Researchers have stopped Hormone Replacement Therapy (HRT) to women involved in a long-term project after finding that the drug greatly increases their risk of heart attacks, strokes, and other coronary problems. The report of their findings was published recently in the Journal of the American Medical Association (JAMA).

"Women should not start or continue to use the therapy to prevent heart disease," the National Heart, Lung and Blood Institute's Jacques E. Rossouw, M.D. told a news conference. "The findings show that it doesn't work. In fact, the therapy increases the chance of a heart attack or stroke. Additionally, it increases the risk of cancer and blood clots," he said.

Dr. Rossouw, who led the study, and colleagues from the Women's Health Initiative (WHI) reported that the trial was discontinued due to apparent increased risks in invasive breast cancer, as well as coronary heart disease, stroke, and pulmonary embolisms in study participants.

"The rate of women experiencing coronary heart disease (CHD) events was increased by 29% for women taking estrogen plus progestin relative to the placebo," the authors noted. The researchers reported that stroke rates were 41% higher in women receiving estrogen plus progestin, and the participants had double the rates of venous thromboembolism (blood clots), invasive breast cancer rates increased by 26%, and total cardiovascular disease was increased by 22% in the estrogen-plus-progestin group.

"The trial results indicate that treatment for up to 5.2 years is not beneficial overall and that there is early harm for CHD, continuing harm for stroke and VTE (blood clots), and increasing harm for breast cancer with increasing duration of treatment," the authors wrote. "The risk-benefit profile is not consistent with the requirements for a viable intervention for the primary prevention of chronic diseases."

The researchers recommended that doctor stop prescribing the HRT combination for long-term use. There appeared to be no increase in risk for those women being treated with dietary changes such as calcium and vitamin D, or those taking only estrogen.

Approximately 38% of postmenopausal women in the United States use hormone replacement therapy. In 2000, 46 million prescriptions were written for Premarin, making it the second most frequently prescribed medication in the United States and accounting for more than $1 billion in sales, and 22.3 million prescriptions were written for Prempro.

"While the U.S. Food and Drug Administration–approved indications for hormone therapy include relief of menopausal symptoms and prevention of osteoporosis, long-term use has been in vogue to prevent a range of chronic conditions, especially heart disease," said Suzanne W. Fletcher, M.D., in an editorial in the same issue of JAMA.