Geographic Variation in Cardiovascular Procedure Use Among Medicare Fee-for-Service vs Medicare Advantage Beneficiaries

Study Questions:

The extent to which different payment models influence observed geographic variation in the use of invasive cardiac procedures is unknown. How do different financial incentives between Medicare Advantage (i.e., managed care plan for Medicare) and Medicare fee-for-service (FFS) reimbursement influence use of invasive cardiac procedures like coronary angiography and percutaneous coronary intervention (PCI)?


These authors used a cross-sectional study of Medicare beneficiaries older than 65 years between 2003-2007. They compared population-based rates of coronary angiography, PCI, and coronary artery bypass grafting (CABG) between Medicare Advantage and Medicare FFS patients.


A total of 878,339 Medicare Advantage patients and 5,013,650 Medicare FFS patients were identified. Compared with Medicare FFS patients, Medicare Advantage patients had lower age-, sex-, race-, and income-adjusted procedure rates per 1,000 person-years for coronary angiography (16.5 [95% confidence interval (CI), 14.8-18.2] vs. 25.9 [95% CI, 24.0-27.9]; p < 0.001) and PCI (6.8 [95% CI, 6.0-7.6] vs. 9.8 [95% CI, 9.0-10.6]; p < 0.001), but similar rates for CABG (3.1 [95% CI, 2.8-3.5] vs. 3.4 [95% CI, 3.1-3.7]; p = 0.33). There were no significant differences between Medicare Advantage and Medicare FFS patients in the rates for “urgent” angiography done in the setting of an acute myocardial infarction hospitalization. Most importantly, rates varied widely across regions among both Medicare Advantage and Medicare FFS patients, and there was only modest statistical correlation between rates in Medicare Advantage and Medicare FFS patients.


The authors concluded: “The degree of geographic variation in procedure rates was substantial among Medicare Advantage beneficiaries” and similar Medicare FFS beneficiaries.


As the Affordable Care Act begins its early implementation phases in the next year, additional research on the effects of different payment models on health care delivery becomes crucial. Substantial geographic variation in use of invasive cardiac procedures like PCI and CABG has been a long-standing observation in health services research. This has led to the perception that financial incentives may push providers to do more in these cases—although surprisingly little empiric evidence is available on how payment models within managed care plans specifically result in this variation. Thus, the current paper by Matlock and colleagues is timely. Their observations suggest that existing managed care plans may lower rates of use for these services, but not be sufficient for diminishing geographic variation. These findings need to be balanced against the fact that no one still knows ‘what rate is right.’ Additional limitations in the current study include that the authors were unable to account for procedural appropriateness and patient preferences or any potential outcome differences that may have resulted from these differences in use. Regardless, these findings are important and should spur further research on optimizing financial incentives.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Aortic Surgery, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Myocardial Infarction, Medicare Part C, Coronary Angiography, Delivery of Health Care, Health Services Research, Coronary Artery Bypass, Angioplasty, Balloon, Coronary, Health Maintenance Organizations, United States, Percutaneous Coronary Intervention

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