Image source: Brighan and Women's Hospital

New technologies can be quickly and widely adopted without close attention to applying them to patients who will truly benefit. Policymakers need to consider how new technologies either become substitutes for or expand upon existing technologies to understand their true cost-effectiveness, Laurence C. Baker, PhD, a professor of health research and policy at Stanford University in Stanford, Calif., said in an interview.

Baker and colleagues examined Medicare data from 2001 to 2005 to determine the relationship between the emergence of CT angiography (CTA) to image the carotid arteries and catheter angiography—the standard of care (Health Aff 2010;29(12):2260-2267).

The researchers found that CTA tests were substituted for catheter angiography in more than 20 percent of cases. But they also found that for each instance of substitution, there were approximately three to four instances of incremental, or expanded, use—cases in which CTA was performed on patients who previously would not have received any test. (The reasons could vary, including the patient's refusal to undergo catheter angiography or the referring physician's willingness to send a patient to CTA rather than no follow-up test just to be sure of the ultrasound results.)

In addition, the incremental use of CTA did not result in an increase in patients being treated for carotid artery disease.

Researchers also addressed potential effects of expanded use of CTA on healthcare spending. When reimbursed according to the 2005 Medicare fee schedule, each instance of CTA incurred costs totaling $514. Similar payments for catheter angiography were about $575. Each substitution could thus produce a small reduction in payments as well as potentially larger savings from the reduced rates of stroke.

Also, in a previous study, Brown and colleagues found that substituting CTA for catheter angiography as a follow-up test for a positive ultrasound is cost effective, reducing spending by $2,353 in 2004 dollars—from $11,531 to $9,178—over a two-year period and leading to very similar health outcomes (J Neuroimaging 2008;18(4):355–359).

In the current study, Baker and colleagues found that for each instance of substitute use, about 3.5 instances of incremental, or expanded, use took place, representing a total cost increase of roughly $1,800. "If each substitution saves more than $2000, there would still be a net savings of more than $200 for each substitute procedure," said Baker.

"We want policymakers to know there are complicated dynamics where new technology is concerned," he said. "And the broader point being that new technology will be more cost effective if it is aimed at people who will benefit the most, but understanding that dynamic is not always clear-cut, especially in cases where new tools have multiple uses and information is incomplete."

In addition, "New technologies frequently spread beyond the narrow situations where effectiveness or cost-effectiveness is well demonstrated. Policymakers and researchers must take this fact into consideration."