Practice Site Heterogeneity within and between Medicaid Accountable Care Organizations

Area of Science:

• Health Services Research
• Healthcare Policy
• Organizational Studies

Background:

• Existing research often treats Accountable Care Organizations (ACOs) as monolithic entities.
• This overlooks crucial variations in the characteristics and experiences of individual practice sites within ACOs.
• Understanding practice-level heterogeneity is vital for effective healthcare reform.

Purpose of the Study:

• To characterize heterogeneity in experience, capacity, and process at the practice site level within and between Medicaid ACOs.
• To analyze variations in process change, prior alternative payment model experience, and high-quality care delivery capacity.
• To inform future research and program design by accounting for practice site characteristics.

Main Methods:

• Observational cross-sectional study utilizing a 2019 survey of 225 administrators from Massachusetts Medicaid ACO practice sites.
• Quantified response clustering by practice site within 17 Medicaid ACOs.
• Employed multilevel logistic models, calculating median odds ratios (MORs) and intraclass correlation coefficients (ICCs) to assess variation.

Main Results:

• Greater heterogeneity was observed *within* ACOs compared to *between* ACOs across all measured variables.
• Intraclass correlation coefficients (ICCs) were consistently low (≤ 0.26), indicating significant practice site variation.
• Findings held true regardless of practice site or ACO characteristics.

Conclusions:

• Medicaid ACOs exhibit considerable diversity in practice site experience and capacity for implementing healthcare initiatives.
• Future accountable care organization research and policy design must explicitly consider the heterogeneity of constituent practice sites.
• Tailoring interventions to individual practice site needs within ACOs may improve reform success.