Heterogeneity in outcome selection, definition and measurement in studies assessing the treatment of cryptoglandular anal fistula: findings from a systematic review.

BACKGROUND: Treatment for cryptoglandular anal fistula (AF) is challenging and a lack of uniform outcomes in the literature prevents direct comparison of treatments. This can be addressed by developing a core outcome set, a standardised set of outcomes reported in all interventional studies for a specific condition. The aim of this systematic review is to assess the range of outcomes, their definitions, and the measurement instruments currently utilised in interventional studies for adult patients with AF. This will inform the development of an AF core outcome set. METHODS: Medline, Embase and The Cochrane Library were searched to identify all patient- and clinician-reported outcomes in studies assessing medical, surgical or combination treatment of adult patients with AF published from January 2008 to May 2020. The resulting outcomes were categorized according to the Core Outcome Measurement in Effectiveness Trials (COMET) taxonomy to better understand their distribution. RESULTS: In total, 155 studies were included, 552 outcomes were extracted, with a median of three outcomes (interquartile range 2-5) per study. Only 25% of studies demonstrated high-quality outcome reporting. The outcomes were merged into 52 unique outcomes and structured into four core areas and 14 domains, with the majority in the domain of physiological or clinical (gastrointestinal) outcomes. The most commonly reported outcomes were healing (77%), incontinence (63%), and recurrence (40%), with no single outcome assessed across all studies. There was a wide variation in outcome definitions and measurement instruments used. CONCLUSIONS: There is substantial heterogeneity in outcomes, definitions, and measurement instruments reported in interventional studies for cryptoglandular anal fistula. This emphasises the need for standardised outcome reporting and measurement.

The development of a cryptoglandular Anal Fistula Core Outcome Set (AFCOS): an international Delphi study protocol.

PURPOSE: Cryptoglandular anal fistula is a disorder with an incidence of around 1 per 5,000 people per year in European countries. Many studies have been conducted to evaluate the effectiveness of interventions for anal fistula. However, there is considerable heterogeneity in the outcomes assessed and reported in these studies. This limits research quality and complicates evidence synthesis. A solution for heterogeneity in outcome reporting is the development of a Core Outcome Set (COS). This paper describes the protocol for the development of a European COS for Anal Fistula (AFCOS). METHODS: The first step will be a systematic review of the literature to identify potential outcomes that may be included in the COS. Patient interviews will be conducted in The United Kingdom and The Netherlands to ensure that both clinician-important and patient-important outcomes are captured. The outcomes will be categorized using the COMET taxonomy and taken forward to a Delphi consensus exercise. In up to three web-based Delphi surveys the outcomes will be prioritized by patients, clinicians (surgeons, gastroenterologists, and radiologists), and (clinical) researchers. The responses will be summarized and reported anonymously in subsequent round(s) facilitating convergence to a consensus opinion. The final COS will be decided during a face-to-face consensus meeting with patients, clinicians, and (clinical) researchers. DISCUSSION: This study protocol describes the development of a European COS for anal fistula to improve research quality, evidence synthesis, and patient care.