Critical Appraisal of the PADUA Classification and Assessment of the RENAL Nephrometry Score in Patients Undergoing Partial Nephrectomy

Purpose: We validated the PADUA classification and assessed the R.E.N.A.L. nephrometry score to predict perioperative complications of partial nephrectomy. In addition, we assessed their interobserver variability, and the ability to predict the use of ischemia and ischemia time. Materials and Methods: Data from consecutive cases of partial nephrectomy with or without ischemia from 3 centers were retrospectively collected. Associations between preoperative variables and complications were evaluated in univariate and multivariate analyses. Reproducibility was assessed by determining Fleiss' generalized kappa and intraclass correlation coefficients in a subcohort scored by 3 physicians with different degrees of urological expertise. Results: A total of 134 partial nephrectomies were included in the study and 31 cases (23%) presented with complications. On univariate analyses complications were associated with age (p = 0.02), tumor size on computerized tomography (p = 0.01), pT stage (p = 0.001), and PADUA (p = 0.001) and R.E.N.A.L. scores (p = 0.02). In 3 multivariate models PADUA score 10 or greater (OR 3.98, p = 0.01), R.E.N.A.L. score 9 or greater (OR 4.21, p = 0.02), tumor size in cm (OR 1.35, p = 0.02) and age (OR 1.04, p = 0.04) were independent predictors of complications. The R.E.N.A.L. nephrometry score predicted the use of ischemia (p = 0.03) and both scores predicted ischemia time (both p < 0.001). Kappa was 0.37 to 0.80 for PADUA components and 0.23 to 0.73 for R.E.N.A.L. components. The intraclass correlation coefficient was 0.73 for PADUA and 0.70 for R.E.N.A.L. score. Conclusions: The highest categories of PADUA and R.E.N.A.L. scores as well as clinical tumor size predict the risk of perioperative complications of partial nephrectomy. Both scores can indicate ischemia time. Their reproducibility is substantial but the implementation of these systems in clinical practice needs further refinement.