Bleeding time prolonged by daily low-dose aspirin is shortened by one medium dose aspirin

Background: In planning surgery, a low-dose aspirin regimen for prevention of thrombotic events is often discontinued in order to avoid the risk of excessive bleeding during surgery. However, this procedure increases the risk from adverse thrombotic events. We propose a different method, which may normalize the prolonged bleeding time caused by low-dose aspirin. We verified the effectiveness of this method in healthy volunteers. Methods: Volunteers with bleeding time prolonged by taking 81 mg of aspirin a day for a period of 1 week were randomly divided into two groups. The test group of 18 volunteers received a dose of 660 mg of aspirin, while the control group of 16 received placebo. Bleeding time and maximum platelet activity were then evaluated. Results: Before 660 mg of aspirin or placebo, bleeding time was prolonged: in the aspirin group from 3.1 ± 0.7 to 6.1 ± 1.4 min (n=18), and in the placebo group from 2.9 ± 0.9 to 6.1 ± 1.5 min (n=16). This prolongation was significant in both groups at the P<0.01 level. In the test group, bleeding time was shortened to 4.5 ± 1.3 min (P<0.01), which is in the normal range, while it remained prolonged in the control group (6.0 ± 1.2 min). Platelet activity, on the other hand, was suppressed in both groups. Conclusion: We conclude that 660 mg of aspirin effectively shortens the bleeding time prolonged by daily low-dose (81 mg) aspirin.