AHA: HT delivery method affects clot risk

Women who use transdermal estrogen therapy alone may have a significantly lower risk of venous thromboembolism than women who take oral estrogen, but not if their patch also contains either norpregnane or nortestosterone derivatives, according to research presented this week at the American Heart Association's Conference on Nutrition, Physical Activity and Metabolism in Colorado Springs, CO.

Marianne Canonico, PhD, of Paul Brousse Hospital in Villejuif, France, and colleagues studied 984 women with venous thromboembolism, including 199 pulmonary embolisms and 785 deep vein thromboses.

Compared to non-hormone users, the researchers found that women taking oral estrogens alone had an increased risk of venous thromboembolism (RR, 1.6) but that those using transdermal estrogen therapy alone had no increased risk. Although oral estrogen use in combination with progestogens and transdermal estrogen in combination with either micronized progesterone or pregnane was not associated with an additional risk, they found that transdermal estrogen combined with either norpregnane or nortestosterone derivatives was associated with a significantly increased risk (RR, 1.4 and 3.0, respectively).

"Transdermal estrogen alone or combined with either micronized progesterone or pregnane derivatives may be safe with respect to venous thromboembolism risk," the researchers said in a statement. But they added that these findings need to be confirmed by other trials.

More details are available online at http://www.americanheart.org/presenter.jhtml?identifier=3046690%20.