Guidelines for the Surgical Treatment of Crohnʼs Perianal Fistulas

The quality of the data supporting or rejecting the use of specific therapies was categorized as follows: A+: Multiple, high-quality randomized controlled trials (RCTs) with consistent results A: Single high-quality RCT or multiple low-quality RCTs with consistent results A−: Single low-quality RCT or multiple RCTs with inconsistent results B+: Multiple, controlled observational studies with consistent results B: Single, controlled observational study B−: Multiple, controlled observational studies with inconsistent results C+: Multiple uncontrolled studies C: Single uncontrolled study D: Expert opinion. Studies vary in design strength and statistical power; all randomized trials are “not equal.” We have attempted to denote differences in study quality, through the use of “plus” sign, e.g., A+ or B+, if the studies are blinded, controlled, and adequately powered, and a “minus” sign, e.g., A− or B−, for those studies that were not, or where results conflicted. Tables are provided to outline the available studies and allow the reader to compare the research trials based on study design. Although the details on study design, types of treatment, primary end points, and results are included in the tables; more detail is provided on certain surgical treatment options in the text. All grades reflect the authors' consensus. Additionally, some surgical treatment options are ineffective despite well-designed studies or have been studied in patients with Crohn's disease (CD) with perianal disease but not specifically perianal fistula. To clarify such results, all agents will be categorized by therapeutic efficacy, as follows: