Aspirin in the primary prevention of cardiovascular disease: current knowledge and future research needs.

In secondary prevention, among a very wide range of survivors of prior occlusive cardiovascular disease (CVD) events and those suffering acute myocardial infarction (MI) or occlusive stroke, aspirin decreases risks of MI, stroke, and CVD death. In these high risk patients, the absolute benefits are large and absolute risks are far smaller so aspirin should be more widely prescribed. In contrast, in primary prevention, aspirin reduces risks of first MI but the evidence on stroke and CVD death remain inconclusive. Based on the current totality of evidence from predominantly low risk subjects where the absolute benefits is low and side effects the same as in secondary prevention, any decision to prescribe aspirin for primary prevention should be an individual clinical judgment by the healthcare provider that weighs the absolute benefit in reducing the risk of a first MI against the absolute risk of major bleeding. If the ongoing trials of intermediate risks subjects show net benefits then general guidelines may be justified with several caveats. First, any decision to use aspirin should continue to be made by the healthcare provider. Second, therapeutic lifestyle changes and other drugs of life saving benefit such as statins should be considered with aspirin as an adjunct, not alternative. The more widespread and appropriate use of aspirin in primary prevention is particularly attractive, especially in developing countries where CVD is emerging as the leading cause of death. In addition, aspirin is generally widely available over the counter and is extremely inexpensive.