Detailed perioperative risk among patients with extreme obesity undergoing nonbariatric general surgery

Background: The obesity epidemic has spread rapidly across the United States. Although overweight and obese patients have a paradoxically lower risk for postoperative morbidity and mortality, the risks associated with extreme classes of obesity (morbid obesity, super obesity, and super-super obesity) have not been described. Methods: We queried the National Surgical Quality Improvement Program database from 2012 to 2016. Of 1,815,251 surgical cases, there were 3,946 vascular cases, 237,777 emergency procedures, and 75,177 cases with missing data that were removed. The remaining 1,378,711 cases were included in this analysis. Multivariable linear and logistic regression was performed to assess the impact of body mass index on postoperative outcomes. Results: Patients within the super obesity and super-super obesity groups had the highest procedure-adjusted mortality risk among all body mass index classes (odds ratio = 2.31 and 2.63, respectively). Morbid obesity and underweight groups had moderate risk (odds ratio = 1.37 and 1.88, respectively), while those in the overweight and obesity class I and II cohorts had improved or equivocal mortality risk compared to normal body mass index class patients. Risk-adjusted and unadjusted multivariable models demonstrated that extreme obesity classes (morbid obesity, super obesity, and super-super obesity) have a graduated escalation of perioperative morbidity, infectious, and critical care complications. Conclusion: Further detailing extreme obesity-related risk beyond the obesity class III umbrella is necessary for accurate risk prediction, especially with the rising prevalence of elective nonbariatric surgery in this population. Preoperative risk assessment tools should consider subgroup risk adjustment to delineate true postoperative complication risk, facilitate patient education, and address modifiable risk factors before surgery.