P0264Proximal Diseaase Extension and Associated Risk Factors in Patients with Distal Ulcerative Colitis

Abstract Background Ulcerative colitis (UC) can progress through proximal extension, but the factors associated with this extension remain unclear. This study evaluated the frequency and risk factors of proximal extension in patients with distal UC. Methods Patients diagnosed with proctitis/proctosigmoiditis or left-sided colitis between 1999 and 2024 were retrospectively analyzed. Demographic and clinical data were obtained from patient files and electronic records. Proximal extension was defined as progression beyond the splenic flexure. Potential risk factors were evaluated using univariate and multivariate analyses, and p 0.05 was considered statistically significant. Results A total of 462 patients (52.4% male) were included. Median age at diagnosis was 37 years. Over a median 9-year follow-up, 123 patients (26.6%) progressed to extensive colitis; median time was 72 months. Patients who progressed were younger at diagnosis than those who did not (median 30 vs 40 years, p 0.001).Initial left-sided colitis (beyond the sigmoid) was associated with higher progression rates than proctitis/proctosigmoiditis (39.3% vs 18.7%, P .001). Patients requiring ≥1 course of systemic steroids progressed more often than those without (37.5% vs 14.4%, p 0.001). Those with ≥2 flares progressed more often than those with 0–1 flare (36.1% vs 17.7%, P .001). Continuously active disease (≥6 months) and a history of 1 flare per year were also associated (p 0.001). Sex, smoking, and immunosuppressive/biologic therapy were not significant. On multivariate analysis, age 40 years at diagnosis, initial left-sided colitis, and ≥1 course of systemic steroid induction were independent predictors of extension (p 0.05). Conclusion During follow-up, approximately one-quarter of patients with distal UC developed proximal disease extension. Age 40 years at diagnosis, initial left-sided colitis, and the requirement for ≥1 course of systemic steroid induction were identified as independent predictors for progression to extensive colitis. Early identification of these high-risk patients may allow closer follow-up and targeted strategies to prevent progression. Conflict of interest: Adin, Hatip: None Ozen Alahdab, Yesim: None Atug, Özlen: None Dr. Kani, Haluk Tarik: Haluk Tarik Kani has been speaker or advisor for Abbvie, Janssen,Sanofi and Takeda.