When doctors evaluate an older person who has fallen and broken a bone, they immediately look for signs of osteoporosis, the brittle-bone disease. Conventional wisdom holds that low bone-mineral density, the hallmark of osteoporosis, is chiefly responsible for fractures when elderly people fall from a standing position. But when an elderly person breaks a bone in a high-trauma accident, such as a car crash or a fall from a ladder, doctors don't usually check bone density.
A new study shows that bone density can play a role in high-trauma accidents too. Participants who sustained a fracture from serious trauma had, on average, significantly lower bone density to begin with than did those who didn't get fractures.
In another study, scientists seeking to identify women at risk of hip fracture have developed an algorithm that estimates a patient's 5-year risk of this injury from ordinary factors that physicians can readily assess.
The studies, both of which appear in the Nov. 28 Journal of the American Medical Association (JAMA), could improve a doctor's ability to identify people at risk of sustaining fractures late in life, when injuries are especially debilitating.
In the first study, researchers drew upon two trials that tracked more than 8,000 women for 9 years and nearly 6,000 men for 5 years. All participants were over age 65. The researchers used X rays to measure participants' bone density.
Women who experienced a high-trauma fracture during the study had about 8 percent less bone density than women who didn't sustain such fractures, says study coauthor Dawn C. Mackey, an epidemiologist at the California Pacific Medical Center Research Institute in San Francisco. Among men, the difference was 6 percent.
A separate analysis of the data shows that women with osteoporosis were more than twice as likely as their healthy counterparts to incur either a low-trauma (standing fall) or high-trauma fracture. For men, that likelihood was more than three times greater.
The findings could change clinical practice, says Sundeep Khosla, a physician at the Mayo Clinic in Rochester, Minn. "Fractures previously defined as due to high trauma, such as ... a motor vehicle crash or a fall from a chair, can no longer be dismissed as being unrelated to osteoporosis," he writes in the same JAMA issue. "Older patients who sustain such fractures should be considered for bone mineral density testing."
In the early days of bone research, policy makers felt that considering high-trauma breaks to be "osteoporotic" would exaggerate the scope of the bone disease, says epidemiologist L. Joseph Melton, also at the Mayo Clinic. But the new study shows that osteoporosis is indeed "a somewhat bigger problem than was recognized," he says. "What [the researchers] are finding here is totally credible."
In the other study, epidemiologist Jane A. Cauley of the University of Pittsburgh and her colleagues analyzed hip-fracture risk in postmenopausal women. By assessing health characteristics of thousands of clinical trial participants, the researchers devised an algorithm for fracture risk based on 11 factors: age, general health, weight, height, race or ethnicity, physical activity, fractures after age 54, parents' hip fractures, smoking, medical steroid use, and diabetes.
The researchers generated a scoring system that doctors might eventually use, along with bone-density scans, to gauge 5-year fracture risk. Doctors may be able to use this information to counsel high-risk women about beneficial lifestyle changes, Cauley says.
Jane A. Cauley
University of Pittsburgh
Graduate School of Public Health
Department of Epidemiology
130 DeSoto Street, Crabtree A524
Pittsburgh, PA 15261
Department of Endocrinology
200 First Street, SW
Rochester, MN 55905
Dawn C. Mackey
San Francisco Coordinating Center
California Pacific Medical Center Research Institute
185 Berry Street, Lobby 4
San Francisco, CA 94107
L. Joseph Melton
Division of Epidemiology
200 First Street, S.W.
Rochester, MN 55905
Center, J.R., et al. 2007. Risk of subsequent fracture after low-trauma fracture in men and women. Journal of the American Medical Association 297:387-394.
Stone, K. . . . J.A. Cauley, et al. 2003. BMD at multiple sites and risk of fracture of multiple types: Long-term results from the study of osteoporosis fractures. Journal of Bone and Mineral Research 18:1947-1954.