MDRD versus CKD-EPI equation to estimate glomerular filtration rate in kidney transplant recipients

BACKGROUND: The new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-based equation was developed to address the systematic underestimation of the glomerular filtration rate (GFR) by the Modification of Diet in Renal Disease (MDRD) Study equation in patients with a relatively well-preserved kidney function. The performance of the new equation for kidney transplant recipients is discussed. METHODS: We analyzed the performances of the CKD-EPI equation in comparison with the MDRD Study equation in 825 stable kidney transplant recipients. Bias, precision, and accuracy within 30% of true GFR were determined. GFR was measured by urinary clearance of inulin (n=488) and plasma clearance of ⁵¹Cr-EDTA (n=337). RESULTS: Mean measured GFR (mGFR) was 50±19 mL/min/1.73 m². On the whole cohort, bias was significantly lower for MDRD Study equation compared with CKD-EPI creatinine. This superiority translates into a better accuracy (80% and 74% for the MDRD and CKD-EPI creatinine, respectively). The best performance of the MDRD Study equation is confirmed both in the subgroups of patients with mGFR <60 mL/min/1.73 m² and between 60 and 90 mL/min/1.73 m². For mGFR >90 mL/min/1.73 m², there were no significant differences between the two equations in terms of performance. CONCLUSIONS: The CKD-EPI creatinine equation does not offer a better GFR prediction in renal transplant patients compared with the MDRD Study equation, even in the earlier CKD stages.