Lemann Index for assessing bowel damage in Crohn's disease: a real world study

Background & aims: The Lemann Index (LI), an endpoint to measure cumulative structural bowel damage in Crohn's disease (CD), has been recently updated and validated. We applied this to investigate predictors of bowel damage in a real-world cohort.

Methods: We performed a retrospective study (2008-2022) involving two tertiary referral IBD centers in the US. MR or CT enterographies were reviewed by study radiologists and endoscopy reports by study gastroenterologists, to calculate LI. Baseline and follow-up LI were calculated. We defined high bowel damage as LI ≥2. Factors associated with high LI were identified in patients with ≥2 LI scores using multivariate logistic regression and then assessed for a change in LI (increase vs. no change/decrease) using a multivariate linear mixed-effects model.

Results: 447 patients with CD had a median first LI of 7 [IQR, 1.25-14.55]. Median LI scores were significantly different when categorized by disease duration; 2.0 [IQR, 0.6-5.9] for <2 years, 2.6 [IQR, 0.6-9.6] for ≥2 and <10 years, and 12.5 [IQR, 6.4-21.5] for ≥10 years with a p <0.01. Disease duration, presence of perianal disease, elevated C-reactive protein, and Harvey-Bradshaw index, were associated with a high LI at inclusion and increase in LI during follow-up (all p <0.01).

Conclusions: The updated LI quantified cross-sectional and longitudinal cumulative bowel damage in a real-world cohort of patients with CD with predictors identified for a longitudinal increase in LI. Further studies for prospective validation of LI and identification of multi-omic predictors of bowel damage are needed.