According to a study, estrogen replacement therapy does not reduce post-menopausal women's risk of having a second stroke. The Women's Estrogen for Stroke Trial (WEST) is the recent study to counter long-held notions about the benefits of hormone replacement therapy, or HRT, on the heart and blood vessels. Catherine Viscoli, a research scientist University of Yale, said that a lot of people thought estrogen was a magic pill.
So-called observational studies, in which women decided on their own whether to go on HRT after menopause, have suggested that the treatment cuts risk of heart attacks and stroke. But some scientists speculated that women who opt for HRT might tend to be healthier, tilting those studies in the treatment's favor. That has led to randomized controlled trials such as WEST, which are considered the gold standard of medical research. Recent randomized trials, in which a coin toss determines who goes on HRT, have found no benefit and perhaps even harm from the treatment.
Joann Manson, chief of preventive medicine at Harvard's Brigham and Women's Hospital, said that there has been a sea change in our understanding of hormone replacement therapy and cardiovascular disease. Manson and other experts now recommend that women go on HRT only for relief of menopausal symptoms or prevention of osteoporosis fractures, although other treatments are available for the latter.
WEST researchers, funded by the National Institute of Neurological Disorders and Stroke, studied 600 postmenopausal women who had recently had an ischemic stroke or transient ischemic attack. Their average age was 75. Ischemic strokes, the more common type of stroke, occur when a clot blocks blood flow to part of the brain. Transient ischemic attacks, or TIAs, occur when the blood flow is only briefly interrupted. Most TIA symptoms disappear within an hour, but they are warning signs that a person is at risk for a more serious stroke.
Half the women in WEST received the standard 1 milligram daily dose of oral estrogen in the form of estradiol. The other half got a placebo. Neither the women nor the researchers knew who got which pills. Patients were studied for three years on average. They stopped receiving the estradiol or the placebo if they had a stroke.
Researchers reported that at the end of the study, 120 women in the estradiol group had died or suffered a non-fatal stroke, compared with 100 in the placebo group, a difference that could have been due to chance. However, there was a "borderline" statistically significant higher number of fatal strokes in the estradiol group — 12 vs. four in the placebo group, Viscoli says. And non-fatal strokes were slightly more debilitating in the estradiol group.
The WEST study parallels another study called the Heart and Estrogen Replacement Study, or HERS, the first randomized hormone replacement therapy trial. HERS used Premarin, the most commonly prescribed estrogen in the USA, and enrolled only women with heart disease. It found no difference in the total number of heart attacks, strokes or blood clots between women on HRT and those on placebo.
Manson is a principal investigator in the Women's Health Initiative, a federally funded study in which 20,000 women have been randomly assigned to Premarin or a placebo. Final results are due in 2004, but an interim analysis after four years found no difference between the HRT and placebo groups.