Significant impact of RENAL nephrometry score on changes in postoperative renal function early after robot-assisted partial nephrectomy

Our objective was to evaluate the significance of the R.E.N.A.L. nephrometry score (RNS)-developed to quantitatively evaluate the complexity of renal tumors in a reproducible manner-in perioperative and renal functional outcomes following robot-assisted partial nephrectomy (RAPN). This study assessed 48 consecutive patients with renal tumors who underwent RAPN. Preoperative RNS for each patient was calculated, and its impact on several parameters associated with perioperative outcomes, including postoperative renal function, was investigated with Spearman's rank correlation test. Mean RNS in the 48 patients was 6.8; of these 48 patients, 21 (43.7 %), 24 (50.0 %), and three (6.3 %) were classified into low-, moderate-, and high-complexity groups, respectively. The RNS was significantly correlated with resected tumor weight and postoperative changes in estimated glomerular filtration rate (eGFR) at both 1 and 4 weeks-but not age, body mass index (BMI), preoperative eGFR, operative time, warm ischemia time, estimated blood loss, postoperative complications, or eGFR- after RAPN. No component of the RNS (R: radius; E: exophytic/endophytic properties; N: nearness of tumor to the collecting system or sinus; A: anterior/posterior; L: location relative to polar lines) alone had a significant impact on postoperative changes in eGFR at 1 and 4 weeks, whereas resected tumor weight was significantly associated with the R and E subcategories. Measurement of total RNS is useful for predicting renal functional outcomes early after RAPN.