Volumetric fat ratio and not body mass index is predictive of ileocolectomy outcomes in Crohn's disease patients

Background: Crohn's disease (CD) patients are typically underweight; however, a growing cohort of overweight CD patients is emerging. The current study investigates whether body mass index (BMI) or volumetric fat parameters can be used to predict morbidity after ileocolectomy for CD. Methods: One hundred and forty-three CD patients who underwent elective ileocolectomy were identified from our Inflammatory Bowel Disease (IBD) Registry. Patient demographics and operative outcomes were recorded. Visceral (VA) and subcutaneous (SA) adiposity and abdominal circumference (AC) were analyzed on preoperative CT scans using Aquarius iNtuition software. A visceral/subcutaneous ratio (VSR) was calculated. Results: BMI correlated with SA (p = 0.0001), VA (p = 0.0001) and AC (p = 0.0001) but not VSR (p > 0.05). BMI, VA and AC did not predict surgical morbidity (p > 0.05). In multivariate regression analysis, family history of IBD (p = 0.009), high American Society of Anesthesiologists score (p = 0.02) and increased VSR (p = 0.03) were independent predictors of postoperative morbidity. Conclusions: The visceral/subcutaneous fat ratio is a more reliable predictor of postoperative outcomes in CD patients undergoing ileocolectomy than conventional adiposity markers such as BMI. Preoperative calculation of the visceral/subcutaneous fat ratio offers the opportunity to optimize high-risk surgical patients, thus improving outcomes.