Background: The aim of fistula surgery is to eradicate the disease while preserving anal sphincter function. The efficacy of the Surgisis® anal fistula plug (Cook Medical, Bloomington, IN, USA) in the treatment of trans-sphincteric fistula-in-ano has been variably reported.
Objectives: To undertake a randomised comparison of the safety and efficacy of the Surgisis anal fistula plug in comparison with surgeon's preference for the treatment of trans-sphincteric anal fistulas.
Design: A randomised, unblinded, parallel-arm, prospective, multicentre clinical trial.
Setting: Hospitals in the UK NHS involving colorectal surgeons accredited by the Association of Coloproctology of Great Britain and Ireland.
Participants: Adult patients suffering from trans-sphincteric fistula-in-ano of cryptoglandular origin.
Interventions: Patients were randomised on a 1 : 1 basis to either the fistula plug or the surgeon's preference [e.g. fistulotomy, cutting seton, advancement flap or ligation of intersphincteric fistula tract (LIFT) procedure].
Main outcome measures: The primary outcome measure was quality of life as measured by the Faecal Incontinence Quality of Life (FIQoL) questionnaire at 12-month follow-up. Secondary outcome measures included clinical and radiological fistula healing rates, faecal incontinence rates, complications rates, reintervention rates and cost-effectiveness.
Results: Between May 2011 and March 2016, 304 participants were recruited (152 fistula plug vs. 152 surgeon's preference). No difference in FIQoL score between the two trial groups was seen at the 6-week, 6-month or 12-month follow-up. Clinical evidence of fistula healing was reported in 66 of 122 (54%) participants in the fistula plug group and in 66 of 119 (55%) participants in the surgeon's preference group at 12 months. Magnetic resonance imaging (MRI) showed fistula healing in 54 of 110 (49%) participants in the fistula plug group and in 63 of 112 (56%) participants in the surgeon's preference group. Variation in 12-month clinical healing rates was observed: 55%, 64%, 75%, 53% and 42% for fistula plug, cutting seton, fistulotomy, advancement flap and LIFT procedure, respectively. Faecal incontinence rates were low at baseline, with small improvement in both groups post treatment. Complications and reinterventions were frequent. The mean total costs were £2738 [standard deviation (SD) £1151] in the fistula plug group and £2308 (SD £1228) in the surgeon's preference group. The average total quality-adjusted life-years (QALYs) gain was much smaller in the fistula plug group (0.829, SD 0.174) than in the surgeon's preference group (0.790, SD 0.212). Using multiple imputation and probabilistic sensitivity analysis, and adjusting for differences in baseline EuroQol-5 Dimensions, three-level version utility, there was a 35-45% chance that the fistula plug was as cost-effective as surgeon's preference over a range of thresholds of willingness to pay for a single QALY of £20,000-30,000.
Limitations: Limitations include a smaller sample size than originally calculated, a lack of blinding that perhaps biased patient-reported outcomes and a lower compliance rate with MRI at 12-month follow-up.
Conclusions: The Surgisis anal fistula plug is associated with similar FIQoL score to surgeon's preference at 12-month follow-up. The higher costs and highly uncertain and small gains in QALYs associated with the fistula plug mean that this technology is unlikely to be considered a cost-effective use of resources in the UK NHS.
Future work: Further in-depth analysis should consider the clinical and MRI characteristics of fistula-in-ano in an attempt to identify predictors of fistula response to treatment.
Trial registration: Current Controlled Trials ISRCTN78352529.
Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 21. See the NIHR Journals Library website for further project information.
Keywords: COST–BENEFIT ANALYSIS; FAECAL INCONTINENCE; FISTULA PLUG; RANDOMISED CONTROLLED TRIAL; TRANS-SPHINCTERIC FISTULA-IN-ANO.
Fistula-in-ano is a common condition in which the inside of the anus is in communication with the outside skin. It is a cause of long-term suffering owing to recurrent infection. Many surgical operations have been proposed to treat fistula-in-ano, with varying degrees of success. These carry the risk of faecal incontinence. The aim of the Fistula-In-Ano Trial (FIAT) was to assess the benefits of a new technology, the Surgisis® anal fistula plug (Cook Medical, Bloomington, IN, USA), compared with other surgical techniques. The FIAT involved 304 participants; 152 participants were treated with the fistula plug and 152 participants were treated with an alternative surgical technique. There were no differences in quality of life (QoL) among participants treated with the fistula plug compared with those receiving other treatments when assessed 12 months following the operation. Successful fistula healing was achieved in 54% of fistula plug-treated participants and in 55% of participants treated with an alternative technique at 12 months following the operation. Few patients suffered from faecal incontinence before their operation and there was a slight improvement following treatment with the fistula plug and other surgical treatments. The only difference seen between the group treated with the fistula plug and those receiving other surgical treatments was in the complication rate at the 6-week assessment time, with the fistula plug group having higher rates of unexpected pain. Economic analysis of the fistula plug compared with the other surgical treatments showed that the fistula plug was more expensive and only produced very small improvements in QoL. On this basis, it is unlikely that decision-makers in the NHS will support the routine use of the fistula plug.