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New Data on Aspirin for Primary Prevention of CVD in Women

Aspirin had only a borderline significant benefit in preventing first major cardiovascular events, with no benefit in preventing death and myocardial infarction.

Most subjects in primary-prevention trials of aspirin have been men. Adding to the evidence base for women are new data from the Women's Health Study, a randomized, double-blind, placebo-controlled trial of low-dose aspirin (100 mg every other day) and vitamin E for preventing cardiovascular disease (CVD) and cancer. Participants were 39,876 initially healthy women (age 45; mean, 55; 28% premenopausal) who demonstrated before randomization that they were likely to adhere to long-term treatment. Researchers now report the findings on aspirin and incident CVD.

During a mean follow-up of 10 years, major CVD events (the primary endpoint) occurred in nonsignificantly fewer aspirin than placebo recipients (2.4% vs. 2.6%, P=0.13). The two groups did not differ significantly in their incidences of MI or death, but the aspirin group had a significantly lower incidence of stroke (1.1% vs. 1.3% with placebo, P=0.04). Aspirin showed a significant advantage for preventing major CVD events among women older than 65, but not among those age 65 or younger. Gastrointestinal bleeding was significantly more common in the aspirin group (4.6%) than in the placebo group (3.8%).

Comment: Overall, this trial somewhat weakens the case for using aspirin for primary prevention of CVD in women. The stroke and age-specific findings, which received considerable press coverage, were secondary and should be viewed in that light. Decisions about aspirin use for primary prevention in women should be made with an understanding that the evidence base is simply not as firm as it is for men. We must remember, however, that aspirin has well-established benefits in women with known CVD and that these new findings do not apply to those women.

— Harlan M. Krumholz, MD, SM

Published in Journal Watch Cardiology April 15, 2005

Citation(s):

Ridker PM et al. A randomized trial of low-dose aspirin in the primary prevention of cardiovascular disease in women. N Engl J Med 2005 Mar 31; 352:1293-304.

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• Medline abstract (Free)

Levin RI. The puzzle of aspirin and sex. N Engl J Med 2005 Mar 31; 352:1366-8.

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• Medline abstract (Free)