Review of guidelines on primary prevention of cardiovascular disease with aspirin: how much evidence is needed to turn a tanker?

AIMS: There are numerous national and international guidelines on the use of aspirin for the primary prevention of cardiovascular disease. Given the uncertainties about aspirin in primary prevention, our aim was to compare the recommendations and the reported evidence in guidelines for the treatment with aspirin of subjects free of cardiovascular disease with or without diabetes. METHODS AND
RESULTS: Guidelines were retrieved through Medline and other electronic databases and through a web-based search for guideline development organizations. The content of the recommendations and the underlying evidence were analysed with qualitative and bibliometric methods. In addition, we searched for recent studies to assess whether they underscore the current recommendations. We included 12 guidelines: six European, three North American, and one each from New Zealand, Australia, and the World Health Organization. Recommendations differ with regard to outcome (morbidity, mortality), time span (years of risk), cut-off percentage between high and low risk, and the dose of aspirin. Most guidelines are not in line with recent evidence, which show that aspirin is of uncertain net value as the reduction in absolute risk for occlusive CV events needs to be weighed against an increase in the risk of major bleeds.
CONCLUSION: We found conflicting recommendations in various guidelines about the use of aspirin for the primary prevention of cardiovascular events, which reflect differences in selection of the evidence and in the timing of publication. According to recent evidence, in general, the use of aspirin seems no longer justifiable in primary prevention in patients with or without diabetes.