Association of preoperative proteinuria with renal functional outcomes after open partial nephrectomy in patients with an anatomically or functionally solitary kidney

Purpose: Nephron-sparing surgery is required for patients with an anatomically or functionally solitary kidney, for postoperative renal function optimization. Open partial nephrectomy in the solitary kidney is associated with reliable, long-term renal function, preventing progression to dialysis. Therefore, we aimed to identify the preoperative factors associated with renal function decline after open partial nephrectomy.

Materials and Methods: Patients who underwent open partial nephrectomy for a renal tumor at our institution between 1986 and 2014, excluding those who underwent ex vivo partial nephrectomy, were retrospectively analyzed. Multivariate linear regression analysis was used to test associations of a postoperative decrease in the estimated glomerular filtration rate (eGFR) with perioperative conditions such as the preoperative eGFR, preoperative proteinuria, tumor size, and intraoperative renal ischemia time. Survival rates were analyzed using the Kaplan-Meier method and log-rank statistics.

Results: In total, 83 patients were included in this study; 5 were excluded. The median follow-up period for the remaining 78 patients was 34 months. The mean preoperative eGFR, tumor diameter, operative time, renal ischemic time, and estimated blood loss were 51±14 ml/min/1.73 m² , 34±22 mm, 243±62 minutes, 41±22 minutes, and 355±333 ml, respectively. In 18 patients (23%), the postoperative eGFR was <30 ml/min/1.73 m² 12 months after surgery. Only 1 patient needed chronic hemodialysis 12 months after surgery. On multivariate analysis, preoperative proteinuria (odds ratio [OR] 8.7, 95% confidence interval [CI] 1.6–58.8, P=0.01) and eGFR (OR 0.83, 95% CI 0.74–0.91, P=0.001) were significant predictors of a decrease in eGFR to <30 ml/min/1.73 m² after surgery. The probability of freedom from eGFR <30 ml/min/1.73 m² after 24 months was higher in patients without preoperative proteinuria (76% vs. 94%, P=0.0027).

Conclusion: Preoperative proteinuria could help stratify patients according to the risk of renal function exacerbation.