Impact of the CKD-EPI Equation for Estimating Renal Function on Eligibility for Cisplatin-based Chemotherapy in Patients With Urothelial Cancer

BackgroundAlthough a creatinine clearance (CrCl) of <60 mL/min, as calculated by the Cockroft-Gault (CG) equation, is a commonly used threshold for “cisplatin-ineligibility,” the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has recently emerged as a more accurate method of estimating renal function. We sought to determine the impact of using the CKD-EPI equation for estimating renal function on cisplatin eligibility.MethodsAll patients pathologically diagnosed with muscle invasive and/or metastatic bladder urothelial carcinoma (T2-4, N or M positive) at Mount Sinai Medical Center between January 1, 2000, and January 27, 2011, were identified. For each patient, CrCl was estimated by using the CG equation and glomerular filtration rate (GFR) was estimated by using the CKD-EPI equation. The patients were considered cisplatin-ineligible if CrCl <60 mL/min or if GFR was <60 mL/min per 1.73 m2.ResultsA total of 116 patients were included. The median CrCl estimated by CG was 58.93 mL/min, whereas the median GFR estimated by CKD-EPI was 64.67 mL/min per 1.73 m2. When using the CG formula, 53% of our cohort was cisplatin ineligible, whereas 46% of the cohort was ineligible when using the CKD-EPI formula. The probability of deeming a patient ineligible when using the CG formula was 17% higher than the probability of deeming a patient ineligible when using the CKD-EPI formula: PR 1.17 (95% CI, 1.03-1.34); P = .0203.ConclusionIn our retrospective study, the CKD-EPI formula was less likely to deem a patient ineligible for cisplatin-based therapy compared with the CG formula. This finding was hypothesis generating, and prospective evaluation is necessary to determine the clinical relevance of using this more accurate method of renal function assessment in chemotherapy decision making.