Skeletal x-ray utilization among Medicare beneficiaries is up, according to a new study published in the Journal of the American College of Radiology. Utilization is up 5.5 percent among radiologists and more than 11 percent among nonradiologists.

The authors studied Medicare claims data from 2003 to 2015. Overall, the utilization rate per 1,000 Medicare beneficiaries increased 9.5 percent during that time.

“Skeletal radiography remains a prevalent, widely performed imaging examination,” wrote Daniel J. Mizrahi, MD, department of radiology at Thomas Jefferson University Hospital in Philadelphia, and colleagues.  

Skeletal x-ray utilization increased a whopping 441 percent among nonphysician providers such as nurse practitioners. Utilization also increased 14.4 percent among chiropractors and podiatrists, and 10.6 percent among orthopedic surgeons. Utilization among primary care physicians (PCPs), meanwhile, decreased 33.5 percent.

“Utilization by PCPs, as well as their share in utilization, has decreased substantially, but utilization by nonphysician providers has increased substantially,” the authors wrote. “This may reflect a tendency on the part of PCPs to scale back their interpretations and instead have the nurse practitioners and physician assistants who work with them take on that responsibility.”

The authors noted their study had limitations. For instance, Medicare data is only going to reflect trends present in Medicare patients, not all patients nationwide. In addition, the study “may have somewhat overestimated the number of examinations read by nonradiologists” due to some nonradiologist physicians filing global claims when performing imaging.

Mizrahi et al. added that the rise in skeletal x-rays was “somewhat surprising” given the success and growth of other modalities. Could more research help explain this trend?

“The facts that the rate increase among nonradiologists has been double that among radiologists, and that most office skeletal radiography is interpreted by nonradiologists, raise concerns about self-referral and quality,” the authors wrote. “In particular, interpretations by nurse practitioners and physician assistants warrant further scrutiny.”