Surgical treatment trends and outcomes for anal fistula: fistulotomy is still accurate and safe. Results from a nationwide observational study.

Purpose: The aim of the present study was to analyse current surgical treatment preferences for anal fistula (AF) and its subtypes and nationwide results in terms of success and complications.

Methods: A retrospective multicentre observational cohort study was conducted. The study period was 1 year (2019), with a follow-up period of at least 1 year. A descriptive analysis of patient characteristics and trends regarding technical options was performed. Univariate and multivariate Cox regression models were used to analyse factors associated with healing and faecal incontinence (FI).

Results: Fifty-one hospitals were involved, providing data on 1628 patients with AF. At a median follow-up of 18.3 (9.9-28.3) months, 1231 (75.9%) patients achieved healing, while 390 (24.1%) did not; failure was catalogued as persistence in 279 (17.2.0%) patients and as recurrence in 111 (6.8%). On multivariate analysis, factors associated with healing were fistulotomy (OR 5.5; 95% CI 3.8-7.9; p < 0.001), simple fistula (OR 2.1; 95% CI 1.5-2.8; p < 0.001), single tract (HR 1.9; 95% CI 1.3-2.8; p < 0.001) and number of preparatory surgeries (none vs. 3; HR 1.8; 95% CI 1.2-2.8; p = 0.006). Regarding de novo FI, in the multivariate analysis previous anal surgery (OR 1.5, 95% CI 1.0-2.4, p = 0.037), age (OR 1.02, 95% CI 1.00-1.04, p = 0.002) and being female (OR 1.7, 95% CI 1.1-2.5, p = 0.008) were statistically related.

Conclusions: Anal fistulotomy is the most used procedure for AF, especially for simple AF, with a favourable overall balance between healing and continence impairment. Sphincter-sparing or minimally invasive sphincter-sparing techniques resulted in lower rates of healing. In spite of their intended sphincter-sparing design, a certain degree of FI was observed for several of these techniques.