Virtual Bone Strength Testing Effective for Osteoporosis Screening in Postmenopausal Women

Screening is key to preventing osteoporosis, which is responsible for an estimated 2 million broken bones per year in the U.S. alone. Osteoporotic fractures dramatically increase mortality rates and cost an estimated $17 billion a year in U.S. health care costs, according to the National Osteoporosis Foundation.

And given the aging population, the number of fractures are expected to rise.

Yet the current standard for detection and diagnosis of osteoporosis, bone mineral density testing with dual-energy x-ray absorptiometry (DXA), is often not effective in detecting patients with weak bones — many who go on to break them, according to the authors of a recent study in Radiology.

A screening strategy combining DXA scans with virtual bone strength testing may detect many more postmenopausal women at risk without increasing overall costs, according Christoph A. Agten, MD, a radiologist at Balgrist University Hospital in Zürich, Switzerland, lead author of the Radiology study.

The most cost-effective osteoporosis screening strategy combined DXA scanning and quantitative CT beginning at age 55, with a follow-up quantitative CT scan every five years. In a simulation model of 1 million patients, this strategy reduced the lifetime risk of hip fracture to 12.8 percent, compared to 18.7 percent for women who did not undergo screening and 15.8 percent in screening with DXA alone.

“It takes quite a lot of bone loss before you can detect a difference in bone mineral density, but the trabecular bone network can change orientation or get thinner, decreasing the structural strength of the bone,” Dr. Agten said. “The bone strength test, or the bone microarchitecture analysis, provides information we do not get using only DXA.”

While this testing method costs about 10 to 12 times more than DXA alone, Dr. Agten’s findings suggest this method could save money by preventing fractures down the line.

Hypothetical Cohort of One Million Post-Menopausal Women

Dr. Agten got the idea to conduct the analysis during his research fellowship at NYU Langone Medical Center, studying under supervisor Gregory Chang, MD, associate radiology professor and section chief of musculoskeletal imaging, who specializes in developing new techniques to assess bone health.

“I’ve worked with basic scientists and engineers and found you can do amazing things with MRI and other advanced methods in the lab,” said Dr. Chang, senior author on the Radiology research. “However, I still practice radiology — and especially in the current climate, we are always worried about the actual value to the health care system and patients.”

To begin his osteoporosis research, Dr. Agten first searched the literature for existing studies on osteoporosis screening strategies and treatments. He taught himself to use TreeAge Pro modeling software, using previously published data to create a hypothetical cohort of one million post-menopausal women.

Each individual had risk factors for fracture, including smoking and a parent with a fracture, randomly assigned based on age-related prevalence. As the model ran, the virtual population cycled through various stages of health (including no fracture, fracture and death) at three-month intervals. Patients were assumed to be treated with oral bisphosphonates if they met existing criteria for osteoporosis, including a T score lower than -2.5 or an estimated 10-year risk for hip fracture of greater than 3 percent on the World Health Organization (WHO) Fracture Risk Assessment Tool, or FRAX.

Dr. Agten compared three strategies: no screening; screening with DXA with rescreening based on T scores; and a combination of DXA and quantitative CT starting at either age 55 or 65 and using three different intervals (three, five or 10 years).

Researchers estimated costs from Medicare reimbursement rates as well as other sources. Any screening strategy that cost $50,000 per quality-adjusted life year was considered very cost-effective, whereas those with a cost of $50,000 to $100,000 were considered cost-effective. After fine-tuning the simulation and navigating crashes and error messages, Dr. Agten realized the combined approach would likely produce optimal results. Once the model was complete, he ran it 1,000 times for a probabilistic sensitivity analysis, which showed the same strategy was the most cost-effective more than 90 percent of the time.

“Those findings were quite reassuring; it could have been the other way around, that every strategy had the exact same amount or proportion of the best results,” he said.

Additional Trials Needed

Though his results are compelling, Dr. Agten said additional prospective clinical trials are needed for newer techniques such as quantitative CT and MRI.

“Once the larger studies are done, you could basically update the model with the new results,” he said. In addition, details about treatment outcomes from newer medications might influence the results.

Dr. Agten is hopeful the study will inspire additional research about how to detect and treat more patients with osteoporosis before they sustain expensive and life-altering fractures. He also hopes other radiologists will consider pursuing cost-effectiveness analyses on newer imaging techniques.

While no single study will change public policy or clinical guidelines, Dr. Chang sees a future in which osteoporosis is treated more like cardiovascular disease, with patients undergoing a personalized panel of diagnostic tests, including more costly options for those with risk factor profiles placing them in greater danger.

“This economic simulation provides a rationale for researchers to try new multicenter trials to determine whether they can improve diagnostic ability or predictive ability using these tests,” Dr. Chang said.

Web Extras

• Access the Radiology study, “Cost-effectiveness of Virtual Bone Strength Testing in Osteoporosis Screening Programs for Postmenopausal Women in the United States,” at https://pubs.rsna.org/doi/full/10.1148/radiol.2017161259