Despite new finding,
hormone replacement therapy still considered promising
BY CAROLINE SEYDEL
Many women going through
menopause take hormones to reduce their risk of heart
disease. Now, a huge national study indicates that a
woman's risk of heart disease increases slightly during
the first two years of hormone use. Despite the slight
increase, however, researchers remain optimistic that
over the long term, hormone therapy may have
cardiovascular benefits.
The study indicates that
women taking active hormones experienced heart attacks,
strokes and blood clots in the legs and lungs slightly
more often than women taking a placebo. Less than one
percent of the women in either the hormone or placebo
group experienced these symptoms. Although the excess
risk among hormone users was extremely small, it probably
represents a real increase, the researchers said.
Marcia L. Stefanick, PhD,
associate professor of medicine and principal
investigator of the Stanford portion of the Women's
Health Initiative, cautions that it's too early to make
sweeping statements about hormone therapy. "When we
get to the 2005 mark, we're going to be able to provide
the long-term picture that we don't have yet,"
Stefanick said.
The study, the hormone
replacement therapy (HRT) trial of the Women's Health
Initiative (WHI), is a nationwide investigation of either
estrogen combined with progestin (in women with a uterus)
or estrogen alone (in women who have had a hysterectomy).
Women were randomly assigned to receive either hormones
or a placebo.
More than 27,000 women are
enrolled in the study, and nearly all of them have
completed two years of therapy. About half have passed
the three-year mark, one-quarter the four-year mark, and
a few have even completed five years. Most did not have
heart disease at enrollment.
Early data suggest that
the mild increase in risk decreases over time, but since
only half the women have reached the third year of
therapy, it's too soon to say with certainty.
The rate of heart disease
among study participants in both groups was lower than
that of the general population, Stefanick said, and as a
result, the long-term picture may be more useful than the
short-term one. Women who participate in lengthy clinical
trials are often healthier than average, at least at the
outset of the trial, she said.
"You certainly don't
attract women who are sick to come into a 10 year
study," Stefanick said. "Within a few years, we
expect they're going to look more like the general
population ... the aging effects are going to set
in."
The low number of
cardiovascular events among the study participants makes
it difficult to determine whether a particular subgroup
of women is more vulnerable to such events. No specific
trait characterizes the women who react negatively to the
hormones, Stefanick said.
Stefanick also pointed out
that women who "try out" hormone therapy to
alleviate the immediate problems of menopausal symptoms,
such as hot flashes, may not continue long enough to
enjoy the potential benefits to their bones and their
cardiovascular system.
"It may be that the
favorable outcome happens later," she said.
"It's pretty unlikely it's going to do much for
their bones in two years, and for a very small percentage
of women, they may have added a risk ... with respect to
their heart."
An earlier study, the
Heart and Estrogen/progestin Replacement Study (HERS),
discovered a similar pattern of increased heart disease
within the first year of hormone therapy. By the third
and fourth years, however, the hormone users had a
decreased risk. Overall, the study found no added benefit
or risk to cardiac health for hormone users.
Unlike the WHI, women in
HERS had heart disease before they began the trial. HERS
also studied a much smaller group, about 2,700 women.
When the HERS data came
out, researchers were surprised because estrogen was
thought to reduce the risk of heart disease. But because
HERS only studied women with existing heart disease, the
short-term increase in risk was thought to be specific to
those women.
That's why the early WHI
data are unexpected, Stefanick said. Because the women in
the WHI have a lower risk of heart disease than the women
in HERS, only a study as large as WHI could detect such a
slight increase.
"These findings that
everybody got so excited about would never have been
detected in a smaller study," Stefanick said.
The WHI Clinical Center at
Stanford held a Special WHI Hormone Trial Event on May 13
in Fairchild Auditorium to discuss the findings with the
women participating in the study. Because the results are
unexpected, the researchers say, it is imperative the
study continue so the long-term effects of hormone use
can be observed.
In general, women in the
trial seem unperturbed by the results, Stefanick said.
None has expressed concern to her, and she doesn't expect
many to drop out.
"Perhaps the real
surprise has been their reaction," she said. A few
of the women who had cardiovascular events even feel
proud to have contributed to a new finding, she said. SR
|
