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Real-world Experience of Anti–tumor Necrosis Factor Therapy for Internal Fistulas in Crohn's Disease: A Retrospective Multicenter Cohort Study

Background: Internal fistula in Crohn's disease is a condition likely to require surgery, although few reports showed successful medical treatments such as anti–tumor necrosis factor (TNF) therapy. We performed a multicenter retrospective cohort study to investigate the outcome of anti-TNF therapy for internal fistula in Crohn's disease. Methods: Data were retrospectively collected from patients with Crohn's disease diagnosed with internal fistula treated with anti-TNF agents (infliximab or adalimumab) between January 2002 and November 2015. Need for surgery and fistula closure were assessed as primary and secondary endpoints. Cumulative rate of surgery was evaluated by the Kaplan–Meier analysis. Prognostic factors for the outcomes were also assessed by univariate and multivariate analyses. Results: A total of 93 Crohn's disease cases were included in the study with a mean follow-up period of 1452.8 days. Fistula locations were entero-entero/colonic (n = 72, 77.4%), enterovesical (n = 16, 17.2%), or enterovaginal (n = 5, 5.4%). Cumulative surgery rate was 47.2%, and fistula closure rate was 27.0% at 5 years from the induction of anti-TNF agents. Lower Crohn's Disease Activity Index and shorter duration from the diagnosis of fistula were independently associated with the lower risk of surgery (P = 0.017 and 0.048, respectively). Single fistula was associated with the successful fistula closure. Second-line surgical treatments were mostly successful for anti-TNF failures. Conclusions: In the present retrospective cohort study, approximately half of patients with internal fistulas avoided surgery for long periods. It may be reasonable to treat quiescent single internal fistulas with anti-TNF agents soon after the diagnosis of internal fistulas.