P0241 The DETECTION Study: DETection by Endoscopy of Colitis in Screening ImplementaTION

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Abstract Background The National Bowel Screening Program (Bowelscreen), a nationwide initiative program, aims to provide direct access to those aged 55-74 (currently 59-69) for colonoscopy assessment deemed high risk for colorectal cancer via positive faecal immunochemical test (FIT). Inflammatory Bowel Disease (IBD) follows a bimodal distribution of onset with European studies reporting 10-15% diagnosis after age 60. Limited published research exists on IBD incidence in Ireland via FIT-based population screening and associated outcomes. We aim to dtermine incidence rates/severity of incident IBD cases found via FIT-based colorectal screening programme and hRetrospective review was conducted of all index colonoscopes conducted in FIT positive screening participants (aged 59-69) in multiple Irish centres between 2015-2024. Inclusion criteria: histological diagnosis of colitis. Parameters measured: distribution of colitis, histology, clinical sequalae/IBD history, faecal calprotectin (FCP) and treatment escalation based on screening colonoscopyow often screening colonoscopy is performed for patients with known IBD and positive FIT. Methods Retrospective review was conducted of all index colonoscopes conducted in FIT positive screening participants (aged 59-69) in multiple Irish centres between 2015-2024. Inclusion criteria: histological diagnosis of colitis. Parameters measured: distribution of colitis, histology, clinical sequalae/IBD history, faecal calprotectin (FCP) and treatment escalation based on screening colonoscopy. Results 203/8070 (2.52%) of index screening colonoscopies analysed reported endoscopic diagnosis of colitis. 105/8070 (1.3%) satisfied diagnostic criteria for classic IBD (65.7% UC; 34.2% Crohn’s), of which the majority were new diagnosis (73.3%). 32% cases of segmental colitis associated with diverticulosis (SCAD) were identified. 21% cases of NSAID induced colitis were identified. UC Colitis distribution: 18.8% pancolitis, 38.4% proctitis and 42.8% left-sided. Crohn’s distribution: 8.3% small bowel solely; 89% colonic and 2.7% mixed. 48% reported symptoms at endoscopy. Median FCP following diagnostic colonoscopy was 216.5μg/g. 10% of newly diagnosed IBD patients required biologic escalation. Conclusion Incidental diagnosis of colitis occurs in 3% of FIT-positive screening participants in a population based screening programme with new diagnoses of IBD including UC, Crohn’s and SCAD requiring treatment. This is a novel, unintended benefit to FIT-based population screening.