title: Discordance of low-density lipoprotein (LDL) cholesterol with alternative LDL-related measures and future coronary events.
abstract: BACKGROUND
  Low-density lipoprotein cholesterol (LDL-C) is the traditional measure of risk attributable to LDL. Non-high-density lipoprotein cholesterol (NHDL-C), apolipoprotein B (apoB), and LDL particle number (LDL-P) are alternative measures of LDL-related risk. However, the clinical utility of these measures may only become apparent among individuals for whom levels are inconsistent (discordant) with LDL-C.
  
  
  RESULTS
  LDL-C was measured directly, NHDL-C was calculated, apoB was measured with immunoassay, and LDL-P was measured with nuclear magnetic resonance spectroscopy among 27 533 healthy women (median follow-up 17.2 years; 1070 incident coronary events). Participants were grouped by median LDL-C (121 mg/dL) and each of NHDL-C, apoB, and LDL-P. Discordance was defined as LDL-C greater than or equal to the median and the alternative measure less than the median, or vice versa. Despite high LDL-C correlations with NHDL-C, apoB, and LDL-P (r=0.910, 0.785, and 0.692; all P<0.0001), prevalence of LDL-C discordance as defined by median cut points was 11.6%, 18.9%, and 24.3% for NHDL-C, apoB, and LDL-P, respectively. Among women with LDL-C less than the median, coronary risk was underestimated for women with discordant (greater than or equal to the median) NHDL-C (age-adjusted hazard ratio, 2.92; 95% confidence interval, 2.33-3.67), apoB (2.48, 2.01-3.07), or LDL-P (2.32, 1.88-2.85) compared with women with concordant levels. Conversely, among women with LDL-C greater than or equal to the median, risk was overestimated for women with discordant (less than the median) NHDL-C (0.40, 0.29-0.57), apoB (0.34, 0.26-0.46), or LDL-P (0.42, 0.33-0.53). After multivariable adjustment for potentially mediating factors, including HDL cholesterol and triglycerides, coronary risk remained underestimated or overestimated by ≈20% to 50% for women with discordant levels.
  
  
  CONCLUSIONS
  For women with discordant LDL-related measures, coronary risk may be underestimated or overestimated when LDL-C alone is used.
  
  
  BACKGROUND
  http://www.clinicaltrials.gov. Unique identifier: NCT00000479.
authors.affiliation: Divisions of Preventive (S.M., J.E.B., P.M.R.) and Cardiovascular Medicine (S.M., P.M.R.), Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: Samia
authors.initials: S
authors.lastname: Mora
authors.forename: Julie E
authors.initials: JE
authors.lastname: Buring
authors.forename: Paul M
authors.initials: PM
authors.lastname: Ridker
mesh_terms: D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D008077:Lipoproteins, LDL
keywords: lipids; lipoproteins; primary prevention