Efficacy of anti-TNF maintenance therapy in Fistulas in Crohn’s Disease patients. In a meta-analysis it was found that TNF antagonists are effective for induction and maintenance of perianal fistula response and remission. 

Efficacy of anti-TNF as induction therapy in fistulas

Efficacy of anti-TNF as maintenance therapy in fistulas

References:

Lee, M. J., Parker, C. E., Taylor, S. R., Guizzetti, L., Feagan, B. G., Lobo, A. J., & Jairath, V. (2018). Efficacy of Medical Therapies for Fistulizing Crohn’s Disease: Systematic Review and Meta-analysis. Clinical Gastroenterology and Hepatology. doi:10.1016/j.cgh.2018.01.030