Objective: To determine the effects of body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) on outcomes after liver resection performed at Veterans Affairs medical centers.
Design, setting, and patients: We queried the Veterans Affairs Surgical Quality Improvement Program database for liver resections (2005-2008) and grouped the patients into 5 BMI categories: normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), obese class 1 (BMI 30.0-34.9), obese class 2 (BMI 35.0-39.9), and obese class 3 (BMI ≥ 40.0). Differences in risk factors and perioperative complications across groups were analyzed in univariate and multivariate analyses.
Results: Of 403 patients who underwent hepatectomy, 106 (26%) were normal weight, 161 (40%) were overweight, 94 (23%) were obese class 1, 31 (8%) were obese class 2, and 11 (3%) were obese class 3. Among these groups, higher BMI was associated with increased rates of hypertension (52%, 61%, 77%, 77%, and 73%, respectively; P = .002) and diabetes (18%, 27%, 36%, 39%, and 45%, respectively; P = .04) and lower incidence of smokers (53%, 35%, 30%, 16%, and 9%, respectively; P < .001). The BMI groups were similar in demographic characteristics and metrics correlating with preexisting liver disease. There were no differences across BMI groups in overall and specific morbidity or in length of stay. Compared with the other groups, obese class 3 patients received more blood transfusions (mean [SD], 4.3 [2.7] in obese class 3 patients vs 1.1 [0.2] in normal-weight patients; P = .02) and had a higher 30-day mortality (27% in obese class 3 patients vs 6% in normal-weight patients; P = .05). Multivariate analyses confirmed obese class 3 as an independent predictor of postoperative mortality.
Conclusions: Obesity did not increase postoperative complications after liver resection in veterans. After adjusting for other clinical factors, extreme obesity (BMI ≥ 40.0) was an independent risk factor for increased mortality.