Medicare Accountable Care Organizations of Diverse Structures Achieve Comparable Quality and Cost Performance

Abstract

Objective: To examine whether an empirically derived taxonomy of Accountable Care Organizations (ACOs) is associated with quality and spending performance among patients of ACOs in the Medicare Shared Savings Program (MSSP).

Data sources: Three waves of the National Survey of ACOs and corresponding publicly available Centers for Medicare & Medicaid Services performance data for NSACO respondents participating in the MSSP (N = 204); SK&A Office Based Physicians Database from QuintilesIMS.

Study design: We compare the performance of three ACO types (physician-led, integrated, and hybrid) for three domains: quality, spending, and likelihood of achieving savings. Sources of performance variation within and between ACO types are compared for each performance measure.

Principal findings: There is greater heterogeneity within ACO types than between ACO types. There were no consistent differences in quality by ACO type, nor were there differences in likelihood of achieving savings or overall spending per-person-year. There was evidence for higher spending on physician services for physician-led ACOs.

Conclusions: ACOs of diverse structures perform comparably on core MSSP quality and spending measures. CMS should maintain its flexibility and continue to support participation of diverse ACOs. Future research to identify modifiable organizational factors that account for performance variation within ACO types may provide insight as to how best to improve ACO performance based on organizational structure and ownership.

Keywords: Accountable Care Organizations; Medicare Shared Savings Program; cost of care; organizational structure; risk-based contracts.