Changes in Plan Composition and Measured Quality Associated with Medicaid Expansion Among Nonelderly Medicaid Managed Care Enrollees
Authors: Nguyen Kevin , Trivedi Amal 
Published: September 2021

Research ObjectiveMedicaid managed care (MMC) has become the dominant method of delivering health services for low‐income Americans enrolled in Medicaid. Following state decisions to extend Medicaid eligibility through the Affordable Care Act, MMC plans enrolled nearly 80% of newly eligible beneficiaries. Many states are adopting performance measurement systems to hold MMC plans accountable for quality of care. Despite the growing importance of measured quality of care in MMC payment and delivery, there is limited understanding of changes in MMC enrollee characteristics or performance measures associated with Medicaid expansion. We examined changes in plan composition among nonelderly MMC enrollees and measured quality of care associated with Medicaid expansion.Study DesignWe used 2012–2018 National Committee on Quality Assurance Adult Medicaid Consumer Assessment of Healthcare Providers and Systems (CAHPS) data, which are enrollee‐level surveys submitted by state Medicaid agencies and individual MMC plans. Enrollee characteristics included age, gender, race/ethnicity, educational attainment, and self‐reported health status. Our four outcomes measured patient experience of care: whether a respondent answered that it was “always or usually” easy to get needed care, had a personal doctor, had timely access to a checkup or routine care, and had timely access to specialty care. We estimated multivariable linear probability models comparing pre‐ versus post‐expansion changes in plan composition and measured quality in expansion versus non‐expansion states. The post‐expansion period was modeled as an event‐study regression to account for changes over time, where the coefficient of interest was a Medicaid expansion‐by‐year term. Models adjusted for sociodemographic characteristics, self‐reported health, and included state, year, and plan fixed effects. Standard errors were clustered at the state level.Population Studied315,563 adult MMC enrollees age 18–64 in the 39 states with comprehensive MMC plans.Principal FindingsMedicaid expansion was associated with statistically significant decreases in the proportion of female MMC enrollees (−8.4 percentage points [PP], p < 0.01), and increases in the proportion of MMC enrollees who were age 55–64 (6.8 PP, p < 0.01), White non‐Hispanic (4.4 PP, p < 0.01), and with a college degree or higher (2.3 PP, p < 0.01). Relative to MMC enrollees in non‐expansion states, enrollees in expansion states were significantly less likely to report access to a personal doctor (−1.6 PP, 95% CI ‐3.0 to −0.1 PP, p < 0.05) and less likely to report timely access to specialty care (−2.1 PP, 95% CI ‐3.4 to −0.8 PP, p < 0.01) in the first year after expansion. Differences were not statistically significant by the second year post‐expansion.ConclusionsMedicaid expansion was associated with substantial changes in MMC plan composition, and there were modest, but temporary, reductions in measured quality of care in the first year post‐expansion.Implications for Policy or PracticeStates use MMC performance data to assign bonus payments based on meeting or exceeding quality targets, withhold capitated payments, and auto‐assign enrollees to plans. State policymakers should recognize that expansions of Medicaid eligibility may change the composition of plan enrollees, with implications for measured quality of care. Particularly for states that compare a plan's performance on measured quality to national benchmarks, accounting for a state's decision to expand Medicaid may mitigate unfair penalization.