Berger JS et al. (2006) Aspirin for the primary prevention of cardiovascular events in women and men: a sex-specific meta-analysis of randomized controlled trials. JAMA 295: 306–313

The impact of a patient's sex on the effectiveness of aspirin treatment in the primary prevention of cardiovascular events in at-risk individuals is not clear. Berger et al. did a meta-analysis to investigate whether the advantages and disadvantages of aspirin treatment varied between sexes.

Six prospective, randomized, controlled trials (involving 95,456 individuals; 51,342 women) reporting the incidence of myocardial infarction (MI), stroke and cardiovascular mortality in patients assigned aspirin treatment or control treatment were included in the analysis. Compared with controls, aspirin therapy reduced the number of cardiovascular events by 12% in women and by 14% in men (P = 0.03 and P = 0.01, respectively). In women, aspirin reduced the risk of stroke by 17% (P = 0.02), which was attributable to a reduced incidence of ischemic, but not hemorrhagic, stroke. Aspirin did not alter the risk of MI in women. In men, aspirin did not reduce the risk of stroke but reduced the risk of MI by 32% compared with controls (P = 0.001). Aspirin increased the risk of bleeding in men and women by similar amounts, but did not alter cardiovascular mortality in either group.

In summary, overall cardiovascular event rates are reduced by aspirin in both sexes, but via different routes. The differences in the response to aspirin were based on small numbers of MIs and strokes and need to be investigated in larger trials before clear conclusions can be drawn.