title: The concept of precision extended to the atherogenic index of plasma.
abstract: BACKGROUND
  The atherogenic index of plasma (AIP), defined as the base 10 logarithm of the ratio of plasma triglyceride (TG) to high density lipoprotein cholesterol (HDL-C), has been employed as a predictor of cardiovascular risk. We seek to quantify the analytical precision of the AIP using the coefficients of variation (CVs) of the TG and HDL-C assays.
  
  
  METHODS
  Error propagation methods are employed to develop a simple formula for the standard deviation of the random analytical error in the AIP assuming that the errors in the TG and HDL-C assays are normally distributed. An alternative derivation assuming log-normal distribution of errors gives nearly identical results while avoiding subtle technical problems.
  
  
  RESULTS
  The SD of the AIP is given by sigma(AIP) approximately = 1/ln(10) square root(CV(TG)(2) + CV(HDL-C)(2)) and this formula will provide SD results that are accurate within 0.4% for CVs of TG and HDL-C less than 5%, as compared with results of Monte Carlo simulation. We also explain that the concept of CV cannot be applied to the AIP since it is a logarithm.
  
  
  CONCLUSIONS
  The formula provides a simple means to quantify the precision of the AIP from precision data available for the TG or HDL-C assays.
authors.affiliation: St. Paul's Hospital Healthy Heart Lipid Clinic and the University of British Columbia Department of Pathology and Laboratory Medicine, Vancouver, BC, Canada. dtholmes@interchange.ubc.ca
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Holmes
authors.forename: Jiri
authors.initials: J
authors.lastname: Frohlich
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Buhr
mesh_terms: D050197:Atherosclerosis / Q000097:blood / Q000175:diagnosis; D001774:Blood Chemical Analysis / Q000592:standards* / Q000706:statistics & numerical data*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood; D009010:Monte Carlo Method; D012015:Reference Standards; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood*
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D008075:Lipoproteins, HDL; D014280:Triglycerides