Women who take hormone therapy that combines estrogen with progestin have double the risk for venous thrombosis ( VT ), a type of blood clot, according to a recent study.
VT affects one to two people in every 1,000. Risk for VT increases with age and is higher in men, blacks and obese individuals. Postmenopausal hormone therapy is associated with a two- to three-fold increased risk of VT.
Researchers studied 16,608 postmenopausal women between ages 50 and 79 years. Participants were randomly assigned to an estrogen drug combination or a placebo. VT occurred in 167 women taking estrogen plus progestin but in only 76 taking placebo. The risk for VT was more than four-times greater in women in their 60s than 50s and more than seven-times greater for women in their 70s. Obese women had a nearly six-times greater risk for VT than normal-weight women.
Researchers say, based on their projections for 10 years for 1,000 women taking estrogen plus progestin, the estimated excess number of events is 18 for VT, six for coronary heart disease, eight for invasive breast cancer, and eight for stroke. Thus researchers say their findings may be important for the use of postmenopausal hormone therapy in the treatment of menopausal symptoms among younger postmenopausal women.