title: Creatinine-or cystatin C-based equations to estimate glomerular filtration in the general population: impact on the epidemiology of chronic kidney disease.
abstract: BACKGROUND
  Chronic kidney disease (CKD) is a major issue in public health. Its prevalence has been calculated using estimation of glomerular filtration rate (GFR) by the creatinine-based equations developed in the Modified Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) study. Recently, new equations based either on cystatin C (CKD-EPI Cys) or both cystatin and creatinine (CKD-EPI mix) have been proposed by the CKD-EPI consortium. The aim of this study was to measure the difference in the prevalence of stage 3 CKD, defined as an estimated GFR less than 60 mL/min/1.73 m2, in a population using these four equations.
  
  
  METHODS
  CKD screening was performed in the Province of Liège, Belgium. On a voluntary basis, people aged over 50 years have been screened. GFR was estimated by the four equations. Stage 3 CKD was defined as a GFR less than 60 mL/min/1.73 m2.
  
  
  RESULTS
  The population screened consisted of 4189 people (47% were men, mean age 63 ± 7y). Their mean serum creatinine and plasma cystatin C levels were 0.88 ± 0.21 mg/dL and 0.85 ± 0.17 mg/L, respectively. The prevalence of CKD in this population using the MDRD, the CKD-EPI, the CKD-EPI Cys and the CKD-EPI mix equations was 13%, 9.8%, 4.7% and 5%, respectively. The prevalence of CKD was significantly higher with the creatinine-based (MDRD and the CKD-EPI) equations compared to the new cystatin C-based equations.
  
  
  CONCLUSIONS
  Prevalence of CKD varies strongly depending on the method used to estimate GFR. Such discrepancies are of importance and must be confirmed and explained by additional studies, notably by studies using GFR measured with a reference method.
  
  
  BACKGROUND
  B70720071509.
authors.affiliation: Department of Nephrology-Dialysis-Transplantation, University of Liège, CHU Sart Tilman, Liège 4000, Belgium. pierre_delanaye@yahoo.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavalier
authors.forename: Olivier
authors.initials: O
authors.lastname: Moranne
authors.forename: Laurence
authors.initials: L
authors.lastname: Lutteri
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Krzesinski
authors.forename: Olivier
authors.initials: O
authors.lastname: Bruyère
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001530:Belgium / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D003404:Creatinine