An international, multicentre, prospective audit and cohort study.
Background
Cryptoglandular anal fistulas are abnormal tracts between the anal canal and the skin, often developing following an anorectal abscess and affecting 1 in 5000 people annually in European countries. Determining the optimal therapy for individual patients remains challenging due to the variety of available surgical interventions and the limited comparative effectiveness evidence of these interventions.
The recently conducted European guidelines for the management of cryptoglandular anal fistulas reflect this issue, offering only four out of 42 total recommendations with a moderate-level recommendation. The other 38 recommendations have a lower level of evidence, indicating that the evidence supporting the treatment modalities is relatively weak.
One of the main reasons for this low level of evidence in treating cryptoglandular anal fistulas is the significant heterogeneity in outcomes, definitions, and measurement instruments used in studies. This lack of robust evidence contributes to substantial variations in clinical practice. To improve this heterogeneity, future studies should utilise a standardised set of outcomes agreed upon by patients and healthcare providers. Therefore, the Anal Fistula Core Outcome Set (AF-COS) and Anal Fistula Core Outcome Measurement Set (AF-COMS) were developed and established a minimum required set of outcomes and selected reporting tools to facilitate comparisons across future studies.
Aim
Explore the associations between patient demographic factors, diagnostic and treatment modalities, and outcomes, as defined by the AF-COS, in real-world clinical settings. The Audit study will provide comprehensive insights into current work-up pathways and treatments with a follow-up of 3 months, while the Cohort study will assess both clinician-reported and patient-reported measures over a 12-month follow-up.
Design
This international, multicentre, prospective Audit and Cohort study will collect short-term (up to 3 months) and long-term (up to 12 months) clinical and patient-reported outcomes according to the AF-COS for patients undergoing surgery for a cryptoglandular anal fistula. In this combined project, both the audit and cohort studies will be conducted concurrently. The design of both studies is aligned so that data from each can be integrated to provide a comprehensive analysis. All sites have the option to participate in either the Audit alone or the Cohort study.
Eligibility
Centre eligibility: Any hospital or surgical unit performing surgery for cryptoglandular anal fistula.
Patient eligibility: Adults (age 18 years and above) undergoing surgery for a cryptoglandular anal fistula. Other aetiologies will be excluded.
Key outcome measures
The key outcome measures are based on the AF-COMS and consist of:
Clinician-reported surgical outcomes
- Clinical fistula healing, at 12 months
- Recurrence, at 12 months
- Radiological healing (if available from regular follow-up), at 12 months
- Complications (classified according to the Clavien-Dindo system) and re-interventions (including only surgical and radiological interventions), at 3 and 12 months
- Development of additional fistulas, at 3 and 12 months
Patient-reported outcomes
Assessed at 30 days, 3 months, 6 months and 12 months
- Quality of Life, assessed using the Anal Fistula Quality of Life Questionnaire (AF-QOL),
- Incontinence, assessed using the Vaizey/St. Marks Incontinence Questionnaire,
- Fistula symptoms, assessed using the AF-QOL,
- Psychological impact of treatment, assessed using the AF-QOL,
- Patient satisfaction, assessed using a numerical rating scale (only at 12 months)
- Decisional regret, assessed using X (only at 12 months)
