Body Mass Index and Mucosal Healing in Japanese Patients with Ulcerative Colitis: A Cross-Sectional Study

Ulcerative colitis (UC) is a chronic inflammatory bowel disease, and obesity is thought to exacerbate disease activity via chronic low-grade inflammation and related metabolic and cytokine dysregulation. However, evidence on the relationship between obesity and UC remains limited and inconsistent. As mucosal healing (MH) is an established therapeutic goal in UC, we aimed to investigate the association between body mass index (BMI) and MH in Japanese patients with UC.

This study included 292 Japanese UC patients. One endoscopist evaluated complete MH (CMH), defined as Mayo endoscopic subscores of 0. Underweight and obesity were defined as BMI <18.5 and ≥25 kg/m2, respectively. For detailed analysis, BMI was divided into quartiles: low: <19.70 kg/m2, lower-middle: 19.70-21.82 kg/m2, upper-middle: 21.83-24.60 kg/m2, and high: ≥24.61 kg/m2. Multivariable logistic regression models were used to adjust for potential confounders and to evaluate the associations of BMI categories with MH.

The mean age, male ratio, CMH rate, and clinical remission rate were 50.3 years, 57.9%, 25.0%, and 59.6%, respectively. No clear association between underweight, normal weight, or obesity and CMH was observed; however, in the quartile analysis, the highest BMI was independently and positively associated with CMH in the younger group but not in the older group (adjusted odds ratios: 0.29, 95% confidence interval: 0.07-0.97).

BMI was independently and inversely associated with CMH in Japanese younger patients with UC, but this association was not observed in older patients.