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February 18, 2002
News this month Contrary to what many experts believed, estrogen replacement therapy (ERT) does not reduce the risk of stroke or death in postmenopausal women who have already had a stroke or a transient ischemic attack (TIA), according to results from a large, randomized trial published in The New England Journal of Medicine. Although estrogen is not given to women solely as stroke prevention treatment, observational reports have suggested estrogen might have protective qualities.
Although estrogen is not given to women solely as stroke prevention treatment, observational reports have suggested estrogen might have protective qualities. Estrogen has been widely prescribed for prevention of osteoporosis (thinning of the bones) and relief of menopausal symptoms such as hot flashes. Researchers at Yale University conducted The Women's Estrogen for Stroke Trial (WEST), which began in 1993. The study followed 664 postmenopausal women who had experienced an ischemic stroke or a TIA within the previous 90 days. Ischemic strokes and TIAs result from blockages in the vessels that supply blood to the brain. Roughly half of the women were given estrogen therapy (1mg of estradiol each day); the remainder were given a placebo. The women—recruited from 21 American hospitals—averaged 71 years of age. More severe strokes among estrogen group The risk of stroke within the first six months after enrollment in the study was also higher among women in the estrogen group. There were no significant differences between treatment groups in the number of TIAs or nonfatal heart attacks; however, participants receiving estrogen were more likely to experience gynecologic complications, particularly vaginal bleeding. “ERT for secondary stroke prevention is not beneficial.”
“We have shown that ERT for secondary stroke prevention is not beneficial,” said principal neurologist and coauthor Lawrence M. Brass, MD, professor of neurology at Yale School of Medicine. “The good news is that we have taken a lot of guesswork out of treating women with strokes. The benefits from estrogen that we hoped for are not there to balance the risks,” says John R. Marler, MD, National Institute of Neurological Disorders and Stroke (NINDS) associate director for clinical trials. HERS study comparison HERS also found no reduction in strokes among women who received hormone replacement.
The HERS results, published in 1998, showed that treating these women with a combination of estrogen and progestin did not reduce heart attacks or death from heart disease. That study also found no reduction in strokes among women who received the hormone replacement. Additional information about the benefits and risks of HRT is expected from the Women's Health Initiative (WHI), a long-term study of more than 27,000 postmenopausal women that is examining whether estrogen or an estrogen/progestin combination can help prevent heart disease. Results from the first two years of the WHI study suggest a small increase in the number of heart attacks, strokes and blood clots in women receiving the hormone therapy. Questions remain 
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 Estrogen not helpful in preventing recurrent strokes Stroke is a major medical problem for women. Half of all strokes occur in women, and women account for 60 percent of all stroke-related deaths. Not only are women more likely to die from strokes, they are also more likely to be disabled. “Not only are women more likely to die from strokes, they are also more likely to be disabled.”
Most strokes in men occur in their 60s and 70s while most women are affected in their 70s and 80s. For this reason, women who have strokes are more likely to be widowed and socially isolated. They are also more likely to have other complicating medical conditions. All of these factors associated with advanced age are also associated with a worse outcome after having a stroke. It's very unusual for a woman to have an ischemic stroke before menopause, and for this reason, there's been a belief that ovarian hormones provided some protective effect. Observational studies have indicated women who take HRT have a 30 to 50 percent reduction in their rate of cardiovascular disease, and many people believed HRT had an important role in reducing the rate of heart disease among women. Surprising study results The HERS trial also showed that during the first year after women began HRT, they experienced a slightly higher risk of clotting events in their veins. After four to five years on HRT, women actually did better. “We found no significant difference in the likelihood of having a second stroke between our two groups.”
WEST trial focus Because of safety concerns raised in the HERS trial, we looked at our data for effects during the first six months after starting therapy. The HERS trial found an initial increase in secondary heart disease events in the estrogen and progestin group at six months into treatment. WEST saw a similar effect of estrogen in stroke patients at six months. While a total of nine women died of ischemic stroke in the estrogen group, only one died of that cause in the placebo group. There was no difference in the incidence of deaths due to cardiovascular disease. “The severity of strokes was greater in the women taking estrogen.”
The severity of strokes was greater in the women taking estrogen. Women randomized to estrogen were half as likely to make a good recovery, as measured by the NIH stroke scale of zero to one. That was surprising to us since animal data has suggested estrogen protects the brain from damage during a stroke. We also looked to see if there was any late emergence of a protective effect of estrogen as there had been in the HERS trial. We found none. What should you do? “We cannot recommend HRT to women who want to reduce their stroke risk.”
At this point, we cannot recommend HRT to women who want to reduce their stroke risk. Women who wish to take HRT for other reasons—to prevent osteoporosis or to relieve menopausal symptoms—should consult their physicians to determine the balance of risks and rewards of HRT for them individually. One out of every six women will be affected by cerebrovascular disease during her lifetime. Be aware of risk factors for stroke:
Women who are at risk for stroke but elect to take HRT may want to modify their risk factors by taking aspirin to reduce the potential of blood clotting problems and by monitoring their blood pressure closely. Estrogen's role in the body is very complex. The hormone has more than 400 effects on the body, and during the next few years, we'll be learning more about what they are and how we might maximize the beneficial effects and minimize any harmful ones. Dr. Brass is an attending neurologist at Yale-New Haven Hospital and professor of neurology and epidemiology and public health at the Yale University School of Medicine. He is also chief of neurology at the VA Connecticut Healthcare System. |
