R.E.N.A.L. Nephrometry scoring: how well correlated are urologist, radiologist, and collaborator scores?

R.E.N.A.L. Nephrometry Score (NS) is an imaging-based (CT/MRI) scoring system commonly used by urologists to standardize the reporting of renal masses by enabling quantification of anatomical characteristics. We sought to examine the inter-rater correlation of NS between urologists, radiologists, and tumor-board collaborators.

We identified adult patients undergoing partial or radical nephrectomy over 10 years (n=2450). Patients with autosomal dominant polycystic kidney disease (ADPKD), metastatic disease, masses >10 cm, and studies in which the study urologists or radiologists partook in patient care were excluded. Preoperative imaging was evaluated and patients with multiphasic CT available were included. Scans were provided to the reviewers to evaluate with a R.E.N.A.L. nephrometry questionnaire. Results were analyzed using kappa correlation coefficients.

One hundred twenty patients met inclusion criteria with mean age of 59.5 years. The majority of cases were partial nephrectomies (72%). Eighty-five percent of the tumors were malignant, with 26% having high-grade histology. The mean (standard deviation) overall NS was 6.8 (1.9) with fair correlation among reviewers (κ=0.222). Collaborators had the highest inter-rater correlation, ranging from 0.41 to 0.84 for NS component scores, compared with 0.42-0.85 for radiologists and 0.36-0.86 for urologists. "R" scores were best correlated (κ>0.8). NS correlation ranged between 0.16 and 0.31 for the groups while the NS complexity category correlation ranged between 0.50 and 0.61.

Despite being naive to NS, inter-radiologist scoring patterns were better correlated than inter-urologist. The urologist and radiologist collaborating in tumor board showed the highest agreement, suggesting that a multidisciplinary approach in the characterization of renal masses may provide benefit to patient management.