Could Preoperative Unintended Weight Loss Predispose to Postoperative Thrombosis in Patients Undergoing Colorectal Cancer Surgery? An Analysis of the NSQIP Data.

Objective: A significant portion of colorectal cancer patients lose weight preoperatively. Here we examine the influence of pre-operative significant weight loss on venous thromboembolism (VTE) risk and determine whether pre-operative BMI and albumin could influence VTE outcomes in patients who have lost significant weight prior to surgery.Methods: We conducted a retrospective cohort study using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) and identified 103,455 colorectal cancer patients undergoing major surgery from 2008 to 2012. Patients were assigned to one of two groups based on whether they lost significant weight preoperatively or not. Simple and stepwise multiple logistic regressions were used to evaluate the association between pre-operative unintended weight loss and 30-days postoperative outcomes. The association between weight loss and postoperative thrombosis was further assessed across several strata.Results: The overall prevalence of pre-operative significant weight loss was 6.8%. Significant weight loss prior to surgery was significantly and independently associated with a higher risk of VTE (adjusted OR 1.23, 95% CI 1.06-1.44), mortality (adjusted OR 1.55, 95% CI 1.35-1.78), composite morbidity (adjusted OR 1.52, 95% CI 1.42-1.62), bleeding (adjusted OR 1.78, 95% CI 1.67-1.91) and return to operation room (adjusted OR 1.29, 95% CI 1.16-1.42). The effect of pre-operative significant weight loss on thromboembolic outcome was evident across patients with a BMI <18.5 kg/m², 18.5 < BMI < 24.99 and BMI >40kg/m².Conclusions: Significant weight loss and BMI both need to be measured preoperatively to stratify patients who are at a higher risk of VTE.