Evaluating the dental care access impacts of the Affordable Care Act’s (ACA) Medicaid expansion and the Supplemental Nutrition Assistance Program (SNAP) among low-income adults in the U.S

Medicaid and Supplemental Nutrition Assistance Program (SNAP) are two large-scale safety net programs in the U.S. that provide public assistance to the low-income population. Over the years both programs have undergone several policy changes and have evolved to cover more needy individuals. This three-paper dissertation is a culmination of three research studies, two of which examine the effect of the Affordable Care Act’s (ACA) Medicaid expansion on outcomes of realized access to dental care i.e., dental visits and out-of-pocket dental care spending, respectively, while the third paper explores the relationship between SNAP participation and dental visits (realized access), and between SNAP participation and unmet dental care need due to cost (perceived access).
The few studies that have examined the impact of the Medicaid expansion on dental visits utilization have shown somewhat mixed findings and are mostly limited to examining early impacts (1-2 years post-expansion). Thus, Study I of this dissertation examined the longer-term impacts of states’ Medicaid expansions on dental visits utilization, by their adult dental benefits coverage level. Restricted data from the Medical Expenditure Panel Survey (MEPS) for the years 2011 through 2017 were obtained; the sample included adults aged 21-64 years with income up to 138% of Federal Poverty Level. A quasi-experimental Difference-In-Difference (DID) study design was used to examine the overall and year-by-year impacts of the Medicaid expansion on annual dental visits based on a states’ adult dental benefits coverage level (i.e., extensive, limited, and emergency-only/no benefits). Overall, expansion states, compared to non-expansion states, saw a 3-6 percentage point increase in annual dental visits in the post-expansion period (2014-2017), relative to the pre-expansion period (2011-2013). Year-by-year examinations revealed that the Medicaid expansion was associated with a significant increase in the likelihood of an annual dental visit among low-income adults in states with extensive benefits in 2014 (nearly 5 percentage points), and in states with limited and emergency-only/no dental benefits in both 2014 (6 percentage points for both) and 2016 (4 and 5 percentage points, respectively).
Expanding Medicaid also has the potential to reduce out-of-pocket dental care spending among low-income adults gaining coverage through Medicaid, especially among states that provide comprehensive adult dental benefits. Thus, Study II of this dissertation examined the impact of states’ Medicaid expansion on out-of-pocket dental care spending among low-income adults residing in states that provided extensive adult dental benefits. A DID study design with a two-part (hurdle) modeling approach was utilized to analyze post-expansion year-by-year changes in: a) the probability of incurring any out-of-pocket dental spending, and b) the amount of out-of-pocket spending (conditional on any spending) between expansion states with extensive benefits and non-expansion states. Overall, a greater proportion of adults in expansion states with extensive dental benefits (58%) reported zero dollars in out-of-pocket dental care spending, compared to those in non-expansion states (31%). Our DID analysis found that, compared to non-expansion states, adults residing in states that provided extensive adult dental benefits and expanded Medicaid were significantly less likely to incur any out-of-pocket dental spending in the first two years of implementing the expansion (2014 and 2015).
There is growing interest in examining SNAP’s spillover impacts on improving healthcare access and outcomes, postulated to be due to SNAP’s ability to reduce food-insecurity thereby potentially freeing up some financial and cognitive resources to seek care. Thus, Study 3 of this dissertation examined the association between participation in SNAP and realized and perceived access to dental care among low-income adults. A sample of SNAP income-eligible adults aged 19-64 was created by pooling MEPS data for the years 2011 to 2017. Applying a propensity score method to control for important differences in characteristics between participants and eligible non-participants, and using a Doubly-Robust approach, multivariable logistic regressions modelling the impact of SNAP participation on annual dental visits and unmet dental care need due to cost were performed. Interestingly, we found that SNAP participants, compared to eligible non-participants, have significantly lower odds of having an annual dental visit (approximately 20%) and significantly greater odds of reporting unmet dental care need due to cost (approximately 40%).
In conclusion, the results of the three studies in this dissertation provide some important insights into the dental care access impacts of the ACA’s Medicaid expansion and provide foundational evidence on the relationship between participation in the Supplemental Nutrition Assistance Program and dental care access among low-income adults. Results from Study I are suggestive of a positive link between the expansion of Medicaid and increased dental visits. However, longer-term impacts were less consistent and varied based on states’ adult dental coverage level thereby warranting further research. Study II results are encouraging and show that providing comprehensive dental benefits in Medicaid adult dental programs is protective against incurring any out-of-pocket expense for those who utilize dental care, with the potential to benefit more low-income individuals when these states expand Medicaid eligibility. Lastly, Study III results show that SNAP participation is associated with lower dental visits utilization and greater unmet dental care need due to cost. While we postulate that this may be due to several reasons, such as, SNAP benefits not being enough to offset non-food costs, and perhaps, the most disadvantaged of all SNAP-eligible families who tend to have fewer resources being more likely to enroll in the program, further research is needed to fully investigate and understand the underlying causal mechanisms through which these associations operate.