Previous studies analyzing the relationship between Body Mass Index (BMI) and complications after partial nephrectomy have been underpowered. We use a national surgical database to explore the association of BMI with postoperative outcomes for Open Partial Nephrectomy (OPN) and Minimally Invasive Partial Nephrectomy (MIPN). Patients and Methods: Years 2005-2012 of the National Surgical Quality Improvement Program (NSQIP) were queried for OPN and MIPN. Postoperative complications were organized according to Clavien Grades and compared across normal weight (BMI kg/m2=18.5-<25.0), overweight (BMI=25.0-<30.0), and obese (BMI≥30.0) patients using standard descriptive statistics and multivariate regression modeling. Results: Of 1667 OPNs and 2018 MIPNs, 46.2% of patients were obese. Operative time was 16.91 minutes longer on average for obese patients (p<0.001). The overall complication rate after OPN was 17.9%, 17.2%, and 17.9% (p=0.945) for normal weight, overweight, and obese patients, respectively; while the overall complication rate after MIPN was 6.9%, 6.3%, and 8.7% (p=0.147). Multivariate regression analysis demonstrated that overweight and obese patients were not at increased risk for any complication grade after OPN and MIPN compared to normal weight patients. When comparing procedures, MIPN had a lower complication rate compared to OPN for obese (8.7% vs 17.9%, p<0.001) and morbidly obese patients (9.2% vs 22.2%, p=0.001). Conclusions: Although surgery in obese patients is longer compared to normal weight patients, it does not appear to increase the likelihood of 30-day postoperative complications for OPN or MIPN. However, obese patients undergoing MIPN had lower complication rates than those undergoing OPN.
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