Early Postoperative Outcomes of Super Morbid Obese Compared to Morbid Obese Patients After Ambulatory Surgery Under General Anesthesia: A Propensity-Matched Analysis of a National Database

BACKGROUND: Patients with body mass index (BMI) ≥50 kg/m2, defined as super morbid obesity, represent the fastest growing segment of patients with obesity in the United States. It is currently unknown if super morbid obese patients are at greater odds than morbid obese patients for poor outcomes after outpatient surgery. The main objective of the current investigation is to assess if super morbid obese patients are at increased odds for postoperative complications after outpatient surgery when compared to morbid obese patients. METHODS: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2017 to 2018 was queried to extract and compare patients who underwent outpatient surgery and were defined as either morbidly obese (BMI >40 and <50 kg/m2) or super morbidly obese (BMI ≥50 kg/m2). The primary outcome was the occurrence of medical adverse events within 72 hours of discharge. In addition, we also examine death and readmissions as secondary outcomes. A propensity-matched analysis was used to evaluate the association of BMI ≥50 kg/m2 versus BMI between 40 and 50 kg/m2 and the outcomes. RESULTS: A total of 661,729 outpatient surgeries were included in the 2017-2018 NSQIP database. Of those, 7160 with a BMI ≥50 kg/m2 were successfully matched to 7160 with a BMI <50 and ≥40 kg/m2. After matching, 17 of 7160 (0.24%) super morbid obese patients had 3-day medical complications compared to 15 of 7160 (0.21%) morbid obese patients (odds ratio [OR; 95% confidence interval {CI}] = 1.13 [0.57-2.27], P = .72). The rate of 3-day surgical complications in super morbid obese patients was also not different from morbid obese patients. Thirty-five of 7160 (0.48%) super morbid obese patients were readmitted within 3 days, compared to 33 of 7160 (0.46%) morbid obese patients (OR [95% CI] = 1.06 [0.66-1.71], P = .80). When evaluated in a multivariable analysis as a continuous variable (1 unit increase in BMI) in all patients, BMI ≥40 kg/m2 was not significantly associated with overall medical complications (OR [95% CI] = 1.00 [0.98-1.04], P = .87), overall surgical complication (OR [95% CI] = 1.02 [0.98-1.06], P = .23), or readmissions (OR [95% CI] = 0.99 [0.97-1.02], P = .8). CONCLUSIONS: Super morbid obesity is not associated with higher rates of early postoperative complications when compared to morbid obese patients. Specifically, early pulmonary complications were very low after outpatient surgery. Super morbid obese patients should not be excluded from outpatient procedures based on a BMI cutoff alone.