Association between nutritional status assessed by body mass index and Crohn's disease phenotype: A Nation-wide analysis.

Background & Aims: Incidence of obesity and Crohn's disease (CD) is increasing globally. Therefore, understanding any associations between adiposity and disease phenotype is crucial. We aimed explore the relationship between nutritional status measured by body mass index (BMI) and phenotypes of CD using a large national recallable data set.

Methods: Using National Institute for Health and Care Research-IBD Bioresource data base, we retrospectively assessed the relationship between BMI and stenosing CD by logistic regression. BMI was the primary variable of interest; CD behaviour was the dependent variable; stenosing CD was the primary outcome. Confounders were adjusted for in a multivariate model.

Results: 8797 patients diagnosed between 1942 and 2020 were included. Mean overall BMI was 26.3 kg/m (SD5.5). 52.7 % had a BMI ≥25 kg/m (mean 30.2 kg/m, SD 4.5). Majority had inflammatory CD (62.9 %) followed by stenosing (25.1 %) and penetrating CD (12 %). Stenosing and penetrating phenotypes were more common in the <25 kg/m BMI group (50.7 %, 50.3 % respectively) p < 0.001. Colonic disease location was more common (27.8 % vs 24.3 %, p = 0.001) in patients with high BMI. On univariate analysis, stenosing disease was positively associated with ileal disease location, disease duration, previous surgery, use of infliximab, ustekinumab, vedolizumab, adalimumab and azathioprine but negatively associated with BMI (OR 0.98, 95%CI [0.968-0.99]). On multivariate analyses, BMI remained negatively associated with stenosing CD (OR 0.98, 95%CI [0.97-0.99]); ileal disease location (OR 3.69, 95%CI [3.22-4.24]), adalimumab (OR 1.47, 95%CI [1.30-1.66]), ustekinumab usage (OR 1.51, 95%CI [1.14-2.01] and azathioprine (OR 1.35, 95%CI [1.19-1.53]).

Conclusions: After multivariate analyses, BMI, ileal disease location and biologic use was negatively associated with a stenosing disease phenotype. This might reflect a change in eating behaviour due to persistent postprandial symptoms related to stenosing disease. Large longitudinal studies are needed to investigate any possible temporal relationship between the obesogenic state and intestinal fibrosis.