Objectives: To analyze long-term changes in both kidneys, and to predict renal function and contralateral hypertrophy after robot-assisted partial nephrectomy. Methods: A total of 62 patients underwent robot-assisted partial nephrectomy, and renal parenchymal volume was calculated using three-dimensional semi-automatic segmentation technology. Patients were evaluated within 1month preoperatively, and postoperatively at 6months, 1year and continued up to 2-year follow up. Linear regression models were used to identify the factors predicting variables that correlated with estimated glomerular filtration rate changes and contralateral hypertrophy 2years after robot-assisted partial nephrectomy. Results: The median global estimated glomerular filtration rate changes were -10.4%, -11.9%, and -2.4% at 6months, 1 and 2years post-robot-assisted partial nephrectomy, respectively. The ipsilateral kidney median parenchymal volume changes were -24%, -24.4%, and -21% at 6months, 1 and 2years post-robot-assisted partial nephrectomy, respectively. The contralateral renal volume changes were 2.3%, 9.6% and 12.9%, respectively. On multivariable linear analysis, preoperative estimated glomerular filtration rate was the best predictive factor for global estimated glomerular filtration rate change on 2years post-robot-assisted partial nephrectomy (B -0.452; 95% confidence interval -0.84 to -0.14; P=0.021), whereas the parenchymal volume loss rate (B -0.43; 95% confidence interval -0.89 to -0.15; P=0.017) and tumor size (B 5.154; 95% confidence interval -0.11 to 9.98; P=0.041) were the significant predictive factors for the degree of contralateral renal hypertrophy on 2years post-robot-assisted partial nephrectomy. Conclusions: Preoperative estimated glomerular filtration rate significantly affects post-robot-assisted partial nephrectomy renal function. Renal mass size and renal parenchyma volume loss correlates with compensatory hypertrophy of the contralateral kidney. Contralateral hypertrophy of the renal parenchyma compensates for the functional loss of the ipsilateral kidney.
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© 2015 The Japanese Urological Association.