MRI assessment of body composition for prediction of therapeutic response to biologic agents in patients with Crohn’s disease.

Abstract

Objectives: Altered body fat and muscle mass in Crohn’s disease (CD) have been linked to adverse disease course and outcomes. Prediction of treatment response or remission (RoR) of small bowel CD (SBCD) to biologic therapy remains challenging. We aimed to establish the prognostic value of body composition parameters measured using MR enterography (MRE) for RoR at 1 year in patients with SBCD commencing biologic therapy. Methods: Participants were identified from those recruited to a prospective, multicentre study investigating the predictive ability of motility MRI for 1 year RoR in patients starting biologic therapy for active SBCD (MOTILITY trial). Myopenia, skeletal muscle:fat and visceral:subcutaneous fat were measured from baseline MRE. RoR at 1 year was judged using a composite of clinical and morphological MRE parameters. We compared the likelihood of RoR in patients with and without myopenia or low skeletal muscle:fat using logistic regression models. Results: Ninety-six participants were included (mean age 38.2 years; 40 (42%) female). There were 34 (35%) responders. There was no significant difference in RoR at 1 year between those patients with and without skeletal muscle myopenia (OR: 0.85, 95% CI: 0.27, 2.66, p-value: 0.78), or those with or without low skeletal muscle:fat (OR: 0.71, 95% CI: 0.19, 2.71, p-value: 0.62). Conclusions: Body composition parameters demonstrated no value for predicting therapeutic RoR in patients commencing biologic therapy for SBCD. Critical relevance statement: Prediction of response to biologic therapy in small bowel Crohn’s disease (SBCD) remains challenging. Body composition parameters cannot predict biologic therapeutic response or remission for SBCD reliably. Key Points: Altered body fat and muscle mass in Crohn’s disease have been linked to adverse outcomes. Prediction of response to biologic therapy in small bowel CD (SBCD) would be useful for treatment optimisation. Body composition parameters measured using MRI cannot reliably predict biological therapeutic response or remission for SBCD. © The Author(s) 2025.