The Clinical Characteristics and Prognosis of Crohn’s Disease in Korean Patients Showing Proximal Small Bowel Involvement: Results from the CONNECT Study

Background/Aims We aimed to evaluate the clinical characteristics and prognosis of Crohn's disease (CD) in patients who showed proximal small bowel involvement using a nationwide Korean CD cohort. Methods We reviewed the data from a cohort of patients diagnosed with CD. The clinical outcomes of patients were evaluated according to the presence of proximal small bowel involvement. Results Among 1,329 patients with CD for whom complete disease location data were available, 222 patients (16.7%) showed involvement of the proximal small bowel. Compared to patients without proximal small bowel involvement, those with small bowel involvement were more likely to display stricturing behavior (19.8% vs 12.7%, p=0.020). The surgery-free survival of patients who showed proximal small bowel involvement was inferior to that of patients without proximal small bowel involvement (10-year surgery-free survival: 58.4% vs 67.7%, respectively, p＜0.001). Additionally, upper gastrointestinal involvement was more common in patients with proximal small bowel involvement than in those without involvement (odds ratio, 1.643; 95% confidence interval, 1.008 to 2.677). Conclusions Proximal small bowel involvement is a poor prognostic factor for the surgery-free survival of Korean patients with CD. Proximal small bowel involvement should be evaluated in patients with CD for predicting long-term clinical outcomes.