More than half of U.S. radiologists practice mainly as generalists, yet those who fit this description dedicate, on average, one-third of their work time to a single subspecialty, according to a study conducted by Harvey L. Neiman Health Policy Institute researchers and published online Nov. 27 in Radiology.

The findings may have ramifications for reimbursement, as CMS’s Quality Payment Program has been working to develop quality metrics based largely on subspecialty-level activities and so may need to refine its categorization criteria, the researchers suggest.

Drawing from the Medicare Physician and Other Supplier Public Use file and other publicly available data sources, Andrew Rosenkrantz, MD, MPA, of New York University and colleagues identified 33,090 radiologists who billed for professional services between 2012 and 2014.

The team used a validated classification system to map services to seven subspecialties and quantify subspecialty-focused effort on the basis of work relative value units (RVUs).

They designated radiologists with more than half of their billed work RVUs in a single subspecialty as subspecialists and all others as generalists.

Among the authors’ other key findings:

• Subspecialization is more common among radiologists who are women, are earlier in their careers, work in larger practices, have academic affiliations and practice in the Northeast.
• Among radiologists practicing as majority subspecialists, neuroradiologists (10.1 percent of all radiologists) and breast imagers (8.4 percent) are most common.
• An academic affiliation is the strongest independent predictor of radiologist subspecialization.

In a news release sent by the American College of Radiology, of which the Nieman organization is a part, senior study author Richard Duszak, MD, notes that CMS currently recognizes only interventional radiology and nuclear medicine as distinct specialties within radiology. All other radiologists, he adds, are generically characterized as diagnostic radiologists.

“That simple grouping system limits the utility of existing CMS physician directory files to evaluate subspecialty work characteristics,” Duszak adds. “Definitions based on methodologies such as ours could potentially be leveraged by CMS as it seeks to promote subspecialty-based metrics in its efforts to advance value-based payments.”