title: The clinical utility of Multiplate analyser measurement in platelet function testing following stroke and transient ischaemic attack.
abstract: BACKGROUND
  Platelet responsiveness to aspirin in people with cerebrovascular disease is poorly understood.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  The Multiplate device gives reproducible, precise results in volunteers and stroke/TIA patients.
authors: Oxford University Hospitals NHS Trust, Oxford, UK; Norfolk and Norwich University Hospital, Norfolk, UK.
authors: Gurdeep S
authors: GS
authors: Mannu
authors: Alistair
authors: A
authors: Macartney
authors: Jonathan R A
authors: JR
authors: Lambert
authors: Joao H
authors: JH
authors: Bettencourt-Silva
authors: Mark
authors: M
authors: Lawn
authors: Hamish
authors: H
authors: Lyall
authors: Anthony Kneale
authors: AK
authors: Metcalf
authors: John F
authors: JF
authors: Potter
authors: John
authors: J
authors: Wood
authors: Allan
authors: A
authors: Clark
authors: Trevor
authors: T
authors: Baglin
authors: Phyo Kyaw
authors: PK
authors: Myint
authors: Kristian M
authors: KM
authors: Bowles
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D016022:Case-Control Studies; D006801:Humans; D002546:Ischemic Attack, Transient / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000401:mortality; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D010979:Platelet Function Tests / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D015203:Reproducibility of Results; D020521:Stroke / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000401:mortality; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010975:Platelet Aggregation Inhibitors
keywords: aspirin resistance; platelet function testing; prognosis; stroke; transient ischaemic attack