Treatment of perianal fistula in Crohn's disease: a systematic review and meta-analysis comparing seton drainage and anti-tumour necrosis factor treatment.

The introduction of anti-tumour necrosis factor (anti-TNF; infliximab and adalimumab) has changed the management of Crohn's perianal fistula from almost exclusively surgical treatment to one with a much larger emphasis on medical therapy. The aim of this systematic review was to provide an overview of the success rates of setons and anti-TNF for Crohn's perianal fistula. Studies evaluating the effect of setons and anti-TNF on Crohn's perianal fistula were included. Studies assessing perianal fistula in children, rectovaginal and rectourinary fistulae were excluded. The primary end-point was the fistula closure rate. Partial closure and recurrence rates were secondary end-points. Ten studies on seton drainage were included (n = 305). Complete closure varied from 13.6% to 100% and recurrence from 0% to 83.3%. In 34 anti-TNF studies (n = 1449), complete closure varied from 16.7% and 93% (partial closure 8.0-91.2%) and recurrence from 8.0% to 40.9%. Four randomized controlled trials (n = 1028) comparing anti-TNF with placebo showed no significant difference in complete or partial closure in meta-analysis (risk difference 0.12, 95% CI -0.06 to 0.30 and 0.09, 95% CI -0.23 to 0.41, respectively). Subgroup analysis (n = 241) showed a significant advantage for complete fistula closure with anti-TNF in two trials with follow-up > 4 weeks (46% vs 13%, P = 0.003 and 30% vs 13%, P = 0.03). Of four included cohort studies, two revealed a significant difference in response in favour of combined treatment (P = 0.001 and P = 0.014). Closure and recurrence rates after seton drainage as well as anti-TNF vary widely. Despite a large number of studies, no conclusions can be drawn regarding the preferred strategy. However, combination therapy with (temporary) seton drainage, immunomodulators and anti-TNF may be beneficial in achieving perianal fistula closure