Prediction of perioperative outcomes following minimally invasive partial nephrectomy: role of the RENAL nephrometry score

Objective characterization of renal mass anatomy facilitates treatment selection and prediction of surgical outcomes. We investigated R.E.N.A.L nephrometry score (NS) efficacy in predicting outcomes after minimally invasive nephron-sparing surgery (MINSS). A total of 250 patients with 252 renal masses underwent MINSS by a surgeon between January 2003 and July 2011. Preoperative films were available for 181 (72 %) renal masses, which were retrospectively assigned a NS. NS was categorized as low, moderate or high, reflecting tumor complexity. Perioperative outcomes were analyzed by NS category. Outcomes for laparoscopic (LPN) versus robotic (RALPN) partial nephrectomy were compared. Multivariable regression was used to investigate predictors of postoperative complications. Among 181 renal masses, 128 (71 %) were managed by LPN and 53 were (29 %) by RALPN. And 103, 74 and 4 renal lesions were low, medium and high complexity, respectively. For low versus medium versus high NS, respective overall complication rate was 5.8 versus 16.0 versus 50.0 % (p = 0.01); mean warm ischemia time (WIT) was 29 versus 33 versus 39 min (p = 0.02); and transfusion rate was 5/103 (4.8 %) versus 6/74 (8.1 %) versus 1/4 (25 %) (p = 0.20). NS category was significantly associated with overall complication rate (p = 0.04) and Clavien grade III complication rate (p = 0.05). Nearness to the collecting system ("N") was significantly associated with overall complications (p = 0.02) and postoperative hemorrhage (p = 0.02). Postoperative outcomes for LPN versus RALPN were statistically similar across all categories. R.E.N.A.L NS is predictive of overall complications and WIT during MINSS. Our data also suggest that "N" score may be used as a single predictor of overall complications and postoperative hemorrhage following MINSS.