Validation of Lémann Index Assessing Bowel Damage in Patients With Crohn Disease

Investigators aimed to evaluate and update the Lémann index for the assessment of cumulative bowel damage in patients with Crohn disease.

The Lémann index, used to assess cumulative bowel damage in Crohn disease, has been validated and updated in a study published in Gastroenterology.

To assess and update the Lémann index, investigators enrolled 134 participants with Crohn disease from 15 centers internationally. The digestive tract was divided into 4 organs for analysis: upper tract, small bowel, colon/rectum, and anus. Each organ was further divided into segments and explored via magnetic resonance imaging (MRI) and endoscopy of each region. Investigators provided organ resection-free cumulative damage evaluations and provided a 0-10 global damage evaluation from the 4-organ, standardized cumulative damage evaluations. Linear regression of investigator assessed damage and the corresponding Lémann index were then studied. An updated index was thus derived and applied to development and validation samples.

The correlation coefficients between the investigator evaluations and Lémann index were 0.91 for upper tract, 0.96 for small bowel, 0.95 for the colon/rectum, and 0.81 for the anus. The mean of the investigator global damage evaluation was 0.8±0.8 (range, 0.0–5.0) while mean of the calculated global Lémann index was 1.2±1.3 (range 0.0–7.9). The correlation coefficient between the two measures was 0.98.

Slope estimates from the linear regression of the investigator global damage evaluation on the global Lémann index were significantly different from 1.0 for all organs and globally, with the exception of the upper tract. Additionally, differences in investigator evaluations between development and validation samples were observed. Therefore, an analysis of pooled data from 272 patients (138 from the development and 134 from the validation sample) was performed. The unbiased correlation estimates for upper tract, small bowel, colon/rectum, and anus were 0.89, 0,97, 0,94, and 0.81, respectively. Globally, the correlation estimate was 0.91 and all estimates were stable when applied to one sample or the other. 

This study had several limitations. Central readings of MRIs and endoscopies were not performed. Additionally, data on previous or on-going treatment was not collected. Finally, no reproducibility study on lesion detection at different examinations or a sensitivity-to-change evaluation of the index were performed.

According to researchers, the Lémann index is, “now validated and updated. It can be easily calculated by inputting the identified lesions and the history of surgical procedures into an excel calculation sheet, and is ready to be used in clinical research and clinical practice.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 


Pariente B, Torres J, Burisch J, et al. Validation and update of the Lémann index to measure cumulative structural bowel damage in Crohn’s disease. Gastroenterol. Published online May 27, 2021. doi:10.1053/j.gastro.2021.05.049