The Effects of State Medicaid Expansion on Low-Income Adult Residents' Access to Healthcare: Multi-Level Modeling

Background and Purpose: Under the Affordable Care Act (ACA), 25 states opted to expand state Medicaid coverage to nearly all low-income adults with income at or below 138% of the federal poverty level as of January 1, 2014 (roughly $33,000 for the family of four). This study aimed to examine how state Medicaid expansion affected insurance status and access to healthcare indicators among low-income state residents aged between 26 and 64 in 2014, the first year of ACA Medicaid expansion. Using multi-level modeling (individuals nested in states), this study compared low-income adult residents who lived in Medicaid expansion states vs. non-expansion states. Additionally, pre- and post-Medicaid expansion data (2012 vs. 2014) were compared.

Methods: The 2012 and 2014 Behavioral Risk Factor Surveillance System data were concatenated and linked to state-level data including Medicaid expansion status (as of January 1, 2014) and other state-level characteristics (e.g., unemployment rate) from the 2014 American Community Survey. The analysis included a nationally representative sample of 560,619 non-elderly adults (26-64) from 50 states and Washington, DC. Among them, 37% were low-income with family income below $35,000. The STATA SVY procedures were used for descriptive statistics. Mixed-effects logistic regression models were tested for four binary, individual-level outcomes (yes/no): (1) have health insurance coverage, (2) have a usual source of care, (3) could not see a doctor due to cost (past 12 months), and (4) visited a doctor for a routine checkup (past 12 months).

Results:  Overall, regardless of their income status, U.S. adults showed improvements from 2012 to 2014 in all four healthcare access indicators. However, the rate of improvement was greater among low-income residents living in the Medicaid expansion states. For example, the insured rate increased from 61.2% in 2012 to 73.70% in 2014 (20.44% increase) among low-income residents in the Medicaid expansion states, while the insured rate increased from 56.41% to 63.46% (13.02% increase) among their low-income counterparts in non-Medicaid expansion states. The final conditional multi-level models with low-income adults indicate that after controlling for individual- and state-level covariates, low-income U.S. adults residing in the Medicaid expansion states were more likely to have health insurance (Odds Ratio [OR]=2.03, p<.001) and have a usual source of care (OR=1.22, p=0.035), and were less likely to not see a doctor due to cost (OR=0.75, p<.001) compared to low-income residents in the non-expansion states.     

Implications. This study clearly demonstrates that state-level Medicaid expansion improved healthcare access among low-income state residents. Fortunately, more states have joined other Medicaid expansion states since its implementation. However, as of January 2016, 19 states have not expanded Medicaid for their low-income residents. Considering the fact that the timely access to adequate healthcare can save healthcare expenditures in the long run, policymakers should examine potential impacts of healthcare disparities among low-income adults living in the non-expansion states. Furthermore, given that about one in four low-income adults were still uninsured in 2014 even among those who lived in the Medicaid-expansion states, stronger outreach efforts are necessary.