Poster Session II - A268 INCIDENCE OF INFLAMMATORY ARTHRITIS BEFORE AND AFTER INFLAMMATORY BOWEL DISEASE DIAGNOSIS: A POPULATION-BASED COHORT STUDY

Abstract Background Arthropathies are a common extra-intestinal manifestation of IBD, yet population-level data on the risk of inflammatory arthritis (IA) among individuals newly diagnosed with inflammatory bowel disease (IBD) is lacking. Aims Describe the incidence of IA among incident IBD cases. Methods We used population-based health administrative data from Ontario, Canada to identify all incident IBD cases diagnosed between April 1, 2003 and March 31, 2020 using previously validated age-specific algorithms. Among individuals in this inception cohort of IBD patients, we identified individuals diagnosed with IA either before or after their IBD diagnosis. IA diagnosis (rheumatoid arthritis, ankylosing spondylitis, other seronegative spondyloarthropathies, arthralgia, joint swelling) required ≥1 hospitalization or emergency department visit or ≥ 2 physician claims with an IA diagnosis code, with ≥1 claim made by a rheumatologist, internal medicine physician, pediatrician, or gastroenterologist. IA diagnoses could occur at any point during data availability (1991-2024). We calculated the time between the diagnoses of IA and IBD, categorizing time into the intervals outlined in the Figure. Age- and sex-standardized IA incidence rates were calculated within each interval. Data were stratified by IBD type, age at IBD diagnosis (