title: Screening for aspirin resistance in stable coronary artery patients by three different tests.
abstract: BACKGROUND
  Aspirin (ASA) failure to inhibit in vitro platelet function had been termed ASA resistance. The prevalence of this phenomenon as measured with different platelet function tests varies widely among studies.
  
  
  OBJECTIVE
  In this study, we propose to determine the prevalence of ASA non-responsiveness in stable coronary artery patients using three different tests.
  
  
  METHODS
  One hundred ninety-one patients with a stable coronary artery disease and receiving secondary ASA prophylaxis (250 mg/day) were tested. For each patient the ASA-induced platelet inhibition was determined using three different tests: Ivy Bleeding time (BT), collagen/epinephrine closure time (CEPI-CT; PFA-100, Dade-Behring) and urinary 11-dehydrothromboxane B2 (uTxB2) excretion level. The agreement between these tests was evaluated by kappa statistics test.
  
  
  RESULTS
  The prevalence of biological ASA resistance was 15.7% (n=30), 20.4% (n=39) and 24.6% (n=47) by BT, PFA-100 and UTxB2, respectively. Only fourteen patients (7.3%) were non-responders for two tests: 6 (3.1%) BT/ PFA-100; 1 (0.5%) BT/UTxB2; 7 (3.7%) PFA-100/UTxB2). A poor agreement was found between these three methods and only 3 patients were resistant with all the tests (1.6%).
  
  
  CONCLUSIONS
  The lack of agreement supposed that different types of aspirin resistance exist. Thus, combination of two tests or more could be a primary solution for a better identification of ASA resistant patients. This hypothesis must be confirmed by a large-scale randomized study with clinically well-defined endpoints.
authors.affiliation: UR. Etude des fonctions plaquettaires, Regional Centre of Blood Transfusion, Farhat-Hached University Hospital, Sousse, Tunisia.
authors.forename: Tahar
authors.initials: T
authors.lastname: Chakroun
authors.forename: Faouzi
authors.initials: F
authors.lastname: Addad
authors.forename: Fatma
authors.initials: F
authors.lastname: Abderazek
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ben-Farhat
authors.forename: Sonia
authors.initials: S
authors.lastname: Hamdi
authors.forename: Habib
authors.initials: H
authors.lastname: Gamra
authors.forename: Mohsen
authors.initials: M
authors.lastname: Hassine
authors.forename: Khaldoun
authors.initials: K
authors.lastname: Ben-Hamda
authors.forename: Meyer M
authors.initials: MM
authors.lastname: Samama
authors.forename: Ismail
authors.initials: I
authors.lastname: Elalamy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001241:Aspirin / Q000494:pharmacology*; D001760:Bleeding Time; D001792:Blood Platelets / Q000187:drug effects*; D003324:Coronary Artery Disease / Q000097:blood* / Q000188:drug therapy* / Q000652:urine; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004351:Drug Resistance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010979:Platelet Function Tests / Q000379:methods*; D013923:Thromboembolism / Q000097:blood / Q000517:prevention & control / Q000652:urine; D013929:Thromboxane B2 / Q000031:analogs & derivatives / Q000652:urine
chemical_list: D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; C049235:11-dehydro-thromboxane B2; D001241:Aspirin