Abstract

Estimates of glomerular filtration rate (eGFR) help assess kidney function. Estimated GFR can be used to classify patients into one of six Chronic Kidney Disease (CKD) categories as recommended by the Kidney Disease Improving Global Outcomes clinical practice guidelines; CKD1 ≥90, CKD2 60–89, CKD3a 45–59, CKD3b 30–44, CKD4 15–29 or CKD5 ≤15 mL/min/1.73 m². The Modification of Diet and Renal Disease (MDRD) study formula was widely adopted to calculate eGFR. The CKD Epidemiology Collaboration (CKD-EPI) formula improved accuracy of CKD staging at eGFR ≥60 mL/min/1.73 m². MDRD and CKD-EPI eGFR were calculated on 111 444 serum creatinine results from adult patients measured as part of the routine Clinical Chemistry service. Application of CKD-EPI eGFR reclassified 18% to a lower (13.9%) or higher (4.0%) CKD stage. CKD staging was lower when <65 years and higher when ≥65 years. Females were more often reclassified compared with males (2.6% vs 0.8%). Overall, CKD-EPI eGFR classified less with CKD (stages 3a-5), unless ≥75 years. Older males and inpatients had higher CKD stages when CKD-EPI eGFR was applied. It has been recommended to replace MDRD eGFR with CKD-EPI eGFR. In general, doing this will have little impact, however, for some patients their CKD classification will be different.