The Impact of Setons on Perianal Fistula Outcomes in Patients With Crohn's Disease Treated With Anti‐TNF Therapy: A Multicentre Study

ABSTRACT Background and Aims We aimed to assess the impact of setons on perianal fistula outcomes in patients with perianal fistulising Crohn's disease (PFCD) treated with anti‐TNF therapy. Methods We included patients treated with their first anti‐TNF therapy for PFCD after undergoing a pelvic MRI between 2005 and 2022 from 6 North American centres. Our exposure was one or more setons at the time of anti‐TNF therapy. Our primary outcome was major adverse fistula outcome (MAFO), a composite of repeat local surgical intervention, hospitalisation, or faecal diversion for PFCD, and our secondary outcome was fistula remission defined clinically. We used 1:1 cardinality matching and propensity score weighting to control for fistula severity based on centrally read MRIs, luminal characteristics, and concomitant therapies. Results Our analysis included 221 patients: 81 with setons and 140 without setons. After cardinality matching, our cohorts were balanced (standardised difference < 0.1 for all covariates). Patients with setons had similar rates of MAFO (HR 1.23; 95% CI, 0.68–2.21) and fistula remission at 6 months (OR, 0.81; 95% CI, 0.41–1.59) and 12 months (OR, 0.63; 95% CI, 0.31–1.27) compared to patients without setons. Our results remained stable when analysed by propensity score weighting and in a sensitivity analysis of patients who underwent an exam under anaesthesia. In patients with abscesses, there were lower rates of MAFO (HR, 0.49; 95% CI, 0.19–1.25) but not statistically significant in patients with setons. Conclusions In this multicentre, setons were not associated with improved fistula outcomes. Future prospective controlled studies are warranted.