Geographic variation in cardiovascular procedure use among Medicare fee-for-service vs Medicare Advantage beneficiaries

Abstract

Importance: Little is known about how different financial incentives between Medicare Advantage and Medicare fee-for-service (FFS) reimbursement structures influence use of cardiovascular procedures.

Objective: To compare regional cardiovascular procedure rates between Medicare Advantage and Medicare FFS beneficiaries.

Design, setting, and participants: Cross-sectional study of Medicare beneficiaries older than 65 years between 2003-2007 comparing rates of coronary angiography, percutaneous coronary intervention (PCI), and coronary artery bypass graft (CABG) surgery across 32 hospital referral regions in 12 states.

Main outcomes and measures: Rates of coronary angiography, PCI, and CABG surgery.

Results: We evaluated a total of 878,339 Medicare Advantage patients and 5,013,650 Medicare FFS patients. Compared with Medicare FFS patients, Medicare Advantage patients had lower age-, sex-, race-, and income-adjusted procedure rates per 1000 person-years for angiography (16.5 [95% CI, 14.8-18.2] vs 25.9 [95% CI, 24.0-27.9]; P < .001) and PCI (6.8 [95% CI, 6.0-7.6] vs 9.8 [95% CI, 9.0-10.6]; P < .001) but similar rates for CABG surgery (3.1 [95% CI, 2.8-3.5] vs 3.4 [95% CI, 3.1-3.7]; P = .33). There were no significant differences between Medicare Advantage and Medicare FFS patients in the rates per 1000 person-years of urgent angiography (3.9 [95% CI, 3.6-4.2] vs 4.3 [95% CI, 4.0-4.6]; P = .24) or PCI (2.4 [95% CI, 2.2-2.7] vs 2.7 [95% CI, 2.5-2.9]; P = .16). Procedure rates varied widely across hospital referral regions among Medicare Advantage and Medicare FFS patients. For angiography, the rates per 1000 person-years ranged from 9.8 to 40.6 for Medicare Advantage beneficiaries and from 15.7 to 44.3 for Medicare FFS beneficiaries. For PCI, the rates ranged from 3.5 to 16.8 for Medicare Advantage and from 4.7 to 16.1 for Medicare FFS. The rates for CABG surgery ranged from 1.5 to 6.1 for Medicare Advantage and from 2.5 to 6.0 for Medicare FFS. Across regions, we found no statistically significant correlation between Medicare Advantage and Medicare FFS beneficiary utilization for angiography (Spearman r = 0.19, P = .29) and modest correlations for PCI (Spearman r = 0.33, P = .06) and CABG surgery (Spearman r = 0.35, P = .05). Among Medicare Advantage beneficiaries, adjustment for additional cardiac risk factors had little influence on procedure rates.

Conclusions and relevance: Although Medicare beneficiaries enrolled in capitated Medicare Advantage programs had lower angiography and PCI procedure rates than those enrolled in Medicare FFS, the degree of geographic variation in procedure rates was substantial among Medicare Advantage beneficiaries and was similar in magnitude to that observed among Medicare FFS beneficiaries.

Figure 1

A Comparison of Cardiovascular Procedure Rates Between Beneficiaries Served by Health Plans Within the Cardiovascular Research Network and Beneficiaries with Fee-For-Service Reimbursement Plans. PCI – Percutaneous Coronary Intervention; CABG – Coronary Artery Bypass Grafting

Figure 2

Figure 2a–c. Comparison of the average a) angiography; b) PCI; and c) CABG age, gender, and race adjusted rates per 1000 person-years between Medicare Advantage beneficiaries and Medicare Fee-for-service beneficiaries from 2003–2007 across the hospital referral regions. PCI – Percutaneous Coronary Intervention; CABG – Coronary Artery Bypass Grafting

Figure 3

Figure 3a–c. The comparison of rates adjusted for age, sex, and race with rates additionally adjusted for presence of diabetes, hypertension, hyperlipidemia, and prior coronary artery disease within the Medicare Advantage population across the hospital referral regions. PCI – Percutaneous Coronary Intervention; CABG – Coronary Artery Bypass Grafting