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

OBJECTIVE: To assess the role of the Arterial Based Complexity (ABC) scoring system in predicting clinically relevant outcomes of a minimally invasive partial nephrectomy (MIPN).

PATIENTS AND METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.