title: Discrepancies between the Cockcroft-Gault and Chronic Kidney Disease Epidemiology (CKD-EPI) Equations: Implications for Refining Drug Dosage Adjustment Strategies.
abstract: The dosages of many medications require adjustment for renal function. There is debate regarding which equation, the Chronic Kidney Disease Epidemiology (CKD-EPI) equation vs. the Cockcroft-Gault (CG) equation, should be recommended to estimate glomerular filtration rate.
  
  
  
  We used a mathematical simulation to determine how patient characteristics influence discrepancies between equations and analyzed clinical data to demonstrate the frequency of such discrepancies in clinical practice. In the simulation, the modifiable variables were sex, age, serum creatinine, and weight. We considered estimated glomerular filtration rate results in mL/min, deindexed for body surface area, because absolute excretory function (rather than per 1.73 m2body surface area) determines the rate of filtration of a drug at a given plasma concentration. An absolute and relative difference of maximum (±) 10 mL/min and 10 %, respectively, were considered concordant. Clinical data for patients aged over 60 years (n = 9091) were available from one hospital and 25 private laboratories.
  
  
  
  In the simulation, differences between the two equations were found to be influenced by each variable but age and weight had the biggest effect. Clinical sample data demonstrated concordance between CKD-EPI and CG results in 4080 patients (45 %). The majority of discordant results reflected a CG result lower than the CKD-EPI equation. With aging, the CG result became progressively lower than the CKD-EPI result. When weight increased, the opposite occurred.
  
  
  
  The choice of equation for excretory function adjustment of drug dosage will have different implications for patients of different ages and body habitus.
  
  
  
  The optimum equation for drug dosage adjustment should be defined with consideration of individual patient characteristics.
authors.affiliation: Division of Nephrology, Dialysis and Transplantation, CHU Sart Tilman, University of Liège (ULg-CHU), 4000, Liège, Belgium. pierre_delanaye@yahoo.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
authors.affiliation: Oriade Laboratory, Vizille, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Guerber
authors.affiliation: Division of Clinical Pharmacology, Center for Interdisciplinary Research on Medicines, University of Liège, Liège, Belgium.
authors.forename: André
authors.initials: A
authors.lastname: Scheen
authors.affiliation: Sheffield Kidney Institute, Northern General Hospital and Department of Infection, Immunity and Cardiovascular Science, University of Sheffield, Sheffield, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Ellam
authors.affiliation: Division of Nephrology, Dialysis and Transplantation, CHU Sart Tilman, University of Liège (ULg-CHU), 4000, Liège, Belgium.
authors.forename: Antoine
authors.initials: A
authors.lastname: Bouquegneau
authors.affiliation: Biochemistry Laboratory, Grenoble University Hospital, Grenoble, France.
authors.forename: Dorra
authors.initials: D
authors.lastname: Guergour
authors.affiliation: Division of Nephrology, Dialysis, Transplantation and Hypertension, CHU Hôpital Nord, University Jean Monnet, PRES Université de LYON, Saint-Etienne, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Mariat
authors.affiliation: Department of Public Health and Primary Care, KU, Leuven Kulak, Kortrijk, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Pottel
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000378:metabolism*; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology* / Q000378:metabolism*; D055815:Young Adult
chemical_list: D004364:Pharmaceutical Preparations