EditorialEstimating GFR Using the CKD Epidemiology Collaboration (CKD-EPI) Creatinine Equation: More Accurate GFR Estimates, Lower CKD Prevalence Estimates, and Better Risk Predictions
Section snippets
Accuracy
GFR estimating equations are derived from regression analysis in which the level of measured GFR is related to the serum concentration of an endogenous filtration marker and to observed clinical and demographic variables that serve as surrogates for the non-GFR determinants of the serum concentration. Age, sex, race, and body weight are surrogates for creatinine generation from muscle, which affects serum creatinine concentration independently from GFR. In principle, GFR estimating equations
Detecting Disease
In principle, decreased GFR in acute and chronic kidney diseases is preceded by alterations in structure that can be detected by pathologic disturbances or markers of kidney damage. Biopsies are usually not obtained in clinical practice and markers of kidney damage are not sensitive; thus, in many patients decreased GFR is the earliest sign of kidney disease. Widespread reporting of estimated GFR using the MDRD Study equation simplifies the detection of CKD defined as GFR <60 mL/min/1.73 m2 [<1
Predicting Prognosis
Decreased GFR is now a well-established risk factor for cardiovascular disease and mortality, as well as for kidney failure. There has been much debate about whether increased risk is apparent for people with CKD stage 3a.25, 26 The ARIC and AusDiab studies reported events during follow-up intervals of 16.9 and 7.5 years, respectively.5, 6 In both studies, the individuals reclassified from CKD stage 3a using the MDRD Study equation to no CKD using the CKD-EPI equation had lower risk than those
Guiding Therapy
There have been few studies comparing the effect of estimating equations on clinical decisions regarding therapy. Since 1998, the US Food and Drug Administration (FDA) has recommended using the Cockcroft-Gault equation for pharmacokinetic studies during drug development to guide dosing in patients with decreased kidney function.27 Since then, the availability of more accurate creatinine assays and kidney function estimating equations has led to reassessment of clinical recommendations and FDA
Conclusions
The CKD-EPI creatinine equation is currently the most accurate method for estimating GFR for diverse populations. The results of the ARIC and AusDiab studies in this issue of AJKD demonstrate some of the useful applications of more accurate GFR estimates. Compared with the MDRD Study equation, the CKD-EPI equation permits more accurate GFR estimation, fewer false-positive diagnoses of CKD, lower prevalence estimates for CKD, and more accurate risk prediction for adverse outcomes. This
Acknowledgements
Aghogho Okparavero, MD, MPH assisted in manuscript preparation.
Financial Disclosure: Dr Levey was principal investigator of the Chronic Kidney Disease Epidemiology Collaboration, is funded by the National Institute of Diabetes and Digestive and Kidney Diseases, and is Editor-in-Chief of the American Journal of Kidney Diseases. Dr Stevens was coinvestigator for the Chronic Kidney Disease Epidemiology Collaboration.
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