Effectiveness of Adalimumab in Perianal Fistulas in Crohn’s Disease Patients Naive to Anti-TNF Therapy

Background: Data regarding the effectiveness of adalimumab (ADA) in the treatment of perianal fistula in patients with Crohn's disease (CD) naive to antitumor necrosis factor (TNF) therapy are scarce. Aim: To assess the effectiveness of ADA in the treatment of perianal fistulas in CD patients naive to anti-TNF therapy. Methods: A retrospective multicenter study was designed. The Fistula Drainage Assessment Index was used to assess the clinical response, and the Van Assche and Ng indexes to classify radiologic response (magnetic resonance imaging). Results: A total of 46 patients (83% women, 83% complex fistula) were included. At 6 months, 72% of patients responded to ADA (54% remission, 18% partial response) and at 12 months 49% responded (41% remission, 8% partial response). Among patients with complex fistula, the response rate was 66% at 6 months and 39% at 12 months. Nine patients escalated the ADA dose to 40mg weekly, 6 for partial response and 3 for absence of response. Thirty-three percent of these patients achieved remission after dose escalation. There was a good correlation between clinical and radiologic assessment of response (kappa = 0.68). In the multivariate analysis, complex fistula was the only predictor of a worse response (hazard ratio 0.083; 95% confidence interval, 0.0009-0.764; P = 0.028). Adverse effects were recorded in 11% of patients. Conclusions: ADA was effective for the treatment of perianal fistulas in CD patients naive to anti-TNF drugs. We found a good correlation between clinical and radiologic assessment of therapy response.