Economic Outcomes in the Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in Coronary Artery Disease Registry: The SPARC Study

Study Questions:

What are the economic outcomes of patients undergoing different noninvasive tests to evaluate suspected coronary artery disease (CAD)?

Methods:

The investigators used the SPARC (Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in Coronary Artery Disease) registry of 1,703 patients who underwent coronary computed tomography angiography (CTA; n = 590), positron emission tomography (PET; n = 548), or single-photon emission computed tomography (SPECT; n = 565) for diagnosis of suspected CAD at 1 of 41 centers. They followed patients for 2 years, and documented resource use, medical costs for CAD, and clinical outcomes. The authors used multivariable analysis and propensity score matching to control for differences in baseline characteristics.

Results:

Two-year costs were highest after PET ($6,647; 95% confidence interval [CI], $5,896-$7,397), intermediate after CTA ($4,909; CI, $4,378-$5,440), and lowest after SPECT ($3,965; CI, $3,520-$4,411). After multivariable adjustment, CTA costs were 15% higher than SPECT (p < 0.01), and PET costs were 22% higher than SPECT (p < 0.0001). Two-year mortality was 0.7% after CTA, 1.6% after SPECT, and 5.5% after PET. The incremental cost-effectiveness ratio for CTA compared with SPECT was $11,700 per life-year added, but was uncertain, with higher costs and higher mortality in 13% of bootstrap replications. Patients undergoing PET had higher costs and higher mortality than patients undergoing SPECT in 98% of bootstrap replications.

Conclusions:

The authors concluded that costs were significantly lower after using SPECT rather than CTA or PET in the evaluation of suspected CAD.

Perspective:

This observational study suggests that the choice of noninvasive tests to evaluate patients with suspected CAD affects subsequent medical costs, with the lowest costs over 2 years of follow-up among patients evaluated by SPECT. The significantly higher costs among patients undergoing CTA or PET were primarily due to higher rates of subsequent invasive cardiac procedures, as there was little difference in initial costs of testing. Furthermore, the higher costs among patients evaluated with CTA or PET do not appear to be explained by differences in baseline characteristics, as costs remained significantly higher even after adjustment. Additional prospective randomized studies are needed to compare the cost-effectiveness of alternative noninvasive testing approaches for patients with symptoms suggestive of CAD while acknowledging that the imaging field is a continuously evolving process that needs to consider technology development, test familiarity, and downstream testing and treatment.

Clinical Topics: Noninvasive Imaging, Computed Tomography, Nuclear Imaging

Keywords: Registries, Coronary Artery Disease, Propensity Score, Tomography, Emission-Computed, Single-Photon, Positron-Emission Tomography


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