New Chronic Kidney Disease and Overall Survival After Nephrectomy for Small Renal Cortical Tumors

ObjectiveTo evaluate kidney functional and overall survival (OS) outcomes in a cohort of patients who underwent partial nephrectomy (PN) or radical nephrectomy (RN) for tumors ≤4 cm.Materials and MethodsWe performed a retrospective study on 2110 patients who underwent PN or RN with normal contralateral kidneys and normal serum creatinine from 1989 through 2012. Estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Primary end points were baseline incidence of CKD, OS, and new onset of eGFR ≤60 and ≤45 mL/min/1.73 m2.ResultsPreoperatively, 30% and 8% of the cohort had eGFR ≤60 and ≤45 mL/min/1.73 m2, respectively. Five-year freedom from eGFR ≤60 mL/min/1.73 m2 was 24% (95% confidence interval [CI], 19%-30%) and 76% (95% CI, 72%-78%) for RN and PN, respectively, and 5-year freedom from eGFR ≤45 mL/min/1.73 m2 was 51% (95% CI, 45%-56%) and 91% (95% CI, 89%-93%) for RN and PN, respectively. On multivariable analysis, hazard ratio for RN vs PN was 4.98 (95% CI, 4.11-6.04, P <.0001) for new onset of eGFR ≤60 mL/min/1.73 m2 and 9.28 (95% CI, 7.26-11.86, P <.0001) for new onset of eGFR ≤45 mL/min/1.73 m2. The RN group had a higher rate of death per year than the partial group (hazard ratio = 1.61, 95% CI, 1.24-2.08, P = .0003).ConclusionThe present study confirms published works demonstrating that a significant proportion of patients have pre-existing CKD. In patients with normal kidney function, RN is associated with a significantly higher risk for developing CKD and worse OS than PN.