Randomized controlled trials in perianal Crohn's disease.

Crohn's disease can be complicated by the development of fistulas, 54% of which involve the perianal region. The presence of perianal fistulas predicts a disabling course of Crohn's disease. The treatment of complex perianal disease is difficult and the chance of complete fistula healing is no more than 50%. The best management of this condition is a combining medical and surgical therapy. Studies which evaluated the efficacy of medical treatments in this setting are small, open label and considered the efficacy on perianal disease as a second outcome or as the result of a subgroup analysis. In the few available trials the efficacy outcomes were evaluated by the Fistula Drainage Assessment but recently it was observed that inflamed fistula tracks often persist, despite the apparent closure of external orifices. Up to now the most strongly evaluated medical treatments for perianal Crohn's disease are the anti-TNFα antibodies. In presence of complex fistulas they are considered the first choice of medical treatment, in combination with surgical therapy. Antibiotics and immunomodulators have not been demonstrated to result in sustained closure of fistulas in Crohn's disease. Their use is recommended as a second line medical treatment. The use of tacrolimus and thalidomide is limited by its side effects. A few evidences support the use of methotrexate and cyclosporine but they are insufficient.