Efficacy of different surgical treatments for management of anal fistula: a network meta-analysis

Abstract

Purpose: Currently, the anal fistula treatment which optimises healing and preserves bowel continence remains unclear. The aim of our study was to compare the relative efficacy of different surgical treatments for AF through a network meta-analysis.

Methods: Systematic searches of MEDLINE, EMBASE and CENTRAL databases up to October 2022 identified randomised controlled trials (RCTs) comparing surgical treatments for anal fistulae. Fistulae were classified as simple (inter-sphincteric or low trans-sphincteric fistulae crossing less than 30% of the external anal sphincter (EAS)) and complex (high trans-sphincteric fistulae involving more than 30% of the EAS). Treatments evaluated in only one trial were excluded from the primary analyses to minimise bias. The primary outcomes were rates of success in achieving AF healing and bowel incontinence.

Results: Fifty-two RCTs were included. Of the 14 treatments considered, there were no significant differences regarding short-term (6 months or less postoperatively) and long-term (more than 6 months postoperatively) success rates between any of the treatments in patients with both simple and complex anal fistula. Ligation of the inter-sphincteric fistula tract (LIFT) ranked best for minimising bowel incontinence in simple (99.1% of comparisons; 3 trials, n = 70 patients) and complex anal fistula (86.2% of comparisons; 3 trials, n = 102 patients).

Conclusions: There is insufficient evidence in existing RCTs to recommend one treatment over another regarding their short and long-term efficacy in successfully facilitating healing of both simple and complex anal fistulae. However, LIFT appears to be associated with the least impairment of bowel continence, irrespective of AF classification.

Keywords: Complex; Fistula-in-ano; Healing; Incontinence; Sphincter preserving.

Fig. 1

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram highlighting the selection process for eligible randomised controlled trials

Fig. 2

Network plots depicting all direct comparisons between different treatments for the following outcomes: short-term success (≤ 6 months after surgery) in patients with a simple and b complex anal fistula, c long-term success (> 6 months after surgery) in patients with complex anal fistula, and bowel incontinence among patients with d simple and e complex anal fistula (nodes correlated with the number of patients receiving each treatment, while the thickness of each line connecting two nodes was proportional to the number of trials in which each treatment was assessed. (AF, advancement flap; ASC-CP, adipose-derived stem cells combined with a collagen plug; CP, collagen plug; FE, fistulectomy; FG, fibrin glue; FO, fistulotomy; FO-M, fistulotomy with marsupialisation; LIFT, ligation of the inter-sphincteric fistula tract)

Fig. 3

Short-term success rates (≤ 6 months after surgery) comparing treatments in patients with simple anal fistula demonstrated by a forest plot (LIFT vs. fistulectomy), b SUCRA curve of relative ranking probabilities, and c rankogram plot. (FE, fistulectomy; LIFT, ligation of the inter-sphincteric fistula tract)

Fig. 4

Different treatment comparisons for short-term healing rates (≤ 6 months after surgery) in patients with complex anal fistula, shown via a forest plot (relative to advancement flap), b heat plot, c SUCRA curve, and d rankogram plot (AF, advancement flap; ASC-CP, adipose-derived stem cells combined with a collagen plug; CP, collagen plug; FG, fibrin glue; LIFT, ligation of the inter-sphincteric fistula tract)

Fig. 5

Long-term success rates (> 6 months after surgery) between different treatments in patients with complex anal fistula illustrated using a forest plot (relative to advancement flap), b heat plot, c SUCRA curve, and d rankogram plot (AF, advancement flap; CP, collagen plug; LIFT, ligation of the inter-sphincteric fistula tract)

Fig. 6

Comparisons between different treatments for minimising bowel incontinence in patients with simple anal fistula demonstrated using a forest plot (relative to fistulectomy), b heat plot, c SUCRA curve, and d rankogram plot (FE, fistulectomy; FO, fistulotomy; FO-M fistulotomy with marsupialisation; LIFT, ligation of the intersphincteric fistula tract)

Fig. 7

Treatment comparisons for minimising bowel incontinence in patients with complex anal fistula using a forest plot (relative to advancement flap), b heat plot, c SUCRA curve, and d rankogram plot (AF, advancement flap; CP, collagen plug; FG, fibrin glue; LIFT, ligation of the inter-sphincteric fistula tract)