title: Evaluation of four different equations for calculating LDL-C with eight different direct HDL-C assays.
abstract: BACKGROUND
  Low-density lipoprotein cholesterol (LDL-C) is often calculated (cLDL-C) by the Friedewald equation, which requires high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG). Because there have been considerable changes in the measurement of HDL-C with the introduction of direct assays, several alternative equations have recently been proposed.
  
  
  METHODS
  We compared 4 equations (Friedewald, Vujovic, Chen, and Anandaraja) for cLDL-C, using 8 different direct HDL-C (dHDL-C) methods. LDL-C values were calculated by the 4 equations and determined by the β quantification reference method procedure in 164 subjects.
  
  
  RESULTS
  For normotriglyceridemic samples (TG<200mg/dl), between 6.2% and 24.8% of all results exceeded the total error goal of 12% for LDL-C, depending on the dHDL-C assay and cLDL-C equation used. Friedewald equation was found to be the optimum equation for most but not all dHDL-C assays, typically leading to less than 10% misclassification of cardiovascular risk based on LDL-C. Hypertriglyceridemic samples (>200mg/dl) showed a large cardiovascular risk misclassification rate (30%-50%) for all combinations of dHDL-C assays and cLDL-C equations.
  
  
  CONCLUSIONS
  The Friedewald equation showed the best performance for estimating LDL-C, but its accuracy varied considerably depending on the specific dHDL-C assay used. None of the cLDL-C equations performed adequately for hypertriglyceridemic samples.
authors.affiliation: Department of Laboratory Medicine, Clinical Center, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, United States.
authors.forename: Marcelo Jose Andrade
authors.initials: MJ
authors.lastname: Oliveira
authors.forename: Hendrick E
authors.initials: HE
authors.lastname: van Deventer
authors.forename: Lorin M
authors.initials: LM
authors.lastname: Bachmann
authors.forename: G Russell
authors.initials: GR
authors.lastname: Warnick
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Nakajima
authors.forename: Masakasu
authors.initials: M
authors.lastname: Nakamura
authors.forename: Ikunosuke
authors.initials: I
authors.lastname: Sakurabayashi
authors.forename: Mary M
authors.initials: MM
authors.lastname: Kimberly
authors.forename: Robert D
authors.initials: RD
authors.lastname: Shamburek
authors.forename: William J
authors.initials: WJ
authors.lastname: Korzun
authors.forename: Gary L
authors.initials: GL
authors.lastname: Myers
authors.forename: W Greg
authors.initials: WG
authors.lastname: Miller
authors.forename: Alan T
authors.initials: AT
authors.lastname: Remaley
mesh_terms: D000465:Algorithms; D001681:Biological Assay / Q000592:standards*; D001774:Blood Chemical Analysis / Q000379:methods* / Q000592:standards*; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL