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Aspirin May Reduce Risk of Repeat Blood Clots

Those on Aspirin About 40% Less Likely to Have Repeat Clots; Expert Calls for More Study
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WebMD Health News
Reviewed by Laura J. Martin, MD

May 23, 2012 -- Aspirin may be effective long-term to reduce the risk of repeat blood clots in veins, new research suggests.

Patients who have these potentially dangerous blood clots, called venous thromboembolism or VTE, often get them in deep veins in the legs. They can then travel up to the lungs and are sometimes fatal.

When the first one occurs, a patient is typically put on an anti-clotting drug, or anticoagulant, for several months. However, staying on these drugs is linked with an increased risk of dangerous major bleeding.

Now, researchers have found that daily aspirin may be a good next step after completing treatment with the initial anti-clotting drug.

"Based on our results, we believe that aspirin can be considered an alterative to extended oral anticoagulant treatment for secondary prevention [of blood clots]," says researcher Cecilia Becattini, MD, PhD, of the University of Perugia in Italy.

Those on aspirin, she found, were about 40% less likely than those on placebo to have a repeat blood clot.

A U.S. expert calls the study findings exciting but says more study is needed.

Blood Clots: The Problem

Doctors know that the risk of a repeat blood clot endures for many years. So they prescribe the anti-clotting drugs for several months after the initial blood clot.

About 20% of patients who have a blood clot without any known risk factors, such as having recent surgery, will have another one within two years after the anti-clotting drugs are stopped.

The drugs are stopped to decrease the risk of major bleeding. "Major bleeding means intracranial, life-threatening, or even fatal bleeding," Becattini tells WebMD.

When patients are on the anti-clotting drugs, such as warfarin (Coumadin, Jantoven), they also have to get blood tests often to see if the dose is OK.

Blood Clots: The Study

Becattini's team evaluated 402 men and women. They had been on anti-clotting drugs for six to 18 months after having a blood clot.

The researchers assigned about half of the study participants to take 100 milligrams of aspirin a day for two years and half to take a placebo pill every day for two years.

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