Benefits of aspirin for postmenopausal women

Dec 13 2005

Aspirin can significantly reduce death rates for postmenopausal women with cardiovascular disease (CVD), researchers reported at the American Heart Association's Scientific Sessions 2005.

"It was known before, and we have shown it again: aspirin therapy is a lifesaving therapy," said Jeffery S. Berger, M.D., lead author and cardiology fellow at Duke University Medical Center in Durham, N.C. "Women with cardiovascular disease should be on aspirin unless there is a medical contraindication such as hypersensitivity or gastrointestinal intolerance."

Data from nearly 9,000 women with CVD demonstrated that those taking aspirin had significantly lower risk of cardiovascular death as well as from all causes of death, compared to women who did not take the over-the-counter drug.

Women with CVD (8,928) enrolled in the Women's Health Initiative Observational Study, a longitudinal multicenter study of 93,676 women aged 50 to 79 years at baseline, were used for this analysis. The primary outcome was the incidence of cardiovascular events, which included heart attack, stroke, cardiovascular death and all-cause mortality.

Among the 8,928 women with stable CVD, 46 percent reported taking aspirin, of whom 30 percent were on 81mg and 70 percent were on 325mg. Six and a half years after enrolling in the Women's Health Initiative's (WHI) Observational Study, 956 of the women with CVD had died.

During 6.5 years of follow-up, 8.7 percent of participants died when compared to the no aspirin group, both 81mg and 325mg groups were associated with a 17 percent reduction in all-cause mortality and a 25 percent lower death rate from all cardiovascular diseases.

For the prevention of cardiovascular events, both 81mg and 325mg were associated with a non-significant 11 percent reduction in stroke, no effect on MI, and a non-significant reduction in events. Compared to 325mg, treatment with 81mg was not significantly different in its effect on all-cause mortality, cardiovascular events or any individual endpoint.

"This was not a randomized trial so we could not demonstrate cause-and-effect," Berger said. "Aspirin was associated with a significant reduction in death, yet we are unable to conclude that aspirin caused the reduction."

Past studies have shown that aspirin can reduce fatal and nonfatal cardiovascular problems in patients with cardiovascular disease. Despite this well known protective effect, less than half of all women in the study took aspirin regularly, Berger said.

"Unfortunately, when you look at the aspirin data, you find that women have been under-represented in many of the studies," he said. "There is no conclusive data that provides the optimal dose or effect of aspirin usage in women."

"That was surprising and disappointing. Many studies have shown that 81 mg is just as effective in the secondary prevention of cardiovascular events as 325 mg. And it is well known that the higher the dose, the more likely you are to suffer side effects. Why so many women were on the higher dose was unclear.

"Whether a woman was taking 81 mg or 325 mg, the reduction in death rate was the same, and that point, I think, is the most noteworthy of the study," Berger said. "It is difficult from this study to say that the 81 mg dose is better than 325 mg, but it does appear that it is as effective as 325 mg."

He also noted that because only postmenopausal women participated in the WHI study, the findings reported today may not apply to young women with CVD.

"We have to do a better job of making sure that women who need aspirin get aspirin," Berger said. "Our study should stimulate physicians to explain the benefits of aspirin to select groups of female patients. For patients who worry about aspirin's side effects, this study shows that the smallest dose necessary is just a baby aspirin a day."