A Multicentre Randomised Controlled Trial Comparing Safety, Efficacy, and Cost-Effectiveness of the Surgisis® Anal Fistula Plug versus Surgeon's Preference for Transsphincteric Fistula-in-Ano: The FIAT Trial

Background: The Biodesign Surgisis anal fistula plug preserves continence, but its efficacy in healing anal fistulae is uncertain. Methods: A randomised trial involving 40 UK hospitals comparing the fistula plug with surgeon's preference (advancement flap, cutting seton, fistulotomy, LIFT procedure) for cryptoglandular transsphincteric anal fistulae. Randomisation was a one-to-one, minimised by age, ASA grade, planned surgery, and presence of secondary tracts. The primary outcome was faecal incontinence quality of life (FIQoL) at 12-months. Secondary outcomes were fistula healing, incontinence rates, and complication and re-intervention rates. A trial-based cost-utility analysis was undertaken. Findings: Between May 2011 and March 2016, 304 participants were equally randomised to fistula plug or surgeon's preference. No differences were seen in FIQoL between the two groups at 12-months. Clinical fistula healing was reported in 66/122 (54%) of the fistula plug and 66/119 (55%) of the surgeon's preference groups at 12-months. Faecal incontinence rates showed a marginal improvement in both groups. Complications and re-interventions were frequent, with significantly more complications in the fistula plug group at 6-weeks (49/142, 35% vs. 25/137, 18%; p=0.002). The mean total costs were £2,738 (s.d. £1,151) for the fistula plug and £2,308 (s.d. £1,228) for the surgeon's preference group (mean difference +£430, p=0.0174). The average total QALYs gained was marginally higher in the fistula plug group. Using multiple imputation and probabilistic sensitivity analysis the fistula plug was 35%-45% likely to be costeffective across a willingness to pay threshold of £20,000-£30,000/QALY. Interpretation: The Biodesign Surgisis® anal fistula plug is associated with similar FIQoL and healing rates to surgeon's preference at 12-months. Higher costs and highly uncertain gains in QALYs mean that the fistula plug may not be considered as a cost-effective treatment in the UK NHS. Trial Registration Number: (ISRCTN 78352529). Funding Statement: The FIAT trial was funded by the NIHR Health Technology Assessment Programme - 07/89/01. Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Ethical committee approval was obtained (10/H0405/29). The trial was overseen by an independent Trial Steering Committee and Data Monitoring and Ethics Committee.