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Epidemiology Study










markers biomarkers


The Study of Osteoporotic Fractures (SOF) was initially established to identify the risk factors associated with osteoporotic fractures in postmenopausal women aged 65 and older. Over time, the scope of the study expanded to include assessment of sleep, cognitive function, osteoarthritis, breast cancer, cognitive function and healthy aging. The study was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging, components of the National Institutes of Health.


Women aged 65 or older are most at risk for developing osteoporosis, a condition that causes the bones to become fragile. The increase in bone frailty makes this group more susceptible to osteoporotic fractures, which commonly occur at the hip, spine and wrist. Although there has been some research pertaining to fracture risk, most studies have not been able to thoroughly investigate this issue due to various limitations. There was a need for longitudinal research of a specific cohort of women, to determine what factors were most strongly related to fracture risk.

Study Design

The Study of Osteoporotic Fractures was a multi-site longitudinal study, which was established to assess women aged 65 and older for risk factors for osteoporotic fractures. The study was operational from 1986 until 2017 and had over 10,000 participants. Study participants were recruited from four U.S. cities: Baltimore, MD; Minneapolis, MN; Pittsburgh, PA; and Portland, OR. Initially, only white women were included in the study because they represented the highest risk group for osteoporotic fractures. However, in 1997 the study began to recruit African American women, as well. Women were excluded from participation at baseline if they had bilateral hip prostheses or were unable to walk without the assistance of another person. Study participants attended a series of clinical visits, where they underwent various physical and mental evaluations. The evaluations included imaging to measure bone density, physical examinations, and questionnaires. In addition to the clinical visits, participants were contacted via telephone or mail every four months to complete follow-up assessments, in order to obtain information regarding falls, fractures, and vital status.

Interventions/Treatment Groups

No interventions or treatment groups were used for this observational study.


Participants were evaluated at predetermined intervals for fractures and information regarding the circumstances which led to the fractures was also collected. Reports of fractures were centrally verified by diagnostic radiological imaging. Assessments for incident breast cancer, stroke, and hip osteoarthritis were also conducted.


The Study of Osteoporotic Fractures concluded in 2017 after 31 years of research. SOF researchers determined that women aged 65 and older with low bone mineral density (BMD) have an increased incidence of bone fracture. Data have shown that factors such as advanced age, poor health, and lack of exercise lead to an increased risk of bone fracture. Findings also indicate that fractures, specifically at the hip, negatively impact quality of life and increase the risk of mortality. SOF data have been used in hundreds of scientific publications. SOF research has been used to improve the understanding of the aging process. SOF findings also led to the standard use of the dual energy X-ray absorptiometry (DXA) scan for osteoporosis screening and treatment. Overall, the study has transformed osteoporosis research and has made significant contributions to the research of healthy aging.

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Biospecimens and Study Datasets
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