The Role of R.E.N.A.L. Nephrometry Score in the Era of Robot-Assisted Partial Nephrectomy

Abstract

PURPOSE: We studied the role of the R.E.N.A.L. nephrometry score (NS) in predicting surgical outcomes in a series of robot-assisted partial nephrectomy (RAPN). PATIENTS AND METHODS: Of 99 cases of minimally invasive partial nephrectomy performed by a single surgeon from 2003 to 2011, 83 were performed with robotic assistance. A trained physician investigator applied the NS to these 83 cases using the preoperative CT scans. Forty-two of these were reviewed by a urology resident to eliminate interobserver variation. Tumors were categorized into noncomplex (NS 4-6) or complex (NS 7-12) tumors, and perioperative outcomes were compared. Outcomes were also compared by each component of the NS. Perioperative outcomes were analyzed using chi-square tests and Mann-Whitney/Kruskal-Wallis tests. Univariate regression was used to analyze trends between nephrometry and outcomes. RESULTS: Strong correlation was found between the two sets of NS (Spearman correlational coefficient 0.814, P<0.001). Comparing between noncomplex and complex tumors, statistical differences were found in operative time (181 min vs 215 min, P=0.028) and ischemia time (21 min vs 24 min, P=0.006). Complication rates, blood loss, conversion rate, and decrease in glomerular filtration rate were similar in both groups. On univariate regression analysis, only warm ischemia time showed a significant trend with the overall NS (P=0.007) and the location score (P=0.031). CONCLUSIONS: A high NS was not associated with clinically worse outcomes during RAPN. Such renal tumors can still be excised safely with robotic assistance without adverse long-term effects.