Post-menopausal women can now plug a few key pieces of information into an online tool to calculate their risk for suffering a hip fracture within the next five years. This is important because, directly and indirectly, hip fracture can lead to serious illness and death — in fact, 23% of hip fracture patients die within a year.
DANGERS NOT ALWAYS APPARENT TO DOCTORS
Researchers at the University of California at Davis have developed a computer model that can help predict, and may even help prevent, hip fractures in women. The algorithm may help women and their doctors make informed decisions about preventive measures such as lifestyle changes, screening tests, medications and other medical interventions. This is a huge improvement, since previously doctors screened only women perceived as being at obvious high risk, leaving out many who would benefit, says lead researcher John Robbins, MD, professor of general medicine at University of California at Davis.
To date, the best available screening tool has been the dual-energy x-ray absorptiometry (DXA) scan, an imaging technique that measures bone mineral density (BMD). However, says Dr. Robbins, BMD is only one of many predictors of hip fracture risk, and most hip fractures occur in women who are not osteoporotic by that standard.
WHO’S AT RISK?
To create the computer model, Dr. Robbins and his team analyzed data from 93,676 participants in the Women’s Health Initiative (WHI), an ongoing national health study that focuses on strategies for preventing heart disease, breast and colorectal cancer and osteoporosis in post-menopausal women (ages 50 to 79). The team identified 11 factors that were predictive of hip fracture — age, general health, weight, height, race/ethnicity, physical activity, history of fracture after age 54, parental hip fracture, current smoking, current corticosteroid use and treated diabetes. The factors were validated in a clinical trial among 68,132 women. The model was also tested in a subset of 10,750 women who had undergone DXA scans to measure BMD. The study appeared in the November 28, 2007, issue of The Journal of the American Medical Association (JAMA).
Here’s information on hip fracture risk that became apparent:
- Age ranks first. “Age is the most predictive factor for hip fracture risk,” said Dr. Robbins.
- Ethnicity plays a complex role. Dr. Robbins found several associations between ethnicity and risk. He noted that while Asian women had been considered at high risk, by doctors based on incidence, this is actually because so many are small and thin. All other things being equal, data revealed that Asian women and African American women are, in fact, at lower risk than white women.
- Height and weight are relevant. For instance, algorithm results indicate that tall, thin post-menopausal women of African ancestry may be at equal risk for hip fracture as short, overweight white women.
- Chronic health problems add to risk. The model also allows physicians to isolate various factors that are often linked, such as diabetes and obesity. “The risk of hip fracture goes down with increasing weight — but up with diabetes,” said Dr. Robbins. “Diabetes is usually associated with increased weight, so this model lets one look at both at the same time and balance them.”
TO FIGURE OUT IF YOU ARE AT RISK…
The greatest benefit of this model is that it is for women whose risk would not be recognized by their physicians. “Thin, post-menopausal white women with prior fractures and a family history of hip fracture don’t need a calculator to tell them they are at risk. They should already be talking about this with their physicians,” said Dr. Robbins. “It is the women whose physicians do not recognize their risk — for instance, tall, thin African American women, who will now be aware of their risk when they talk with their doctors.”
Post-menopausal women can calculate their five-year risk of hip fracture using the “Hip Fracture Risk Calculator” tool available online at http://hipcalculator.fhcrc.org/. What should you do if you take the test and learn that you are at risk? Dr. Robbins advises asking your primary care physician for a bone density test. “If the DXA shows a low bone mineral density, discuss options for building up your bones with your physician,” he says.
Dr. Robbins plans to test the computer model among other groups of women — and men, too — for further refinement. “We need to see if it holds for other populations,” he said. “It should not yet be used as ‘the answer,’ but just as a tool to further knowledge. The more a physician and patient know, the better they are prepared to make reasonable judgments.”
However, prevention is even better than prediction — with age comes thinning of the bones, for everyone. The right diet and regular weight bearing exercise keep bones stronger than they’d be otherwise, regardless of your risk.