Aspirin may prevent recurrence of deep vein blood clots

Blood-thinning, or "anticoagulant," therapy is used to prevent another clot, which occurs in about 20 percent of patients. However, extended use of warfarin can increase the risk for bleeding, so researchers wanted to know whether aspirin would be a good alternative after two years of treatment with warfarin.

"Aspirin given after a standard course of anticoagulant treatment may reduce recurrence of venous thromboembolism without increasing complications," said lead researcher Dr. Cecilia Becattini, from the Internal and Cardiovascular Medicine and Stroke Unit at the University of Perugia.

So aspirin can be an alternative after an initial period of warfarin treatment, Becattini said, and "patients could be shifted to aspirin after talking it over with their doctor."

The study was published in the May 24 issue of the New England Journal of Medicine.

An accompanying journal editorial noted that venous thromboembolism, which includes deep vein thrombosis (blood clots in the legs) and pulmonary embolism (a clot in the lungs), occurs in two to three people per 1,000 yearly.

The danger of a venous thromboembolism is that a clot can break loose and travel to the lungs, heart or brain, resulting in a heart attack, stroke, difficulty breathing or even death.

For the study, Becattini's team randomly assigned 402 patients to receive aspirin or an inactive placebo after receiving other anticoagulant treatment for six to 18 months.

All of the patients had had a first episode of venous thromboembolism and had not had any risk factors that might have predicted it, the researchers noted.

Over two years of follow-up, 28 (6.6 percent) of those taking aspirin had a venous thromboembolism recur, compared with 43 (11.2 percent) of those receiving a placebo, the study found.

One patient in each group had an episode of major bleeding, the authors noted.

"Aspirin reduced the risk of recurrence when given to patients with unprovoked venous thromboembolism who had discontinued anticoagulant treatment, with no apparent increase in the risk of major bleeding," the researchers concluded.

Dr. Richard Becker, author of the journal editorial and professor of medicine and director of the Duke Cardiovascular Thrombosis Center at Duke University Medical Center, said, "I consider these findings important, but preliminary."

He added, "Aspirin would not at this time be considered the standard of care to reduce the recurrence of deep vein thrombosis."

Becker also noted that this study is too small to change practice.

There are two larger trials under way and if the findings support those of this study, then aspirin may be an option for some patients, particularly those patients at high risk for bleeding with warfarin, he said.

"I do not want to give the impression that the standard of care has changed because of this study," Becker said.

Bayer HealthCare helped fund the study.

More information: For more about venous thromboembolism, visit the U.S. National Library of Medicine.

Journal reference: New England Journal of Medicine

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