External validation of the Arterial Based Complexity (ABC) scoring system in renal tumors treated by minimally invasive partial nephrectomy

To assess the role of the Arterial Based Complexity (ABC) scoring system in predicting clinically relevant outcomes of a minimally invasive partial nephrectomy (MIPN).We retrospectively reviewed 350 consecutive patients who underwent a MIPN between 2013 and 2014. Tumor complexity was evaluated according to the ABC scoring system. Complications, surgical, and renal outcomes were recorded.There were respectively 36 (10.3%), 229 (65.4%), 43 (12.3%), and 42 (12.0%) patients in category 1, 2, 3S, 3H. Multivariate regression showed category assignment was associated with warm ischemia time (P < 0.001), estimated blood loss (P = 0.001), and operative time (P = 0.032). On multivariate analyses, tumor size was the only independent predictor of overall (P = 0.035) and minor (P = 0.032) complications, but ABC category failed to predict complications (P > 0.05 for all). For renal function, ABC category failed to predict postoperative estimated glomerular filtration rate at 1 day and 6 months (P > 0.05 for both).In MIPN, the ABC scoring system predicted a prolonged warm ischemia time and operative time, and an added estimated blood loss. This scoring system was not a predictor for the occurrence of complications and postoperative renal function.