Preoperative proteinuria correlates with renal function after partial nephrectomy for renal cell carcinoma

Purpose: Preoperative proteinuria is a prognostic factor of chronic kidney disease (CKD). We assessed the association between preoperative proteinuria and postoperative renal function after partial nephrectomy (PN). Methods: We retrospectively reviewed our records of patients with a single malignant renal mass who underwent PN between 2000 and 2021. Patients with data on preoperative proteinuria were included. Baseline characteristics and eGFR differences over time between patients with and without proteinuria were evaluated. Univariate and multivariable logistic regression models (LRM) tested for presence of CKDIII or higher at 12-month and at last follow-up. Results: Two hundred ninety-five patients were included. Twenty-two of them had preoperative proteinuria. No differences of age, smoking status, hypertension or diabetes, tumor size and use of ischemia were observed. Patients with proteinuria had a higher rate of CKD-III at baseline. At a median follow-up of 46.5 months (IQR 19-82), 117 patients developed de novo CKD-III, without differences in the two groups. No differences in decline in eGFR were observed. At univariate LRM, predictors of CKD-III at 12 months after PN were preoperative proteinuria (OR 3.2, 95%CI 1.4-7.8, p = 0.005), age and baseline eGFR, while predictors of CKD-III at last follow-up were age and baseline eGFR. At multivariable LRM, only baseline eGFR predicted CKD-III at 12-month and at last-follow-up. Conclusions: Preoperative eGFR is the only independent predictor of long-term renal function after PN. Preoperative proteinuria correlates with renal function at 12 months. Proteinuria should be assessed before PN to identify patients at higher risk of renal functional deterioration in the 12 months following PN.