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Association of Coronary CT Angiography or Stress Testing With Subsequent Utilization and Spending Among Medicare Beneficiaries
Study Questions:
What is the utilization and spending associated with functional (stress testing) and anatomical (cardiac computed tomography angiography [CCTA]) noninvasive cardiac testing in a Medicare population?
Methods:
This was a retrospective, observational cohort study using claims data from a 20% random sample of 2005-2008 Medicare fee-for-service beneficiaries 66 years or older with no claims for coronary artery disease (CAD) in the preceding year, who received nonemergent, noninvasive testing for CAD (n = 282,830). The main outcome measures were rates of cardiac catheterization, coronary revascularization, acute myocardial infarction, all-cause mortality, and total and CAD-related Medicare spending over 180 days of follow-up. To examine the relationship between the index test and subsequent health care expenditures, which are right-skewed in distribution, a generalized linear model with a log link and gamma distribution specified for the error term was used.
Results:
Compared with stress myocardial perfusion scintigraphy (MPS), CCTA was associated with an increased likelihood of subsequent cardiac catheterization (22.9% vs. 12.1%; adjusted odds ratio [AOR], 2.19; 95% confidence interval [CI], 2.08-2.32; p < 0.001), percutaneous coronary intervention (7.8% vs. 3.4%; AOR, 2.49; 95% CI, 2.28-2.72; p < 0.001), and coronary artery bypass graft surgery (CABG) (3.7% vs. 1.3%; AOR, 3.00; 95% CI, 2.63-3.41; p < 0.001). CCTA was also associated with higher total health care spending ($4,200 [$3,193-$5,267]; p < 0.001), which was almost entirely attributable to payments for any claims for CAD ($4,007 [$3,256-$4,835]; p < 0.001). Compared with MPS, there was lower associated spending with stress echocardiography (−$4,981 [−$4,991 to −$4,969]; p < 0.001) and exercise electrocardiography (−$7,449 [−$7,452 to −$7,444]; p < 0.001). At 180 days, CCTA was associated with a similar likelihood of all-cause mortality (1.05% vs. 1.28%; AOR, 1.11; 95% CI, 0.88-1.38; p = 0.32) and a slightly lower likelihood of hospitalization for acute myocardial infarction (0.19% vs. 0.43%; AOR, 0.60; 95% CI, 0.37-0.98; p = 0.04).
Conclusions:
The authors concluded that Medicare beneficiaries who underwent CCTA in a nonacute setting were more likely to undergo subsequent invasive cardiac procedures and have higher CAD-related spending than patients who underwent stress testing.
Perspective:
This study suggests that patients who undergo CCTA frequently undergo additional cardiac testing, particularly cardiac catheterization, and subsequent coronary revascularization with percutaneous coronary intervention or CABG. In fact, the rate of use of invasive procedures after CCTA was more than double the rate after stress testing, even after adjustment for potential confounding factors. This higher use of invasive procedures after CCTA then leads to substantially higher spending for medical care at 180 days. The data highlight the need for studies to critically appraise the use of CCTA in clinical practice, including appropriateness, rationale for additional downstream testing/procedures, and subsequent outcomes.
Keywords: Myocardial Perfusion Imaging, Odds Ratio, Coronary Artery Disease, Myocardial Infarction, Follow-Up Studies, Fee-for-Service Plans, Cardiac Catheterization, Electrocardiography, Percutaneous Coronary Intervention, Coronary Angiography, Tomography, Confidence Intervals, Medicare, Coronary Artery Bypass, United States, Linear Models, Echocardiography, Exercise Test
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