Mesenteric Fat Is Less among Patients with Complicated Crohnʼs Disease: A Real Association?

Abstract

Purpose: Mesenteric fat has been associated with more complicated (penetrating and stricturing) disease behaviors among patients with Crohn's disease (CD), suggesting that it is immunologically active. However, this conclusion was based on a cross-sectional analysis with the manual quantification of visceral fat at the level of the umbilicus, which is rather mobile and non-specific. We quantified mesenteric fat at L5-S1, and determined if it was independently associated with complicated CD. Methods: A retrospective study was performed on 176 consecutive CD patients, comparing inflammatory (non-stricturing non-penetrating) with complicated disease (Table). Mesenteric fat was determined at the time of behavior classification. Mesenteric fat was calculated based on CT and CT enterography, using software (TeraRecon, Foster,CA) highlighting the visceral fat by its specific Hounsfield units on a fixed cross sectional level of L5-S1 excluding retroperitoneal, intramuscular, subcutaneous, and intrathecal fat. The association of mesenteric fat with complicated disease behavior was determined after adjustment for disease-specific variables in a logistic regression analysis.TableResults: As expected, patents with complicated disease behavior had a younger age at diagnosis, longer disease duration, and were more likely to have received immunomodulator therapy (Table). There was no difference in mesenteric fat between those with penetrating or stricturing behaviors. Mesenteric fat was significantly lower (92 vs. 66 cm2) among patients with complicated disease. This was confirmed in the multivariate analysis with mesenteric fat negatively associated with complicated disease behavior (p=0.002). Conclusion: Contrary to recent literature, we found that mesenteric fat is negatively associated with complicated (penetrating or stricturing) Crohn's disease. Decreased quantity of mesenteric fat may be important in the development of complicated disease behavior, or, alternatively, may be the result of that behavior. Future prospective studies are necessary to provide measurements prior to the development of penetrating or stricturing complications, to better understand the role of mesenteric fat on the pathogenesis of Crohn's disease.