Impact of state Medicaid expansion on cross-sector health and social service networks: Evidence from a longitudinal cohort study

Objective: To examine the impact of state Medicaid expansion on the delivery of population health activities in cross-sector health and social services networks. Community networks are multisector, interorganizational networks that provide services ranging from the direct provision of individual social services to the implementation of population-level initiatives addressing community outcomes. Data Sources: We used data measuring the composition of cross-sector population health networks 2006–2018 National Longitudinal Survey of Public Health Systems (NALSYS) linked with the Area Health Resource File. Study Design: A difference-in-differences approach was used to examine the impact of expansion on organization engagement in population health activities and network structure. Data Collection/Extraction Methods: Stratified random sampling of local public health jurisdictions in the United States. We restricted our data to jurisdictions serving populations of 100,000 or more and states that had NALSYS observations across all time periods, resulting in a final sample size of 667. Principal Findings: Results from our adjusted difference-in-differences estimates indicated that Medicaid expansion was associated with a 2.3 percentage point increase in the density of population health networks (p < 0.10). Communities in states that expanded Medicaid experienced significant increases in the participation of local public health, local government, hospital, nonprofit, insurer, and K-12 schools. Of the organizations with significant increases in expansion communities, nonprofits (7.7 percentage points, p < 0.01), local public health agencies (6.5 percentage points, p < 0.01), hospitals (5.8 percentage points, p < 0.01), and local government agencies (6.0 percentage points, p < 0.05) had the largest gains. Conclusions: Our study found increases in cross-sector participation in population health networks in states that expanded Medicaid compared with nonexpansion states, suggesting that additional coverage gains are associated with positive changes in population health network structure.