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 Lémann 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.