Jan. 17, 2006 -- Low-dose aspirin has a different cardiovascular benefit for women than it does for men, but the risk to both sexes is the same, according to new findings.
It has been shown that people who have had a heart attack can benefit from low-dose aspirin. But there's ongoing debate over who -- if anyone -- should take aspirin to prevent a first heart attack or stroke.
New information comes from an analysis of data collected in six large clinical trials. In those trials, more than 51,000 women and more than 44,000 men took daily aspirin tablets or inactive placebo pills. None of the men and women had previously had heart disease.
Aspirin cut men's risk of heart attack by 32%, but not their risk of stroke. Aspirin cut women's risk of stroke by 17%, but not their risk of heart attack. And aspirin increased the risk of "major bleeding" - from potentially life-threatening stomach or intestinal ulcers -- by 70% for both men and women. All of these benefits and risks are small but significant.
The study, done by Duke University researcher Jeffrey S. Berger, MD, and SUNY-Stony Brook researcher David L. Brown, MD, appears in the Jan. 18 issue of The Journal of the American Medical Association. It shows that at the cost of a small but potentially life-threatening risk of "major bleeding events" -- mostly stomach or intestinal ulcers -- men and women each get a small but potentially life-saving benefit from daily aspirin.
"Men and women at elevated risk of cardiovascular disease benefit from aspirin, but each individual needs to discuss this with his or her doctor before deciding to take aspirin," Brown tells WebMD. "The decision to take daily aspirin is never as simple as we would like it to be, because biology is not as simple as we would like it to be."
Daily Aspirin? You Decide
One question lies at the heart of whether to take aspirin to prevent a first heart attack or stroke: Does the benefit outweigh the risk?
There are several ways to look at this. The first is to look at the numbers. Berger, Brown, and colleagues calculate that if 1,000 men or 1,000 women took low-dose aspirin for six and a half years:
- It would prevent three "cardiovascular events" -- death from heart disease, nonfatal heart attack, or nonfatal stroke -- among women.
- It would prevent four cardiovascular events among men.
- It would cause 2.5 potentially life-threatening "major bleeding events" among women.
- It would cause three major bleeding events among men.
But a better way to weigh the benefit against the risk is to look at a person's individual risk for heart attack or stroke. Risk goes up as people accumulate risk factors for heart attack or stroke. These factors include:
- Age. Starting at age 45, stroke/heart attack risk increases each year.
- Family history. A close relative who had a heart attack or stroke at a relatively young age raises your own risk.
- Diabetes. People with high blood sugar levels -- whether or not they have full-blown diabetes -- are at higher risk of heart attack and stroke.
- High blood pressure.
- High cholesterol.
- Smoking. If you've ever smoked cigarettes, you have a higher risk of heart attack and stroke.
Robert J. Myerburg, MD, director of cardiology at the University of Miami Miller School of Medicine, notes that daily aspirin definitely benefits people who've already had a heart attack. Its use to prevent a first heart attack, he says, remains controversial.
"The important thing is not to confuse the long-term preventive benefit of aspirin with its use at the time of onset of a heart attack -- that is a completely different story," Myerburg tells WebMD. "In preventing a first heart attack, over the long term, you see only a small benefit."
How small? Laurence S. Sperling, MD, director of the Emory Heart Center risk reduction program, says people who take daily aspirin have 0.1% to 0.2% fewer heart attacks per year than those who don't take aspirin.
"For women, there is not nearly as profound an effect as in men -- and women's major benefit is stroke prevention, not heart attack prevention," Sperling tells WebMD. "So for people at low to intermediate risk of heart attack, I would not be glib about taking an aspirin a day."