title: Which lipid measurement should we monitor? An analysis of the LIPID study.
abstract: OBJECTIVE
  To evaluate the optimal lipid to measure in monitoring patients, we assessed three factors that influence the choice of monitoring tests: (1) clinical validity; (2) responsiveness to therapy changes and (3) the size of the long-term 'signal-to-noise' ratio.
  
  
  METHODS
  Longitudinal analyses of repeated lipid measurement over 5 years.
  
  
  METHODS
  Subsidiary analysis of a Long-Term Intervention with Pravastatin in Ischaemic Disease (LIPID) study-a clinical trial in Australia, New Zealand and Finland.
  
  
  METHODS
  9014 patients aged 31-75 years with previous acute coronary syndromes.
  
  
  METHODS
  Patients were randomly assigned to 40 mg daily pravastatin or placebo.
  
  
  METHODS
  We used data on serial lipid measurements-at randomisation, 6 months and 12 months, and then annually to 5 years-of total cholesterol; low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol and their ratios; triglycerides; and apolipoproteins A and B and their ratio and their ability to predict coronary events.
  
  
  RESULTS
  All the lipid measures were statistically significantly associated with future coronary events, but the associations between each of the three ratio measures (total or LDL cholesterol to HDL cholesterol, and apolipoprotein B to apolipoprotein A1) and the time to a coronary event were better than those for any of the single lipid measures. The two cholesterol ratios also ranked highly for the long-term signal-to-noise ratios. However, LDL cholesterol and non-HDL cholesterol showed the most responsiveness to treatment change.
  
  
  CONCLUSIONS
  Lipid monitoring is increasingly common, but current guidelines vary. No single measure was best on all three criteria. Total cholesterol did not rank highly on any single criterion. However, measurements based on cholesterol subfractions-non-HDL cholesterol (total cholesterol minus HDL cholesterol) and the two ratios-appeared superior to total cholesterol or any of the apolipoprotein options. Guidelines should consider using non-HDL cholesterol or a ratio measure for initial treatment decisions and subsequent monitoring.
authors.affiliation: Centre for Research in Evidence-Based Practice, Bond University, Gold Coast, Queensland, Australia.
authors.forename: Paul P
authors.initials: PP
authors.lastname: Glasziou
authors.forename: Les
authors.initials: L
authors.lastname: Irwig
authors.forename: Adrienne C
authors.initials: AC
authors.lastname: Kirby
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Tonkin
authors.forename: R John
authors.initials: RJ
authors.lastname: Simes
mesh_terms: D054058:Acute Coronary Syndrome / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D001315:Australia; D005260:Female; D005387:Finland; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D006949:Hyperlipidemias / Q000188:drug therapy*; D008055:Lipids / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009520:New Zealand; D017035:Pravastatin / Q000627:therapeutic use*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008055:Lipids; D017035:Pravastatin
keywords: Epidemiology; Public Health; Vascular Medicine