The estimation of glomerular filtration rate in an Australian and New Zealand cohort

Abstract

Background: Accurate estimation of glomerular filtration rate (GFR) allows early detection of renal disease and maximizes opportunity for intervention.

Aim: To assess the accuracy of estimated GFR (eGFR) in an Australian and New Zealand cohort with chronic kidney disease using the 4-variable Modification of Diet in Renal Disease equation (MDRD(4V)), the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, and the Cockcroft and Gault equation with actual and ideal body weight.

Methods: Retrospective review of patients who had measured GFR (mGFR) by 51Cr-EDTA clearance and simultaneous measurements of serum biochemistry and anthropometrics. eGFR was compared with mGFR using the concordance correlation coefficient (CCC) and Bland-Altman measures of agreement.

Results: 178 patients had 441 radioisotope measurements of GFR. Mean mGFR of was 22.6 mL/min per 1.73 m(2) . The MDRD(4V) equation using the 'black' correction factor was most accurate with a mean eGFR of 19.74 (CCC 0.733, bias -2.86). The CKD-EPI equations also using the 'black' correction factors were almost as good at 19.11 (CCC 0.719, bias -3.49). The Cockcroft-Gault creatinine clearance values had the poorest agreement with mGFR. In the 18 nonwhite non-Asian patients, the MDRD(4V) and CKD-EPI equations were generally less accurate although the use of the 'black' correction factor resulted in greater accuracy for both equations.

Conclusion: The MDRD(4V) equation was the most accurate. However, its accuracy might be less for nonwhite non-Asian patients if the 'black' correction factor is omitted. Further study of the estimation of GFR in Australian and New Zealand ethnic subgroups would be helpful.