Cost-Effective Imaging: What Parameters Determine Value?

Value-Based Care in Cardiometabolic Health May 2012, Vol 1, No 1
Mary Mosley

Chicago, IL—The rapid growth of medical imaging in cardiovascular (CV) medicine, as well as downward pressure on reimbursement have brought an increased focus on cost and the need to show cost-effectiveness.

at a rate of 13% to 22% annually, according to a US Government Accountability Office and Medicare Payment Advisory Commission study, compared with 9% annually for other physician services, stated Rita F. Redberg, MD, MSc, FACC, Professor of Medicine and Director, Women’s Cardiovascular Services, Division of Cardiology, University of California, San Francisco Medical Center, in a session at the 2012 American College of Cardiology (ACC) meeting. Healthcare spending is projected to double to $4.1 trillion by 2016, an estimated 20% of the US gross domestic product, and an increase from 16% in 2012.

Yet, how to define value and cost-effectiveness for medical imaging is “not straightforward,” said Rory Hachamovitch, MD, MSc, FACC, Section of Cardiovascular Imaging, Department of Cardiovascular Medicine, Cleveland Clinic, OH. The nature of imaging makes determining its costeffectiveness complex, in part because of its relation to outcomes—the usual denominator in cost-effectiveness equations—that can be indirect, and its unclear metric. Change in subsequent treatment may be the best end point, stated Dr Hachamovitch. Data for costeffectiveness of CV medical imaging are in their infancy. Little prospective data are available, although ongoing studies may soon start to provide the necessary evidence.

“Imaging provides an immediate result and information that may be used to avoid or implement a treatment strategy,” said Dr Redberg. She noted that the bar is higher for the cost-effectiveness of diagnostic testing, because it does not translate directly to outcomes.

“We must consider how the information will change management, and how change in management will lead to change in outcomes, and whether that same end point could be achieved without doing the test,” Dr Redberg said.

Historically, diagnostic end points, such as coronary anatomy or presence or absence of disease, have been used, but this is shifting to prognostic or outcomes- based end points. Net reclassification improvement (NRI), that is, “what is the net gain in reclassifying patient risk status with the addition of data, with the notion that this optimally enhances subsequent patient management,” is now a popular metric to show the value of an imaging test.

One application of the NRI metric was shown by Shaw and colleagues in a study of more than 4500 patients who were prospectively enrolled in a multicenter registry (JACC CV Imaging. 2010;3:1139-1148). A weighted multivariable model of prognostically important information from nuclear studies and treadmill score data showed that NRI was approximately 3 times greater with nuclear studies, but the cost was nearly 40 times greater (both compared with a treadmill exercise test). The cost-effectiveness ratio, calculated as cost per NRI, was approximately $60 per exercise test and more than $600 for nuclear imaging, Dr Hachamovitch said. The challenge is, “what is a clinically meaningful effect in terms of diagnosis?”

The results of imaging tests must be used to drive subsequent treatment for it to be cost-effective and clinically relevant. A study by Ling and colleagues (J Am Coll Cardiol. 2012;59:E2143) presented at the 2012 ACC Fellowship Young Investigators Award session illustrated the concept of the “interface between what is seen on the test and what is best for the patient to achieve benefit,” said Dr Hachamovitch.

In this single-site study of 661 patients (average 30% ejection fraction, 34% abnormal myocardium) who underwent stress/rest positron emission tomography with fluorodeoxyglucose imaging, complete revascularization compared with medical therapy was associated with improved survival, whereas incomplete revascularization increased risk.

Other issues for determining valuebased cost-effectiveness of imaging include downstream costs resulting from information obtained from imaging; false-positives that may lead to more tests or unnecessary treatment; direct costs for performing and interpreting a test; indirect costs, such as those incurred as a consequence of medical care (eg, loss of work time); temporal changes (short-term vs long-term); and variations in cost by geography and payer.

Cost-effectiveness—a comparison of 2 alternative treatments on outcomes— is a method to obtain better value for healthcare dollars spent. In general, cost-effectiveness studies in the United States use a cut-off of $50,000 per quality-adjusted life-year saved; below that figure a new technology or treatment is considered to be cost-effective. In imaging, this is most often the comparison of one imaging modality against another.

Dr Hachamovitch stated that costeffectiveness data need to be defined for CV imaging tests.

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Last modified: July 16, 2012
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