ANAHEIM, CALIF. -- In the first analysis of gender differences in heart disease based on many studies, researchers at Duke University Medical Center have shown that women respond as well as men to medical treatment for heart disease.
The result dispels a growing concern among health policy makers that a woman's heart may not respond to drug treatment the same as a man's. It also means that physicians, who traditionally have not recognized heart disease as quickly in women, need to see women as candidates for the same type of therapies as men.
Duke researcher Leslee Shaw and cardiologist Dr. Robert Califf reported their results Wednesday at the 68th annual American Heart Association meeting.
"We know women have higher mortality rates than men from heart attack," Shaw said. "We can attribute most of the poorer outcome in women to the fact that most women with heart disease are, in general, older and sicker. But there still has been the nagging question of whether women should be getting a different treatment regimen."
Prior to this study, it had been difficult to gauge whether women and men get the same treatment benefit from any given drug in a clinical trial because large populations of patients must be enrolled in any study to satisfy statistical requirements for proof of treatment. Since most therapies for heart disease only reduce death rates moderately, the number of patients enrolled in any given study must be large -- several thousand people -- to see any gender differences in treatment. Few such studies have enrolled enough women to be able to accurately assess if women respond differently than men due to concerns about child-bearing potential or the advanced age of women with heart disease.
To overcome this problem, the Duke researchers pooled the results of 165 individual clinical trials in what is called a meta-analysis. They looked at the published results of clinical trials on all of the major classes of cardiovascular drugs, including the affects of aspirin therapy, the clot-busters t-PA and streptokinase, calcium channel blockers and beta blockers, among others. The researchers reasoned that pooling the results of many small studies would give an opportunity to observe statistical differences in response to treatment that looking at studies individually would not.
The combined studies included more than 46,000 women and almost 160,000 men with heart disease.
The results showed that in randomized, blinded clinical trials women and men respond equally to drug treatments.
"The key result here is that when the physician's judgment is taken out of the equation, women respond as well as men to a variety of drug treatments," Shaw said. "Observational studies have shown that in practice, women receive less treatment than men. Whether physicians can accurately identify risk of heart disease in women is still an issue. This analysis shows there is no reason to consider women with heart disease a separate group that must be treated differently."
The findings have implications for policy makers since there are initiatives at the federal level to mandate the inclusion of women in any clinical trial in proportion to their representation in the population. Such a mandate would make it much more difficult, time consuming and costly to carry out clinical trials on new drugs or treatment protocols, since fewer women than men have heart disease. In addition, it shows that even though some previous clinical trials have not included enough women to show a specific treatment affect, there is no reason to assume women won't benefit if the overall result showed a benefit, the researchers said.
"There is a growing concern among federal health care leaders that women, who have been under represented in clinical trials, may not get the same benefit as men from current treatments,"Califf said. "This study clearly sends a message that we should not withhold a treatment from women simply because it hasn't been proven effective expressly in women."