Though warfarin prevents recurrent blood clots, it requires regular blood monitoring, can interact with foods and other drugs, and may increase bleeding risk when taken for an extended period.
"Ask your cardiologist if you could benefit from aspirin."
Cecilia Becattini, MD, from the Internal and Cardiovascular Medicine and Stroke Unit at the University of Perugia in Italy, found that switching warfarin users to aspirin after they had taken the drug for at least six months offered protection from another deep vein blood clot.
During the double-blind multi-center study patients who had previously suffered a deep vein blood clot and had been taking warfarin for six to 18 months to prevent a recurrence were assigned to one of two groups. Of the participants, 205 were assigned to take 100 milligrams of aspirin daily, while 197 took an inactive drug.
Researchers found that aspirin reduced the risk of another blood clot following the discontinuation of warfarin with no apparent additional risks.
After two years, 28, or 7 percent of patients, in the aspirin group had experienced another blood clot, while 43, or 11 percent, in the non-intervention group experienced a recurrence. Both were just as safe.
Adverse events were similar among both groups, with one participant from each suffering an episode of major bleeding.
The study was funded by the University of Perugia, a grant-in-aid from Bayer HealthCare, and an Aventis Fellowship for Clinical Research from the International Society of Thrombosis and Haemostasis.
Several researchers received consulting or lecture fees from major drug companies including Bayer Healthcare, which produces aspirin.
The study was recently published in the New England Journal of Medicine.