Evaluation of the benefits and risks of low-dose aspirin in the secondary prevention of cardiovascular and cerebrovascular events.

BACKGROUND: In spite of the clear evidence of benefit of aspirin in the secondary prevention of cerebrovascular and cardiovascular thrombotic events, its use in patients at high risk due to a previous event remains suboptimal. A possible explanation for this underuse is concern regarding the relative benefit in relation to the potential risk for serious gastrointestinal events.

OBJECTIVE: To compare the benefit and gastrointestinal risk of aspirin use for the secondary prevention of thromboembolic events.

DESIGN: A meta-analysis was conducted using 6 trials (6300 patients) meeting the inclusion requirement of use of low-dose aspirin (< or =325 mg/d) in approved secondary prevention indications.

RESULTS: Aspirin reduced all-cause mortality by 18%. In addition, aspirin use reduced the number of strokes by 20%, myocardial infarctions by 30%, and other "vascular events" by 30%. Alternately, patients who took aspirin were 2.5 times more likely than those in the placebo group to have gastrointestinal tract bleeding. The number needed to treat for aspirin to prevent 1 death from any cause of mortality was 67, while 100 needed to be treated to detect 1 nonfatal gastrointestinal tract bleeding.

CONCLUSION: Aspirin use for the secondary prevention of thromboembolic events has a favorable benefit-to-risk profile and should be encouraged in those at high risk.