Association of Obesity With Septic Complications After Major Abdominal Surgery
Authors: Usha Gurunathan, Ivan L. Rapchuk, Marilla Dickfos, Peter Larsen, Andrew Forbes, Catherine Martin, Kate Leslie, Paul S. Myles
Journal: JAMA Network Open (2019)

<h3>Importance</h3> Body mass index (BMI) has been the most common obesity measure to assess perioperative risk; however, cardiometabolic risk is associated with the burden of visceral fat. Definitive evidence on the association of visceral fat measures, such as waist circumference and waist-to-hip ratio (WHR), with postoperative complications is lacking. <h3>Objective</h3> To compare the value of waist circumference with the value WHR and BMI in predicting adverse outcomes, including major septic complications and persistent disability, following major abdominal surgery. <h3>Design, Setting, and Participants</h3> This planned secondary analysis of the Restrictive vs Liberal Fluid Therapy for Major Abdominal Surgery (RELIEF) randomized clinical trial took place at 47 centers in 7 countries between October 2013 and September 2016, with 90-day follow-up. A total of 2954 adult RELIEF participants were coenrolled in this secondary analysis. Data analysis took place from December 2018 to September 2019. <h3>Exposures</h3> Waist circumference, WHR, and BMI measurements. <h3>Main Outcomes and Measures</h3> The primary outcomes were 30-day major septic complications and 90-day persistent disability or death. <h3>Results</h3> Of 2954 eligible participants, 2755 were included (mean [SD] age, 65.9 [12.9] years; 1426 [51.8%] men) in the final analysis. A total of 564 participants (20.6%) experienced at least 1 major septic complication within 30 days after surgery (sepsis, 265 [9.7%]; surgical site infection, 409 [14.9%]; anastomotic leak, 78 [2.8%]; pneumonia, 104 [3.8%]). Waist circumference had a statistically significantly larger odds ratio (OR) and discrimination indices as well as a smaller prediction error than WHR or BMI for 30-day major septic complications or death (waist circumference: OR, 1.44; 95% CI, 1.28-1.62;<i>P</i> &lt; .001; area under the receiver operating characteristic curve, 0.641; net reclassification index, 0.266; integrated discrimination improvement [score × 10<sup>4</sup>], 152.98; Brier score, 0.162; WHR: OR, 1.15; 95% CI, 1.03-1.28;<i>P</i> = .01; area under the receiver operating characteristic curve, 0.621; net classification index, 0.199; integrated discrimination improvement [score × 10<sup>4</sup>], 28.47; Brier score, 0.164; BMI: OR, 1.33; 95% CI, 1.17-1.50;<i>P</i> &lt; .001; area under the receiver operating characteristic curve, 0.629; net reclassification index, 0.205; integrated discrimination improvement [score × 10<sup>4</sup>], 85.61; Brier score, 0.163) but not for any other outcomes. <h3>Conclusions and Relevance</h3> In this secondary analysis of the RELIEF randomized clinical trial, waist circumference was observed to be superior to other adiposity indices in predicting 30-day major septic complications alone or in conjunction with death following elective major abdominal surgery. Findings suggest that waist circumference is a useful adiposity measure that should be incorporated in preoperative risk assessment for such complications. <h3>Trial Registration</h3> ClinicalTrials.gov identifier:NCT01424150