Hormone therapy during menopause can reduce hot flashes, night sweats, and other symptoms that impact a woman’s quality of life, including certain vaginal issues. It also can help prevent bone loss.
However, hormone therapy – often called hormone replacement therapy (HRT) – has a confusing history when it comes to cardiovascular health. UAB Medicine cardiologist Gretchen Wells, M.D., explains how changing interpretations of research have left some women unsure whether they can safely use this proven treatment.
Early research
Over the years, multiple studies found that women who received menopausal hormone therapy had fewer cardiac events compared to those who did not. However, Dr. Wells says these studies were merely observational, meaning that hormone therapy had not been thoroughly studied in randomized, controlled clinical trials – the gold standard for evaluating medical treatments.
“For example, the women in the observational studies who took hormone therapy may have had healthier lifestyles, greater access to medical care, and other advantages that could independently lower their cardiovascular risk,” Dr. Wells said.
Providers still found these results encouraging, at least. By the 1990s, hormone therapy was widely promoted and increasingly prescribed to help prevent cardiovascular disease and other conditions associated with aging.
Putting HRT to the test
In 1993, the federal government launched the much broader Women’s Health Initiative (WHI) to study strategies for preventing several major chronic diseases in postmenopausal women. One of its clinical trials for HRT gave women estrogen-progestin or estrogen alone, while others received a placebo. The study randomized women who were free of cardiovascular disease at the time of study enrollment to determine if there was a decrease in cardiovascular events.
The results showed that the women taking the combined estrogen-progestin HRT – prescribed for women with an intact uterus – had a statistically significant increase in cardiovascular events. The estrogen-only trial, for women who had undergone hysterectomy, found no significant effect on cardiac events, but it did show a small yet statistically significant increase in strokes. Both trials were stopped early.
“The conclusion was that hormone therapy did not reduce the risk of cardiovascular disease in the postmenopausal woman,” Dr. Wells said.
However, the study population did not include enough younger women beginning hormone therapy as they entered menopause. Participants ranged from age 50 to 79 but averaged 63 years old – about 12 years beyond the typical menopause age.
“The Women’s Health Initiative studied chronic disease prevention in the postmenopausal woman, not the perimenopausal woman,” Dr. Wells said. “And those are two entirely different patient populations.”
Therefore, the WHI established that hormone therapy should not be prescribed to prevent heart disease in postmenopausal women. However, it did not directly test the cardiovascular effects of beginning treatment near menopause to relieve symptoms.
A later review by the National Institutes of Health (NIH) agreed that the WHI’s findings did not discount the value of hormone therapy for treating menopause symptoms.
Cardiovascular risk may vary
The timing seems to matter, Dr. Wells says, because women who start hormone therapy around the time of menopause appear to have fewer cardiac events than those who start it well after menopause begins.
How estrogen is delivered may matter, too. Oral estrogen first passes through the liver, where it can increase certain proteins that may cause a higher risk of blood clots. And blood clots can travel to the lungs, which also may contribute to a higher stroke risk.
“If there’s a concern about clotting, for example, many women opt for a patch, where the medication is absorbed through the skin and bypasses the liver, which is where the clotting factors are made,” Dr. Wells said.
Is HRT right for you?
“Some women believe the WHI findings mean they cannot take hormones, but that is not the case for everyone,” Dr. Wells said.
Still, hormone therapy should not be considered as a way to prevent heart attack or stroke, she says. When HRT is used to relieve menopause symptoms, the prescribing doctor will consider factors such as smoking, age, time since menopause, blood pressure, cholesterol, and diabetes before starting a patient on hormone therapy. The doctor also will consider any history of heart attack, stroke, blood clots, or estrogen-sensitive cancer.
For women who choose HRT, they should see the prescribing doctor regularly to review their therapy and be sure to inform him or her about any new cardiovascular conditions or other major health changes.
“Every woman should have a conversation with her physician about whether hormone therapy is the right thing for her to do,” Dr. Wells said.