Aspirin irreversibly inhibits platelet cyclooxygenase and impairs platelet aggregation in doses as low as 60 mg every other day. A clinical history of bleeding diathesis, active ulcer disease or aspirin allergy is a major contraindication. Dosage appears unimportant, usually ranging from 60 mg every other day up to 325 mg daily. Secondary prevention Secondary prevention trials with aspirin have demonstrated reduced cardiovascular and cerebrovascular endpoints. A meta-analysis of over 70,000 patients with arterial disease or risk factors for arterial disease reported a 25% decrease in vascular events and an 18% decrease in vascular deaths with aspirin-based antiplatelet therapy (Antiplatelet Trialists' Collaboration, 1994 [M]). Primary prevention Primary prevention studies in patients not selected for cardiovascular risk factors have shown minimal benefit. Some studies have shown reduced non-fatal myocardial infarction, but this was not supported by meta-analysis (Eidelman, 2003 [M]; Hayden, 2002 [M]; Nowak, 2003 [R]). Patients with hyperlipidemia are at intermediate risk and may derive greater benefit from aspirin than the lower-risk populations studied in primary prevention trials. The recommendation for aspirin in hyperlipidemic patients is supported by this reasoning, and by the low cost and risk of this therapy (Manson, 1991 [B]; Peto, 1988 [A]). |