Prediction of partial nephrectomy outcomes by using the diameter-axis-polar nephrometry score

Objectives: To evaluate the utility of diameter-axis-polar nephrometry score to evaluate partial nephrectomy outcomes.

Methods: Renal tumors of 127 patients with a functional contralateral kidney who underwent partial nephrectomy were scored using the diameter-axis-polar and R.E.N.A.L nephrometry scores. The mean tumor diameter was 2.9 cm (range 1.0-8.0 cm) and warm ischemic time was 27.3 min (range 12-46 min). All patients underwent (99m)Tc- mercaptoacetyltriglycine renal scintigraphy preoperatively and 6 months postoperatively to assess effective renal plasma flow. We compared nephrometry scores with estimated glomerular filtration rate, effective renal plasma flow and ischemic time.

Results: The mean serum creatinine level was 0.84 mg/dL preoperatively and 0.93 mg/dL at 6 months postoperatively. The mean estimated glomerular filtration rate decreased from 74.2 to 66.9 mL/min/1.73 m(2) . Effective renal plasma flow of the operated kidney decreased to 73.5% from baseline (from 157.0 to 114.3 mL/min/1.73 m(2)). Univariate and multivariate analyses showed that diameter-axis-polar score had a stronger association with the percent change in estimated glomerular filtration rate, effective renal plasma flow in the treated kidney and ischemia time compared with the R.E.N.A.L score.

Conclusions: Diameter-axis-polar nephrometry score is a useful tool for the assessment of small renal tumors amenable to partial nephrectomy, and it better predicts postoperative functional changes and ischemic time compared with the R.E.N.A.L nephrometry score.