ABSTRACT
AIM: Faecal incontinence (FI) is a prevalent issue which can have a detrimental impact on the patient's quality of life. Current international guidelines lack strong treatment recommendations due to few studies in the field, in combination with the heterogeneity in outcome reporting. To address this, a core outcome set (COS) is proposed to standardize outcome reporting in FI studies, facilitating meta-analyses and enhancing therapeutic recommendations. Through several steps outlined by COMET 'what' to measure will be determined prior to determining 'how' to measure these outcomes. This systematic review aims to identify 'what' outcomes have been used in FI intervention studies so far in adult patients as a starting phase for the development of a future COS for FI. METHOD: Medline, Embase and the Cochrane library were searched to identify all outcomes reported in comparative effectiveness trials assessing one or more treatment option in adult patients suffering from FI. The outcomes were categorized according to the Core Outcome Measurement in Effectiveness Trials (COMET) taxonomy to standardize outcome terminology, assess completeness, and inform subsequent steps in COS development. RESULTS: A total of 109 studies were included, which revealed 51 unique outcomes classified into 38 domains within four core areas. On average four outcomes were reported per study (range 1-11). The most commonly reported outcomes were "severity of FI" (83%), "quality of life" (64%), "number of FI episodes" (40%), "anorectal motor function" (39%), and "frequency of bowel movements" (16%). CONCLUSION: This systematic review offers an overview of outcomes reported in FI studies, highlighting the heterogeneity between studies. This heterogeneity emphasizes the need for standardizing outcome reporting which can be established through the creation of a COS.