Aspirin Reduces Risk of Recurring Blood Clots by 42%
In people who experienced venous blood clots with no obvious cause, aspirin reduced the risk of recurring blood clots by up to 42%, according to a new study in the journal Circulation.
The research provides clear evidence that aspirin can reduce these recurrent venous thromboembolic events across a broad cross-section of patients with unprovoked venous thromboembolic disease.
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“The strength of the findings should have a significant impact on the care of patients worldwide, particularly where long-term treatment with anticoagulant therapy is problematic,” says lead study author John Simes, MD, director of the National Health and Medical Research Council Trials Centre and professor at the University of Sydney in Australia.
More than 1 million people worldwide experience unprovoked venous thromboembolism each year—and without ongoing treatment, there’s a 10% risk of them having another event in the first year and a 30% risk over 10 years, according to the authors.
While long-term oral anticoagulants are the standard treatment, they say less than 50% of these patients continue taking these medications after 6 months, due to the cost of treatment and monitoring, inconvenience, and the risk of bleeding.
“The evidence is strong for the use of aspirin in patients not taking anticoagulant therapy; it is not, however, an alternative treatment to oral anticoagulants or newer oral agents when these are still recommended,” Simes says.
In the International Collaboration of Aspirin Trials for Recurrent Venous Thromboembolism (INSPIRE) analysis, he and his colleagues looked at data from two similar independent studies.
In all, they analyzed data from 1,224 patients who received 100mg of aspirin daily to treat blood clots. The patients were monitored for at least 2 years.
Simes says the main benefits of treatment with aspirin they identified include:
• clear reductions in venous thromboembolic events (about 40% relative risk reduction compared with no treatment).
• similar relative reductions in arterial events (albeit less in absolute terms as this group was not at high risk for arterial events).
• an excellent safety profile without significant increases in major bleeds.
• relative convenience of therapy without the need for blood tests.
• low cost.
Aspirin also reduced the risk of major vascular events—symptomatic venous thromboembolism, myocardial infarction, stroke, and cardiovascular death—by more than a third.
“The relative treatment effects appeared similar for each prespecified subgroup, but larger absolute benefits were seen among men and older patients who were at greater risk of further venous thromboembolic events,” Simes says.
Currently, he and his colleagues are collaborating with other researchers to look at the role of adjuvant aspirin in preventing recurrence in patients with colorectal cancer.
Simes says they also plan to undertake additional research that will determine methods for adjusting for non-adherence with protocol therapy as well as examining the health-economic benefits of therapy.
Although the research showed very promising results, the authors recommend patients talk with their health care providers before taking aspirin after stopping treatment with anticoagulants.
—Colleen Mullarkey
Reference
Simes J, Becattini C, Agnelli G, Eikelboom JW, Kirby AC, Mister R, et al. Aspirin for the prevention of recurrent venous thromboembolism: The INSPIRE Collaboration. Circulation. 25 August 2014. [Epub ahead of print].