Study finds NPP-billed imaging increased 27% from 2016–2020

A new study by the Harvey L Neiman Health Policy Institute found that rates of diagnostic imaging interpretation by non-physician providers (NPP) are on the rise from 2.6% to 3.3% of all imaging studies. The study, published in Current Problems in Diagnostic Radiology, found that the rate of NPP-billed imaging increased 27% from 2016-2020.

The study assessed over 110 million non-invasive imaging claims from the Optum Clinformatics Datamart from 2016 to 2020—more than 3 million (3%) of which could be attributed to NPPs. Although the highest overall rates of NPP interpretation of images were seen in rural and small-town areas, the most significant growth in the rates of NPP-interpreted imaging over the study period were seen in both metropolitan (+31%) and micropolitan (+19%) areas.

"In previous studies evaluating the impact of expanding NPP scope of practice in a subset of U.S. states, we have shown that NPPs are associated with increased imaging utilization in the primary care and emergency department settings, meaning NPPs in these settings order more imaging than physicians," explained Eric Christensen, Ph.D., Research Director at the Neiman Institute.

"This study looked directly at NPPs practicing radiology and explored where, geographically, NPPs are contributing more to image interpretation."

Another important facet of the study was the categorization of each provider by the scope-of-practice (SOP) regulations in his/her state. "As some states are granting NPPs greater autonomy, our finding that the greatest growth in NPP imaging was among those states with less stringent SOP laws matched our expectations," notes Casey Pelzl, MPH, lead author of the study.

"Interestingly, the growth in NPP-billed imaging was only observed in the metropolitan areas of states with less restrictive SOP legislation, but this growth was not echoed in micropolitan and small town/rural areas in these same states."

The researchers also compared urban versus rural areas to determine if NPPs may play a role in expanding geographic access to radiology services.

"While the historical higher rates of imaging by NPPs in more rural areas supported our access hypothesis, disproportionate growth in urban areas suggests other forces at play. Although NPPs have been shown by some to increase access and decrease costs in the primary care setting, their value in providing highly specialized services such as image interpretation is unknown," states Richard Duszak, MD, a co-author, and the Chair of Radiology at the University of Mississippi Medical Center.

"Our study did not assess the quality of imaging interpretation delivered by NPPs, but as this practice increases, need clearly exists for future study to inform future SOP laws around the country."