Inflammatory Bowel Disease in the Post-STRIDE II Era: Epidemiology and Long-Term Clinical Outcomes from a Population-Based Study.

Background/Objectives: Inflammatory bowel disease (IBD) includes Crohn's disease (CD) and ulcerative colitis (UC). The availability of an increasing number of new molecules approved for IBD treatment has increased our ability and aspirations to change the trajectory of the disease. The Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) II consensus (2018) is the current suggested strategy for IBD management, which recommends a treat-to-target approach. The primary objective of this study is to describe the clinical history of IBD in the post-STRIDE II era and to quantify the burden of IBD in terms of hospitalisation rate. The secondary objective is to estimate the 6-year risk of intestinal resection among IBD patients. Methods: A population-based time series analysis was conducted on administrative data; retrospective data from January 2011 to December 2021 were collected for the Local Health Authority "Roma 1" population (∼1.5 million residents). Hospitalisation and surgical events were prospectively recorded for patients newly diagnosed between January 2018 and February 2022 (n = 556), with follow-up throughout May 2024. A Kaplan-Mayer survivor analysis was performed to estimate the cumulative surgery risk. Results: In 2021, the IBD prevalence was 218.3 cases/100,000 people (77.2 CD, 141.1 UC). The incidence trend slowly increased during the last decade, up to 5.3 (CD) and 9.4 (UC) cases/100,000 ppl/year. The yearly hospitalisation rate remained stable, near 16.5%. The 6-year cumulative risk of surgery was 36% for CD and 20% for UC. Conclusions: The incidence of IBD has increased in the last few decades, with substantial stability in regard to the incidence of surgery and hospitalisations. Thus, the current IBD management approach has only had a small effect on changing the natural history of the disease.