Medicare beneficiaries enrolled in the Medicare Advantage programs have lower rates of angiography and percutaneous coronary intervention procedures than do those enrolled in fee-for-service Medicare, but procedure rates in both groups vary widely by geographic region, according to findings from a large cross-sectional study.
Compared with more than 5 million Medicare fee-for-service patients from across 32 hospital referral regions in 12 states, the more than 878,000 Medicare Advantage patients included in the study had lower age-, sex-, race-, and income-adjusted angiography procedure rates (16.5 vs. 25.9 per 1,000 person-years) and percutaneous coronary intervention (PCI) procedure rates (6.8 vs. 9.8). The differences persisted after adjusting for additional cardiac risk factors in the Medicare Advantage beneficiaries, Dr. Daniel D. Matlock of the University of Colorado, Aurora, and his colleagues reported July 9 in JAMA.
The rates of coronary artery bypass graft (CABG) surgery were similar in the two groups (3.1 vs. 3.4), as were the rates of urgent angiography and PCI (3.9 vs. 4.3, and 2.4 vs. 2.7, respectively), the investigators reported (JAMA 2013;310:155-62).
In addition to the variations in procedure rates by Medicare plan type, wide variations in procedure rates were also noted across hospital referral regions. For example, angiography rates per 1,000 person-years ranged from 9.8 to 40.6 for Medicare Advantage beneficiaries, and from 15.7 to 44.3 for Medicare fee-for-service beneficiaries; the PCI rates ranged from 3.5 to 16.8 and from 4.7 to 16.1 for the groups, respectively; and the rates for CABG surgery ranged from 1.5 to 6.1, and from 2.5 to 6.0 for the groups, respectively. The degree of variation was similar in the two groups, , the investigators noted.
No significant correlation was seen between the Medicare Advantage and fee-for-service beneficiaries for angiography across the regions, and only modest correlations were seen for PCI and CABG surgery, they said.
"The finding that Medicare Advantage patients have lower rates of angiography and PCI underscores the need for additional research to determine the extent to which this is attributable to differences in population characteristics, more efficient utilization of procedures among Medicare Advantage patients (i.e., overutilization in Medicare FFS), or harmfully restrictive management of utilization in Medicare Advantage," the investigators wrote.
The similarities in the degree of regional variations in the two groups suggest that "factors beyond payment mechanisms influence practice variations," they noted, adding that the variation in this study may be a function of the availability of the procedures – a possibility that they argued deserves further study, along with patient-level factors and "implicit professional norms or the local practice culture."
The investigators point out that "geographic variation in health services in the Medicare fee-for-service population has fueled the perception of an inefficient, ineffective U.S. health care system," and they argue that shedding light on the sources of variability will, therefore, remain an important "research and quality improvement endeavor" until the causes of geographic variation are understood.
The study was supported by the National Heart, Lung, and Blood Institute and the Cardiovascular Research Network. Medicare data were obtained under an Agency for Healthcare Research and Quality grant.