van Dongen Koen W , Duijvestein Marjolijn , van Ruler Oddeke , Peeters Koen C M J , van der Meulen-de Jong Andrea E , Richir Milan C , van Schaik Fiona D M , Pierik Marie J , Mundt Marco W , Zimmerman David D E , Han-Geurts Ingrid J M 
Published: January 2025

Abstract

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 was 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 fecal 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 12 statements, including screening of all PAF patients (regardless of the complexity, biological behavior, and co-existent perianal symptoms) and referral of PAF patients for a colonoscopy in case of elevated FCP levels (≥150 mcg/g) and/or in case of one clinical major criterion (defined as: unintentional weight loss, unexplained diarrhea, PSC, UC, &gt;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.