Report from SCCT: Cost-effectiveness studies favor CTA over conventional ways to diagnose coronary artery disease

July 10, 2007

Award-winning studies presented at the Society of Cardiovascular Computed Tomography meeting suggest that cardiac CT angiography may be more cost-effective than myocardial perfusion SPECT and a good financial choice when performed after a positive nondiagnostic stress test to weed out unnecessary cardiac catheterization.

Award-winning studies presented at the Society of Cardiovascular Computed Tomography meeting suggest that cardiac CT angiography may be more cost-effective than myocardial perfusion SPECT and a good financial choice when performed after a positive nondiagnostic stress test to weed out unnecessary cardiac catheterization.

Dr. James K. Min, director of cardiac CT at New York Presbyterian Hospital, and colleagues retrospectively examined private payer claims for coronary artery disease-related costs and clinical outcomes in two large regional health plans. Min emphasized the need for such research because 8% of the $2.3 trillion healthcare expenditure in 2007 will be spent on imaging.

In the study, 1833 patients underwent CTA, and another 7732 received myocardial perfusion SPECT imaging as the initial diagnostic test for coronary artery disease. No other test had been performed on the CTA or SPECT patients in the prior 12 months. To control for potential selection bias, age, gender, and cardiac risk scores were identical between the two groups.

Min found that CTA patients, when compared with a matched set of SPECT patients, had 36% lower costs by an average of $1716 per patient. CTA patients also had lower rates of hospitalization and lower rates of angina or myocardial infarction.

The SPECT cohort used significantly more antiplatelet agents and showed a trend toward higher use of beta blockers compared with the CTA patients. Those who underwent SPECT imaging also were more likely to undergo catheter angiography and percutaneous or surgical procedures.

Dr. Srikanth Sola and colleagues from The Cleveland Clinic Foundation designed a mathematical model with a hypothetical population of 1000 patients to test the cost-effectiveness of coronary CTA. The model was developed so that the occurrence of coronary artery disease in the population could vary from 1% to 100%.

Patients with an abnormal or nondiagnostic stress echo or stress SPECT study would follow one of two approaches: a conventional strategy consisting of catheter angiography or CTA. In the CTA arm, only patients with an abnormal or nondiagnostic CTA study were referred for cardiac cath. The remaining patients in the CTA arm were treated medically.

Researchers determined the percentage of diagnostic versus nondiagnostic studies from the current literature and costs from Medicare part B and private insurer data. The outcome of the model was the average cost per patient for the entire population of patients who were then referred to stress testing.

Based on the model, for example, 422 patients would have gone directly to cath based on the stress echo or stress SPECT alone, but only half that number would have received x-ray coronary angiography if CTA had been included in the imaging strategy, Sola said.

He found that including CTA as an intermediate test is cost-effective when the percentage of privately insured patients ultimately found to have coronary artery disease is 60% or less. The cutoff point for cost-effectively applying the CTA strategy to Medicare is lower than with private insurers because of its lower reimbursement rates. To produce a positive return from intermediate CTA, the prevalence of coronary artery disease among Medicare patients must be lower than 30%.

"A strategy utilizing coronary CTA as the next step to evaluate patients with an abnormal or nondiagnostic stress test is cost savings for a population with low to intermediate prevalence of disease," Sola said.

Both studies won awards for best abstracts at the conference.

For more from the Diagnostic Imaging archives:

CMS gets an earful on reimbursement for coronary CTA

Coronary artery CT assesses sudden death risk from all cardiovascular causes

Coronary CTA triages patients with chest pain