P1214Disease severity, comorbidities and patient age are risk factors for fibrotic complications in Ulcerative Colitis

Abstract Background Clinical complications of fibrosis, such as strictures and stenosis, occur in 1-11% of patients with Ulcerative Colitis (UC). Evidence on the burden of these complications in UC is limited. We aimed to identify risk factors associated with these outcomes in patients with a confirmed UC diagnosis. Methods We conducted a retrospective cohort study using de-identified data from Maccabi Healthcare Services (MHS), an Israeli nationwide insurer and provider. Individuals with confirmed UC diagnosis between 2002 and 2024 with no documentation of colorectal malignancies were included in the analysis. We defined fibrotic complications as obstruction, stricture, or stenosis post-UC diagnosis. Multivariable time-dependent Cox regression was used to assess demographic, clinical, and treatment-related risk factors associated with fibrotic complications. Results Among 6,994 UC patients, we identified 100 cases with fibrotic complications. Older age at UC diagnosis was independently associated with a higher risk of fibrotic complications (HR: 1.81; 95%CI: 1.05, 3.13) for patients aged 41-65 and (HR: 2.75; 95%CI: 1.3, 5.8) in patients over 65, compared to those aged 18-40. The presence of any comorbidity at diagnosis (hypertension, diabetes, chronic obstructive pulmonary disease, cardiovascular disease, chronic kidney disease, or non-colorectal cancer) was also independently associated with a higher risk (HR: 1.73; 95% CI: 1.04, 2.88). Diagnosis of proctitis at presentation, compared with more extensive disease (HR: 0.49 95%CI: 0.31, 0.78), and UC diagnosis in later years (2020-2023) compared to 2002-2007, were independently associated with a lower risk (HR: 0.19; 95%CI: 0.04, 0.82). Notably, use of biologics was associated with increased risk (HR: 4.47; 95%CI: 2.55, 7.83). No significant associations were found for smoking, extra-intestinal manifestations at UC diagnosis, or medication use duration. Conclusion UC patients with extensive disease, comorbidities, and older age at presentation are at increased risk of fibrotic complications, suggesting them as an important group for targeted intervention with potential anti-fibrotic therapies. The observed association with biologics use may reflect confounding by disease severity, warranting further research. Conflict of interest: Dr. Shapiro, Ilona: No conflict of interest Igho-Osagie, Ebuwa: Employee of Merck & Co. Sharman Moser, Sarah: No conflict of interest Lawlor, Garrett: Employee of Merck & Co. Hoshen, Moshe: No conflict of interest Liu, Gui: Employee of Merck Co & Inc Gazit, Sivan: No conflict of interest Rieder, Florian: No conflict of interest Ben-Tov, Amir: No conflict of interest