Efficacy and Safety of Endorectal Advancement Flap for the Treatment of Anal Fistula: A Systematic Review and Meta-Analysis

AIM: Complex anal fistula poses a significant challenge for anorectal surgeons due to its high risks of recurrence and incontinence. A sphincter-preserving procedure named endorectal advancement flap (ERAF) is gradually being applied to clinical practice. Therefore, this meta-analysis aims to evaluate the efficacy and safety of ERAF in managing anal fistula. METHODS: We searched PubMed, Embase, Cochrane, and Web of Science databases for relevant manuscripts published from 29 August 2003 to 29 August 2023. Among these studies, outcomes included healing rate, recurrence rate, incontinence rate, and complications. Furthermore, the quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS) and the Cochrane risk-of-bias tool. The heterogeneity was determined using the chi-squared test and I-2 statistic. A random effects model was applied if significant heterogeneity (p < 0.05 and I-2 > 50%) was observed. Sensitivity analysis was conducted by excluding studies with a high risk of bias. RESULTS: Thirty-eight studies were included in the present analysis, involving 1559 participants. The pooled healing rate and recurrence rate of ERAF were 65.5% (95% confidence intervals (CI): 57.6%-73.4%) and 19.6% (95% CI: 14.8%-24.4%), respectively. The pooled incontinence rate was 10.6% (95% CI: 6.0%-15.1%). According to the subgroup analysis, the healing rate, recurrence rate, and incontinence rate of ERAF for fistula associated with inflammatory bowel disease (IBD) were 53.9% (95% CI: 38.1%-69.7%), 32.6% (95% CI: 21.3%-43.8%), and 2.8% (95% CI: 0%-10.6%), respectively. For patients without IBD, the healing rate, recurrence rate, and incontinence rate of ERAF were 70.6% (95% CI: 63.9%-77.4%), 15.7% (95% CI: 9.9%-21.5%), and 16.5% (95% CI: 8.1%-24.9%), respectively. We observed that bleeding, local infection or abscess, flap dehiscence, and haematomas were the common complications, with incidences of 2.2% (95% CI: 0%-4.5%), 9.5% (95% CI: 4.7%-14.4%), 10.4% (95% CI: 0.0%-21.6%), and 12.4% (95% CI: 0%-27.6%), respectively. CONCLUSIONS: ERAF may be an optional treatment for anal fistula from the perspective of effectiveness and safety.