Clinician System Affiliation, Practice Size, and Medicare ACO Participation

Area of Science:

• Health Services Research
• Healthcare Policy
• Medical Economics

Background:

• Policymakers, including the Centers for Medicare and Medicaid Services (CMS), aim to increase provider engagement in accountable care organizations (ACOs).
• There is a specific interest in expanding ACO participation among smaller physician groups and independent providers.
• Understanding factors influencing ACO participation is crucial for effective policy design.

Purpose of the Study:

• To examine how practice size and health system affiliation influence clinician participation in ACOs.
• To quantify the potential impact of engaging different practice types on overall ACO participation rates.

Main Methods:

• Analysis of clinician-level participation data in ACOs.
• Stratification of participation rates based on practice size and health system affiliation.
• Modeling the impact of enrolling non-participating practices into ACOs.

Main Results:

• Clinicians in larger practices and those affiliated with health systems demonstrate higher rates of ACO participation.
• Engaging the largest 800 non-ACO practices could increase clinician participation by approximately 25 percentage points.
• Achieving similar participation gains would necessitate enrolling over 35,000 smaller practices.

Conclusions:

• Practice size and health system affiliation are key determinants of ACO participation.
• Prioritizing larger, system-affiliated practices for ACO engagement offers a more efficient strategy for increasing overall participation rates.
• Targeting smaller, independent practices for ACO enrollment yields comparatively smaller increases in clinician participation.