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Questions and Answers About the Estrogen-Alone Study

Questions

Questions and Answers About the WHI Postmenopausal Hormone Therapy Trials


Q. Why did the NIH stop the trial?

A. The NIH carefully reviewed the latest data and concluded that, with nearly 7 years of follow-up completed, estrogen-alone hormone therapy did not appear to affect (either decrease or increase) the risk of heart disease, the main question of the trial. More importantly, there appeared to be an increased risk of stroke, and the NIH believes that an increased risk of stroke is not acceptable in a prevention trial in healthy women, especially if estrogen does not reduce heart disease risk.

Further, the NIH felt that, with nearly 7 of the expected 8 years of follow-up completed, the study results were not likely to change if the trial continued for another year. The NIH believes that enough data are available to give an overall assessment of the risks and benefits of the estrogen use in this trial.

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Q. What are the study's findings?

A. The following findings show disease risks of estrogen-alone use compared to placebo. The number of cases given represent an average for every 10,000 women each year:

  • Fatal and non-fatal strokes. Increased risk--12 cases more (44 cases in those on estrogen alone and 32 in those on placebo).
  • Venous thrombosis (blood clot, usually in one of the deep veins of the legs). Increased risk--6 cases more (21 cases in those on estrogen alone and 15 in those on placebo).
  • Coronary heart disease. No significant difference in risk (neither increased nor decreased)--5 fewer cases (49 cases in those on estrogen alone and 54 in those on placebo).
  • Colorectal or total cancer. No significant differences in risk (neither increased nor decreased)--1 more case for colorectal cancer and 7 fewer cases for total cancer (for colorectal cancer, 17 cases in those on estrogen alone and 16 in those on placebo; for total cancer, 103 cases in those on estrogen alone and 110 in those on placebo).
  • All deaths or those for a specific cause. No significant difference in risk (neither increased nor decreased)--3 more deaths (for all deaths, 81 in those on estrogen alone and 78 in those on placebo).
  • Breast cancer. Uncertain effect--7 fewer cases (26 cases in those on estrogen alone and 33 in those on placebo). This finding was not significant.
  • Bone fractures. Increased benefit--6 fewer hip fractures (11 cases in those on estrogen alone and 17 cases in those on placebo).

The results did not differ by race or ethnicity, or body mass index (BMI).

A separate report will be published in the near future about the effect of estrogen alone on dementia and cognitive function. That report will contain information on women age 65 and older who participated in the estrogen-alone WHI Memory Study (WHIMS), an ancillary study of the WHI hormone trials. In 2003, WHIMS reported an increased risk of dementia in women taking estrogen plus progestin who were aged 65 and older.

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Q. What happens now with the estrogen-alone study?

A. Participants were asked on March 1, 2004, to stop their study medication and are being told whether they took the active drug or the placebo. WHI also gave this information to the women's personal health care provider, if desired. Participants were asked to continue in the follow-up phase of the study, which is due to last until 2007. During the follow-up phase, the women will continue to undergo tests to monitor their health, including annual mammograms.

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Q. What happens with the WHI--is it ended?

A. The WHI was launched in 1991 and consists of a set of clinical trials and an observational study, which together involve more than 161,000 generally healthy postmenopausal women.

The clinical trials were designed to test the effects of postmenopausal hormone therapy, diet modification, and calcium and vitamin D supplements on heart disease, fractures, and breast and colorectal cancer.

  • The hormone trial had two studies--of estrogen-alone therapy and of estrogen-plus-progestin therapy. Those studies have now ended. The women in these studies are now participating in a follow-up phase, which should last until 2007.

  • The clinical trials on diet modification, and calcium and vitamin D supplements are continuing as planned and should end in 2005. The participants will then enter a follow-up phase.

The observational study is looking for predictors and biological markers for disease. It is continuing as planned and should end in 2005.

Analyses of data from the WHI studies are under way and further findings will be reported.

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April 2004

 

 
 
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