Comparison of 1-Year Colectomy Risk Between the US and Korean Patients with Acute Severe Ulcerative Colitis: A Propensity Score Matching Analysis.

Background: Colectomy risk after acute severe ulcerative colitis (ASUC) has not been compared between Eastern and Western countries. We compared the 1-year colectomy risk after ASUC between Korea and the USA.

Methods: Data on patients admitted for ASUC to five tertiary referral hospitals in Korea and Mount Sinai Hospital, New York, the USA, between January 2015 and January 2019 were reviewed retrospectively. For comparability between groups, a 1:1 propensity score matching (PSM) was performed. The primary outcome was colectomy, and secondary outcomes were mortality, readmission, and venous thromboembolism (VTE) within 1-year of the index admission for ASUC. The risk of each outcome was compared using Cox proportional hazards model in pre-matched cohort and Kaplan-Meier analysis with log-rank test in post-matched cohort.

Results: 290 ASUC patients were included in the study (121 Korea, 169 the USA). After PSM, 56 patients were selected in each group with no significant differences in baseline variables. At 1 year after ASUC, colectomy was less common in Korea than in the USA [3 (5.4%) vs. 24 (42.9%), p < 0.001]. The cumulative colectomy risk was significantly higher in the USA than in Korea in pre-matched cohort [adjusted hazard ratio 7.89, 95% confidence interval 3.23 to 19.22] and in post-matched cohort (log-rank p < 0.001), while there was no difference in cumulative risk of mortality, readmission, and VTE.

Conclusion: Colectomy risk within 1 year of ASUC is significantly higher in the USA than in Korea. We observed no differences in mortality, readmission, and VTE between the two groups.