Platelet responsiveness to aspirin in people with cerebrovascular disease is poorly understood.To determine: (i) normal reference range, imprecision and reproducibility of the Multiplate instrument in healthy volunteers naive to aspirin; (ii) imprecision and reproducibility of the Multiplate instrument in acute stroke and transient ischaemic attack (TIA); (iii) the relationship between aspirin responsiveness and clinical outcome.We evaluated platelet function response to three agonists [Adenosine Diphosphate (ADP), Arachidonic Acid (AA), Collagen (Col)] using the Mulitplate platelet function analyser in a two-phase pilot study. In phase 1, we recruited healthy volunteers to determine the normal reference range and imprecision of the Multiplate instrument. In phase 2, we assessed platelet function in acute stroke or TIA patients presenting to hospital. These patients were bled within 24 h of presentation and between 12 and 24 h after ≥75 mg dose of Aspirin. Patients were followed up to 1 yr to assess mortality and recurrent cardiovascular event.Overall, 29 healthy volunteers and 81 stroke/TIA patients were recruited. On assessing components of variance, Multiplate testing is reproducible and precise in volunteers and stroke/TIA patients. In stroke patients receiving aspirin, Bland-Altman plots show initial day 1 measurement provided a reliable measure of continuing response to aspirin at day 3. We defined one-third of patients as aspirin resistant [31.8% (95% CI: 22.1%-42.8%)] using cut off mean aggregation of ≥23.08% for AA and mean aggregation of ≥80.76% for ADP.The Multiplate device gives reproducible, precise results in volunteers and stroke/TIA patients.

Type

Journal article

Journal

European journal of haematology

Publication Date

02/2015

Volume

94

Pages

138 - 144

Addresses

Oxford University Hospitals NHS Trust, Oxford, UK; Norfolk and Norwich University Hospital, Norfolk, UK.

Keywords

Humans, Ischemic Attack, Transient, Platelet Aggregation Inhibitors, Platelet Function Tests, Treatment Outcome, Area Under Curve, Case-Control Studies, Reproducibility of Results, Platelet Aggregation, Time Factors, Aged, Aged, 80 and over, Middle Aged, Stroke