[Aspirin dosage for prevention of cerebral infarct: arguments for low dosage].

Acetylsalicylic acid (ASS) is one of the best examined substances used in secondary prevention after TIA and stroke. Since different strategies and measurement variables were used in numerous randomised, double-blind, placebo-controlled studies (one end-variable, such as non-fatal stroke, myocardium infarction and vascular mortality, or combined end-variables, such as TIA, stroke and death), meta-analysis was necessary to prove that ASS resulted in about 22% reduction of secondary stroke. There is disagreement over the optimal dosage to prevent a stroke: earlier studies considered > or = 975 mg ASS per day, sometimes in combination with other substances, while more recently, lower dosages of about 300 mg per day or even as low as < or = 100 mg per day have been proposed. Higher and lower dosages were effective compared with placebo but with no significant difference in risk reduction, despite the trend towards a transient but insignificant reduction of secondary events for the high dosage. All available studies demonstrated a strictly dose-related gastro-intestinal hemorrhagic bleeding complication rate. Since no data are available from a direct comparison in a large sample size trial to prove the superiority of low-dose ASS (< or = 300 mg per day) over high dosages (> or = 975 mg per day) in secondary prevention of stroke, we believe that the lowest dosage of < or = 100 mg per day should be recommended for safety reasons.