WEDNESDAY, Feb. 2, 2005 (HealthDayNews) -- Stroke survivors who stop taking daily aspirin as recommended by their physician triple their risk of having another stroke within just one month, researchers say.
While the exact reasons for this sudden jump in danger is unknown, Swiss investigators speculate that stopping aspirin increases blood platelet activity linked to stroke-inducing clots.
The findings were reported Feb. 2 at the American Stroke Association's International Stroke Conference in New Orleans.
Researchers in Lausanne, Switzerland, evaluated 309 patients who had suffered a stroke or a transient ischemic attack (TIA), the so-called "mini-strokes" that can precede a stroke. All of the patients were placed on long-term 100-milligram or 300-milligram daily aspirin regimens to help prevent repeated episodes of stroke or heart attack. The researchers also evaluated 309 patients who had had a stroke or TIA more than six months before the study, and were on aspirin therapy due to similar risk factors, such as high blood pressure or coronary heart disease.
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 control group had done so -- leading the researchers to conclude that those with stroke were more than three times as likely to have stopped their aspirin than those with similar risk factors, but no new stroke or TIA.
While 77 percent 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 percent occurred from day nine through 30, the researchers said.
How might stopping aspirin lead to increased stroke risk so quickly? Study co-researcher Dr. Alexandre Maulaz, of the Centre Hospitalier Universitaire de Vaud, Lausanne, said the exact reasons remain unclear, but he speculated that discontinuing aspirin may boost blood platelet numbers and lead to more clots forming.
And he pointed out that the control group in the study, as well as those with stroke history, all had stroke risk factors to begin with. "The possible risk of stroke after stopping aspirin was greater only in patients with many cardiovascular risk factors," he said, "mainly ischemic heart disease. This conclusion cannot be extrapolated for all kinds of persons who take aspirin."
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 t 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."
While most patients who are prescribed stroke prevention therapy are vigilant about following it, Buxton said, sometimes an upcoming surgery will require patients to discontinue their stroke prevention therapy. "If you have to go off aspirin therapy before surgery, the doctor must weigh the benefits and risks," he said.
Every 45 seconds, another person in America suffers a stroke, while every three minutes stroke will claim another life, according to statistics from the American Stroke Association. These "brain attacks" occur when blood flow to the brain is interrupted. Some occur when blood flow in an artery is obstructed, while other forms of stroke are characterized by hemorrhaging from a ruptured vessel.
Stroke can leave its victims with major disabilities, such as an inability to walk without assistance, trouble speaking or swallowing, or one-sided paralysis. Many stroke victims require nursing home care.
Among the warning signs and signals of stroke: a sudden numbness or weakness of the face, arm or leg, especially on just one side of the body, sudden confusion, trouble speaking or understanding, sudden trouble seeing in one or both eyes, trouble walking, dizziness, loss of balance, or sudden severe headache with no apparent cause.
Aspirin use is often prescribed to patients who have had stroke or heart attack as a way to prevent future attacks. But the American Heart Association warns that no one should start aspirin therapy without first consulting their doctor.
In the Swiss study, the average patient age was 71 years, with 62 percent of study participants men. Risk factors in each group were similar, with 69 percent having high blood pressure, 20 percent diagnosed with diabetes and 14 percent smokers. Twice as many individuals -- 36 percent -- in the stroke group had heart disease, compared to 18 percent in the control group. Similar numbers in both groups were taking either 100 milligrams or 300 milligrams of aspirin daily.
The study points out the importance of following doctor's orders to take aspirin daily and not to change the regimen without permission, Maulaz said.
To learn more about aspirin use and stroke prevention, visit the American Heart Association.