Radiology: CTA more cost-efficient than MPI SPECT

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The utilization of CT angiography (CTA) in individuals without known coronary artery disease (CAD) results in lower healthcare costs compared to myocardial perfusion imaging (MPI) with SPECT, according to research published this month in Radiology.

“This study represents, to our knowledge, the first large-scale multicenter clinical and costs outcomes data for individuals without known CAD who underwent multidetector CT for initial coronary evaluation,” the authors wrote.

Researchers from the Greenberg Division of Cardiology, department of medicine; Weill Medical College of Cornell University, New York Presbyterian Hospital in New York City; Health Benchmarks in Woodland Hills, Calif.; the School of Public Health at the University of California at Los Angeles; and Emory University School of Medicine in Atlanta, analyzed data from two large regional health plans, encompassing a total enrolled membership of more than 6.5 million lives.

From this cohort, the team captured patient-level and clinical costs from 2002 through 2006 of 8,235 individuals, without known CAD, who had undergone CTA or MPI SPECT as an initial CAD diagnostic test and met inclusion criteria for the study. From this group, 1,647 patients had a CTA exam, while 6,588 had an MPI SPECT procedure performed.

“Absence of known CAD was identified by no prior claims within 12 months of the diagnostic test; prior claims were indicated by any CAD-related procedure code (ICD-9),” the authors wrote.

Pretest clinical risk estimates were also calculated (cardiac medications, baseline cardiac risk score and baseline comorbidity evaluation) for the study population. Cost-outcome measures were defined by the researchers as the actual insurance-paid claims in a one-year follow-up period after the CTA or MPI SPECT exam was performed.

“Because the baseline cost of myocardial perfusion SPECT was higher than that of multidetector CT, the baseline cost of the initial diagnostic test was excluded to ensure that the differences in baseline test cost did not obscure any significant differences in downstream healthcare costs,” the authors noted.

For each group of patients, CTA and MPI SPECT, the team classified total costs during follow-up into CAD-related costs, cardiovascular medications, additional diagnostic tests including crossover testing, coronary revascularization, hospitalization and myocardial infarction or angina.

Primary prognostic clinical outcome measures were identified by reimbursements in the one year following the diagnostic imaging test. Secondary clinical outcomes included the incidence of use of cardiovascular treatments, which were separated into medical therapy and interventional therapy.

“No significant differences existed between multidetector CT and myocardial perfusion SPECT groups for any demographic, cardiac risk factor, or cardiac-related medication,” the authors reported.

The team’s retrospective analysis found that unadjusted downstream CAD-related healthcare costs were lower for CTA than MPI SPECT at 1 month ($1,572 vs. $2,531), 6 months ($3,052 vs. $4,082) and one year ($3,542 vs. $4,605).

The researchers noted that no differences were observed between patients who underwent CTA and those who underwent MPI SPECT for either myocardial infarction or CAD-related hospitalization in the year following their initial diagnostic imaging test.

“With the combination of the costs and clinical outcomes results, our analysis of actual practice patterns suggests that for individuals suspected of having CAD, multidetector CT is cost-efficient and infrequently results in additional downstream testing,” the authors wrote.