External validation of RENAL nephrometry score to assess the perioperative parameter for laparoscopic partial nephrectomy in a single institution

Objective: RENAL nephrometry score (RNS) has been proposed as an anatomical classification system for renal masses to investigate the influence on perioperative outcomes and complications. The aim of this study was to assess the system for external validation on laparoscopic partial nephrectomy (LPN). Materials and methods: The single-surgeon database enrolled patients who had undergone LPN from December 2008 to September 2013. Renal tumors were divided into low-, intermediate-, and high-complexity groups according to the RNS sum score. We reviewed perioperative outcomes including operation time (OT), length of stay (LOS), estimated blood loss (EBL), ischemia time (IT), conversion to open surgery rate, estimated glomerular filtration rate (eGFR), and complications. We also assessed the individual characteristic parameters in the present study. The data was collected retrospectively and analyzed by SPSS Statistics 18. Results: A total of 53 patients were enrolled, with a mean age of 49.2 years. Of the 53 patients, there were 15 low-, 26 intermediate-, and 12 high-RNS lesions. Significant difference was observed in major complication rate between low- and high-score groups. Both radius and nearness were independent predictors of major complication rate. Also, there was a significant difference in eGFR change between low- and high-complexity tumor group. Fair degree correlation was found between IT and eGFR change (p < 0.05). Conclusion: The RNS is a valuable tool to categorize renal tumors based on the anatomic features when predicting major complication rate. The renal function can be affected after a high-complexity tumor surgery is performed. Also, IT is a fair degree correlation factor of the renal function loss