Utilization rates of noninvasive diagnostic imaging procedures for Medicare population vary regionally

The utilization rates of noninvasive diagnostic imaging procedures such as computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) for the Medicare population vary substantially from region to region, with Atlanta, GA, having the highest utilization rate and Seattle, WA, having the lowest, according to a study in the April issue of the American Journal of Roentgenology (www.ajronline.org).

"Underlying regional variation in imaging utilization raises concerns about cost and quality," said Laurence Parker, PhD, lead author of the study. "Wide geographic variation in utilization raises questions about underutilization and quality on the low side and overutilization and costs on the high side," said Parker.

Researchers at the Thomas Jefferson University Hospital in Philadelphia, PA, calculated the overall noninvasive diagnostic imaging procedure utilization rate based upon data from the Centers for Medicare and Medicaid Services Physician Supplier Procedure Summary Files for 1998-2007. Results showed that in 2007, the Atlanta region had the highest utilization rate, with 4.60 procedures per capita - compared to 3.47 in 1998 and 3.95 in 2002; and Seattle had the lowest utilization rate in 2007, with 2.99 procedures per capita - compared to 2.33 in 1998 and 2.69 in 2002.

"Per capita utilization in the highest region has been about 50 percent greater than in the lowest region over the course of the study, with this percentage increasing from 1998 to 2007," said Parker. "This is a substantial difference, greater than the increases within regions from 1998 to 2007. However, it's a much smaller difference than the eightfold variation in Medicare payments reported in previous studies, and we think a more accurate number," he said.

"When we focus on high-technology, high-cost imaging categories, like CT, MRI and PET, many categories of imaging show more than 100 percent greater utilization. Many of the high variation categories are types of cardiovascular imaging," said Parker.

"There are many factors involved in regional variation in utilization, including morbidity and risk factors in the population, access-to-care factors, and general population factors. However, it seems very clear that there is substantial regional variation in imaging utilization, and it should be further explored," he said.

While regional variations exist, Medicare Payment Advisory Commission (MedPAC) statistics show that overall Medicare per-beneficiary imaging growth for 2006, 2007 was only 2 percent nationally - at or below the growth rate of other physician services.