title: Comparison of low-density lipoprotein cholesterol concentrations measured by a direct homogeneous assay and by the Friedewald formula in a large community population.
abstract: BACKGROUND
  We compare the direct homogeneous low-density lipoprotein cholesterol (LDL-C) assay with the Friedewald formula (FF) for determination of LDL-C in a large community-dwelling population.
  
  
  METHODS
  A total of 21,194 apparently healthy subjects aged 40 to 79 years with triglyceride (TG) concentrations <4.52 mmol/l were enrolled. LDL-C were directly measured by the enzymatic homogeneous assay (LDL-C (D)) and also estimated by the FF (LDL-C (F)). Paired t-test, Pearson's correlation coefficient and linear regression analysis were performed and the concordances of the National Cholesterol Education Program (NCEP) risk category were estimated.
  
  
  RESULTS
  Both in fasting (n=3270) and nonfasting samples (n=17,924), LDL-C (D) highly correlated with LDL-C (F): r=0.971 and 0.955, respectively. Concordant results for NCEP categories were 84.8% for fasting samples and 80.1% for nonfasting samples. However, the bias between the 2 measurements increased in samples with TG concentrations >1.69 mmol/l, especially in nonfasting samples.
  
  
  CONCLUSIONS
  The results showing less variability of the direct LDL-C assay than that of the FF in nonfasting samples suggest that epidemiological studies can use LDL-C measured by the direct assay both in fasting and nonfasting samples.
authors.affiliation: Department of Hygiene and Preventive Medicine, School of Medicine, Iwate Medical University, Morioka, Japan. ktanno@iwate-med.ac.jp
authors.forename: Kozo
authors.initials: K
authors.lastname: Tanno
authors.forename: Tomonori
authors.initials: T
authors.lastname: Okamura
authors.forename: Masaki
authors.initials: M
authors.lastname: Ohsawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Onoda
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Itai
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Sakata
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Nakamura
authors.forename: Akira
authors.initials: A
authors.lastname: Ogawa
authors.forename: Kazuko
authors.initials: K
authors.lastname: Kawamura
authors.forename: Akira
authors.initials: A
authors.lastname: Okayama
mesh_terms: D000328:Adult; D000368:Aged; D015982:Bias; D008078:Cholesterol, LDL / Q000097:blood*; D015991:Epidemiologic Measurements; D005215:Fasting; D005260:Female; D006801:Humans; D008297:Male; D008722:Methods; D008875:Middle Aged; D012044:Regression Analysis; D015203:Reproducibility of Results; D012111:Residence Characteristics; D014280:Triglycerides / Q000097:blood
chemical_list: D008078:Cholesterol, LDL; D014280:Triglycerides