What is the Women's Health Initiative?

The Women's Health Initiative (WHI) is a long-term study sponsored by the National Institutes of Health (NIH) that is looking at ways to prevent heart disease, breast and colon cancer, and osteoporosis.

The hormone therapy part of the study has two 'arms' (seperate portions) - one looking at estrogen therapy (ET) for women without a uterus and one looking at estrogen plus progestogen therapy (EPT) for women with a uterus. When they enrolled in the study, all participants were considered healthy, were past menopause, and had few or no menopause related symptoms. 

The EPT portion of the study followed 16,608 healthy women with a uterus, who were ages 50 to 79 when they entered the study, and who took either combined estrogen and progestin or a placebo. Prempro was the hormone used. The goal of this 8-year trial was to study the relationship between HT and its possible benefits for heart disease and hip fracture, as well as its possible risks for breast cancer, endometrial cancer, and blood clots. The trial was not intended to study the effect of HT on menopausal symptoms or on other conditions such as Alzheimer's disease.

On July 9, 2002 , the NIH halted the EPT arm of the trial after 5.2 years, concluding that the risks for the study group on combined HT outweighed the benefits. Another part of the WHI study that examined the use of estrogen alone in women who have had a hysterectomy was stopped in March, 2004. 

In the EPT arm of the study, the WHI investigator's reported 7 more cases of heart disease events (like heart attacks), 8 more cases of stroke, 8 more cases of breast cancer and 18 more cases of blood clots per 10,000 women per year in HT users compared to non-users.

Positive outcomes from the EPT arm of the WHI include a 24% reduction in total fractures and 34% reduction in hip fractures. This would result in 5 fewer hip fractures per 10,000 women. The risk of colon cancer was reduced by 37% in the HT group, which resulted in 6 fewer cases per 10,000 women. The benefit appeared after 3 years of use and became more significant over time.

The Estrogen-only arm of the WHI study was stopped in March, 2004 after a follow-up of 6.8 years revealed no effect on the risk of heart disease and a slight increase in risk of stroke. 10,739 postmenopausal women were enrolled between the ages of 50 and 79 who had undergone a hysterectomy. Twelve more cases of stroke per 10,000 women was observed during this trial. Six fewer hip fractures per 10,000 women was seen in the women taking estrogen. Importantly, there was no increase in risk of breast cancer in this arm of the WHI trial.

What is the controversy?

As the data has been further analyzed, limitations have become apparent and many questions are being raised about how to interpret the results. For instance, the average age of WHI participants was 63 years of age and 18 years from their menopause. This does not necessarily provide information for women and physicians seeking information who are younger in age and closer to the menopause transition. 

In fact, women with moderate or severe menopausal symptoms were discouraged from participating in the study. Only 12% of WHI participants reported moderate or severe symptoms. These quality of life altering symptoms are the primary reason many women use HT. Therefore, it is important for women to be aware of the limitations of this study as they contemplate the use of HT. It is certainly appropriate to talk to your doctor about the WHI results and the implications they may have for you as an individual.