Robotic partial nephrectomy for renal tumours in obese patients: Perioperative outcomes in a multi-institutional analysis

Introduction: We sought to evaluate the association of obesity with surgical outcomes of robotic partial nephrectomy (RPN) using a large, multicentre database. Methods: We identified 1836 patients who underwent RPN from five academic centres from 2006–2014. A total of 806 patients were obese (body mass index [BMI] ≥30 kg/m2). Patient characteristics and outcomes were compared between obese and non-obese patients. Multivariable analysis was used to assess the association of obesity on RPN outcomes. Results: A total of 806 (44%) patients were obese with median BMI of 33.8kg/m2. Compared to non-obese patients, obese patients had greater median tumour size (2.9 vs. 2.5cm, p<0.001), mean RENAL nephrometry score (7.3 vs. 7.1, p=0.04), median operating time (176 vs. 165 min, p=0.002), and median estimated blood loss (EBL, 150 vs. 100 ml, p=0.002), but no difference in complications. Obesity was not an independent predictor of operative time or EBL on regression analysis. Among obese patients, males had a greater EBL (150 vs. 100 ml, p<0.001), operative time (180 vs. 166 min, p<0.001) and warm ischemia time (WIT, 20 vs. 18, p=0.001), and male sex was an independent predictor of these outcomes on regression analysis. Conclusions: In this large, multicentre study on RPN, obesity was not associated with increased complications and was not an independent predictor of operating time or blood loss. However, in obese patients, male gender was an independent predictor of greater EBL, operative time, and WIT. Our results indicate that obesity alone should not preclude consideration for RPN.