Kamyar Kalantar-Zadeh, M.D., M.P.H., Ph.D., principal investigator at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed), is the author of an invited editorial in JAMA. The editorial accompanied a study that included data from more than 1 million adults, and indicated the use of a newer risk prediction equation that classified fewer individuals as having chronic kidney disease and more accurately categorized the risk for death and end-stage renal disease. The study and its accompanying editorial were published in the May 9 issue of JAMA.

Glomerular filtration rate (GFR) is used in the diagnosis of chronic kidney disease (CKD) and is an independent predictor of all-cause and cardiovascular mortality and kidney failure in a wide range of populations, according to background information in the article. Clinical guidelines recommend reporting estimated GFR when serum creatinine level is measured. "The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation more accurately estimates GFR than the Modification of Diet in Renal Disease (MDRD) Study equation using the same variables [age, sex, race, and serum creatinine level], especially at higher GFR, but definitive evidence of its risk implications in diverse settings is lacking," the authors write.

Kunihiro Matsushita, M.D., Ph.D., of Johns Hopkins University, Baltimore, and colleagues conducted a study to evaluate whether estimated GFR calculated by the CKD-EPI equation predicts risk for adverse outcomes more accurately than the MDRD Study equation in a broad range of populations. The study consisted of a meta-analysis of data from 1.1 million adults (18 years of age and older) from 25 general population cohorts, 7 high-risk cohorts (of vascular disease), and 13 CKD cohorts. The participants were from 40 countries or regions of Asia,

Europe, North America and South America, the Middle East, and Oceania. Data transfer and analyses were conducted between March 2011 and March 2012. The primary adverse outcomes analyzed were all-cause mortality (84,482 deaths from 40 cohorts), cardiovascular mortality (22,176 events from 28 cohorts), and end-stage renal disease (ESRD) (7,644 events from 21 cohorts).

The prevalence of CKD stages 3 to 5 (<60 mL/min/1.73 m2) was lower by the CKD-EPI equation than by the MDRD Study equation in the general population cohorts (6.3 percent vs. 8.7 percent, respectively) and in the high-risk cohorts (14.6 percent vs. 17.7 percent).

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