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.