title: A comparison of six major platelet function tests to determine the prevalence of aspirin resistance in patients with stable coronary artery disease.
abstract: OBJECTIVE
  We sought to compare the results obtained from six major platelet function tests in the assessment of the prevalence of aspirin resistance in patients with stable coronary artery disease.
  
  
  RESULTS
  201 patients with stable coronary artery disease receiving daily aspirin therapy (> or =80 mg) were recruited. Platelet aggregation was measured by: (i) light transmission aggregometry (LTA) after stimulation with 1.6 mM of arachidonic acid (AA), (ii) LTA after adenosine diphosphate (ADP) (5, 10, and 20 microM) stimulation, (iii) whole blood aggregometry, (iv) PFA-100, (v) VerifyNow Aspirin; urinary 11-dehydro-thromboxane B(2) concentrations were also measured. Eight patients (4%, 95% CI 0.01-0.07) were deemed resistant to aspirin by LTA and AA. The prevalence of aspirin resistance varied according to the assay used: 10.3-51.7% for LTA using ADP as the agonist, 18.0% for whole blood aggregometry, 59.5% for PFA-100, 6.7% for VerifyNow Aspirin, and finally, 22.9% by measuring urinary 11-dehydro-thromboxane B(2) concentrations. Results from these tests showed poor correlation and agreement between themselves.
  
  
  CONCLUSIONS
  Platelet function tests are not equally effective in measuring aspirin's antiplatelet effect and correlate poorly amongst themselves. The clinical usefulness of the different assays to classify correctly patients as aspirin resistant remains undetermined.
authors.affiliation: Faculty of Pharmacy, Université de Montréal, Montréal, Québec, Canada.
authors.forename: Marie
authors.initials: M
authors.lastname: Lordkipanidzé
authors.forename: Chantal
authors.initials: C
authors.lastname: Pharand
authors.forename: Erick
authors.initials: E
authors.lastname: Schampaert
authors.forename: Jacques
authors.initials: J
authors.lastname: Turgeon
authors.forename: Donald A
authors.initials: DA
authors.lastname: Palisaitis
authors.forename: Jean G
authors.initials: JG
authors.lastname: Diodati
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology*; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D003324:Coronary Artery Disease / Q000097:blood / Q000188:drug therapy*; D051545:Cyclooxygenase 1 / Q000378:metabolism; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010979:Platelet Function Tests / Q000379:methods; D012016:Reference Values; D013928:Thromboxane A2 / Q000378:metabolism
chemical_list: D010975:Platelet Aggregation Inhibitors; D013928:Thromboxane A2; D051545:Cyclooxygenase 1; D001241:Aspirin