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WHI Background and Overview

WHI Update

Why WHI?

WHI Community Prevention Study

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Background and Overview

What was the Women's Health Initiative?

The Women's Health Initiative (WHI) was a long-term national health study that focused on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in postmenopausal women. These chronic diseases are the major causes of death, disability and frailty in older women of all races and socioeconomic backgrounds.

This multi-million dollar, 15-year project, sponsored by the National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI), involved 161,808 women aged 50-79, and was one of the most definitive, far reaching clinical trials of women's health ever undertaken in the U.S. The WHI Clinical Trial and Observational Study attempted to address many of the inequities in women's health research and provide practical information to women and their physicians about hormone therapy, dietary patterns and calcium/vitamin D supplements, and their effects on the prevention of heart disease, cancer and osteoporosis.

A Community Prevention Study (CPS), a 5-year cooperative venture with CDC, was a study of strategies to enhance adoption of healthful behaviors through a multi-disciplinary approach. The purpose of the CPS was to develop community-based public health interventions models which would achieve healthful behaviors in women aged 40 and over.

A New Era in Women's Health: the Women's Health Initiative

To respond to the crucial need for the involvement of women in medical research, the NIH in 1990 established the Office of Research on Women's Health (ORWH). The earliest undertakings of the ORWH included the development of a research agenda to identify and address gaps in the biomedical community's knowledge of women's health and the strengthening and revitalization of already existing NIH guidelines and policies for the inclusion of women and minorities in clinical studies.

With the growing scientific interest in research on women's health, Dr. Bernadine Healy, then director of the NIH, launched WHI in April 1991.

How was WHI conducted?

The WHI study had three components: a randomized clinical trial, an observational study, and a community prevention study.

The randomized controlled clinical trial (CT) enrolled 68,132 postmenopausal women between the ages of 50-79. The clinical trial had three study components. If eligible, women could choose to enroll in one, two, or all three of the components. The components were:

  • Hormone Therapy (HT): This component examined the effect of HT on the prevention of heart disease and osteoporosis, and any associated risk for breast cancer. Women participating in this component took hormone pills or a placebo (inactive pill).
  • Dietary Modification: The Dietary Modification component evaluated the effect of a low-fat, high fruit, vegetable and grain diet on the prevention of breast and colorectal cancer and heart disease. Study participants followed either their usual eating pattern or a low-fat eating program.
  • Calcium/Vitamin D: This component started up to 2 years after a woman joined one or both of the other studies. It evaluated the effect of calcium and vitamin D supplementation on the prevention of osteoporosis-related fractures and colorectal cancer. Women in this component took calcium and vitamin D pills or a placebo.

The observational study (OS) examined the relationship between lifestyle, health and risk factors and specific disease outcomes. This component tracked the medical history and health habits of approximately 93,676 women.

Recruitment for the observational study was completed in 1998 and participants were followed for 8 to 12 years.

The community prevention study (CPS) was a unique collaborative venture between the Centers for Disease Control and Prevention (CDC), and the National Institutes of Health. Eight University-based Prevention Centers underwritten by CDC conducted and evaluated health programs that encouraged women of all races and socioeconomic backgrounds to adopt healthful behaviors such as improved diet, nutritional supplementation, smoking cessation, exercise and early detection of treatable health problems. The goal of the community prevention study was to develop carefully evaluated, model programs that could be implemented in a wide range of communities throughout the U.S. For additional information on the CPS, please contact Ms. Patricia Riley at (770) 488-5395.

Where Did the WHI CT/OS Take Place?

The WHI clinical trial and observational study was conducted at 40 clinical centers nationwide. The Fred Hutchinson Cancer Research Center in Seattle, WA served as the WHI Clinical Coordinating Center for data collection, management, and analysis. Recruitment began in September 1993 and continued through December 1998 for those women who chose to "be part of the answer". 

Study participants got the personal satisfaction of knowing that they were contributing to their own health and the health of women for generations to come.

Department of Health and Human Services National Institutes of Health National Heart, Lung, and Blood Institute

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