title: The Cockroft and Gault formula for estimation of creatinine clearance: a friendly deconstruction.
abstract: OBJECTIVE
  To review the derivation of the Cockroft and Gault formula for estimating creatinine clearance from serum creatinine in a historical context.
  
  
  METHODS
  The derivation described by Cockroft and Gault was reviewed, and an alternative formula was sought using the data reported in the paper.
  
  
  RESULTS
  Cockroft and Gault used 24 hour urine creatinine data expressed as mg/kg body weight and mathematical manipulation of a linear regression equation which introduced body weight as an independent variable into the formula. This involved a circular logic and may have been mathematically invalid. A more logical equation not containing body weight was derived from the data.
  
  
  CONCLUSIONS
  The Cockcroft and Gault formula has been validated by long usage but the derivation appears logically insecure. Nevertheless, its role in estimating renal function at the bedside is established.
authors.affiliation: Medical Department, Southland Hospital, Invercargill, New Zealand. Alasdair.millar@health.wa.gov.au
authors.forename: J Alasdair
authors.initials: JA
authors.lastname: Millar
mesh_terms: D003404:Creatinine / Q000378:metabolism*; D003627:Data Interpretation, Statistical; D049673:History, 20th Century; D006801:Humans; D007677:Kidney Function Tests / Q000266:history / Q000706:statistics & numerical data*; D016014:Linear Models; D008128:Logic; D055641:Mathematical Concepts
chemical_list: D003404:Creatinine