A “considerable number” of coronary CT angiography (CCTA) studies are currently being ordered for inappropriate indications based on appropriateness criteria guidelines, according to a study published in the September issue of the Journal of the American College of Radiology.

While the results signal a need for better physician education on appropriate test ordering, recent expansions in the guidelines have boosted the number of appropriate orders.

“We feel that this reflects the growth of the technology and confidence in its results,” wrote study authors Sula Mazimba, MD, MPH, of Kettering Medical Center in Kettering, Ohio, and colleagues.

The authors sought to evaluate the utilization pattern of CCTA in their large community hospital through a retrospective analysis of CCTA studies ordered from 2006 to 2008. Ordering indications were categorized based on published appropriateness criteria developed in 2006 by the American College of Cardiology Foundation in conjunction with a number of other professional societies. Studies also were categorized based on a 2010 update to the criteria.

A total of 243 CCTA studies were included in the analysis, and the results showed that 67.1 percent were ordered for chest pain. Based on the 2006 criteria, 43.2 percent were classified as inappropriate, while another 39.1 percent were categorized as uncertain, leaving a minority of studies ordered for appropriate indications, according to the authors.

The 2010 appropriateness guidelines resulted in a regrading of a significant number of studies, explained Mazimba and colleagues. Although inappropriate testing remained at a similar level of 48.1 percent, the number of uncertain cases was greatly reduced with many reclassified as appropriate. Based on the 2010 criteria, only 2.8 percent of studies were categorized as uncertain, and 49 percent were now considered appropriate.

“This shift was partly driven by a more positive view in the 2010 [appropriateness criteria] of patients with low to intermediate risk for [coronary artery disease]. Because most of the indications for CCTA in our study were due to chest pain, this resulted in the reclassification of these patients into the appropriate category,” wrote the authors.

The authors noted the small increase in inappropriate testing was the result of the 2010 guidelines looking less favorably on CCTA for patients at high risk for coronary artery disease and reclassifying some uncertain indications as inappropriate.

Mazimba and colleagues wrote that the changes to appropriateness criteria reflect increased familiarity with CCTA in the imaging community. “The indications for CCTA will most likely continue to increase over time as more clinical experience and published literature accrue. Ongoing education will be important to ensure that physicians keep up with this rapidly moving target.”