According to a study in the April issue of the American Journal of Roentgenology (AJR), geographic variation in noninvasive diagnostic imaging utilization in the Medicare population is approximately 50 percent higher in the highest regions compared to the lowest regions and cardiovascular and high-technology procedures show the greatest regional variation.

Lead author Laurence Parker, MD, from the Center for Research on the Utilization of Imaging Services within the department of radiology at Thomas Jefferson University Hospital in Philadelphia, and colleagues noted that overall regional variation appears to be on the increase.
 
“There are many factors involved in regional variation for utilization, including morbidity and risk factors in the population, access-to-care factors, and general population factors,” said Parker. “However, it seems very clear that there is substantial regional variation in imaging utilization, and it should be further explored.”

From the study period between 1998 to 2007, the researchers reviewed Physician Supplier Procedure Summary Master Files from the Centers for Medicare & Medicaid Services (CMS) to evaluate billing records for all 32–37 million fee-for-service beneficiaries. The records provided the total number of each type of procedure performed, which were then categorized according to the 10 CMS geographic regions.

For each year of the study, overall noninvasive diagnostic imaging procedure utilization rates and the ratio of the highest to lowest region were calculated.  In addition, each of these numbers was calculated for 28 noninvasive diagnostic imaging categories, including CT, MRI and PET, said the researchers.

The authors wrote that Atlanta had the highest utilization rate, with 4.6 procedures per capita. and the lowest was Seattle, with 2.99 procedures per capita. “This overview of geographic variation in radiology utilization is not reassuring,” they noted.

Over the course of the 10-year study, the relative risk ranged between 1.47 and 1.56. However, the researchers found that cardiovascular noninvasive diagnostic imaging and high-technology, high-cost noninvasive diagnostic imaging including MRI, PET and nuclear medicine presented high regional relative risk, at 70.2.

“Underlying regional variation in imaging utilization are concerns about cost and quality,” said Parker and colleagues. “Wide geographic variation in utilization raises questions about underutilization and quality on the low side and overutilization and costs on the high side.”

The authors concluded that “the most rational practice of medicine should presumably show as little variation as possible.”