title: Characterization of the antiplatelet effect of aspirin at enrollment and after 2-year follow-up in a real clinical setting in Japan.
abstract: BACKGROUND
  Aspirin is an antiplatelet drug widely used for the prevention of cardiovascular diseases. It has been reported that some patients who exhibit a reduced antiplatelet effect of aspirin have higher cardiovascular risk. It is still controversial whether the antiplatelet effect of aspirin diminishes after a few years of treatment. This study aimed to evaluate the antiplatelet effect of aspirin and its 2-year change in Japanese patients.
  
  
  RESULTS
  Collagen-induced platelet-aggregability was measured at enrollment by conventional optical aggregometer in 239 patients undergoing antiplatelet therapy with aspirin alone. Among them, 167 patients were evaluated after 2 years. Whole blood aggregability based on the screen-filtration method was also evaluated. Optical aggregometer studies showed that 27% of patients were low-responders. Multivariate analyses revealed that female sex and non-use of calcium-channel blockers were associated with low responsiveness. The antiplatelet effect of aspirin did not decrease after 2 years. Similar data were obtained with the whole blood aggregometer.
  
  
  CONCLUSIONS
  In this Japanese patient group, 27% were low-responders to aspirin, and the antiplatelet effect of aspirin did not decrease after a 2-year interval.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Ikeda
authors.forename: Ryoji
authors.initials: R
authors.lastname: Taniguchi
authors.forename: Shin
authors.initials: S
authors.lastname: Watanabe
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kawato
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kondo
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Shirakawa
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Yamane
authors.forename: Masanao
authors.initials: M
authors.lastname: Toma
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tamura
authors.forename: Kanako
authors.initials: K
authors.lastname: Takahashi
authors.forename: Haruyo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Yuka
authors.initials: Y
authors.lastname: Yoshikawa
authors.forename: Arata
authors.initials: A
authors.lastname: Tabuchi
authors.forename: Toru
authors.initials: T
authors.lastname: Kita
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kimura
authors.forename: Hisanori
authors.initials: H
authors.lastname: Horiuchi
mesh_terms: D000368:Aged; D001241:Aspirin / Q000493:pharmacokinetics / Q000494:pharmacology*; D001780:Blood Coagulation Tests; D002121:Calcium Channel Blockers / Q000494:pharmacology; D003094:Collagen / Q000494:pharmacology; D004351:Drug Resistance / Q000187:drug effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology*; D010979:Platelet Function Tests; D012737:Sex Factors; D013997:Time Factors
chemical_list: D002121:Calcium Channel Blockers; D010975:Platelet Aggregation Inhibitors; D003094:Collagen; D001241:Aspirin