Impact of Extremes of BMI on Outcomes following Lung Resection.

Background:  Body mass index (BMI) has been shown to be an independent predictor of survival following lung resection surgery. This study aimed to quantify the short- to midterm impact of abnormal BMI on postoperative outcomes.

Methods:  Lung resections at a single institution were examined between 2012 and 2021. Patients were divided into low BMI (<18.5), normal/high BMI (18.5-29.9), and obese BMI (>30). Postoperative complications, length of stay, and 30- and 90-day mortality were examined.

Results:  A total of 2,424 patients were identified. Of these patients, 2.6% (n = 62) had a low BMI, 67.4% (n = 1,634) had a normal/high BMI, and 30.0% (n = 728) had an obese BMI. Overall postoperative complications were higher in the low BMI group (43.5%) when compared with normal/high (30.9%) and obese BMI group (24.3%) (p = 0.0002). Median length of stay was significantly higher in the low BMI group (8.3 days) compared with 5.2 days in the normal/high and obese BMI groups (p < 0.0001). Ninety-day mortality was higher in the low (16.1%) compared with the normal/high (4.5%) and obese BMI groups (3.7%) (p = 0.0006). Subgroup analysis of the obese cohort did not elucidate any statistically significant differences in overall complications in the morbidly obese. Multivariate analysis determined that BMI is an independent predictor of reduced postoperative complications (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.94-0.97; p < 0.0001) and 90-day mortality (OR, 0.96; 95% CI, 0.92-0.99; p = 0.02).

Conclusion:  Low BMI is associated with significantly worse postoperative outcomes and an approximate fourfold increase in mortality. In our cohort, obesity is associated with reduced morbidity and mortality following lung resection surgery, confirming the existence of the obesity paradox.