CKD-EPI instead of MDRD for candidates to kidney donation

The determination of the glomerular filtration rate (GFR) is critical for the selection of a potential kidney donor. The complex and impractical techniques for the measurement of GFR have led to the development of equations to estimate GFR. Modification of diet in renal disease (MDRD) formula is the most widely used but its performance is poor because it systematically underestimates GFR above 60 mL/min. A new formula called the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) seems to overcome this limitation but needs to be tested in healthy potential kidney donors.

From 2007 to 2011, a cross-sectional study was performed on 85 adults who were candidates for living-related kidney donation. GFR was measured by nonradiolabeled iothalamate clearance determined by high-performance liquid chromatography, and renal function was estimated by using CKD-EPI and MDRD equations. The overall performance of the equations was analyzed, and the estimation for GFR above 90 mL/min was studied by means of receiver operating characteristic curves.

The mean (SD) (range) of the measured GFR was 116 (24) (64-160) mL/min per 1.73 m(2), estimated GFR with CKD-EPI was 108 (22) (64-153) mL/min per 1.73 m(2), and MDRD was 99 (28) (46-157) mL/min per 1.73 m(2). CKD-EPI presented lower bias (3.3 vs. 10.2 mL/min/1.73 m(2)), higher precision [interquartile range (minimum value-maximum value), 25 (53-140) vs. 32 (43-161) ml/min] and higher accuracy (100% vs. 89%) compared with MDRD.

The CKD-EPI equation showed a higher performance than the MDRD equation in the GFR estimation of healthy population. CKD-EPI is applicable instead of MDRD, to subjects or candidates for kidney donation to avoid wrong GFR underestimates, which may lead to an inappropriate exclusion of candidates.