The Women's Health Initiative (WHI) was a series of clinical studies initiated by the U.S. National Institutes of Health (NIH) in 1991, to address major health issues causing morbidity and mortality in postmenopausal women. It consisted of three clinical trials (CT) and an observational study (OS). In particular, randomized controlled trials were designed and funded that addressed cardiovascular disease, cancer, and osteoporosis. In its entirety, the WHI enrolled more than 160,000 postmenopausal women aged 50–79 years (at time of study enrollment) over 15 years, making it one of the largest U.S. prevention studies of its kind, with a budget of $625 million. A 2014 analysis calculated a net economic return on investment of $37.1 billion for the estrogen-plus-progestin arm of the study's hormone trial alone, providing a strong case for the continued use of this variety of large, publicly funded population study. In the years following the WHI, studies have shown a decrease in breast cancer rates in postmenopausal women, attributed to the decline in use of hormone replacement therapy. However, initial interpretation and communication about the studies' findings have come under harsh criticism for failing to clarify that the studies were weighted toward women already 60 or older (average age 63). This meant that women in their 50s, who tend to be healthier (and have more menopausal symptoms), were underrepresented. Systemic hormone therapy has decreased dramatically among U.S. women since the WHI results were published because the findings are being misapplied to treatment decisions for women in their 40s and 50s who have distressing vasomotor symptoms. Motivation for the expanded study of women's health In the 1980s, it had become apparent that past biomedical research had focused disproportionately on white men, often neglecting prevention and treatment studies of diseases that are either unique to or more common in women and minorities. In 1985, the Public Health Service Task Force on Women's Health Issues issued recommendations that biomedical and behavioral research should be expanded to provide for the inclusion diseases and conditions identified among women of all age groups. In 1986, the NIH issued recommendations that women be included in all research studies. To further promote the study of women, in 1990, the NIH created the Office of Research on Women's Health. In 1990, however, a report was published by the General Accounting Office (GAO), at the request of the Congressional Caucus on Women's Issues, which stated that this NIH