Ratio of Visceral to Subcutaneous Fat Area Is a Biomarker of Complicated Crohn's Disease

Abstract

Fat wrapping and mesenteric hypertrophy are characteristics of Crohn's disease (CD). In patients with CD, mesenteric adipose tissue releases higher levels of adiponectin, which could up-regulate production of tumor necrosis factor-α and increase the risk for aggressive disease. We investigated whether a higher ratio of visceral to subcutaneous fat was associated with complicated (fistulating or stricturing) CD. We identified patients with a confirmed diagnosis of CD who had computed tomography scans of their abdomens (n = 50). Areas of subcutaneous and visceral fat were measured in 1 cross-sectional scan that was taken at the level of the umbilicus. The mesenteric fat index (MFI), defined as the ratio of areas of visceral to subcutaneous fat, was compared between patients with complicated (strictures and fistulas) and inflammatory CD. The mean age of the patients with complications (n = 29) was 49.3 ± 15.6 years, and in patients with inflammatory CD (n = 21) it was 37.7 ± 19.1 years. The MFI was significantly higher (P = .001) in patients with complicated disease (0.67 ± 0.29) than in those with uncomplicated disease (0.23 ± 0.10) and was the only variable that remained significantly different on multivariate analysis. The area under the receiver operating curve for the MFI was 0.95 (95% confidence interval, 0.89-1.0), and an MFI of 0.29 identified patients with complicated CD with 93% sensitivity and 81% specificity. A high ratio of areas of visceral to subcutaneous fat (MFI) is a marker of aggressive CD. Further studies are needed to determine the roles of adipose tissue in pathogenesis of CD.