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.