DALLAS — Daily aspirin therapy in postmenopausal women with stable cardiovascular disease was associated with a 25% reduction in the risk of cardiovascular mortality in the Women's Health Initiative Observational Study.
That's the good news.
The bad news? Aspirin was being used by fewer than half of the nearly 9,000 women in the study in whom this safe and inexpensive therapy was indicated for secondary cardiovascular prevention, Dr. Jeffrey S. Berger said at the annual scientific sessions of the American Heart Association.
That's a rate far lower than is typical in men with established cardiovascular disease. Indeed, only 46% of the 8,928 postmenopausal women with stable cardiovascular disease in the Women's Health Initiative (WHI) Observational Study were on aspirin. Ideally, that figure ought to be in excess of 90%, since only 5% or fewer aspirin candidates have medical contraindications, observed Dr. Berger, a cardiology fellow at Duke University, Durham, N.C.
While today aspirin is well recognized as a key element in secondary prevention, many of the studies that established the drug's efficacy underenrolled or excluded women. This deficiency was the impetus for the aspirin substudy within the longitudinal WHI cohort study, which involved almost 94,000 women aged 50–79 at entry.
During a mean 6.5 years of follow-up, 8.7% of the nearly 9,000 women with stable cardiovascular disease at study entry died. All-cause mortality was 17% lower in women on aspirin vs. aspirin nonusers.
Roughly 70% of aspirin users were taking 325 mg/day, with the remainder on 81 mg/day. The mortality reduction was the same with the lower and higher dosages, which would seem to favor the use of 81 mg/day. The sole caveat concerns aspirin resistance, known to be more prevalent in women. It's possible 325 mg is able to overcome mild aspirin resistance and protect affected women, Dr. Berger said.