Can new technology expand osteoporosis screening capabilities?

Ultrasound vs. DXA: Providers debate the pros and cons

Convenient. Easy-to-use. Portable. Less expensive for the provider as well as the patient. These are all reasons that women's health centers might consider adding a device that uses ultrasound for bone densitometry to enhance or establish an osteoporosis screening program.

The news isn't all good, however. As with any new technology, there are cautions, limited-use recommendations, and opposition to the new technique.

Kaiser Permanente Medical Care of Northern California has provided bone densitometry as a health plan benefit since 1991, says Bruce Ettinger, MD, senior investigator in the division of research at the HMO in Oakland and former president of the North American Menopause Society.

Ettinger's organization provided bone densitometry exams to 20,000 members last year, and all exams were performed with dual-energy X-ray absorptiometry (DXA) measurement of the hip and spine.

"We consider DXA to be the most accurate way to diagnose and follow patients with osteoporosis," Ettinger explains. Peripheral densitometry such as ultrasound of the heel does not give as precise a measurement and is hard to use over a period of time to measure a patient's response to treatment, he adds.

Other experts in the field agree that DXA of the hip and spine is the gold standard, but they argue that ultrasound of the heel does have a place in a women's health program.

"Ultrasound is an appealing way to monitor bone health. There is no radiation and no requirement for a licensed radiology technician to operate the equipment," says Steven R. Goldstein, MD, professor of OB/GYN and co-director of the bone densitometry program at the New York City University School of Medicine. "The equipment is also inexpensive," Goldstein adds.

Typically, ultrasound devices cost about $30,000, while DXA equipment runs anywhere from $70,000 to $150,000.

"DXA is still best for measuring bone density, but a combination of the two exams is the ideal," says Goldstein. "Ultrasound can be a good screening test with DXA used to confirm a diagnosis of osteoporosis and follow a patient's response to treatment."

Reimbursement guidelines restrictive

At women's health centers, the approach is a cautious.

"We've offered DXA for three years, but we added the Sahara Clinical Bone Sonometer [manufactured by Hologic in Waltham, MA] for several reasons," says Nancy L. Richter, manager of the Women's Health Center of Bethlehem (PA).

"A lot of our patients enter menopause without a baseline DXA," Richter says.

Managed care and Medicare generally will not cover a DXA exam unless the women has a specific risk factor such as a history of taking thyroid medication or a naturally occurring menopause prior to age 45, Richter explains.

"With the cost of DXA ranging from $150 to $200, patients are reluctant to pay for it themselves," adds Richter. At the same time, Richter says patients are more educated about osteoporosis and ask about the exam.

While Medicare and managed care guidelines for bone density exams may still prevent ultrasound exams from being covered for many women, the lower cost of the exam may not present such an obstacle for women who want a baseline reading.

"The ultrasound device is very affordable, and the exam costs patients $45," says Richter. Of all of the peripheral bone density measurements, Richter prefers the heel measurement because it is a weight-bearing bone and contains the type of bone most often affected by osteoporosis.

Richter uses ultrasound as a screening tool. "If the woman's ultrasound exam indicates a problem, we order a DXA," she says. "We also use DXA to track the woman's bone density as she is treated."

The ultrasound at North Shore Women's Center at Beth Page, PA, is also used for initial osteoporosis risk screenings, says Stuart Weinerman, MD, director of the metabolic bone program.

Although his center doesn't plan on ultrasound replacing the need for DXA, Weinerman says the real benefit of ultrasound is the greater scope of women who can be screened for osteoporosis. In addition to using ultrasound at health fairs for both the general public and for industry customers, Weinerman is checking the possibility of using ultrasound at other women's centers.

"Our other center has a high Medicaid population," he explains. "Although we do recommend DXA exams for many of the patients, the process to schedule a time for an exam and arrange transportation to and from the exam makes it difficult for many patients. The ultrasound device is inexpensive enough to allow us to have one at the center, and the test takes only six seconds to produce a reading, so we can test the woman at the time she is already in the center."

Making the screening easy to access will make it more attractive to most of his patients, adds Weinerman.

Richter will use ultrasound screening as an additional form of osteoporosis education at community health fairs. In addition, Richter is planning to take the ultrasound device to physician offices. The mobile ultrasound osteoporosis screening will strengthen ties with the physicians who refer to her center and also will reach women who may not have been aware of the center, Richter says.

Evaluate results carefully

As with any screening exam, a health care provider has to be careful how the results are evaluated and how treatment is determined.

There are years of data from use of DXA to establish parameters for interpretations, but the ultrasound data is less extensive, points out Weinerman.

"Ultrasound of the bone is a good screening tool but DXA can be used for more accurate diagnosis if the screening shows that the patient is at risk," he adds.

Anyone buying ultrasound equipment to measure bone density should look carefully at the manufacturer's studies documenting false-negatives and false-positives, suggests Goldstein. A false reading that indicates high risk is not a problem for the patient because more extensive tests can correct the false reading and produce an accurate diagnosis. It's the false reading of no or little risk that concerns Goldstein.

"I don't want patients to walk away with a false sense of security," he explains. Even with a risk of false readings, Goldstein does think that ultrasound of bone is a good way to deliver periodic exams to younger women who might normally wait until they have an overt symptom of osteoporosis for testing.

The most encouraging aspect of ultrasound testing is the increased availability to more people, says Weinerman. "It is better to have some way of measuring risk of osteoporosis than none because it is unacceptable in today's health care environment to ignore osteoporosis as an important issue."