Clinical efficacy of adalimumab versus infliximab and the factors associated with recurrence or aggravation during treatment of anal fistulas in Crohn's disease

BACKGROUND/AIMS Infliximab has proven to be effective in the treatment of perianal fistulas in Crohn's disease (CD) but the efficacy of adalimumab is still unclear. The aim of this study is to assess the clinical efficacy of adalimumab and compare the results with those for infliximab. METHODS Forty-seven CD patients treated for perianal fistulas with infliximab from September 2005 to December 2010 (n=31), or with adalimumab from November 2010 to May 2012 (n=16), were enrolled in this retrospective study. The following patient characteristics were analyzed; intestinal lesion site, fistula classification, seton placement, index of inflammatory bowel disease, C-reactive protein level, follow-up period, and the cumulative rate of nonrecurrence or aggravation of fistula. RESULTS There were no significant differences in the intestinal lesion site, fistula classification, inflammatory bowel disease index, C-reactive protein level, and the frequency of injection between the infliximab group and the adalimumab group. The cumulative rate of nonrecurrence or aggravation of fistula was 62.5% in the adalimumab group and 83.9% in the infliximab group at 24 months after treatment (P=0.09). The risk factors for recurrence or aggravation may be related to seton placement (P=0.02), gender (P=0.06), and fistula classification (P=0.07). CONCLUSIONS There was no significant difference in the clinical efficacy of adalimumab and infliximab in the treatment of perianal fistulas in CD. However, fistula classification may be an important risk factor for recurrence or aggravation. The preliminary findings in this study show that further research is warranted.