Stroke survivors who stopped taking their prescribed daily aspirin tripled their risk of having another stroke within the month, according to research presented at the American Stroke Association's International Stroke Conference 2005.
"This is the first controlled retrospective study to investigate the potential risk of suffering ischemic stroke shortly after discontinuing aspirin," said Patrik Michel, M.D., co-author of the study and director of the acute stroke unit at Lausanne University Hospital in Lausanne, Switzerland.
The results confirm and extend previous observations in stroke survivors who stopped taking aspirin.
Aspirin is the most often prescribed medication to prevent a recurrent stroke or heart attack, Michel said. This study reinforces the importance of compliance with aspirin therapy in patients with symptomatic atherosclerosis, including previous stroke. Patients and physicians should be aware of a possible increased risk of stroke when aspirin is stopped.
Researchers selected 309 patients who had a stroke or transient ischemic attack (TIA) and were on long-term aspirin therapy for secondary prevention of heart attack and stroke. They matched these patients with 309 control patients who had a stroke or TIA more than six months before and were also taking long-term aspirin therapy.
The average age of the entire study population was 71 years, and 62 percent were men. In each group about 69 percent had hypertension, 20 percent had diabetes, and 14 percent were smokers. In the study group, 52 percent had dyslipidemia compared to 58 percent in the control group (not statistically significant). In the study group, 36 percent had coronary heart disease compared to 18 percent in the control group (a statistically significant difference). Also, a similar number of patients in both groups were taking either a 100 mg or 300 mg dosage of aspirin.
Researchers found that 13 patients in the stroke group had discontinued aspirin within four weeks before their stroke, while only four patients did in the control group. Therefore, patients with stroke or TIA were 3.25 times more likely to have interrupted their aspirin than patients with similar risk factors but no new stroke or TIA. Seventy-seven percent of the ischemic strokes related to aspirin discontinuation occurred in the first eight days after aspirin was stopped; the other 23 percent occurred from day nine to 30.
"Although the absolute risk of suffering a substantial stroke during a short period of aspirin discontinuation is probably not very high, this difference is meaningful, and patients and physicians should be informed about this potential risk," Michel said.
About one-third of patients in the study group discontinued aspirin themselves because of minor bleeding or lack of compliance. In about two-thirds of patients, physicians had ordered aspirin discontinuation for minor bleeding or minor surgical procedures.
The current literature suggests that many diagnostic or surgical procedures, such as cataract surgery or dermatological procedures, may be safely performed while the patient is taking low-dose aspirin.
Michel said a prospective, controlled, randomized trial should be conducted to prove exactly what the stroke risk is from discontinuing aspirin use. He said that such a trial should be a cooperative effort between neurologists, general practitioners, and sub-specialists doing diagnostic and surgical procedures for which aspirin is often discontinued.
Lead author on the study is Alexandre Maulaz, M.D. Other co-authors are Daniel Bezerra, M.D.; Bartolomeij Piechowski-Joywiak, M.D.; and Julien Bogousslavsky, M.D.