Operative Risk for Major Lung Resection Increases at Extremes of Body Mass Index

Although body mass index (BMI) has been used in risk stratification for lung resection, many models only take obesity into account. Recent studies have demonstrated that underweight patients also experience increased postoperative complications. We explored the relationship of extremes of BMI to outcomes after lung resection for non-small cell cancer.

Patients in the Society of Thoracic Surgeons General Thoracic Surgery Database (2009 to 2014) undergoing elective lung resection for cancer were evaluated. Multivariable logistic regression was used to adjust for potential confounders including functional status and spirometry.

We evaluated 41,446 patients (median 68 years of age; 53% female) grouped by BMI: underweight (<18.5 kg/m²; 3.0%), normal (18.5 to 24.9 kg/m²; 33.5%), overweight (25 to 29.9 kg/m²; 35.4%), obese I (30 to 34.9 kg/m²; 18.1%), obese II (35 to 39.9 kg/m²; 6.4%), and obese III (≥40 kg/m²; 3.6%). Pulmonary complication rates were higher in underweight and obese III patients compared to normal BMI patients (p < 0.001). On multivariable analysis, compared to patients with normal BMI, being underweight was associated with an increased risk of pulmonary complications (adjusted odds ratio [OR]: 1.41, 95% confidence interval [CI]: 1.16 to 1.70) and any postoperative event (adjusted OR: 1.44, 95% CI: 1.26 to 1.64). Obese III patients had an increased risk of any major postoperative complication (adjusted OR: 1.18, 95% CI: 1.02 to 1.36). Overweight and obese class I to II patients had a lower risk of pulmonary complications and any postoperative event.

BMI is associated with postoperative complications after lung resection for cancer. Being underweight or severely overweight is associated with an increased risk of complications, whereas being overweight or moderately obese appears to have a protective effect.