"Our study found that estrogen plus progestin increased the bone mineral density and decreased the risk of fracture in healthy postmenopausal women. However, when we analyzed hormone therapy's effects on health overall, we determined that hormone therapy has no benefit to women, even those at high risk of fracture," said lead author and principal investigator Jane Cauley, Dr.P.H., professor of epidemiology at the University of Pittsburgh. "We do not recommend use of hormone therapy for any purpose other than short-term relief of menopausal symptoms."
The study, part of the Women's Health Initiative (WHI), included 16,608 participants ages 50 to 79 years, half of whom took estrogen plus progestin, and half of whom took placebo, for five years. During that time, 733 women in the hormone therapy group experienced a fracture, while 896 women in the placebo group had a fracture. Also, hip bone mineral density - a measurement of bone strength - increased by nearly 4 percent in the hormone therapy group, compared with a 0.14 percent increase in the placebo group.
The results were consistent in women who were considered at low, medium and high risk of fracture based on their risk factors, which included age, body mass index, smoking, history of falls, calcium intake, personal and family history of fracture and past use of hormones.
But when researchers examined the overall effects of hormone therapy as summarized in the global index created by WHI researchers in 2002, they determined that the benefit of fracture reduction does not outweigh the risks, even for women at high risk of fracture.
"Considering the overall unfavorable effects of hormone therapy, and the availability of other therapies for prevention and treatment of osteoporosis, we do not recommend treatment with estrogen and progestin in asymptomatic women," said Dr. Cauley. "Our results are consistent with those coming out of previous WHI reports, showing that the benefits of hormone therapy do not outweigh the risks."
The ongoing WHI includes 161,000 women participating in a set of clinical trials or an observational study designed to test preventive measures for heart disease, osteoporosis and cancer of the breast and colon. WHI is sponsored by the National Heart, Lung and Blood Institute, one of the National Institutes of Health.
The results reported here are based on data from the group testing the health effects of hormone therapy. While follow-up is ongoing, this intervention ended three years early, in July 2002, due to findings that the hormone combination was linked to increased incidence of breast cancer. Since that time, subsequent WHI findings also have pointed to increases in heart disease in the group that took hormone therapy, and lack of overall benefit of the therapy.