P1242 Incidence of Acute Severe Ulcerative Colitis in a Changing Landscape of Increased Disease Prevalence and More Effective Therapies
Authors: Nario S , Wu M Y , Tung C , Kiely C 
Published: January 2025

Abstract

Background
Over the past 60 years, there has been a growing worldwide health burden of Ulcerative Colitis (UC), with increasing disease prevalence and incidence.1,2 With the rise in UC patient population, more effective therapeutic options to induce remission have become available (biologic therapies and small molecule inhibitors). Approximately 15-25% of patients with UC will experience at least one episode of Acute Severe Ulcerative Colitis (ASUC). First diagnosis of UC accounts for 10-20% of ASUC presentations, and 34% of patients will experience ASUC within a year of UC diagnosis.3 We aim to ascertain the effect of increased therapeutic options and increased UC prevalence on the incidence of ASUC hospital admissions. We hypothesised that with increased availability of more effective UC maintenance therapy through the Australian Pharmaceutical Benefits Scheme (PBS), there would be a reduction in ASUC presentations in patients with existing UC diagnosis, including within first year of UC diagnosis. We further hypothesised that with the increase in UC incidence, there would be an increase in ASUC presentations in first diagnosis of UC.

Methods
Data was collected retrospectively on patients admitted with ASUC to a quaternary Sydney hospital between January 2014 and December 2023.1,2 A modified Truelove and Witts criteria was used to identify ASUC presentations.4 Patients admitted with ASUC were classified as "relapse" if they were on maintenance UC therapy at time of presentation, "refractory" if presented during treatment of a UC flare, and "new diagnosis" if first presentation and no previous history of UC.

Results
Over the 10-year period, there were a total of 167 admissions of ASUC among a total of 122 patients. On average, there were 13.9 ± 2.5 patients with 16.8 ± 3.5 presentations each year. The highest number of ASUC presentations were in 2022 and 2018. The average number of refractory and relapse presentations were not significantly different (6.8 vs 7.1, p = 0.8). Over 38.4% of ASUC presentations were within the first year of diagnosis. The number of ASUC episodes and number of patients presenting with ASUC did not appear to increase over the past decade (Table 1, Figure 1).

Conclusion
Despite an increasing worldwide incidence and prevalence of UC, we did not find an increasing incidence of ASUC admissions. The increased availability of more effective options for treatment of UC may explain the stable number of ASUC presentations, reflecting better disease control in the outpatient setting. Interestingly, despite increasing UC incidence, the incidence of ASUC presentation in first diagnosis UC did not appear to increase over time.

References
1.Alatab S, Sepanlou SG, Ikuta K, et al. The global, regional, and national burden of inflammatory bowel disease in 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet Gastroenterol Hepatol. 2020;5(1):17-30. doi:10.1016/S2468-1253(19)30333-4
2.Forbes AJ, Frampton CMA, Day AS, Kaplan GG, Gearry RB. The Epidemiology of Inflammatory Bowel Disease in Oceania: A Systematic Review and Meta-Analysis of Incidence and Prevalence. Inflamm Bowel Dis. Published online December 30, 2023. doi:10.1093/IBD/IZAD295
3.Dinesen LC, Walsh AJ, Protic MN, et al. The pattern and outcome of acute severe colitis. J Crohns Colitis. 2010;4(4):431-437. doi:10.1016/J.CROHNS.2010.02.001
4.Sturm A, Maaser C, Calabrese E, et al. ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 2: IBD scores and general principles and technical aspects. J Crohns Colitis. 2019;13(3):273-284. doi:10.1093/ECCO-JCC/JJY114