P426 Meta-analysis of endorectal advancement flap vs. ligation of the intersphincteric fistula tract for Crohn’s and cryptoglandular high perianal fistulas

High perianal fistulas require sphincter saving surgery due to the risk of incontinence. The ligation of the intersphincteric fistula tract (LIFT) preserves the anal sphincter function and is an alternative to the endorectal advancement flap (AF). We aimed to evaluate both procedures for Crohn's and cryptoglandular fistulas in terms of success rates, recurrences and incontinence. A systematic review and meta-analysis were performed according to the PRISMA guidelines. MEDLINE, EMBASE and the Cochrane library were systematically searched up to September 13, 2017. All randomised controlled trials, cohort studies and case series (>5 patients) describing the AF or LIFT procedure in high perianal fistulas of Crohn’s and/or cryptoglandular origin were included. Studies not describing post-operative outcomes or length of follow-up were excluded. Other exclusion criteria were patients <18 years, stomata, rectovaginal/rectourinary and low perianal fistulas, fistulas with no external opening, and fistulas due to other aetiologies. Also combinations of techniques or other variants of the techniques such as anocutaneous flaps were excluded. A proportional meta-analysis was performed using a random-effects model. The literature search resulted in 1017 studies of which 31 remained for inclusion (Figure 1). Flow-diagram of study inclusion. Five studies were randomised controlled trials, seven studies were prospective cohort studies and 19 were retrospective cohort studies. A total of 1307 patients were evaluated (AF: 799, LIFT: 508), and 74 had Crohn’s disease (AF: 47, LIFT: 27). In Crohn’s perianal fistulas, weighted success and recurrence rates were not significantly different between AF and LIFT (66% vs. 71% and 31% vs. 29%, respectively). In cryptoglandular fistulas also no significant differences were found between the AF and LIFT-procedure in the success (72% vs. 70%) and recurrence rates (22% vs. 19%). Subgroup analysis of the studies with a minimal follow-up period of 6 months did not significantly change the weighted success and recurrence rates for both aaetiologies. The post-operatively developed incontinence rates were significantly higher after AF compared with LIFT (7.8% vs. 1.6%). In both Crohn’s and cryptoglandular high perianal fistulas, weighted success and recurrence rates are not significantly different between the AF and LIFT-procedure. Continence seems better preserved after the LIFT-procedure in both indications; however, more studies on Crohn’s perianal fistulas are required to draw a definite conclusion.