WASHINGTON — Coronary CT angiography appears to be a less expensive alternative to myocardial perfusion SPECT imaging as an initial diagnostic screen for coronary artery disease, according to an analysis of data from two large regional health plans presented at the annual meeting of the Society of Cardiovascular Computed Tomography.
The average 12-month downstream coronary artery disease-related cost for patients who underwent coronary CT angiography (CTA) as an initial screen for coronary artery disease (CAD) was $1,716 lower per patient than for those who underwent SPECT, said Dr. James K. Min of Cornell University, New York. By comparison, the average cost of a nuclear study ranged from $3,000 to $4,000, he said.
“CT may be a potential, cost-efficient alternative to SPECT for the initial evaluation of patients with suspected coronary artery disease,” said Dr. Min.
The researchers analyzed private payer data from two large regional health plans with more than 6.5 million members from 2002 to 2005. The database included membership information, pharmacy claims, and inpatient and outpatient service claims.
The researchers identified patients who underwent CTA or MP SPECT imaging as an initial diagnostic screen for coronary artery disease. Information was collected for 1 year prior to and 1 year after the test.
Only patients without known coronary artery disease were included. These were patients who did not have any coronary artery disease-related procedure codes for the previous 12 months. CT and MP SPECT claims included only those with coronary heart disease codes.
For each patient, the researchers calculated a cardiac risk score. The score was a weighted average of several risk factors, including use of digitalis, anticoagulant agents, antiplatelet agents, ACE inhibitors, β-blockers, antihypertensive medication, and antidiabetic medications, as well as the presence of other clinical cardiac conditions. The researchers also assessed each patient's overall health status using the Charleston Comorbidity Index.
Each patient in the CTA group was matched with four patients in the SPECT group based on age, gender, and cardiac risk score. Both groups had an average age of 51 years. About two-thirds of the patients in each group (68%) were women. The average cardiac risk score was 0.20 in the CTA group and 0.19 in the SPECT group.
A total of 1,833 patients were identified who had an initial diagnostic screen with CTA; they were matched with 7,332 patients who had SPECT imaging.
In addition to a cost difference for the two modalities, the researchers noted that the use of antiplatelet therapy was greater among SPECT patients after the initial diagnostic test.
There was also a trend toward greater use of ACE inhibitors and statins in the SPECT group, though this did not achieve significance.
“In terms of follow-up diagnostic tests, patients who initially underwent CT angiography were more likely to undergo nuclear stress testing in the follow-up period, while patients who underwent nuclear stress testing were more likely to undergo invasive coronary angiography,” said Dr. Min. Looking at any diagnostic test, there was an 18% relative risk reduction in patients who underwent initial coronary evaluation with CT angiography.
The researchers also looked at clinical outcomes. Patients who underwent initial SPECT imaging had a higher rate of surgical or percutaneous interventions in the follow-up period compared with those who had CTA—1.2% compared with 0.4%, respectively.
“CTA patients experienced lower rates of both hospitalization as well as angina or myocardial infarction,” Dr. Min said at the meeting.
“From this we tentatively conclude that compared to MP SPECT patients, patients who underwent CT as an initial diagnostic test incurred lower 12-month total coronary disease-related costs,” said Dr. Min.
Dr. Min disclosed that he receives research support from GE Healthcare, which manufacturers both technologies.
A CTA reveals diffuse, mixed plaque in the left anterior descending artery.
Here, a multidetector CT volume rendered image shows calcification in the left anterior descending and right coronary arteries. Photos courtesy Dr. James K. Min