• Kunihiro Matsushita, Marcello Tonelli, Anita Lloyd, Andrew S Levey, Josef Coresh, Brenda R Hemmelgarn, and Alberta Kidney Disease Network.
• Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. kmatsush@jhsph.edu
• Am. J. Kidney Dis. 2012 Aug 1; 60 (2): 241-9.

BackgroundThe CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine-based equation for estimated glomerular filtration rate (eGFR) is more accurate than the MDRD (Modification of Diet in Renal Disease) Study equation. However, it has not been determined whether the improvement in risk categorization applies to all segments of the population.Study DesignPopulation-based cohort study.Setting & ParticipantsAdults (aged ≥18 years) who did not have kidney failure at baseline and had at least one serum creatinine measurement and dipstick proteinuria evaluation in a province-wide laboratory registry from Alberta, Canada, in 2002-2007 (N = 1,010,988).PredictoreGFR categories of ≥90, 60-89, 45-59, 30-44, and 15-29 mL/min/1.73 m(2).OutcomesAll-cause mortality, acute myocardial infarction, end-stage renal disease, and doubling of serum creatinine level.MeasurementsGFR was estimated by the CKD-EPI and MDRD Study equations.ResultsThe CKD-EPI equation reclassified 22.6% and 1.2% of participants to a higher and lower eGFR category, respectively, and decreased the prevalence of CKD stages 3 and 4 from 9.2% to 7.3%. Of 70,071 participants with eGFR(MDRD) of 45-59 mL/min/1.73 m(2), 30.8% were reclassified to eGFR(CKD-EPI) of 60-89 mL/min/1.73 m(2), and after adjusting for potential confounders, participants reclassified had a lower risk of all-cause mortality (incidence rate ratio [IRR], 0.77; 95% CI, 0.69-0.86), acute myocardial infarction (IRR, 0.73; 95% CI, 0.60-0.88), end-stage renal disease (IRR, 0.55; 95% CI, 0.32-0.94), and doubling of creatinine level (IRR, 0.78; 95% CI, 0.59-1.04) compared with those not reclassified. Similar findings were observed for those reclassified to a higher eGFR category from other eGFR(MDRD) categories. Net reclassification improvements based on eGFR categories were positive for all outcomes (range, 0.146-0.256; all P < 0.001).LimitationsRelatively short follow-up (median, 2.8 years), lack of data for some potential confounders (eg, smoking), and mainly white participants.ConclusionsThese results suggest that the CKD-EPI equation more accurately categorizes individuals regarding clinical risk than the MDRD Study equation.Copyright © 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

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