Skip to contents
NHLBI Women's Health Initiative
Women's Health Initiative banner











Estrogen-Alone Study

Estrogen-Plus-Progestin Study





WHI Background and Overview

WHI Update

Why WHI?

WHI Community Prevention Study

Additional Resources


Sample Letter to Estrogen-Alone Participants

NHLBI letter head

February, 2004


Dear WHI Estrogen-alone Participant:

I am writing to tell you important news about the WHI Estrogen-alone study you are participating in. Based on recent review and careful consideration of data collected, the National Institutes of Health (NIH) has decided to stop study pills in the Estrogen-alone trial in which you are participating, and ask you to enter the follow-up phase. This letter explains this decision and the actions we would like you to take.

You were previously informed that the estrogen plus progestin (E plus P) study pills in women with a uterus were stopped in July 2002, because the data showed that the risks were greater than the benefits. The Data and Safety Monitoring Board (DSMB), which oversees the safety of the participants, recommended that action. Up to now, the DSMB has recommended that the Estrogen-alone study in women without a uterus continue and has provided close monitoring of participants.

In November and December 2003 the DSMB again closely reviewed data from the Estrogen-alone study. The data showed some benefits of estrogen alone but also some continued risks. The members were split on whether or not the trial should continue. They recommended either sending a very clear letter to participants informing them of both the risks and benefits of estrogen alone, or stopping study pills in the Estrogen-alone study and allowing participants to enter a follow-up phase. The National Heart, Lung, and Blood Institute (NHLBI), and the other Institutes at the NIH who are actively involved in the scientific aspects of the study, have considered the recommendation of the DSMB. After careful thought, the NIH has decided that women in the Estrogen-alone study should stop taking their study pills. The NIH has informed the DSMB of this decision.

Women in the Estrogen-alone study can now enter the follow-up phase which is intended to last for several more years. During the follow-up phase we will study the long-term effects of the hormone therapy taken up to now.

Why is the Estrogen-alone study now going into a follow-up phase?

The current results show that estrogen alone does not appear to affect the risk of heart disease. At the same time, estrogen alone appears to increase the risk of stroke and decrease the risk of hip fracture. It does not appear to increase the risk of breast cancer.

  • The current study results indicate that the increased risk of stroke is similar to that found in the study of Estrogen plus Progestin when that trial was stopped in 2002. The NIH believes that an increased risk of stroke is not acceptable in healthy women in a research study, especially if estrogen only does not prevent heart disease.
  • With nearly 7 years of follow-up completed, the study results are not likely to change if study pills are continued for one more year. Thus, the NIH believes that enough data have been obtained to provide an overall assessment of the risks and benefits of the use of estrogen in this trial.
  • Stopping the active phase of the study will allow WHI researchers to analyze the data and make public all the risks and benefits of estrogen alone. This will include information on the WHI Memory Study participants who are taking estrogen alone.

When will more information be reported about the risks and benefits of estrogen alone?

  • The WHI researchers will begin their analyses of the data from the estrogen alone study immediately. We expect that the first report of these results will come out within the next two months. The report will include data collected right up to the end of February, 2004.
  • When the updated results are ready for publication, the WHI investigators will provide you with more detailed information about study results.

What are we asking you to do?

  • Please stop taking the pills given to you as part of the hormone study.
  • Do not throw away any left-over hormone study pills or bottles. Your WHI clinical center staff will let you know how to return them.
  • Continue your regular WHI clinical center contacts, and please complete study forms, so that we can continue to follow your health. We have much more to learn from the Hormone Program even after you stop taking your study pills.
  • Continue to participate in any other WHI programs you joined. For example, if you are in the Calcium and Vitamin D Program please continue to take those study pills as you have in the past. The DSMB has reviewed these programs as well and recommended that they continue. There are still many important questions to answer about women's health.

I have asked the WHI Clinical Coordinating Center in Seattle to send you this letter. You will be given more information by your WHI Clinical Center as it becomes available, including information that will be posted on the World Wide Web at: Please share this letter with your health care provider. Your local WHI clinical center will be contacting you so you can have your questions answered, and to make arrangements for your next visit. You can also contact your clinical center if you have additional questions.

Thank you for your continuing dedication to the WHI Hormone Program. Your participation in WHI has already made a great contribution to the health of women: and as the data unfold. that contribution will become clear to all other women and their health care providers.

Sincerely yours,

Barbara Alving, M.D.
Acting Director
National Heart, Lung, and Blood Institute


Department of Health and Human Services


National Institutes of Health

National Heart, Lung, and Blood Institute

Please send us your feedback, comments, and questions
by using the appropriate link on the page, Contact the NHLBI.

Note to users of screen readers and other assistive technologies: please report your problems here.

Link to DHHS Link to NIH Link to NHLBI Link to DHHS Link to WHI Home