Stroke survivors who stop taking daily aspirin as recommended by their physicians U triple their risk of having another stroke within just one month, researchers say.

Although the exact reasons for this sudden increase in danger are unknown, Swiss investigators speculate that stopping aspirin increases blood platelet activity that is linked to stroke-inducing clots.

The Study

Researchers in Lausanne, Switzerland, evaluated 309 patients who had experienced a recent stroke or a transient ischemic attack (TIA), also known as a mini-stroke. All of the patients were placed on long-term 100-or 300-milligram (mg) daily aspirin regimens to help prevent a heart attack or repeated episodes of stroke.

The researchers also evaluated a control group of 309 patients who had had a stroke or TIA more than six months before the study and were already on aspirin therapy due to risk factors, such as high blood pressure or coronary heart disease.

Risk factors in each group were similar, with 69% having high blood pressure, 20% diagnosed with diabetes and 14% smokers. Twice as many individuals (36%) in the recent stroke group had heart disease, compared with the control group (19%). Similar numbers of people in both groups were taking either 100 or 300 mg of aspirin daily.


Among the patients with a recent stroke history, 13 had stopped taking daily aspirin in the month preceding their stroke. In contrast, just four patients in the other group had stopped taking aspirin.

This leads the researchers to conclude that those who had had a recent stroke were more than three times as likely to have stopped their aspirin therapy than those who had similar risk factors, but no new stroke or TIA.

While 77% of the ischemic strokes (in which blood flow to the brain is decreased) related to discontinuing aspirin occurred in the first eight days after the aspirin was stopped, the other 23% occurred from day nine through day 30, the researchers report.


The study findings do not surprise Dr. William Buxton, a neurologist on staff at Santa Monica-UCLA Medical Center, and an assistant clinical professor of neurology at the David Geffen School of Medicine at the University of California, Los Angeles. "The study reinforces a lot of our suspicions that going off aspirin or other anti-platelet medications, even for a short time, may put people at risk of stroke."

Study co-researcher Dr. Alexandre Maulaz, of the Centre Hospitalier Universitaire de Vaud, Lausanne, speculates that discontinuing aspirin may boost blood platelet numbers and lead to more clotting.

However, he points out that that both groups in the study had stroke risk factors at the outset. "The possible risk of stroke after stopping aspirin was greater only in patients with many Cardiovascular risk factors, he says, "mainly ischemic heart disease. This conclusion cannot be extrapolated for all kinds of persons who take aspirin."

Risks Vs. Benefits

Although most patients who are prescribed stroke prevention therapy are vigilant about following it, Buxton says, sometimes an upcoming surgery will require patients to discontinue their aspirin therapy. "If you have to go off aspirin therapy before surgery, the doctor must weigh the benefits and risks," he says.

The study points out the importance of following doctor's orders to take aspirin daily and not to change the regimen without permission, Maulaz says.

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