Waist Circumference and Waist/Hip Ratio Are Better Predictive Risk Factors for Mortality and Morbidity after Colorectal Surgery Than Body Mass Index and Body Surface Area

Objectives: To determine whether body fat distribution, measured by waist circumference (WC) and waist/hip ratio (WHR), is a better predictor of mortality and morbidity after colorectal surgery than body mass index (BMI) or body surface area (BSA). Background: Obesity measured by BMI is not a consistent risk factor for postoperative mortality and morbidity after abdominal surgery. Studies in metabolic and cardiovascular diseases have shown WC and WHR to be better outcome predictors than BMI. Methods: A prospective multicenter international study was conducted among patients undergoing elective colorectal surgery. The WHR, BMI, and BSA were derived from bodyweight, height, and waist and hip circumferences measured preoperatively. Uni- and multivariate analyses were performed to identify risk factors for postoperative outcomes. Results: A total of 1349 patients (754 men) from 38 centers in 11 countries were included. Increasing WHR significantly increased the risk of conversion [odds ratio (OR) = 15.7, relative risk (RR) = 4.1], intraoperative complications (OR = 11.0, RR = 3.2), postoperative surgical complications (OR = 7.7, RR = 2.0), medical complications (OR = 13.2, RR = 2.5), anastomotic leak (OR = 13.7, RR = 3.3), reoperations (OR = 13.3, RR = 2.9), and death (OR = 653.1, RR = 21.8). Both BMI (OR = 39.5, RR = 1.1) and BSA (OR = 4.9, RR = 3.1) were associated with an increased risk of abdominal wound complication. In multivariate analysis, the WHR predicted intraoperative complications, conversion, medical complications, and reinterventions, whereas BMI was a risk factor only for abdominal wall complications; BSA did not reach significance for any outcome. Conclusions: The WHR is predictive of adverse events after elective colorectal surgery. It should be used in routine clinical practice and in future risk-estimating systems.