Conference Coverage
Aspirin may substantially reduce the risk of recurrent stroke when used immediately after a transient ischemic attack (TIA), according to a study published online ahead of print May 18 in the Lancet. Aspirin appears to reduce the risk of disabling stroke to a greater extent than it reduces the risk of nondisabling stroke. This finding suggests that aspirin has a neuroprotective effect, researchers said.
“The risk of major stroke is very high for only the first few days after TIA and minor ischemic stroke, and observational studies show substantially greater benefits of early medical treatment in the acute phase than do longer-term trials,” said Peter M. Rothwell, MD, PhD, Action Research Professor of Neurology at the University of Oxford, UK, and his colleagues.
Previous studies of patients with acute stroke have found that aspirin reduced the risk of recurrent stroke by 13%, but the effect of aspirin on the risk of recurrence after TIA had not been reported. Researchers hypothesized that short-term benefits of early aspirin had been underestimated. To test this hypothesis, Dr. Rothwell and his colleagues examined the time course of the effects of aspirin and dipyridamole, and studied the risk and severity of recurrent ischemic stroke following aspirin treatment. In addition, investigators compared the severity of early recurrent strokes between treatment groups. The effect of aspirin and dipyridamole in secondary prevention of stroke was also observed.
The investigators pooled data for 15,778 participants in 12 trials of aspirin versus control in secondary prevention. Patients were randomized less than 48 hours after a major acute stroke. They also obtained data on the nature and timing of the following outcome variables: recurrent stroke, recurrent ischemic stroke, acute myocardial infarction, intracerebral hemorrhage, fatal extracranial bleeding, and other causes of death. Data were also obtained on the severity and outcome of all recurrent strokes. In addition, researchers gathered individual data on severity of stroke at study entry. The researchers classified recurrent stroke according to the following three time periods: less than six weeks, six to 12 weeks, and more than 12 weeks after randomization.
Aspirin reduced the six-week risk of recurrent ischemic stroke by about 60%. The benefit of aspirin was greatest during the first two weeks, but further benefit accrued up to 12 weeks. Aspirin also decreased the risk of a fatal or disabling stroke by 70% to 80% over the first few days and weeks. Data suggested that administering dipyridamole plus aspirin versus aspirin alone had no impact on the risk or severity of recurrent ischemic stroke within 12 weeks. One fatal extracranial bleed within 12 weeks of randomization was reported. Aspirin did not reduce the severity of recurrent stroke that occurred at 12 or more weeks after TIA.
“Our findings confirm that medical treatment substantially reduces the risk of early recurrent stroke after TIA and minor stroke and identifies aspirin as the key intervention. The considerable early benefit from aspirin warrants public education about self-administration after possible TIA,” the researchers said.
Some limitations of this study include the time period of the trials (the 1980s and 1990s), since medical care has changed since then, and more detailed investigation and intensive lowering of blood pressure and lipids are now possible, the researchers said.
—Erica Robinson