MONDAY, March 3, 2003 (HealthDayNews) -- The timing of hormone therapy may be the key to whether it can slow down heart disease.
That's the conclusion of researchers who reviewed numerous studies on the cardiovascular effects of hormone replacement therapy (HRT).
If begun during menopause, when the cardiovascular system is still relatively healthy, HRT may be beneficial, the researchers conclude in the new issue of Menopausal Medicine.
"One of the really important messages for people to hear about is, we do not yet have the definitive answer of how HRT affects cardiovascular disease in women," says Dr. Richard H. Karas, co-author of the review and director of the preventive cardiology center at Tufts-New England Medical Center in Boston.
Last year, traditional thinking about HRT -- that it could protect a woman from heart disease and other ailments associated with aging -- was dramatically altered when the Women's Health Initiative (WHI), a large-scale study, was halted early. The reason: it found that women on HRT had more cardiovascular and other health problems than those on a placebo.
And an earlier study, the Heart and Estrogen/progestin Replacement Study (HERS), which looked at hormone therapy's effects in women with heart disease, found an increased risk of cardiovascular problems with the first year of treatment, no affect after 4.1 years of follow-up, and then a trend toward benefits in the fourth and fifth years.
However, other previous studies had found benefits.
One of the largest, the Nurses' Health Study, looked at more than 120,00 women aged 30 to 55 and found the users of HRT were at less risk for cardiovascular problems than those who never took it.
Why the discrepancy?
"We focused on the hypothesis that one of the possible explanations for the differences in the studies is that the more recent studies looked at HRT in elderly or older women, whereas the earlier studies looked at the effects of HRT in younger women," Karas says. "And there may be important differences in those two groups of women."
The crucial issue may be the time at which the therapy begins, say Karas and his co-author, Thomas B. Clarkson, a professor of comparative medicine at Wake Forest University Baptist Medical Center who evaluated numerous human and monkey studies.
In the HERS study, the average age of the participants was 67 and menopause had occurred 18 years before, the authors note in their review. In the WHI, the women averaged 63 years of age, and many were in their 70s before getting hormone therapy for the first time.
In Clarkson's own research on monkeys, hormone therapy begun at the time of menopause inhibited fatty buildup in cardiac arteries by 70 percent. When delayed for a time comparable to six years in women, there was no benefit on the monkey arteries.
Hormone therapy may work best, they conclude, on healthy cardiovascular systems. If begun too late, it may not only not help, but harm.
"Maybe HRT only works if you start when you have healthy tissues," Karas speculates.
Another expert, Dr. Leon Speroff, director of the Women's Health Research Unit at Oregon Health & Science University in Portland, praises the new review as an excellent critical look at the medical literature, especially the WHI.
"Too many organizations have taken a non-critical look at it," he says. "And there are a lot of reasons to criticize it."
The timing of hormone therapy studied in the WHI doesn't mirror clinical practice, he adds, since most women go on hormones when hot flashes and other symptoms of menopause begin.
"It takes healthy tissue to respond to estrogen," Speroff says. "This is true for the cardiovascular system and the brain. The evidence is pretty conclusive over the last 10 years that women with coronary artery disease should not be treated with estrogen in the expectation that it will reduce the risk of another cardiovascular event."
"Whether hormone therapy early in the postmenopausal years will prevent primary coronary heart disease has not been disproven," he adds.
What should women do?
"Talk to your doctor," Karas says. By assessing risks for heart disease and other diseases, you and your doctor should be able to come to a comfortable decision about hormone therapy.
Such discussions should take place annually, Speroff says.
More information
To see frequently asked questions about hormone therapy, visit the American College of Obstetricians and Gynecologists. For a discussion of the benefits and risks of HRT, see The National Women's Health Information Center.
