Baseline Wall Thickness Is Lower in Mucosa-Healed Segments 1 Year After Infliximab in Pediatric Crohn Disease Patients

Objectives: We aimed to quantitatively investigate the therapeutic response to combined immunosuppression treatment by magnetic resonance enterography (MRE) in active luminal Crohn disease (CD) in the pediatric population. Methods: Pediatric patients with moderate-to-severe luminal CD, who received scheduled infliximab and azathioprine, were included in this preliminary study. Ileocolonoscopy and MRE were performed at baseline and at 1 year, and Simple Endoscopic Score for Crohn's Disease (SES-CD) and Magnetic Resonance Index of Activity (MaRIA) scores were calculated. The correlation between SES-CD and MaRIA scores were investigated with analysis per person and per segment. Results: A total of 167 segments from 17 patients were evaluated by both Ileocolonoscopy and MRE. SES-CD and MaRIA scores showed significant correlations on both per-person analysis (rho = 0.699, P < 0.001) and per segment analysis (rho = 0.596, P < 0.001). Analysis according to ileocolonic location of each segment revealed that the correlation strength was strongest in the right colon (p = 0.653, P < 0.001), whereas the correlation in the rectum was statistically insignificant (rho = 0.29, P = 0.096). A comparative analysis of MaRIA components revealed a significantly thinner bowel wall thickness at baseline in endoscopically healed segments (50/65) compared with unhealed segments (15/65) (median 4.3 vs 7.2 nun, P = 0.036). Conclusions: Therapeutic response to combined immunosuppression at 1 year assessed by MRE correlates with ileocolonoscopy in pediatric patients with CD. Bowel wall thickness of the involved segments at baseline may affect treatment response to combined immunosuppression.