Association of Urine Dipstick Proteinuria and Postoperative Renal Function Following Robotic Partial Nephrectomy

Introduction: In patients with normal estimated renal function before robot-assisted partial nephrectomy (RPN), there is still a risk for de Novo chronic kidney disease (CKD). We assessed the role of dipstick spot proteinuria in risk stratifying patients for CKD progression. Materials and Methods: From our prospectively maintained, institutional review board-approved database of patients undergoing RPN, we queried those with estimated glomerular filtration rate (eGFR) >60 and bilateral functional units. We assessed proteinuria through dipstick (trace or above) on voided urine in preoperative urologic appointment <3 weeks before RPN. Proteinuric patients were compared with the remainder of the cohort with parametric comparisons for continuous and chi-squared analysis for categoric variables. Multivariate logistic regression analyses were performed assessing the risk of de Novo CKD stage III development, estimated by the CKD-EPI equation. Results: We found 269 patients with eGFR >60 preoperatively, of whom 57 (21%) had proteinuria preoperatively. In univariate analysis, these patients were more likely to be diabetic (p = 0.023) and to be on an angiotensin converting enzyme inhibitor or angiotensin receptor blocker (p = 0.001) but had similar age (p = 0.13), body mass index (p = 0.09), and tumor size (p = 0.56) with similar rates of hypertension (p = 0.07). At a median 16 months, controlling for confounding variables, preoperative proteinuria on urinary dipstick was associated with a 2.3× (95% confidence interval 1.03-4.95) increased risk of de Novo CKD stage III progression. Conclusions: Patients with proteinuria preoperatively, despite a normal eGFR, likely have intrinsic medicorenal disease. These patients should be counseled preoperatively that they have a higher risk of CKD progression following RPN.