Predicting Factors of Fistula Healing and Clinical Remission After Infliximab-Based Combined Therapy for Perianal Fistulizing Crohn's Disease

Perianal fistulizing Crohn's disease (PFCD) treatment is based on fistula drainage, antibiotics, immunosuppressant (IS) drugs, and infliximab. Our aim was to study the effectiveness of combination therapy on PFCD and to search for clinical or imaging features associated with the initial complete clinical response and its stability overtime. Patients and methods All patients with PFCD treated in our tertiary center between 2000 and 2005 by infliximab in combination with seton placement and/or IS and evaluated by MRI before treatment were included in the study. Basal clinical and MRI characteristics were recorded. Response to treatment was evaluated after the infliximab induction regiment and at the end of the follow-up. Results Twenty-six patients were included and followed-up for an average 4.9 years. A complex fistula was present in 69% (18/26 patients) of cases and eight (8/26 patients) had an ano-vaginal fistula. After infliximab induction therapy, 13 patients (50%) achieved a complete clinical response. The initial clinical response was significantly associated with the absence of both, active intestinal disease (54% vs. 8%, P = 0.03) and active proctitis (77% vs. 23%, P = 0.01). No initial MRI characteristics were linked to the initial response. In multivariate analysis, only the presence of active proctitis was associated with the lack of response (P = 0.047). At the end of the follow-up, 42% of the patients remained in clinical remission. No clinical characteristics were associated to sustained response when among long-standing responders two exhibited a normal post-treatment MRI. Conclusion An initial complete response of PFCD was observed in half of the patients after combined therapy including infliximab that decreased to 42% later on. Complete healing of fistulas on MRI was possible but unusual. The initial response seemed related to the absence of active intestinal disease, especially in the rectum, when the long-term response could not be predicted by the basal characteristics of patients.