A Critical Appraisal of Nephrometry in Robot-Assisted Partial Nephrectomy: Why the RPN Score Outperforms R.E.N.A.L....

To critically appraise the Radius, Exophytic/endophytic, Nearness of tumor to collecting system or sinus, Anterior/posterior, Location relative to polar lines (R.E.N.A.L.), Preoperative Aspects and Dimensions Used for an Anatomical classification (PADUA), and Radius, Position, iNvasion of sinus (RPN) nephrometry systems with respect to their classification of tumor complexity for surgical planning in robot-assisted partial nephrectomy (RAPN) and to compare their statistical validity, methodological rigor, and predictive performance.

A structured synthesis of published evidence identified large multicenter series, prospective cohorts, and meta-analyses from 2009 to 2025 that evaluated the predictive accuracy, methodological design, and clinical relevance of these systems. Key evaluation domains included statistical validation, anatomical parameter selection, and correlation with surgeon-perceived difficulty in RAPN.

Both the R.E.N.A.L. and PADUA scores were developed using empirically selected parameters and have historically been validated based on their correlation with perioperative outcomes. However, evidence in the literature now shows that such correlations are inconsistent and often clinically irrelevant in RAPN. In contrast, the RPN score was developed using a statistically modeled approach, reflecting the real-world surgical difficulty of RAPN as perceived by experienced robotic surgeons.

Current evidence does not support the continued use of R.E.N.A.L. and PADUA scores as validated tools in RAPN. The RPN score, with its statistically validated, anatomy-based methodology and alignment with surgical difficulty, represents a scientifically superior and clinically practical alternative for standardizing tumor complexity in RAPN.