Usefulness of the diameter–axial–polar nephrometry score for predicting perioperative parameters in robotic partial nephrectomy

Purpose: The present study aimed to verify the association between diameter–axial–polar (DAP) nephrometry and surgical outcomes, postoperative renal function, and perioperative complications in patients undergoing robotic partial nephrectomy (RPN). Methods: Diameter–axial–polar nephrometry was assessed using computed tomography or magnetic resonance imaging on 158 patients who received RPN between July 2007 and February 2013. Demographic data, surgical data, and perioperative complications were recorded, and percent change between the preoperative and last estimated glomerular filtration rate (eGFR) was determined. Linear regression analysis was conducted to assess the relationship between the DAP sum score and warm ischemia time (WIT), estimated blood loss (EBL), and percent decrease in eGFR. Multivariable linear regression analysis was conducted to determine the relationship between each DAP scoring parameter and surgical outcomes. Results: The median patient age was 50.5 years and median DAP sum score was 6. On linear regression, the DAP sum score was associated with WIT and EBL. On multivariable regression, all DAP parameters were associated with WIT, but the polar distance was not associated with EBL. Patients with a higher DAP sum score showed greater decrease in eGFR after RPN. Patients with a DAP sum score of 6 or higher had a higher risk of major complications than those with a DAP sum score below 6. Conclusions: Diameter–axial–polar nephrometry predicted WIT and EBL in patients who underwent RPN. It was also associated with the decrease in eGFR and rate of major perioperative complications, and thus can be useful for surgical planning or patient counseling before RPN.