The Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration Formulas Versus Measured or Estimated Creatinine Clearance in Kidney Transplant Recipients

BackgroundEstimation of glomerular filtration rate (eGFR) after renal transplantation is performed with the use of methods that are standardized for a population of nontransplantation patients with chronic kidney disease. The aim of the study was to compare the performance of GFR estimation formulas in renal transplant recipients.MethodsThe Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas were compared with measured creatinine clearance or clearance estimated by the Cockroft-Gault (C-G) formula. The influence of age, body mass index, and eGFR on the relative performance of these formulas also was studied by subgroups analysis.ResultsMean measured or estimated creatinine clearance overestimates the values of GFR calculated using the MDRD or CKD-EPI equation. This was statistically significant (P < .05) in whole-study population and in subgroups of patients at age above 25 years, with body mass index above 25, and in a subgroup with eGFR-MDRD <50 mL/min/m2. The mean bias from creatinine clearance was 7.46 mL/min for MDRD, 4.4 mL/min for CKD-EPI and −1.65 mL/min for C-G formula. There was a statistically significant (P < .05) negative correlation between eGFR value and bias from creatinine clearance for all 3 methods of estimation. The correlation coefficient was −0.4 for MDRD, −0.36 for CKD-EPI, and −0.46 for C-G clearance.ConclusionsMeasured and estimated creatinine clearance overestimate values of eGFR calculated by the MDRD or CKD-EPI formula in a population of kidney transplant recipients, especially in subjects with obesity and worse renal function. Accuracy of analyzed GFR estimation formulas decreases with deterioration of renal graft function.