The goals of osteoporosis research include identifying women at risk for this disease of thinning bones and developing therapies to prevent and treat it. A recent study published in the
Journal of the American Medical Association (JAMA)
suggests that a surprising number of postmenopausal women are at impending risk for osteoporosis, though neither they—nor their doctors—know it.
About the study
This study was part of the National Osteoporosis Risk Assessment (NORA), an observational study of postmenopausal women in primary care physician practices throughout the United States. The 200,160 women followed in this study were aged 50 or older, postmenopausal, and able to move about independently. They also had not been previously diagnosed with osteoporosis and had not had a bone mineral density (BMD) test in the preceding 12 months. Women who were currently taking calcitonin (Miacalcin), raloxifene (Evista), or bisphosphonates such as alendronate (Fosamax) were also excluded from the study.
The women were enrolled in the study between September 1997 and March 1999. Upon enrollment, each woman filled out a questionnaire about personal and family history of fractures, lifestyle behaviors, and medication use, and was given a BMD test. Approximately 12 months later, each woman was given a follow-up questionnaire that included questions about new fractures. Researchers then compared the BMD test results with the information about fractures provided on the questionnaires.
Of the 200,160 women who enrolled in the study, BMD tests showed that 39.6% had osteopenia (low bone mineral density) and 7.2% had full-blown osteoporosis. Among the 163,979 who filled out the second questionnaire, those diagnosed with osteoporosis had a fracture rate about four times that of women with normal BMD. Women with osteopenia had a fracture rate of 1.8 times that of women with normal BMD.
These findings indicate that without BMD testing, nearly 50% of women at risk of fracture would not be identified, even with regular visits to their primary care physicians. And more importantly, the risk of fracture is a fairly short-term one. The women found to have osteoporosis were at markedly increased risk for a fracture within 12 months of the diagnosis.
BMD testing was performed using peripheral BMD measurements of the forearm, finger or heel rather than dual-energy x-ray absorptiometry (DXA) of the hip or spine (called central DXA). Central DXA is considered the gold standard of bone density testing. However, central DXA equipment is prohibitively expensive and not consistently covered by health insurance, especially for women younger than 65. In lieu of central DXA, peripheral BMD tests proved effective in identifying women at risk for fractures.
There are several limitations in the design of this study that should be considered along with the study's results. Although the sample of women was a large one, it was not entirely representative of U.S. women aged 50 and older because it excluded women who had been diagnosed with osteoporosis, women being treated for osteoporosis, and women who had a recent BMD test.
In addition, all the information about medical history, family history, risk factors and fractures was self-reported by the participants and not corroborated with medical records. It's possible that this compromised the precision of some of the answers provided by the women, especially the answers involving long-term recall.
How does this affect you?
In an editorial accompanying this article, Charles Chestnut, MD, of the Osteoporosis Research Center at Seattle's University of Washington Medical Center explains that many doctors and researchers have long suspected that "a significant number of postmenopausal women in primary care practices have clinically significant low BMD" and that such women are at increased risk of fracture within one year. The results of this study indicate that peripheral DXA can identify many of these women. The availability of this lower-cost alternative to central DXA may mean that more women can get BMD tests and, if necessary, begin preventive measures to ward off a fracture.
Research has shown us that weight-bearing exercise and a diet rich in calcium and vitamin D can help prevent thinning bones. There are also five FDA-approved drugs for the prevention and treatment of osteoporosis. And speaking of medications, it's also important to note that this study was funded and managed by Merck & Company, manufacturers of the osteoporosis drug Fosamax. Although Merck would certainly benefit from a discovery that more women might benefit from osteoporosis medication, independent investigators reviewed the data from this study and performed quality assurance assessments of the BMD testing equipment.
Research also continues to show that regular weight-bearing exercise and a diet rich in calcium and vitamin D promotes bone integrity. In conjunction with early BMD testing, there's a real chance that the numbers of women who suffer from osteoporosis and its side effects could be substantially decreased.
Siris ES, et al. Identification and fracture outcomes of undiagnosed low bone mineral density in postmenopausal women: results from the National Osteoporosis Risk Assessment. Journal of the American Medical Association
. Dec 12, 2001. 286(22):2815-2822.
Chestnut CH. Osteoporosis, an underdiagnosed disease
. Journal of the American Medical Association
. Dec 12, 2001. 286(22):2865-2866.
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