Bias or Biology?

Clearly, there are divergences in the way that men and women are diagnosed
and treated for heart disease. But how much of this difference is due to
ingrained prejudices in society and medicine, and how much is due to actual
dissimilarities in men's and women's physiologies? Are women's coronary
arteries different from men's? Do the risk factors that have been proven to
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."

Other Women's Issues