title: Clinical risk implications of the CKD Epidemiology Collaboration (CKD-EPI) equation compared with the Modification of Diet in Renal Disease (MDRD) Study equation for estimated GFR.
abstract: BACKGROUND
  The 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.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  Adults (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).
  
  
  METHODS
  eGFR categories of ≥90, 60-89, 45-59, 30-44, and 15-29 mL/min/1.73 m(2).
  
  
  RESULTS
  All-cause mortality, acute myocardial infarction, end-stage renal disease, and doubling of serum creatinine level.
  
  
  METHODS
  GFR was estimated by the CKD-EPI and MDRD Study equations.
  
  
  RESULTS
  The 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).
  
  
  CONCLUSIONS
  Relatively short follow-up (median, 2.8 years), lack of data for some potential confounders (eg, smoking), and mainly white participants.
  
  
  CONCLUSIONS
  These results suggest that the CKD-EPI equation more accurately categorizes individuals regarding clinical risk than the MDRD Study equation.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. kmatsush@jhsph.edu
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Matsushita
authors.forename: Marcello
authors.initials: M
authors.lastname: Tonelli
authors.forename: Anita
authors.initials: A
authors.lastname: Lloyd
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levey
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Hemmelgarn
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood; D011237:Predictive Value of Tests
chemical_list: D003404:Creatinine