JAMA: CCTA in nonacute settings increases expenditures
Cardiac CT - 1.51 Mb
MRI (left) and CT (right) coronary angiography. Source: J Am Coll Cardiol Img, 2011; 4:50-61.
Medicare beneficiaries who underwent coronary CT angiography (CCTA) in nonacute settings had a higher likelihood of undergoing subsequent invasive cardiac procedures and have increased coronary artery disease (CAD) spending compared with patients who underwent stress testing, according to a study published March 7 in the Journal of the American Medical Association. In response, several researchers submitted letters supporting and challenging the author’s findings.

For the study, Jacqueline Baras Shreibati, MD, of Stanford University School of Medicine in Stanford, Calif., and colleagues compared utilization and spending rates associated with stress testing and CCTA noninvasive cardiac testing in a Medicare population.

The authors evaluated claims data from a random sample of 2005-2008 Medicare fee-for-service beneficiaries who were 66 years or older, had no claims for CAD in the previous year and received non-emergent, noninvasive testing for CAD; 282,830 patients were identified.

Shreibati et al assessed cardiac catheterization, revascularization, acute MI, all-cause mortality and total and CAD-related Medicare spending over 180 days of follow-up. Of the cohort, patients had a median age of 73.6, 46 percent were men and 89 percent were white.

Myocardial perfusion scintigraphy (MPS) imaging was the most frequently used diagnostic test (46.8 percent), followed by stress echo (28.5 percent), ECG (21.6 percent) and CCTA (3.1 percent).

The researchers found patients who underwent CCTA had lower mean spending compared with patients who underwent MPS, $10,894 vs. $11,616, respectively. However, these patients had a higher mean spending when compared with patients who underwent stress echo or exercise ECG, $8,636 and $7,467, respectively.

It was also noted that 7.4 percent of patients underwent additional noninvasive testing, 11.1 percent underwent cardiac catheterization, 4.6 percent underwent coronary revascularization (3.1 percent underwent PCI and 1.6 percent underwent CABG), 0.37 percent were hospitalized for acute MI and 1.1 percent died. Also, it was found that additional noninvasive testing was performed more often after CCTA compared with MPS.

“Patients who underwent CCTA were nearly twice as likely to undergo subsequent cardiac catheterization as patients who underwent MPS and roughly 2.5 times as likely to undergo coronary revascularization,” the authors wrote.

CCTA was linked to higher total healthcare spending, which the authors found to be mostly attributed to payments for any CAD claims. The authors found that patients undergoing CCTA had "nearly 50 percent higher CAD-related expenditures than patients undergoing MPS. There was lower spending associated with stress echo and exercise electrocardiography when compared to MPS. CCTA also was associated with a lower rate of all-cause mortality and a lower likelihood of hospitalization for acute MI.

“This higher use of invasive procedures after CCTA appears to have led in turn to substantially higher spending for medical care at 180 days,” the authors wrote.

While the authors said that a normal CCTA result may reduce the need for further testing, they said that an inconclusive or positive CCTA could lead to additional functional testing, invasive angiography, or both.

“The net effect of CCTA on subsequent cardiac testing is therefore uncertain and may either increase or decrease use of such testing, depending on the patient population and the practice patterns of physicians,” Shreibati wrote.

“The increased use of invasive procedures and the higher spending on care after CCTA documented in this study suggest that clinicians and policy makers should critically evaluate the use of CCTA in clinical practice, based on studies of subsequent outcomes,” the authors summed.

In a research letter, Joseph A. Ladapo, MD, PhD, of the New York University School of Medicine in New York City, and Pamela Douglas, MD, of the Duke University Medical Center in Durham, N.C., wrote that Shreibati and colleagues “placed too little emphasis on the potential for an unmeasured difference in sensitivity between the two approaches [stress testing and CCTA].”

“Because patients with positive stress test results are more likely to undergo follow-up cardiac catheterization, the sensitivity and specificity derived from a population selected for angiographic confirmation are overestimated and underestimated, respectively,” Ladapo and Douglas wrote. While the authors said that CCTA studies could have the potential to be linked to the same bias, it may be to a lesser degree, as the test is usually performed as an adjunct study and results may not drive the decision to perform cardiac catheterization.

“This difference may play a role in explaining the higher rates of cardiac catheterization, percutaneous coronary intervention, and coronary artery bypass graft surgery seen in patients evaluated by CCTA; indeed, these higher rates are expected in any population with a high pretest probability of CHD [coronary heart disease] being evaluated with a more sensitive test,” Ladapo and Douglas summed.

In an additional letter, Ron Blankenstein, MD, and Udo Hoffmann, MD, MPH, of Brigham and Women’s Hospital and Massachusetts General Hospital in Boston, respectively, said that the current study by Shreibati et al has two very important limitations.

They went on to say that the strength of CCTA lies in its high negative predictive value and ability to rule out significant stenosis among CAD patients. Additionally, they said that older age is the most important factor in the prevalence of CAD and said that older patients may have increased testing and subsequent testing because they may have coronary artery calcification that is linked to nondiagnostic or false-positive exams.

“Thus, it has been suggested that the most efficient use of CCTA (defined as a significant change in post-test probability for both a negative and a positive examination) is in men younger than 55 years and women older than 65 years,” Blankenstein and Hoffmann wrote. However, the mean age of the current study was 74 years.

They cited as a second limitation the fact that this study used a study cohort between 2005 and 2008, but it wasn't until 2010 that codes went into effect for CCTA. The authors said that the timing of the study was “premature.”

In response, Shreibati et al wrote, “We would contend, however, that the ultimate measure of the value of CCTA will be its effect on clinical outcomes, not its sensitivity or specificity.” And while Shreibati and colleagues agreed that younger patients may be better candidates for CCTA, as Blankenstein and Hoffmann suggested, they said that older patients have and will continue to receive these types of tests.