Predictors of bowel damage in the long-term progression of Crohn's disease

BACKGROUND Crohn's disease (CD) is a chronic inflammatory bowel disorder that progresses to bowel damage (BD) over time. An image-based index, the Lemann index (LI), has been developed to measure cumulative BD. AIM To characterize the long-term progression of BD in CD based on changes in the LI and to determine risk factors for long-term progression. METHODS This was a single-center longitudinal cohort study. Patients who had participated in prospective studies on the accuracy of magnetic resonance imaging using endoscopy as a gold standard and who had a follow-up of at least 5 years were re-evaluated after 5-12 years. RESULTS Seventy-two patients were included. LI increased in 38 patients (52.8%), remained unchanged in 9 patients (12.5%), and decreased in 25 patients (34.7%). The small bowel score and surgery subscale significantly increased (P = 0.002 and P = 0.001, respectively), whereas the fistulizing subscale significantly decreased (P = 0.001). Baseline parameters associated with BD progression were ileal location (P = 0.026), CD phenotype [stricturing, fistulizing, or both (P = 0.007, P = 0.006, and P = 0.035, respectively)], disease duration > 10 years (P = 0.019), and baseline LI stricturing score (P = 0.049). No correlation was observed between BD progression and baseline clinical activity, biological markers, or severity of endoscopic lesions. CONCLUSION BD, as assessed by the LI, progressed in half of the patients with CD over a period of 5-12 years. The main determinants of BD progression were ileal location, stricturing/fistulizing phenotype, and disease duration.