Perianal Fistulizing Crohn's Disease: Utilizing the TOpClass Classification in Clinical Practice to Provide Targeted Individualized Care.

Background & aims: Perianal fistulation is a challenging phenotype of Crohn's disease, with significant impact on quality of life. Historically, fistulae have been classified anatomically in relation to the sphincter complex, and management guidelines have been generalized, with lack of attention to the clinical heterogenicity seen. The recent 'TOpClass classification system' for perianal fistulizing Crohn's disease (PFCD) addresses this issue, and classifies patients into defined groups, which provide a focus for fistula management that aligns with disease characteristics and patient goals. In this article, we discuss the clinical applicability of the TOpClass model and provide direction on its use in clinical practice.

Methods: An international group of perianal clinicians participated in an expert consensus to define how the TOpClass system can be incorporated into real-life practice. This included gastroenterologists, inflammatory bowel disease surgeons, and radiologists specialized in PFCD. The process was informed by the multi-disciplinary team management of 8 high-volume fistula centres in North America, Europe, and Australia.

Results: The process produced position statements to accompany the classification system and guide PFCD management. The statements range from the management of patients with quiescent perianal disease to those with severe PFCD requiring diverting-ostomy and/or proctectomy. The optimization of medical therapies, as well as the use of surgery, in fistula closure and symptom management is explored across each classification group.

Conclusion: This article provides an overview of the system's use in clinical practice. It aims to enable clinicians to have a pragmatic and patient goal-centered approach to medical and surgical management options for individual patients with PFCD.