The evolution of the Women's Health Initiative: perspectives from the NIH.

The Women's Health Initiative (WHI) addresses some of the major health concerns of postmenopausal women. It is designed to test whether long-term preventive measures will decrease the incidence of cardiovascular disease, certain cancers, and fractures, and it seeks to find better predictors of future health and disease in older women. This report traces the evolution of the clinical trial and observational study (CT/OS) components of WHI from early planning in the 1980s to the current status of the WHI CT/OS as an integrated, ongoing clinical study. Particular attention is directed to the antecedent planning meetings and feasibility studies that formed the underpinnings of the WHI. The issues of hormone replacement therapy and of the optimal diet for postmenopausal women were investigated for almost a decade prior to WHI. However, no studies of sufficient size and duration to confidently test the value and risks of these approaches were initiated because of the cost and insufficient political commitment. The initiation of WHI in 1991 represents the confluence of scientific need and capability with the social priorities to improve the health and welfare of women.