The Medicaid expansion did not crowd out access for medicaid recipients with disabilities in Oregon.

Background: The Affordable Care Act (ACA) substantially increased the number of Medicaid enrollees, which could have reduced access to health care services for those already on Medicaid before the expansion.

Objective: To examine the association of the ACA expansion on health care access and utilization for adults ages 18-64 years who have qualified for Supplemental Security Income (SSI) in Oregon.

Methods: We used Oregon Medicaid claims and enrollment data from 2012 to 2015 and information from the American Community Survey and the Local Area Unemployment Statistics. Multivariate regressions compared changes in health care access and utilization before and after the expansion among Medicaid recipients who qualified for SSI across counties in Oregon with higher and lower Medicaid enrollment increases due to the expansion. Health care access and utilization outcome measures included: primary care visits, non-behavioral health outpatient visits, behavioral health outpatient visits, emergency department (ED) visits and potentially avoidable ED visits.

Results: The Medicaid expansion led to an uneven increase in Medicaid enrollment across Oregon's counties (mean increase from the first quarter of 2012 to the third quarter of 2015: 12.4% points; range: 7.3 to 18.6% points). Access and utilization outcomes for SSI Medicaid recipients were mostly unaffected by differential enrollment increases. ED visits increased more in counties with a larger Medicaid enrollment increase (estimate: 1.8, p < 0.05), but adjusting for pre-expansion trends eliminated this association.

Conclusions: We did not find evidence that an increase in Medicaid enrollment due to the ACA negatively impacted access and utilization for adult Medicaid recipients on SSI, who were eligible for Medicaid prior to expansion.