Multi-institutional Retrospective Validation and Comparison of the Simplified PADUA REnal Nephrometry System for the Prediction of Surgical Success of Robot-assisted Partial Nephrectomy

Background: The use of a nephron-sparing surgery for the treatment of localized renal masses is being pushed to more challenging cases. However, this procedure is not devoid of risks, and the Radius, Exophytic/Endophytic, Nearness, Anterior/Posterior, Location (RENAL) and Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) classifications are commonly employed in the prediction of complications. Recently, the Simplified PADUA REnal (SPARE) scoring system has been proposed with the aim to provide a more simple system, to improve its reproducibility to predict postoperative risks. Objective: We aim to retrospectively validate and compare the proposed new SPARE system in a multi-institutional population. Design, setting, and participants: The Transatlantic Robotic Nephron-sparing Surgery (TRoNeS) study group collected data from 737 patients subjected to robot-assisted partial nephrectomy (RAPN) between 2010 and 2016 at three tertiary care referral centers. Of these patients, 536 presented complete demographic and clinical data. Outcome measurements and statistical analysis: Renal masses were classified according to the SPARE, RENAL, and PADUA nephrometry scores, and surgical success was defined according to the margin, ischemia, and complication scores. Results and limitations: Of 536 patients, 340 were male; the median age was 61 (53-69) yr and preoperative tumor size was 30 (22-43) mm. The margin, ischemia, and complication score was achieved in 399 of cases (74.4%). All three nephrometry scores were significant predictors of surgical outcomes both in univariate and in adjusted multivariate logistic regression model analysis. In accuracy analysis, the area under the curve (AUC) of the SPARE scoring system (0.73) was significantly higher than those of the PADUA (0.65) and RENAL (0.68) nephrometry scores in predicting surgical success.