Estrogen patch may lower risk of clots

A skin patch that delivers hormone replacement therapy may be safer than pills for women, according to a study published Monday in Circulation.

The Estrogen and Thromboembolism Risk (ESTHER) study found that oral, but not transdermal estrogen increases the risk of venous blood clots in postmenopausal women. Those taking oral estrogen had a 4.2 times higher risk compared to women not taking estrogen replacement, while those using the patch had 0.9 times the risk. The research was led by French researcher Marianne Beau Yon de Jonage-Canonico.

Life-threatening blood clots, called venous thromboembolisms, are a somewhat rare but dangerous side effect of oral hormone therapies, according to Dr. Eliot A. Brinton, a University of Utah cardiovascular geneticist. "This is probably the first time we can show clearly the difference between the patch and the pill. The pill seemed to cause a slight increase in blood clots, while the patch did not."

It's good news, said Brinton, for women who want to use estrogen for menopause symptom relief. And it's especially valuable information for women who have had blood clots or a family history of clots. Those women need to use low-dose pills or a transdermal patch and be very careful about the use of progestins, he said.

The study doesn't mean that every woman should choose the patch over the pill to manage postmenopausal symptoms, Brinton said. The patch carries its own set of side effects, including rash, and some people have a hard time getting it to stay on. It also doesn't work quite as well for some women in terms of symptom relief.

"It gets back to what we've always said. Estrogen therapy always needs to be individualized. Estrogen is rather controversial, so the best thing for a patient is to find a caring and empathetic doctor and work with that doctor to go through the pluses and minuses, the pros and cons, and see what works. Customize the treatment, and if it doesn't work, try again."

The U. is one of nine centers around the country participating in another study, the Kronos Early Estrogen Prevention Study, or KEEPS. They have been recruiting women who are early into menopause and providing them with a low dose of oral Premarin or a low-dose patch called Climara or a placebo. The risk, they believe, is comparable for all three.