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Debate: Heel ultrasound to assess density, fracture
Does it bring new value to the table?
A new multicenter study suggests that a simple ultrasound exam of the heel might be able to indicate whether a woman is at risk for an osteoporotic-related fracture.1 And investigators believe the test may be a good way to select women for more extensive bone density testing through dual-energy X-ray absorpitometry (DEXA).
In the three-year study, more than 6,000 women between age 70 and 85 were screened with heel-bone quantitative ultrasound (QUS), a diagnostic test that was used to calculate the bone stiffness index, an indicator of bone strength at the heel. Investigators then used this index along with risk factors such as recent falls, age, and history of fractures to develop a prediction rule to estimate fracture risk.
The results showed that roughly a quarter of the women were at lower risk and three-quarters were at an elevated risk of a fracture. A repeated series of follow-up questionnaires sent to the women at six-month intervals over 32 months showed that slightly more than 6% of the women in the higher risk group developed a fracture, while only 1.8% of women in the lower-risk group suffered a facture.1
Investigators conclude that these results show that QUS, when used in conjunction with clinical factors, is not only effective at identifying women at risk of fractures who should receive further evaluation, it also is effective at identifying those women who don't need further evaluation. Nonetheless, some experts question the exam's value where DEXA technology is widely available.
Exam is simple and inexpensive
The benefits of the approach are that the exam can be inexpensively carried out by physicians and nurse practitioners with a simple, hand-held ultrasound device in a routine office visit, and there is no ionizing radiation involved, says Idris Guessous, ND, the lead author of the study and a senior research fellow in the Department of Internal Medicine at Lausanne (Switzerland) University Hospital. Further, he emphasizes that the assessment combines bone status and clinical risk factors that have previously been shown to independently predict the risk of osteoporotic fracture.
"A prediction rule that uses heel quantitative ultrasound…would certainly be easier to adapt to the growing demand for osteoporosis management in the next decades," says Guessous. In addition, he stresses that unlike DEXA, QUS can be used not only to evaluate bone density, but also bone quality. However, not all experts agree that this application has been proven. Felicia Cosman, MD, clinical director of the National Osteoporosis Foundation and a professor of clinical medicine at Columbia University in New York City, says, "That is very controversial, and we have really never been able to show there is really something additive from the ultrasound exam beyond the bone density measurement."
In addition, while Cosman sees some value in QUS for patients who do not have access to DEXA technology, she does not see much benefit in using the exam in areas where DEXA is widely available. "I think, in general, if people have access to DEXA tests of the hip and the spine, they are much better off getting those tests because the hip bone density measurement is the one that has been shown to be the most predictive of fracture risk – both in the hip, which is the most important site of osteoporosis-related fracture, as well as throughout the rest of the skeleton," says Cosman. "The spine, I think, takes a close second place, particularly for younger individuals where sometimes you see bone loss in the spine earlier than you might see it in the hip."
It is also unclear whether front-line clinicians, such as internal medicine physicians and nurse practitioners, would welcome an additional test. "Adding anything to the office is difficult," says Cosman. However, she acknowledges that for primary care clinicians who want to offer bone density exams, QUS offers a practical way to do that.
In fact, Guessous is hoping to better define the effectiveness of the prediction rule in the clinical setting and to assess its validity in non-Caucasian women. "Osteoporosis is a major public health issue, and it is expected to increase in association with the worldwide aging of the population," he says. "The development of strategies to better identify women who need treatment, and those who do not need treatment, is crucial."