Monitoring aspirin therapy with the Platelet Function Analyzer-100

Jette Mortensen, Tina Svenstrup Poulsen, Erik Lerkevang Grove, Jens Refsgaard, Helle Ladefoged Nielsen, Susanne Bendesgaard Pedersen, Sofie Sommer Thygesen, Anne-Mette Hvas, Steen Dalby Kristensen

Research output: Contribution to journalJournal articleResearchpeer-review


OBJECTIVE: Low platelet response to aspirin has been reported to be associated with a high incidence of vascular events. The reported prevalence of aspirin low-responsiveness varies, which may be explained by poor reproducibility of the methods used to evaluate aspirin response and low compliance. The Platelet Function Analyzer-100 (PFA-100) is a commonly used platelet function test. We aimed to assess the reproducibility of the PFA-100 and the agreement with optical platelet aggregometry (OPA) in healthy volunteers and in patients with coronary artery disease (CAD) treated with low-dose aspirin. MATERIAL AND METHODS: Twenty-one healthy volunteers and 43 patients with CAD took part in the study. During treatment with aspirin 75 mg daily, all participants had platelet function assessed in duplicate with the PFA-100 and OPA on 4 consecutive days. Additionally, platelet function was assessed before aspirin treatment in healthy subjects. Serum-thromboxane B(2) (S-TxB(2)) was measured to assess compliance. RESULTS: In healthy volunteers not receiving aspirin, duplicate measurements resulted in coefficients of variation (CV) of 7.9 % for the PFA-100 and 5.2 % for OPA. During aspirin treatment, CVs were significantly higher (healthy volunteers: PFA-100: 15.6 %, OPA: 19.2 %; patients: PFA-100: 26.6 %, OPA: 16.8 %). Two of the 64 participants were classified as aspirin low-responders with both methods, indicating poor agreement (Kappa coefficient 0.05). Compliance was excellent, as S-TxB(2) was completely inhibited in all participants. CONCLUSIONS: Aspirin treatment affects the reproducibility of both PFA-100 and OPA. This imprecision should be considered carefully if the methods are used for monitoring aspirin treatment. Additionally, these methods do not identify the same individuals as being aspirin low-responders.
Original languageEnglish
Book seriesScandinavian Journal of Clinical and Laboratory Investigation. Supplement
Issue number8
Pages (from-to)786-92
Number of pages6
Publication statusPublished - 1. Jan 2008


  • Adult
  • Arachidonic Acid
  • Aspirin
  • Coronary Artery Disease
  • Female
  • Health
  • Humans
  • Male
  • Middle Aged
  • Monitoring, Physiologic
  • Platelet Aggregation
  • Platelet Function Tests

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