Patient REnal and Tumor Attribute Score (PRETA Score): a comprehensive renal nephrometry score for use in patients with renal masses planned for minimally invasive nephron sparing surgery.

Few comprehensive nephrometry scoring systems correlate renal morphology and patient factors like presence of chronic kidney disease (CKD) with the trifecta outcomes after partial nephrectomy (PN). We have proposed a new nephrometry score that correlates these factors to perioperative outcomes in minimally invasive PN. Records of all patients who underwent robot assisted laparoscopic PN at our institute were retrospectively reviewed. Baseline patient characteristics and imaging features were noted. Centrality Index or C-Index score and Mayo Adhesive Probability (MAP) score were calculated. Intraoperative and post-operative outcomes along with trifecta outcomes of PN were also noted. A total of 63 patients underwent PN, of which 50 had positive and 13 had negative trifecta outcomes. A total of 22 patients developed post-operative complications, with the majority being Clavien-Dindo Grade 1 and Grade 2 complications. Size of the tumor, presence of CKD, Centrality Index, Mayo Adhesive Probability score, nearness to hilum, and presence of congenital anomaly of the kidney or solitary kidney were significant predictors of negative trifecta outcomes on multivariate analysis. Based on these parameters we developed the Patient REnal Tumor Attribute (PRETA) score. The score ranges from 6 to 14. Patients with a score of 6 were at low risk of negative trifecta outcomes, those with a score of 7-10 were at moderate risk, and those with a score > 10 were at high risk. Prospective validation of this score was then done on the next 15 consecutive PN patients. In developing this score, we have done away with redundant parameters and have incorporated patient factors which have an important effect on patient outcomes after minimally invasive PN.