Effects of Body Mass Index on Postoperative Outcomes and Complications for Patients Undergoing Emergency Abdominal Surgery: A NSQIP Review

Introduction: Body mass index (BMI) is closely related to morbidity and mortality, and emergency general surgery is an independent risk factor for postoperative complications and death. Study Design: This was a retrospective analysis of NSQIP data from 2018 evaluating outcomes for patients undergoing urgent or emergent abdominal surgery, based on BMI. We first analyzed the impact of patient demographics and comorbidities, including obesity (BMI ≥30), on multiple postoperative outcomes. We then stratified patients by WHO BMI classification and analyzed the same variables. Results: In the first analysis, obesity was found to increase the risk of superficial and deep surgical site infection and decrease the risk of pneumonia. The most prevalent risk factor was open surgery, which increased the risk of most postoperative complications. After stratification, we did not identify the previously described “obesity paradox.” We found no protective factors for overweight patients or those with mild obesity. However, patients at the extremes of BMI tended toward worse outcomes, including longer operative times and hospital stays. Furthermore, patients with class II or III obesity were typically at higher risk for organ space infection, pulmonary embolism, return to the operating room, and 30-day mortality. Conclusion: Body mass index clearly impacts postoperative outcomes in patients undergoing urgent or emergent abdominal surgery. While the obesity paradox was not identified in this study, outcomes generally fared worse for patients at BMI extremes. The most prevalent risk factor across all BMI classifications, for multiple postoperative complications and outcomes including 30-day mortality, was open versus laparoscopic surgery.