Body Mass Index and Adverse Perioperative Outcomes Following Hepatic Resection

The effect of obesity on perioperative outcomes following hepatic resection is not clearly defined. We sought to understand the implications of obesity on post-hepatectomy outcomes in a nationally represented cohort of patients. Using a retrospective cohort design, we studied the effect of obesity on complications and 30-day mortality using multivariable logistic regression using comprehensive clinical data from the American College of Surgeons National Surgical Quality Improvement Program (2005-2008). During our study period, 3,960 patients underwent hepatic resection; 32.4% had a normal body mass index (BMI; 18.5-24.9 kg/m(2)), 2.5% were underweight (< 18.5 kg/m(2)), 33.4% were overweight (25.0-29.9 kg/m(2)), and 31.7% were obese (> 30.0 kg/m(2)). 23.3% had at least one post-operative complication and the overall mortality rate was 2.5%. Compared to normal patients, obese patients had significantly higher unadjusted odds of having a complication (26.5% vs. 21.3%, OR 1.34, 95% CI 1.12-1.61) and dying (3.0% vs. 1.7%, OR 1.79, 95% CI 1.05-3.05). The obese were also more likely to have multiple complications compared to normal BMI patients (6.1% vs. 3.7%, OR 1.70, 95% CI 1.17-2.46). After risk adjustment, obesity was associated with attenuated but significantly higher odds of having any perioperative complication (OR 1.24, 95% CI 1.01-1.55), but was not a significant predictor of mortality. After adjusting for other clinical factors, the degree of obesity is independently associated with an increasing complication rate but not mortality. Risk adjustment may not capture the total clinical risk of patients at the extremes of BMI.