Radiologists—especially those working at teaching hospitals—see some of the country’s most clinically complex Medicare patients, according to a report published in the February edition of Academic Radiology.

First author Andrew B. Rosenkrantz, MD, MPA, and colleagues pooled data from more than half a million radiologists across the country for their study, which strived to assess Medicare patient complexity by both physician specialty and radiologist characteristics in an effort to gather information CMS can use to ensure the success of the impending Medicare Access and CHIP Reauthorization Act (MACRA).

MACRA, which is expected to impact most physicians across the U.S., was signed into law in 2015 and will begin to impact payment adjustments next year. One aspect of the act—the Merit-based Incentive Payment Service, or MIPS—isn’t exactly thrilling to radiologists, who could see either positive, neutral or negative adjustments to their payment models based on a composite performance score calculated by CMS.

Payments will become increasingly value-based under MIPS, the authors said. Since the stipulation will play a role in the majority of American practices, and in both community and academic settings, CMS is looking to “recognize variation in physicians’ practices in determining value-based payment adjustments.”

“Physicians caring for sicker patients, as may be anticipated among university and other tertiary care centers, will be challenged in obtaining the same clinical outcomes and resource utilization as those caring for healthier patients,” Rosenkrantz et al. wrote. “Meaningfully measuring physician outcomes and resource utilization  requires appropriate patient risk adjustment.”

The researchers used Medicare’s preferred measure of clinical complexity, known as the Hierarchical Condition Category (HCC) risk score, to evaluate 549,194 physicians across 54 specialities. Of those specialties, they found, interventional radiology ranked fourth.

Close behind were nuclear medicine in 16th place and diagnostic radiology in 21st. Nephrology, infectious disease, and hospice and palliative care were the top three categories for patient complexity, respectively.

Of the 31,175 radiologists studied, complexity risk scores were higher for those who worked at teaching versus nonteaching hospitals and for practice sizes with 100 members or more, Rosenkrantz and co-authors wrote. Urban practices were also more likely than rural ones to see more complex patients, and subspecialists recorded higher risk scores than generalized radiologists. Among noninterventional specialities, patient complexity was highest for cardiothoracic radiologists and lowest for breast imagers.

The teaching affiliation proved to be the strongest independent predictor of patient complexity across the authors’ multivariable analyses, they wrote.

“At the national level, compared to most other physician specialties, radiologists on average serve more Medicare beneficiaries of higher clinical complexity,” they said. “To our knowledge, there is little previous work focusing on this aspect of radiologists’ practice, which may become increasingly relevant as the specialty prepares itself for future risk-bearing contracts and physician performance measure transparency initiatives, and as academic centers in particular strive to ensure appropriate payment for their unique patient populations.”