External validation of four nephrometry scores for trans-peritoneal robotic partial nephrectomy

INTRODUCTION: External validation of four nephrometry scores (NS): Centrality index (C-index), arterial based complexity (ABC), preoperative aspects and dimensions used for an anatomical (PADUA) and radius expohytic/endophytic nearness anterior/posterior location (RENAL) scoring systems in patients who have undergone trans-peritoneal robotic assisted partial nephrectomy (RAPN). MATERIAL AND METHODS: A prospective database for RAPN has been maintained. Individual NSs were performed on 3-dimensional reconstructions of MDCT/MRI studies retrospectively by a board certified uroradiologist. Univariate Cox Proportional-Hazard Regression Analysis was performed for each NSs to valuate its predictability for the following parameters: Warm Ischemia Time (WIT), Estimated Blood Loss (EBL), Operative Time (OT), Complication Rates and Positive Margin Rates. RESULTS: 78 RAPNs were performed for suspected renal malignancies. The mean OT, EBL and WIT time was 186.5 minutes (SD – 33.8), 125.5 mls (SD – 188.91) and 16.7 minutes (SD – 5.6) respectively. The overall complication rate was 20.5% (16/78) of which only 2.6% (2/78) were Clavien Grade 3 or higher complications. The mean change in creatinine change at Day – 1 was 12.54 μmol/L (SD – 18.05). On the Cox regression analysis only the Centrality index predicted prolonged WIT with statistical significance: C-Index (0.02), ABC (0.2), PADUA (0.2), RENAL (0.9). ABC predicted operative time with statistical significance: C-index (0.45), ABC (0.0004), PADUA (0.25), RENAL (0.3). None of the NSs could predict overall complication: C-index (0.5), ABC (0.2), PADUA (0.13), RENAL (0.5). None of the NSs predicted EBL: C-index (0.3)0, ABC (0.8), PADUA (0.2), RENAL (0.7). None of the NSs predicted Positive Margin Rates: C-index (0.4), ABC (0.4), PADUA (0.9), RENAL (0.8). CONCLUSIONS: C-index was able to predict prolonged WIT. ABC was a strong predictor of OT. PADUA and RENAL were poor predictors for all measured parameters.