Self-selected aspirin use for ≥180 days/year was associated with a lower risk of subsequent MI (RR 0.72; 95% CI 0.55-0.95) and CVD-related mortality compared to 0-13 days/year.
Observational (n=18,496)
Does self-selected aspirin use reduce the risk of subsequent MI, stroke, CVD-related mortality, and total mortality in participants with no previous reported CVD?
Self-selected aspirin use was associated with reduced risks of MI, CVD mortality, and total mortality, but the presence of residual confounding highlights the need for randomized trials to confirm these effects in primary prevention.
Effect estimate: RR 0.72 (95% CI 0.55-0.95)
BACKGROUND: The randomized aspirin component of the Physicians' Health Study (PHS) was terminated early, after 5 years, primarily because of the emergence of a statistically extreme (P<.00001) 44% reduction of first myocardial infarction (MI) among those assigned to aspirin. As a result, there were insufficient numbers of strokes or cardiovascular disease (CVD)-related deaths to evaluate these end points definitively. METHODS: Data on self-selected aspirin use were collected until the beta carotene component ended as scheduled after 12 years. Posttrial use of aspirin was assessed at the 7-year follow-up among 18 496 participants with no previous reported CVD. Randomized and posttrial observational results in the PHS were compared, and differences between those self-selecting aspirin and those not were examined. RESULTS: At 7 years, 59.5% of participants without CVD reported self-selected aspirin use for at least 180 d/y, and 20.8% for 0 to 13 d/y. Use was significantly associated with family history of MI, hypertension, elevated cholesterol levels, body mass index, alcohol consumption, exercise, and use of vitamin E supplements. In multivariate analyses, self-selected aspirin use for at least 180 vs 0 to 13 d/y was associated with lower risk for subsequent MI (relative risk RR, 0.72; 95% confidence interval CI, 0.55-0.95), no relation with stroke (RR, 1.02; 95% CI, 0.74-1.39), and significant reductions in CVD-related (RR, 0.65; CI, 0.47-0.89) and total mortality (RR, 0.64; CI, 0.54-0.77). CONCLUSION: These associations between self-selected aspirin use and CVD risk factors increase the likelihood of residual confounding and emphasize the need for large-scale randomized trials, such as the ongoing Women's Health Study, to detect reliably the most plausible small to moderate effects of aspirin in the primary prevention of stroke and CVD-related death.
Cook et al. (Mon,) conducted a observational in No previous reported cardiovascular disease (n=18,496). Self-selected aspirin use vs. 0 to 13 days/year was evaluated on Subsequent myocardial infarction (RR 0.72, 95% CI 0.55-0.95). Self-selected aspirin use for ≥180 days/year was associated with a lower risk of subsequent MI (RR 0.72; 95% CI 0.55-0.95) and CVD-related mortality compared to 0-13 days/year.