The risk of having another stroke is tripled within one month if aspirin therapy is discontinued, Swiss researchers reported here at the American Stroke Association’s International Stroke Conference 2005.

Dr. Patrik Michel of Lausanne University and colleagues collected data on all patients who had been admitted to their institution with either transient ischemic attack (TIA) or stroke between January 2002 and April 2004.

They selected 309 new stroke patients who had already been prescribed long-term aspirin for secondary prevention of heart attack and stroke prior to the defining stroke event. As a comparison, they chose another 309 patients with a six-month or longer history of stroke who were on long-term aspirin therapy.

Michel reported that 13 patients in the study group stopped taking aspirin in the month before their new stroke, and 4 patients in the control group had a recurrent stroke. “Therefore, risk of stroke is three times higher if aspirin is stopped” compared with patients with similar risk factors but who continue aspirin therapy, Michel said.

Although the numbers are small, “they are significant on a statistical level,” the Swiss researcher told Reuters Health. He acknowledged that the study has some limitations. “The absolute risk (of having a stroke with aspirin discontinuation) is low, but there is still an increased risk,” he said.

Michel said that in about two thirds of cases, the physician ordered the aspirin discontinuation because the patient was scheduled for minor surgery or procedures, had nosebleeds or for other reasons. In one third of cases, the patient discontinued therapy on his own.

The risk of stroke was highest in the 8 to 10 days following discontinuation of therapy from a “rebound” effect, Michel noted. He pointed out that patients undergoing surgery are instructed to discontinue aspirin one week prior to the procedure. “It may be safer to have the procedure without aspirin discontinuation. We need to weigh the risks and benefits of stopping aspirin.”

Michel added that it is also important to educate patients about the importance of continuing long-term aspirin therapy and the risks of discontinuation.