P0474 Five-Year Clinical Outcomes and Disease Course of Newly-Diagnosed Moderate-to-Severe Ulcerative Colitis: A Prospective Nationwide Multicentre MOSAIK Cohort Study in Korea
Authors: Ye B D , Kim H J , Park D I , Park Y S , Lee K M , Im J P , Jung S A , Jeen Y T , Cha J M , Cheon J H , Hong S N , Kim Y , Choi J M , Lee Y , Lee C K 
Published: January 2025

Abstract

Background
While the incidence of moderate-to-severe ulcerative colitis (UC) is rising in Asia, comprehensive data on its long-term disease course in Asian populations remain scarce.

Methods
The MOSAIK (MOderate-to-Severe ulcerAtive colItis in Korea) study is a prospective, multicentre, hospital-based, inception cohort that enrolled 353 patients newly diagnosed with moderate-to-severe UC between August 2014 and February 2017.1 Clinical outcomes and predictors of a disabling disease course were evaluated over 5 years of follow-up.

Results
Among 353 patients, the median age at UC diagnosis was 37.6 years (standard deviation, 15.2) with male predominance (58.9%, 208/353) (Table 1). Baseline disease activity was predominantly moderate (93.2%, 329/353) rather than severe (6.8%, 24/353), with median full Mayo Clinic Score (MCS) of 8 (Interquartile range [IQR], 7–9) and partial MCS of 6 (IQR, 5–7). Disease extent at diagnosis showed proctitis (10.7%, 37/353), left-sided colitis (46.7%, 162/353), extensive colitis (42.7%, 148/353). The median duration of follow-up was 4.9 years (IQR, 2.1–5.0), with 214 patients (60.6%) completing the 5 years (week 260). Treatment patterns during follow-up included: oral 5-aminosalicylates (96.3%, 340/353), topical 5-aminosalicylates (70.8%, 250/353), systemic corticosteroids (65.7%, 232/353), immunomodulators (38.5%, 136/353), biologics (20.1%, 71/353), and JAK inhibitors (1.7%, 6/353). At 5 years, the major disease outcomes were: relapse (62.9%), hospitalisation (26.9%), and proximal disease extension (29.5%). The colectomy rate was notably low (0.6%) with no mortality. A disabling disease course occurred in 171 patients (48.4%), with cumulative probabilities increasing from 41.0% at 1 year, 51.1% at 3 years, to 53.9% at 5 years. Baseline elevated white blood cell count was independently associated with a disabling disease course (adjusted hazard ratio, 1.062, 95% confidence interval, 1.004–1.123, P=0.0353). Using unsupervised clustering analysis (K-Means) of partial MCS, with missing data imputed using random forest, we identified 5 distinct disease trajectory patterns. These trajectories effectively discriminated clinical outcomes including relapse, persistent disease activity, hospitalisation, and disabling disease course (Figure 1).

Conclusion
In this Korean inception cohort, 48.4% of patients with moderate-to-severe UC revealed a disabling disease course over 5 years. Novel clustering analysis based on partial MCS identified 5 distinct disease trajectories that effectively predicted clinical outcomes, providing a potential framework for risk stratification.

Funding
This study was supported by Janssen Korea Ltd..

References
1.Lee CK, Lee KM, Park DI, et al. A new opportunity for innovative inflammatory bowel disease research: the moderate-to-severe ulcerative colitis in Korea (MOSAIK) cohort study. Intest Res. 2019;17(1):1–5.