Jan. 6, 2005 - Menopausal hormone therapy may make stroke more likely and more severe. The latest study shows that this therapy raises stroke risk by 29% and makes death, disability, or dependence after stroke 56% more likely.
The news comes from a review of 28 studies with a total of nearly 40,000 participants. The review was conducted by stroke medicine professor Philip Bath and medical statistician Laura Gray of England's University of Nottingham. Their report appears on BMJ Online First.
Menopausal hormone therapy should not be recommended for stroke prevention, write the researchers. "Hormone replacement therapy does not reduce the risk of stroke in postmenopausal women," they write.
In fact, it may raise the risk and severity of stroke. Menopausal hormone therapy was most strongly linked to ischemic stroke, the most common type of stroke. In ischemic stroke, a blood clot blocks the flow of blood to the brain.
Caution Sounded for High-Risk Patients
The data suggest that people with a high stroke risk -- including those who've already had a stroke or who have heart disease -- "should stop taking [menopausal hormone therapy] unless there is a strong contrary medical reason," say the researchers.
Two other types of stroke -- hemorrhagic strokes and transient ischemic attacks (TIAs), often called mini strokes -- weren't associated with hormone therapy. A hemorrhagic stroke involves bleeding inside or around brain tissue. A TIA temporarily blocks blood flow to the brain, but symptoms resolve.
In the past, experts hoped that menopausal hormone therapy could help prevent stroke. That's because premenopausal women have a lower stroke risk than men. Stroke incidence also rises rapidly after menopause.
Previous studies on this have had conflicting results. Some showed that menopausal hormone therapy didn't help or hurt stroke risk. Others found this treatment to be a stroke hazard.
Menopausal hormone therapy has also come under scrutiny for its possible negative impact on other conditions, such as heart disease and breast cancer. In light of those concerns, women may want to weigh the risks and benefits of this treatment with their health care provider.
The data analyzed in the study varied in scope. The smallest study had 59 participants; the biggest had more than 16,000. Three trials included men, and three excluded women who had had hysterectomies. Follow-up times ranged from less than a year to almost seven years.
It didn't matter if estrogen was taken alone or combined with a progestin. That led the researchers to suggest that "estrogen itself ... might be the culprit."
There's a little fine print to note.
Plant-based estrogens (phytoestrogens) weren't studied. However, there's no proof that that makes a difference, say the researchers. Some hormone doses may have been too high and some studies too short. On average, the studies lasted three years. Taking menopausal hormone therapy orally or through the skin could also make a difference, say the researchers.