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Birth Control Pills Have Low Risk for Heart
Excerpt
By Analysis By Keith Isaacson, M.D.Special to ABCNEWS.com
Study shows birth control pills, regardless
of the dosage, add only a low risk of heart disease.
This week's New England Journal of Medicine (NEJM)
contains a study that focuses on the risks of a heart attack in
women who have ever taken or are currently taking oral contraceptives.
When people read or hear about studies tying a risk factor to
a serious disease, they often fear that this catastrophe will
happen to them; the true likelihood is often misunderstood. For
example, a study may report that a certain factor increases the
risk of developing an illness by 40 percent. Many patients with
that risk factor may interpret these headlines as meaning that
they have a 40 percent chance of developing that illness. However,
if the original risk of developing the illness were only 10 percent,
the factor would only increase the risk to 14 percent, a much
smaller difference.
The goal of the NEJM study, conducted by Dr. Bea Tanis
and colleagues, was to see if the risks of a heart attack are
increased due to the particular hormonal composition of different
birth control pills. Modern oral contraceptives contain different
combinations of hormones, usually estrogen and a type of progesterone.
The terms first-, second-, and third-generation are used to refer
to the specific combinations of hormones found in a particular
birth control pill. This was a case-controlled study comparing
the birth control pill intake history of 248 women who had heart
attacks to 925 women who were matched by age and did not have
a heart attack. The researchers wanted to see if women who had
heart attacks were more or less likely to have taken the pill
and, if so, what types of birth control pills they had taken.
As might be expected, women in the reproductive age (14-50 years
old) who had heart attacks were older, more likely to smoke, more
likely to have elevated cholesterol and diabetes, and to have
a strong family history of heart disease than women who did not
have heart attacks. In fact, it is estimated that over 70 percent
of the risk of a heart attack in young women is due to smoking
alone. So, the primary question asked by patients wondering whether
they should take birth control pills is: What is the chance that
the pill will cause me to have a heart attack?
It has been estimated that the overall risk of a heart attack
in a young woman is 3 per million per year . If we plug
that number into the study in this week's NEJM , we find
that taking the birth control pill raises the overall risk to
6 per million. If we break it down further by the types of birth
control pills, the risks are 3 per million (unchanged from the
overall risk) for first-generation, 7.5 per million for second-generation,
and 3 per million (same as first-generation) for third-generation.
To re-emphasize, these risks are so small that any increased risk
remains clinically insignificant on an individual basis.
To have the most powerful impact on reducing the risk of heart
disease in young women, our attention should be focused on controlling
smoking, hypertension and diabetes. Birth control pills, regardless
of the hormonal content, add very little to the risk of heart
disease in this patient population. Moreover, patients should
be very cautious when trying to interpret results reported from
large studies. Patients should not hesitate to gather useful health
care information from their health care provider, the Internet
and the media.
Dr. Isaacson is the Director of Minimally Invasive Gynecologic
Surgery at the Massachusetts General Hospital in Boston. He is
also an Associate Professor of Obstetrics, Gynecology and Reproductive
Biology at Harvard Medical School
Reference
Source 104
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