Low-dose aspirin and stroke. "It ain't necessarily so".

Most clinicians have assumed that very low doses of aspirin might be effective in preventing stroke and death in patients presenting with transient ischemic attacks (TIAs) and stroke. In fact, 325 mg/day or less are often advocated despite the large numbers of well-designed, prospective controlled studies involving stroke-threatened patients that demonstrate the effect of doses greater than 975 mg/day and the paucity of studies using lower doses. The Antiplatelet Trialists concluded that " . . . if aspirin is to be used prophylactically in routine medical practice there appears to be no good reason to use a dose higher than 300-325 mg/day " This was based on a meta-analysis of studies of a heterogeneous group of clinical trials (TIA, stroke, surgical trials, myocardial infarction, unstable angina) using a heterogeneous group of end points (definite stroke, probable or definite nonfatal myocardial infarction, and all deaths that might have been vascular or hemorrhagic). In addition, studies using any drug thought to have a platelet antiaggregant effect were included. The authority of this group is impressive. Nevertheless, we have serious reservations that low dose might not be as effective as high dose. Of course, if the side effects were not different and it were possible that the higher dose was more effective, it would be used. Unfortunately, evi-