Long-term outcome of perianal fistulizing Crohn's disease treated with infliximab.

Background & Aims: Little is known about the long-term efficacy of infliximab for patients with fistulizing perianal Crohn's disease. We evaluated outcomes and predictors of outcomes in these patients.

Methods: The medical records of 156 patients treated with infliximab for fistulizing perianal Crohn's disease at 2 referral centers from 1999 through 2010 were reviewed through September 2011. Cumulative probabilities of fistula closure and recurrence were estimated by using the Kaplan-Meier method. Predictors of outcomes were identified by using a Cox proportional hazards model.

Results: When infliximab treatment began, only 17.9% of patients had a simple fistula; seton drainage was performed for 97 patients (62%). Concomitant immunosuppressants were given to 90 patients (56%). After a median follow-up period of 250 weeks, 108 patients (69%) had at least 1 fistula closure. Cumulative probabilities of first fistula closure were 40% and 65% at 1 and 5 years, respectively. Factors that predicted fistula closure were ileocolonic disease (hazard ratio [HR] = 1.88), concomitant immunosuppressants (HR = 2.58), duration of seton drainage <34 weeks (HR = 2.31), and long duration of infliximab treatment (HR = 1.76). Of the 108 patients with fistula closure, cumulative probabilities of first fistula recurrence were 16.6% and 40.1% at 1 and 5 years, respectively. Forty-four patients (28.9%) developed an abscess during follow-up. A number of infliximab infusions greater than 19 was associated with less abscess recurrence (HR = 0.33). At the maximal follow-up time, 55% of patients had fistula closure.

Conclusions: About two-thirds of patients with fistulizing perianal Crohn's disease had fistula closure, and one-third had fistula recurrence after infliximab initiation. Combination therapy, duration of seton drainage less than 34 weeks, and long-term treatment with infliximab were associated with better outcomes.