Women At Risk
Almost 20 million American women, or nearly half of those past menopause, have thinning bones and don't know it, one of the largest osteoporosis studies to date suggests.
The study was funded by Merck & Co., which makes an osteoporosis drug.
Using a relatively inexpensive imaging technique on 200,160 healthy women 50 and older, researchers found full-fledged osteoporosis in 7 percent and low bone density in an additional 40 percent.
The women were then followed for a year to see how many broke bones. The fracture rate in women with low bone density was nearly double that of women with normal bones, and four times higher in women with osteoporosis.
"The report reaffirms the existence of a large population of women expected to live well into the 21st century who are at risk for future fracture," wrote Ethel Siris of Columbia
University College of Physicians and Surgeons, New York.
The study shows not only that bone-thinning is "grossly underdiagnosed" in postmenopausal women but that bone density can be used to predict the risk of fractures in as little as a year, said Siris who led the study.
The study is published in Wednesday's Journal of the American Medical Association.
"The message to doctors is, when you look around your waiting rooms and make assumptions of who is at risk for osteoporosis, you really have no clue," Siris said.
Dr. Felicia Cosman, clinical director of the National Osteoporosis Foundation, said the findings are not surprising to osteoporosis experts. Previous estimates suggested that about 8 million American women have osteoporosis and 14 million more have low bone mass, she said.
"Age, personal or family history of fracture, Asian or Hispanic heritage, smoking, and cortisone use were associated with significantly increased likelihood of osteoporosis," the study said.
"Higher body mass index, African-American heritage, estrogen or diuretic use, exercise, and alcohol consumption significantly decreased the likelihood," it said.
Doctors should measure bone mass in all postmenopausal women who have had fractures or a family history of osteoporosis, and in all women 65 and older, Siris said.
Various drug treatments including estrogen hormone replacement therapy are taken by millions of post-menopausal women to stem and in some cases reverse osteoporosis, which strikes older women much more often than men.
"Such under-identification of osteoporosis risk implies under-treatment of osteoporosis," Charles Chesnut III of the University of Washington Medical Center, Seattle, wrote in an accompanying editorial.
"Based on the current study, strategies to identify, manage, and treat osteoporosis in primary care need to be established and implemented -- hopefully, sooner rather than later," he wrote.
Low-dose X-rays of the hip and spine are considered the gold standard measurement of bone density and strength, but the technique requires large machines that may cost $75,000 or more. This studused smaller devices that may cost as little as $10,000 to measure bone density at the heel, forearm or finger.
While none of the participants in the study had been diagnosed with osteoporosis or low bone density, 11 percent - 22,096 women - reported having had fractures after age 45, before the study began. Those fractures should have been a tip-off to doctors, the researchers said.
Fractures were found to be more common among women with risk factors such as smoking, older age and a family history of osteoporosis. But many other women thought to be at low risk also had broken bones.
The study included 18,000 black women, who previous studies have shown face a lower osteoporosis risk than whites. The prevalence of low bone mass and osteoporosis among them was still significant - 32 percent and 4 percent respectively.
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