Low Surgery Rates in Early Crohn's Disease: Results from a Prospective Population-Based Inception Cohort-The Inflammatory Bowel Disease in South-Eastern Norway III Study.

Background and aims: The emergence of biologic therapy has coincided with a decline in surgery rates for Crohn's disease (CD). This study aims to describe the disease course, including intra-abdominal surgery rates, biologic therapy use, and variables associated with biologic therapy initiation in a cohort of newly diagnosed CD patients.

Methods: The Inflammatory Bowel Disease in South-Eastern Norway (IBSEN) III study is a population-based inception cohort study. From 2017 to 2019, newly diagnosed inflammatory bowel disease patients were included for prospective follow-up. The present study included CD patients ≥ 18 years. Clinical, endoscopic, and demographic data were collected at diagnosis and 1-year follow-up. Data were analyzed by using the Kaplan-Meier method and regression analyses.

Results: In total, 424 CD patients (median age 37.0 years (range 18-80), female 55.0%) were included. At diagnosis, 50.5% presented with ileal disease and 80.7% with inflammatory behavior. Within a 1-year follow-up, 39.6% of patients received their first biologic therapy and 5.2% required intra-abdominal surgery. Systemic steroid treatment, CRP ≥ 5.0 mg dL-1, Harvey-Bradshaw Index score > 4, ileocolonic disease and penetrating disease behavior at diagnosis were independently associated with increased risk of initiation of biologic therapy, while age > 40 years was associated with decreased risk.

Conclusion: A high proportion of patients had ileal disease and inflammatory behavior at diagnosis. Still, nearly 40% started biologic therapy within the 1-year follow-up, while only 5% required intra-abdominal surgery.