- Paper Report
- Open Access
Coronary event risk needs to be quantified before advising aspirin for primary prevention
- Joanna Lyford1
© Biomed Central Ltd 2001
- Received: 7 March 2001
- Published: 18 October 2001
- Aspirin, coronary heart disease, primary prevention, meta-analysis
The benefit of aspirin in the secondary prevention of coronary heart disease greatly outweighs the possible damage from hemorrhage. In primary prevention the situation is less clear cut. This study aims to discover the thresholds of cardiovascular and coronary risk at which benefits of treatment are sufficiently great and potential costs small enough to justify the use of aspirin in primary prevention.
Aspirin significantly reduced all cardiovascular events by 15% (95% confidence interval [CI] 6% to 22%) and myocardial infarctions (MIs) by 30% (95% CI 21% to 38%). It also significantly reduced all deaths by 6% (95% CI -4% to 15%). However, aspirin also nonsignificantly increased strokes by 6% (95% CI -24% to 9%) and significantly increased bleeding complications by 69% (95% CI 38% to 107%). The increased risk of major bleeding balanced the reduction in cardiovascular events when cardiovascular event risk was 0.22% per year. At a coronary heart disease event risk of 1.5% per year, aspirin appeared to give an acceptable outcome, with one MI prevented and without any important bleeding for every 77 patients treated. At a lower coronary heart disease risk level of 0.5% per year, however, aspirin is unattractive. At this level of risk, the chance of having a significant bleed was higher than that of preventing MI. Harm from aspirin is unlikely to outweigh benefit provided the cardiovascular event risk is 30.8% per year, equivalent to a coronary risk of 0.6% per year.
Meta-analysis of four randomized trials of aspirin for primary prevention in order to quantify benefit and harm from aspirin treatment at different levels of coronary heart disease (CHD) risk. The trials included the US Physicians Health Study, the UK Doctors study, the Thrombosis Prevention Trial, and the Hypertension Optimal Treatment (HOT) study.
In a related editorial the authors are congratulated on their approach:
Lowe GDO: Who should take asprin for primary prophylaxis of coronary heart disease? Heart 2001, 85:245-246.