Are the Formulas Used to Estimate Renal Function Adequate for Patients Treated With Cisplatin-Based Chemotherapy After Nephroureterectomy for Upper Tract Urothelial Carcinoma?

There is no established method for calculating renal function in patients with upper tract urothelial carcinoma that are treated with radical nephroureterectomy followed by cisplatin-based chemotherapy. We compared the renal function values obtained using the Cockcroft-Gault, Modification of Diet in Renal Disease, Chronic Kidney Disease Epidemiology Collaboration, and Wright formulas with the endogenous creatinine clearance (eCrCl) values for the same patients. The 4 mathematical formulas were all found to underestimate eCrCl. The values obtained with the Wright formula were most closely associated with eCrCl. Objective The relationship between endogenous creatinine clearance (eCrCl) and renal function values obtained using mathematical formulas has not yet been fully elucidated, especially in patients with upper tract urothelial carcinoma that are treated with radical nephroureterectomy followed by cisplatin-based chemotherapy. Methods Sixty patients who received cisplatin-based chemotherapy for locally advanced or metastatic upper tract urothelial carcinoma after radical nephroureterectomy between 2000 and 2012 were retrospectively identified. eCrCl was measured based on 24-hour urine specimens obtained immediately prior to each cycle of chemotherapy. Renal function was estimated with 4 different formulas: the Cockcroft-Gault, Modification of Diet in Renal Disease, Chronic Kidney Disease Epidemiology Collaboration, and Wright formulas. We evaluated the relationship between eCrCl and the renal function values obtained with each formula using the Pearson correlation coefficient and κ statistics. Results The median eCrCl was 53.9 mL/min. The Pearson correlation coefficients and κ statistics for the relationships between eCrCl and the renal function values obtained with each of the mathematical formulas ranged from 0.600 to 0.763 and from 0.29 to 0.67, respectively. Among the patients with eCrCl of ≥ 60 mL/min, 70%, 60%, 50%, and 20% were estimated to have the renal function values of < 60 mL/min by the Cockcroft-Gault, Modification of Diet in Renal Disease, Chronic Kidney Disease Epidemiology Collaboration, and Wright formulas, respectively. Conclusions All 4 of the tested formulas underestimated eCrCl. The values obtained with the Wright formula were most closely associated with eCrCl.