Background The new global epidemic, overweight and obesity, has a significant role in the etiology of liver tumors. However, the impact of body weight on the outcome after liver resection is unknown. Methods We carried out a prospective study of 684 patients who underwent liver resections. Patients were stratified according their body mass index (BMI) as follows: normal (<25 kg/m(2)) (52%), overweight (25-29 kg/m(2)) (34%), and obese (>= 30 kg/m(2)) (14%), and according to the extent of resection, as either minor or major hepatectomy. Preoperative and intraoperative characteristics and outcomes were prospectively studied. The Dindo-Clavien classification of morbidity was used. Results Overall postoperative morbidity and morbidity rates were not influenced by BMI. Pulmonary complications were significantly more frequent in obese patients irrespective of the extent of resection. During major resection obese had longer pedicular clamping and more frequently required blood transfusion. After major resection, major morbidity (Dindo-Clavien grade III or more) was more frequent in obese (57%) and overweight (54%) patients than in patients of normal body weight (35%; P < 0.05), including a higher rate of respiratory complications and ascites and longer intensive care unit (ICU) and hospital stays. Obesity and overweight were independent predictors of major morbidity (OR 2.6, 95% CI 1.2-5.8 and OR 1.9, 95% CI 1.2-3.2, respectively), and obesity was a predictor of the need for blood transfusion (OR 3.3, 95% CI 1.4-7.9) after major resections. Conclusions Obese and overweight patients are at increased risk of potentially life-threatening morbidity after major hepatic resections. Because the risk of mortality is not increased significantly, there is no justification for a compromise in the indication or extent of surgery.
