title: Prevalence of decreased glomerular filtration rate in patients seeking non-nephrological medical care--an evaluation using IDMS-traceable creatinine based MDRD as well as Mayo Clinic quadratic equation estimates.
abstract: BACKGROUND
  Data on the prevalence of decreased glomerular filtration rate in Europe are limited. Most of the available studies did not employ laboratory methods providing creatinine concentrations traceable to the reference method, i.e. isotope dilution mass spectrometry (IDMS).
  
  
  METHODS
  We therefore conducted a cross-sectional study in the principality of Liechtenstein consecutively enrolling adult patients seeking non-nephrological medical care from whom serum samples were referred for renal function assessment. All measurements were done in one central laboratory. The estimated glomerular filtration rate (eGFR) was calculated based on the determination of IDMS-traceable creatinine by a kinetic Jaffe method (Roche Diagnostics, Switzerland) by means of the MDRD and Mayo Clinic quadratic equations. We further estimated the incidence of end stage renal disease during the next 5 years.
  
  
  RESULTS
  For 43% (n=9378) of the entire population>or=25 years renal function assessment was available. An eGFR indicating chronic kidney disease (CKD) stages 3-5 was found in 4.93% when using the MDRD equation and in 3.98 % when using the Mayo Clinic quadratic equation. The two equations had a very good agreement in classifying patients to have an eGFR consistent with CKD stages 3-5 (Cohen's kappa 0.887). Further calculations suggested that among patients aged 80 or younger, annually 42 per 100,000 are going to develop an eGFR<15 ml/min/1.73 m2 over the next 5 years.
  
  
  CONCLUSIONS
  4-5% of patients seeking non-nephrological medical advice have an eGFR consistent with CKD stages 3-5, and a considerable number of subjects is expected to develop end stage renal disease over a 5 year period. In order to obtain comparable kidney function estimates among different institutions it is not only important to use standardized methods to measure creatinine but rather to employ standardized methods to calculate a GFR estimate.
authors.affiliation: Vorarlberg Institute for Vascular Investigation and Treatment (VIVIT), Carinagasse 47, 6800 Feldkirch, Austria. lorenzrisch@hotmail.com
authors.forename: Lorenz
authors.initials: L
authors.lastname: Risch
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Saely
authors.forename: Ulrich
authors.initials: U
authors.lastname: Neyer
authors.forename: Guenter
authors.initials: G
authors.lastname: Hoefle
authors.forename: Ghazaleh
authors.initials: G
authors.lastname: Gouya
authors.forename: Manfred
authors.initials: M
authors.lastname: Zerlauth
authors.forename: Gerhard M
authors.initials: GM
authors.lastname: Risch
authors.forename: Martin
authors.initials: M
authors.lastname: Risch
authors.forename: Heinz
authors.initials: H
authors.lastname: Drexel
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003404:Creatinine / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000503:physiopathology*; D007676:Kidney Failure, Chronic / Q000503:physiopathology; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged
chemical_list: D003404:Creatinine