Medicaid Expansion and Health Plan Quality in Medicaid Managed Care.

Objective: To assess the effect of the 2014 Medicaid expansion on Medicaid managed care plan quality.

Data Sources: Three composite measures of plan-level quality constructed from the Health Care Effectiveness Data and Information Set.

Study Setting: One hundred and sixty-three plans in 27 Medicaid expansion states and 100 plans in 14 nonexpansion states.

Study Design: Quasi-experimental difference-in-differences (DID) analysis, comparing quality before (2011-13) and after (2014-15) Medicaid expansion in states that elected to expand Medicaid eligibility and those that did not.

Principal Findings: Mean plan enrollment increased from 130,533 to 274,259 in expansion states and from 105,449 to 148,194 in nonexpansion states. The proportion of enrollees receiving recommended preventive care increased from 62.6 to 65.2 percent in expansion states and from 59.3 to 62.5 percent in nonexpansion states (adjusted DID: -0.7 percentage points [95% CI -2.2, 0.7]). The proportion of enrollees receiving recommended chronic disease care management increased from 65.4 to 66.0 percent in expansion states and from 62.5 to 63.1 percent in nonexpansion states (adjusted DID: 1.1 percentage points [95% CI -0.5, 2.6]). We observed similar patterns for the receipt of recommended maternity care.

Conclusions: Medicaid expansion increased enrollment in managed care plans, but it did not result in erosion of quality.