This week’s question was, “How long do you require patients or controls to go without aspirin before platelet aggregometry?”
The answers are below…
a. 48 hours: 5 (14%)
b. 7 days: 11 (32%)
c. 10 days: 14 (40%)
d. 14 days: 5 (14%)
This is a wide spread of answers, reflecting the lack of agreement in this area. The Red Cross requires platelet donors be aspirin-free for only 48 hours, but the new CLSI standard, H58 requires the subject be off aspirin for 14 days. It seems 14 days is long for people who are prescribed aspirin subsequent to a cardiovascular event–few would be willing to take that much risk. Conversely, aspirin could affect aggregometry results for at least seven days.
Our next Quick Question asks the same about Plavix. It will be interesting to learn if we see the same spread of results.