The first study to examine the appropriateness of CT colonography (CTC), or virtual colonoscopy, has found the procedure was used appropriately among asymptomatic Medicare beneficiaries, according to findings published online March 29 in Journal of General Internal Medicine.

CTC also may have expanded colorectal cancer screening rates from rates seen with optical colonoscopy, reported Hanna M. Zafar, MD, of the Perelman School of Medicine at the University of Pennsylvania in Philadelphia, and colleagues.

In 2009, the Centers for Medicare & Medicaid Services (CMS) decided to end coverage for screening CTC over concerns about its use in patients with appropriate clinical indications. “Our results provide several important insights on CTC utilization in the presumed asymptomatic Medicare population in the last two years preceding this coverage decision,” wrote the authors.

Zafar and colleagues conducted a cross-sectional study of all 10,538 asymptomatic Medicare beneficiaries who underwent CTC between January 2007 and December 2008, and compared those data with a matched cohort of 160,113 asymptomatic beneficiaries who underwent optical colonoscopy over the same time period.

Results showed that overall, 83 percent of the CTC population had at least one clinical indication relatively appropriate for CTC. These indications included incomplete optical colonoscopy, sedation risk and chronic anticoagulation risk, according to the authors. Patients undergoing high-risk screening, which is an inappropriate indication, were less likely to receive CTC.

Assessing how many patients would not have been screened absent the option of CTC was outside the scope of the study, but the authors indicated the results suggest that CTC expanded the screening population rather than just replacing optical colonoscopy.

With regard to patient demographics, CTC utilization was higher among women, patients older than 65 years of age, white patients and those with higher household incomes. “These findings raise the possibility that future coverage of screening CTC might exacerbate disparities in colorectal cancer screening while increasing overall screening rates,” wrote Zafar and colleagues.

On average, CTC costs less than one third what optical colonoscopy costs, though patients with suspected polyps on CTC are referred to optical colonoscopy, raising downstream costs.

A study in the April issue of The Lancet delves further into the balance between screening yield, participation and costs associated with CTC.