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Estrogen Does Not Prevent Recurrent Strokes: Study Shows

Estrogen Does Not Prevent Recurrent Strokes: Study Shows

Wednesday October 24, 2001 By Amy Norton

NEW YORK (Reuters Health) - Despite some past evidence that hormone replacement might lower stroke risk in older women, new research shows that estrogen therapy does not protect women from recurrent strokes and may instead carry some risks.

The findings add to growing evidence that hormone replacement therapy does not have the cardiovascular benefits doctors once believed.

In a study of 664 postmenopausal women who had recently suffered strokes, researchers found that estrogen replacement therapy (ERT) did not reduce their rate of further strokes. What's more, when they did suffer strokes, women on ERT were slightly more likely than non-users to die or have neurological damage.

These findings show that older women should not go on ERT solely for the prevention of recurrent strokes, according to Dr. Catherine M. Viscoli and colleagues at the Yale University School of Medicine in New Haven, Connecticut. Their report is published in the October 25th issue of The New England Journal of Medicine.

The women in the study had all suffered strokes within the previous 3 months. As for women with more "remote strokes" who are already on hormones, they "would probably be wise to have a careful discussion with their doctors" about whether to stay on the therapy, Dr. Walter N. Kernan, a co-author on the study, told Reuters Health.

Many doctors have long thought hormone replacement therapy might help protect women's cardiovascular health, warding off heart disease and, possibly, stroke. But recent research has questioned that reasoning.

In July, the American Heart Association issued guidelines stating that women should not receive hormone replacement for the sole purpose of preventing recurrent heart attacks. This came after several studies suggested the combination therapy of estrogen and progestin actually raises the risk of recurrent heart attack, at least temporarily.

The fact that the proposed cardiovascular benefits of hormone replacement have not panned out in recent studies is "really surprising," Viscoli said in an interview.

There have been some strong reasons to believe in the idea, including studies showing hormone users had lower rates of death from cardiovascular causes and the fact that hormone replacement can improve women's cholesterol levels.

But the current evidence on hormones and stroke risk looks negative, according to Viscoli. She noted that a large, ongoing trial called the Women's Health Initiative is looking at whether hormone replacement can help prevent the onset of cardiovascular disease. But so far, the early results have shown a slightly increased risk of strokes and heart attacks.

Currently, the only well-established benefits of hormone replacement are in reducing menopause symptoms, such as hot flashes, and in preserving bone mass.

In the current study, Viscoli and her colleagues followed women who had had either an ischemic stroke or a "mini-stroke" known as a transient ischemic attack. An ischemic stroke occurs when blood flow to the brain is obstructed, and is the most common type of stroke.

Some of the women took a daily dose of oral estrogen, while the rest took an inactive placebo. After an average of nearly 3 years, the researchers found no difference in the risk of nonfatal stroke between the two groups.

Only a small number of women suffered fatal strokes, but there were 12 deaths in the ERT group, compared with 4 in the placebo group. Women on estrogen were also slightly more likely to show neurological impairment after suffering a stroke.

The researchers conclude that the results "add to the evolving body of evidence from clinical trials that do not show a benefit of estrogen for women with established vascular disease."

SOURCE: The New England Journal of Medicine 2001;345:1243-1249.

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