title: Estimating glomerular filtration rate using the new CKD-EPI equation and other equations in patients with autosomal dominant polycystic kidney disease.
abstract: BACKGROUND
  No studies have compared the performance of equations for estimating glomerular filtration rate (GFR) in patients with autosomal dominant polycystic kidney disease (ADPKD), where the declining GFR typically is followed for many years or even decades. This was the purpose of the present investigation.
  
  
  METHODS
  101 ADPKD patients with chronic kidney disease stages 1-5 were recruited and GFR was measured with the (51)Cr-EDTA clearance method, and estimated with the Modification of Diet in Renal Disease Study (MDRD) equation with 4 variables, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the Cockcroft-Gault equation adjusted for body surface area and the MDRD equation with cystatin C. Performance was evaluated by mean bias, precision and accuracy.
  
  
  RESULTS
  The MDRD equation with cystatin C had 97% of GFR estimates within 30% of measured GFR (accuracy). Both the CKD-EPI and Cockcroft-Gault equations had an accuracy of 90% whereas the MDRD equation had an accuracy of 83%. This difference of accuracy was especially marked with GFR >60 ml/min/1.73 m(2).
  
  
  CONCLUSIONS
  For estimating GFR in ADPKD patients the MDRD equation with cystatin C incorporated had the best performance. The CKD-EPI or the Cockcroft-Gault equations showed better performance compared to the 4-variable MDRD equation.
authors.affiliation: Department of Nephrology, Copenhagen University Hospital, Herlev, Denmark. bjorch02@heh.regionh.dk
authors.forename: Bjarne
authors.initials: B
authors.lastname: Orskov
authors.forename: Malene L
authors.initials: ML
authors.lastname: Borresen
authors.forename: Bo
authors.initials: B
authors.lastname: Feldt-Rasmussen
authors.forename: Ole
authors.initials: O
authors.lastname: Østergaard
authors.forename: Inga
authors.initials: I
authors.lastname: Laursen
authors.forename: Svend
authors.initials: S
authors.lastname: Strandgaard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D016891:Polycystic Kidney, Autosomal Dominant / Q000503:physiopathology*; D015203:Reproducibility of Results; D055815:Young Adult