Interdisciplinary Comparison of PADUA and R.E.N.A.L. Scoring Systems for Prediction of Conversion to Nephrectomy in Patients with Renal Mass Scheduled for Nephron Sparing Surgery

We examined interdisciplinary variability using 2 established preoperative nephrometry scores to predict conversion to nephrectomy in patients with a renal mass who were scheduled for partial nephrectomy.A total of 229 consecutive candidates for partial nephrectomy were included in this study at a single institution between January 2013 and May 2017. Patient, tumor and treatment characteristics were assessed. The PADUA (preoperative aspects and dimensions used for an anatomical) score and the R.E.N.A.L. (radius, exophytic/endophytic, nearness of tumor to collecting system or sinus, anterior/posterior, location relative to polar lines) score were independently calculated by board certified radiologists and urological residents using computerized tomography or magnetic resonance imaging. Statistical analyses were done with the κ statistic, ROC curves, and univariable and multivariable binary logistic regression analyses.Partial nephrectomy was performed in 198 of the 229 cases (86.5%) while 31 (13.5%) were converted to nephrectomy. The prevalent tumor stage was pT1a, noted in 94 of the 229 cases (41.1%), and the predominant histological entity was clear cell carcinoma, found in 128 (55.9%). Radiologist and urologist interdisciplinary comparison of the PADUA and R.E.N.A.L. scores revealed a κ of 0.40 and 0.56, respectively. ROC curve analyses demonstrated a higher AUC predicting conversion to nephrectomy using the PADUA score by the urologist and the radiologist (0.79 and 0.782) compared to that of the R.E.N.A.L. score (0.731 and 0.766, respectively). Using a cutoff of 10 or greater the PADUA score determined by the urologist had 81% sensitivity and 71% specificity, and it was independently associated with conversion to nephrectomy (OR 10.98, p<0.001).Our results indicate higher prediction of conversion to nephrectomy when using the PADUA score compared to the R.E.N.A.L. score. Calculation of the PADUA and the R.E.N.A.L. score by physicians without specialized radiological training is feasible and might achieve comparable results to predict conversion to nephrectomy compared to the gold standard provided by board certified radiologists. This information is helpful if nephrometry scores are not regularly included in the radiology report.