Interobserver reproducibility of RENAL nephrometry score in comparison to simplified PADUA Renal nephrometry score.

Introduction: Nephron-sparing surgery (NSS) is the standard of care for renal tumors, especially in the early stages. RENAL Nephrometry scores provide a comprehensive presurgical predictive module for the choice of NSS or Radical Nephrectomy. The validity and reliability of Nephrometry scores is being tested continuously with advancement in the surgical techniques. The Simplified PADUA Nephrometry score (SPARE NS) is a newer proposed score which aims to better the reproducibility of the previously established nephrometry scores. Materials and Methods: The retrospective observational study studied the comparative inter-observer reliability of RENAL (RENAL NS) and SPARE nephrometry scoring systems amongst two radiologists while assessing solid renal tumors in contrast-enhanced computed tomography scans of 42 patients. Interobserver reliability for all components of both scores, final scores and risk grading was done by Kendall's Concordance Coefficient (Tau). Results: Both RENAL NS and SPARE NS showed strong to excellent agreement (RENAL NS = 78.57% and SPARE NS = 88.09%) among observers with comparable correlation co-efficient (RENAL NS = 0.944 and SPARE NS = 0.935). Lesion radius and exophytic/endophytic properties were the most reproducible components of RENAL NS with 97.61% and 92.85% agreement, respectively. Location across polar lines was the least reproducible component with 85.71% agreement among observers. Exophytic rate (97.61%) and Rim location were the most reproducible components of SPARE NS. The final lesion risk stratification by both observers for both was concordant in 92.85% of cases. Conclusion: The SPARE system of scoring matches up to the RENAL NS in total score and risk stratification reproducibility. However, the individual components of the SPARE score are more reproducible than those of RENAL NS, bringing about better compliance among radiology consultants. Comparable reproducibility with the RENAL NS, lesser number of variables, and ease of doing make SPARE NS a plausible option for the customary preoperative assessment of renal tumors.