Dynamic CT-based body composition analysis predicts surgical risk in Crohn's disease with small bowel stenosis: a retrospective cohort study.

Background: Reliable predictors of surgical risk in Crohn's disease (CD) with small bowel stenosis are lacking. Longitudinal CT enterography (CTE) derived body composition parameters may improve risk stratification. Aims: To evaluate whether longitudinal CTE-derived body composition changes predict surgical risk in CD patients with small bowel stenosis. Methods: This retrospective cohort study analyzed 385 CD patients between January 2018 and June 2022 with paired CTE scans. High-risk patients (n = 96) required surgery for complications; low-risk patients (n = 289) achieved medical remission. Skeletal muscle (SM), subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and intermuscular adipose tissue (IMAT) metrics at L3-L5 levels were measured and normalized by vertebral height. Gender-stratified analyzes and Cox regression identified predictors. Results: There were 289 cases in the low-risk group and 96 cases in the high-risk group. Interaction terms (time and gender) were tested, males showed significant reductions in L3-L4 skeletal muscle index (SMI) (p < 0.001), L3-L4 IMAT index (p < 0.001, p = 0.04), and L4-L5 VAT density (p = 0.008, p = 0.005). Independent predictors of surgical risk included SAT density at L5 level in baseline (p = 0.005), SMI at L3 level in follow up (p < 0.001), VAT/total adipose tissue index (VTR) (p = 0.004), delta SMI at L4 level (p < 0.001), age (p < 0.001), platelet count (p = 0.010), erythrocyte sedimentation rate (p < 0.001), and stenosis length (p = 0.001). Conclusion: Dynamic body composition parameters, particularly delta SMI and adipose tissue parameters, serve as valuable imaging biomarkers for predicting surgical necessity in CD patients with small bowel stenosis.