Accuracy of R.E.N.A.L. nephrometry score in predicting perioperative outcomes of minimally invasive partial nephrectomy: impact of different surgical techniques.

Background: Previous studies have demonstrated the ability of the R.E.N.A.L. (Radius, Exophytic/Endophytic, Nearness, Anterior/Posterior, Location) nephrometry score to predict perioperative outcomes, but those studies have not considered the impact of different surgical approaches on predictive accuracy. Therefore, this study aimed to evaluate whether different minimally invasive surgical techniques affect the accuracy of the R.E.N.A.L. score in predicting perioperative outcomes, particularly the achievement of trifecta.

Methods: We conducted a retrospective analysis of clinical data from 623 patients who underwent robot-assisted partial nephrectomy (RAPN) or laparoscopic partial nephrectomy (LPN) in our clinical institution. Correlations between the R.E.N.A.L. score and operative time (OT), length of stay (LOS), estimated blood loss (EBL), change in estimated glomerular filtration rate (eGFR), postoperative complications, and time of drain removal were calculated. Logistic regression analysis was used to identify predictors of achieving trifecta outcomes in both surgical groups. The Simplified PADUA REnal (SPARE) nephrometry system was used as a control to compare with R.E.N.A.L. score.

Results: In the RAPN group, both the R.E.N.A.L. score and grade showed a strong correlation with postoperative outcomes. However, in the LPN group, R.E.N.A.L. grade was not statistically correlated with OT (P=0.07) or postoperative complications (P=0.08), and the SPARE score showed no correlation with change in eGFR (P=0.69). Additionally, SPARE grade was not correlated with change in eGFR (P=0.57) or postoperative complications (P=0.28). In both univariate and adjusted multivariable logistic regression models, the R.E.N.A.L. score was an independent predictor of achieving trifecta in the RAPN group, but it was not a predictor in the LPN group. The SPARE score exhibited similar differential predictive validity between the two surgical techniques. In the RAPN group, the area under the receiver operating characteristic (ROC) curves (AUCs) for predicting trifecta achievement were 0.643 for the R.E.N.A.L. score and 0.613 for the SPARE score.

Conclusions: The R.E.N.A.L. score is an effective tool for preoperatively assessing the complexity of renal masses. However, different surgical techniques can influence the predictive accuracy of the R.E.N.A.L. score, with it being more accurate in predicting trifecta achievement following RAPN compared to LPN.