Published January 14, 2015
Women who want to use hormone replacement therapy may be less likely to have a stroke if they use low-dose patches instead of pills, Canadian researchers reported on Thursday.
Their study of British women showed that those who used estrogen patches to control symptoms of menopause did not have any higher risk of stroke than women who did not use HRT.
The study, published in the British Medical Journal, adds to a very slowly growing body of evidence that could rehabilitate the use of HRT, which plummeted in 2002 after the publication of the Women's Health Initiative study, which found an increased risk of ovarian cancer, breast cancer, strokes and other health problems from hormone therapy.
Sales of U.S. market leader Wyeth's combined estrogen-progestin therapy Prempro have fallen by about 50 percent since 2001 to around $1 billion a year. Wyeth is now owned by Pfizer.
But many experts who studied HRT said there was some evidence that if women took a lower dose and if they took HRT by means other than a pill, the risks might not be as high.
Samy Suissa of McGill University in Montreal and colleagues used Britain's national medical database to pick out 15,700 women over 50 who had strokes and nearly 60,000 who had not.
Women who had used low-dose transdermal patches to get their HRT had almost precisely the same risk of stroke — very slightly less, in fact — than women who used no HRT.
"I think that these are promising findings," said Dr. JoAnn Manson of Brigham and Women's Hospital and Harvard Medical School in Boston, who helped lead the Women's Health Initiative and who was not involved in Suissa's study.
Suissa's team found that 7.7 percent of stroke patients had been given a prescription for some form of HRT within the previous year of their stroke. And 6.9 percent of women who did not have a stroke got some form of HRT.
"The risk of stroke was not increased with use of low estrogen dose patches compared with no use, whereas the risk was increased with high dose patches," Suissa's team wrote.
HRT pills raised the risk of stroke by 25 percent to 30 percent, regardless of the formulation. High-dose patches raised the risk by 88 percent.
Delivering low doses of hormones through the skin bypasses the liver and may reduce the whole-body effects, Suissa's team said in their report.
Menopause can cause serious symptoms, including debilitating hot flashes, sleep disturbances and a lack of energy. Women also become more susceptible to heart disease, osteoporosis and some cancers after menopause.
Experts in HRT and menopause say women should be able to choose to use hormones to treat these symptoms, but should take the lowest dose possible for the shortest possible time. Before 2002 HRT was regularly prescribed to prevent heart disease and osteoporosis, but the experts now recommend against this.
Manson said the ongoing Women's Health Initiative study will look at different doses of hormones. Her team found two years ago that low-dose HRT pills did not raise the risk of stroke and said more study is needed to be sure.
"If there was an option that didn't raise the risk of stroke, that would be a tremendous breakthrough," Manson said in a telephone interview.
Makers of HRT patches include Novogyne, a joint venture of Novartis Pharmaceuticals Corp and Noven Pharmaceuticals Inc, which was acquired last year by Japan's Hisamitsu Pharmaceutical Co Inc and Janssen-Cilag, part of Johnson & Johnson.