Adalimumab or infliximab: which is better for perianal fistula in Crohn's disease?

Fistulotomy alone induced remission in 85% of patients with simple perianal fistula without rectal inflammation. However, if active inflammation is present in the rectum, the risk of delayed healing or fecal incontinence increases after fistulotomy. Therefore, a noncutting seton placement is preferred, along with appropriate medical treatment when active inflammation is present. The introduction of anti-tumor necrosis factor (anti-TNF) agents has significantly changed the management of fistulizing CD. Anti-TNF agents are recommended in conjunction with adequate drainage, using a seton for a complex perianal fistula. The first placebo-controlled study included 94 CD patients with fistulas (including 85 with perianal fistulas), and showed that 68% (infliximab 5 mg/kg group) and 56% (infliximab 10 mg/kg group) achieved the primary endpoint, defined as a reduction of ≥50% from baseline in the number of draining fistulas. The ACCENT II study showed a higher remission rate in the infliximab maintenance group, compared with the placebo group at 54 weeks (36% vs. 19%, P =0.009). No placebo-controlled randomized studies have evaluated the efficacy of adalimumab as a primary outcome variable in patients with fistulizing CD. However, the effect of adalimumab on Crohn’s perianal fistula has been reported as a secondary endpoint in three large, multicenter, doubleblind, placebo-controlled trials. Currently, there are no head-to-head comparison trials with infliximab and adalimumab. An observational cohort study involving 327 patients (183 infliximab and 144 adalimumab) reported that both Perianal fistula complicating CD is common with up to 90% in patients with rectal involvement. Of importance, perianal disease is more commonly detected in East Asia, involving 58.8% of CD patients in Guangdong (China), 30.3% in Hong Kong, and 33.3% of pediatric and 43.1% of adult patients in Korea. Treatment goals for perianal fistula are reduction of abscess drainage and symptoms, and ultimately resolution of fistula discharge, improvement in quality of life, with preservation of continence, fistula healing, and avoidance of proctectomy and a stoma. The treatment of perianal fistula should be individualized according to fistula location, presence of abscess, and disease activity, and multidisciplinary approaches are helpful, especially in cases of both medical and surgical treatments are required. Simple asymptomatic perianal fistulas usually do not require treatment. For symptomatic simple perianal fistulas, antibiotics, most commonly metronidazole and ciprofloxacin, are considered first-line treatment. Although antibiotics improve fistula symptoms and may contribute to healing, they do not induce complete fistula closure, and the fistula often deteriorates after their discontinuation. In addition, metronidazole should be used cautiously, because of ad-