Predicting trifecta outcomes after robot-assisted nephron-sparing surgery: Beyond the nephrometry score.

Purpose: RENAL nephrometry score (RNS) was devised for deciding the approach for renal tumors. It is increasingly used in predicting perioperative outcomes with variable results. The actual difficulty encountered during surgery depends on a number of other variables. The main purpose of this prospective study was to identify these variables which are not addressed by current RNS. Materials and Methods: Forty-nine patients undergoing robotic nephron sparing surgery from January 2015 onward were included. RNS was calculated from the imaging. Operating surgeon rated each surgery on a Likert scale of 0-4 after the completion of the procedure. The questionnaire was pre-validated in 5 cases before administration. The correlation between the surgeon rating and RNS with perioperative parameters and trifecta outcomes were calculated. Results: Forty-seven percent surgeries were rated easy, and 53.0% were rated as difficult. Surgeries for hilar, posterior location and presence of supernumerary vessels were found to be the a cause of difficulty. Trifecta outcomes were achieved in 37/49 patients (75.5%). The mean rating was 2.580±0.900 in trifecta negative patients while it was 1.410±0.832 in trifecta positive patient (p<0.0001). Surgeon's rating correlated positively with trifecta outcomes (likelihood ratio=15.75, p=0.006). Conclusions: The RNS remained a useful tool for determining renal tumor complexity. The intraoperative difficulty faced by the surgeon can be rated which can better predict perioperative trifecta outcomes. A useful predicting tool can be developed using the two parameters (RNS and surgeon rated difficulty).