title: Discordance between apolipoprotein B and low-density lipoprotein particle number is associated with insulin resistance in clinical practice.
abstract: BACKGROUND
  Discordance between measures of atherogenic lipoprotein particle number (apolipoprotein B [ApoB] and low-density lipoprotein [LDL] particle number by nuclear magnetic resonance spectroscopy [LDL-PNMR]) is not well understood. Appropriate treatment considerations in such cases are unclear.
  
  
  OBJECTIVE
  To assess discordance between apoB determined by immunoassay and LDL-PNMR in routine clinical practice, and to characterize biomarker profiles and other clinical characteristics of patients identified as discordant.
  
  
  METHODS
  Two retrospective cohorts were evaluated. First, 412,013 patients with laboratory testing performed by Health Diagnostic Laboratory, Inc., as part of routine care; and second, 1411 consecutive patients presenting for risk assessment/reduction at 6 US outpatient clinics. Discordance was quantified as a percentile difference (LDL-PNMR percentile - apoB percentile) and attainment of percentile cutpoints (LDL-PNMR ≥ 1073 nmol/L or apoB ≥ 69 mg/dL). A wide range of cardiovascular risk factors were compared.
  
  
  RESULTS
  ApoB and LDL-PNMR values were highly correlated (R(2) = 0.79), although substantial discordance was observed. Similar numbers of patients were identified as at-risk by LDL-PNMR when apoB levels were < 69 mg/dL (5%-6%) and by apoB values when LDL-PNMR was < 1073 nmol/L (6%-7%). Discordance (LDL-PNMR > apoB) was associated with insulin resistance, smaller LDL particle size, increased systemic inflammation, and low circulating levels of "traditional" lipids, whereas discordance (apoB > LDL-PNMR) was associated with larger LDL particle size, and elevated levels of lipoprotein(a) and lipoprotein-associated phospholipase A2 (Lp-PLA2).
  
  
  CONCLUSIONS
  Discordance between apoB and LDL-PNMR in routine clinical practice is more widespread than currently recognized and may be associated with insulin resistance.
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA. Electronic address: svarvel@hdlabinc.com.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Varvel
authors.affiliation: Foundation for Health Improvement and Technology, Richmond, VA, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Dayspring
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Yvette
authors.initials: Y
authors.lastname: Edmonds
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Dawn L
authors.initials: DL
authors.lastname: Thiselton
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Leila
authors.initials: L
authors.lastname: Ghaedi
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Szilard
authors.initials: S
authors.lastname: Voros
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: McConnell
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Maciek
authors.initials: M
authors.lastname: Sasinowski
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: Dall
authors.affiliation: Health Diagnostic Laboratory, Inc., Richmond, VA, USA.
authors.forename: G Russell
authors.initials: GR
authors.lastname: Warnick
mesh_terms: D000368:Aged; D001055:Apolipoproteins B / Q000097:blood*; D002318:Cardiovascular Diseases / Q000097:blood* / Q000473:pathology; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008077:Lipoproteins, LDL / Q000097:blood*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D001055:Apolipoproteins B; D008077:Lipoproteins, LDL