promote heart disease in men-including smoking, a high- fat diet, and lack of exercise-apply equally to women? Can women derive the same heart benefits from a change in lifestyle?
In trying to answer these questions, one almost immediately stumbles into a gaping void of epidemiologic information pertaining to women's heart disease. Whatever differences there may be in the incidence and development of coronary disease in men and women, the discrepancies in the amount it has been studied in each sex are striking.
Until the last few years, nearly every large-scale study of heart health has excluded women as a matter of policy. The Veterans Administration Cooperative Study, one of the first to document the benefits of coronary surgery for angina; the Multiple Risk Factor Intervention Trial (known,
tellingly, as "Mr. Fit"), which showed that heart attacks could be reduced by eliminating certain risk factors; and the U.S. Physicians Study, which demonstrated that aspirin could help prevent heart attacks-none enrolled a single woman.
The reasons for what now seems a glaring omission? There's no way to measure the role that institutional prejudice, inertia, or gender bias may have played. But one factor that did enter the calculation-as it enters every epidemiologic study-was cost.
"Large-scale studies seek to enroll as many participants as their budgets will allow. Because heart disease is far more common in middle-aged men than in middle-aged women, most early studies, working with limited financial resources, focused on men," says Meir Stampfer, Harvard professor of epidemiology and nutrition. "As a result, researchers missed out on some of the unique features of coronary disease in women."
It is an omission that Stampfer and his colleagues have helped redress through the Nurses' Health Study and Nurses' Health Study II, which have enrolled more than 200,000 women over the past 19 years. The studies have assessed women's heart disease in light of a wide array of variables:smoking, nutrition, physical activity, use of oral contraceptives, and more.
"From all the evidence we've gathered to date, it's fair to say that whatever constitutes a risk factor for coronary disease in one sex is a risk factor in the other sex as well," Stampfer says.
There are a few exceptions--diabetes, for instance, increases women's chances of coronary disease slightly more than it does men's-but, in general, if something is bad-or good-for men's coronary arteries, it will have the same effect on women's arteries. This research has convincingly put the lie to the myth-still flickering in some quarters-that women can smoke and
magically avoid heart disease. "The Nurses' Health Study showed that even low levels of cigarette use-one to four cigarettes a day-doubles a woman's risk of heart attack," he says.
The Nurses' Health Studies also have explored whether there is a link between oral contraceptive use and coronary disease in women. The findings,Stampfer says, ought to be reassuring to some women and alarming to others.
"Women who use oral contraceptives and do not smoke are at no extra risk for coronary disease. Women who smoke and do not use oral contraceptives face a risk of coronary disease three to four times above normal. Women who smoke and use oral contraceptives face 20 to 30 times the risk" That increase, he adds, lasts only as long as women continue to smoke. Kicking the habit
rapidly returns their risk to normal.
The studies of oral contraceptives, while encouraging, need to be updated in light of recent changes in the chemical formulation of birth-control pills, Stampfer adds. "Modern contraceptives are often prescribed at lower doses than the contraceptives of just a few years ago. There has been some suggestion that lower doses may actually confer a protective effect against coronary disease, but there's no documented proof."
http://www.fauxpress.com/kimball/med/heart/Bias.html
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