Absence of conflict of interest.
Citation
Highlights
- The study's objective was to examine the impact of the Affordable Care Act (ACA) Medicaid expansion among documented agricultural workers on health insurance coverage; employer-paid health insurance coverage; government-sponsored health insurance coverage; employment; and public benefits receipt.
- The authors used a difference-in-differences design to estimate the impacts of ACA Medicaid expansion on health insurance coverage and other outcomes using individual worker data from the National Agricultural Workers Survey (NAWS), a nationally representative survey of hired crop workers that includes information about the demographic, employment, and health characteristics of these workers. The authors used a statistical model to compare health insurance coverage and other outcomes over time for documented farm workers in states that did and did not expand Medicaid in 2014.
- The study’s findings suggested that Medicaid expansion was associated with higher rates of health insurance coverage among documented farm workers.
- This study receives a low evidence rating. This means we are not confident that the estimated effects are attributable to Affordable Care Act (ACA) Medicaid expansion; other factors are likely to have contributed.
Intervention Examined
Affordable Care Act (ACA) Medicaid Expansion
Features of the Intervention
As enacted in 2010, the ACA included provisions that would expand Medicaid eligibility to all adults with incomes within 138% of the federal poverty level, beginning in 2014. In 2012, the U.S. Supreme Court ruled that states could opt out of the ACA Medicaid expansion and continue to use pre-existing Medicaid eligibility requirements. Approximately half of all states opted to expand Medicaid eligibility in 2014. Several additional states opted to expand Medicaid eligibility in subsequent years.
Prior to the ACA, Medicaid eligibility was more restrictive, with individuals needing to meet more restrictive means testing and belong to a Medicaid-eligible demographic group, such as parents or individuals with disabilities.
Features of the Study
The study used a difference-in-differences design to estimate the impacts of ACA Medicaid expansion on health insurance coverage and other outcomes for documented farm workers.
The study used individual worker data from the National Agricultural Workers Survey (NAWS), a nationally representative survey of hired crop workers. The NAWS uses a repeated independent annual cross-section design to sample documented farm workers. Workers sampled for the NAWS were surveyed three times a year through face-to-face interviews. The study analyzed data from 2007 through 2016, before and after the ACA Medicaid expansions in 2014.
The study sample included 9,950 documented farm workers in the United States. One quarter of the workers were female, 53.4% were married, and 44.9% were foreign-born. The average age of farm workers was about 38 years old. On average, the sample received 9.4 years of schooling and the annual family income was $27,443. The treatment group consisted of documented farm workers in states that implemented the ACA Medicaid expansion in 2014. The comparison group consisted of documented farm workers in states that did not implement the ACA Medicaid expansion in 2014 as well as documented farm workers in a few states that expanded in 2014 but had already implemented a prior comprehensive Medicaid expansion.
The authors used a statistical model to compare health insurance coverage over time for documented farm workers in states that did and did not expand Medicaid in 2014. The analysis used a difference-in-differences model that included state-fixed effects and year-fixed effects and controlled for select individual-level demographic and employment characteristics.
Findings
Public Benefits Receipt
- Study findings suggested that states that expanded Medicaid in 2014 experienced larger increases in overall health insurance coverage among documented farm workers than states that did not expand Medicaid.
- Study findings suggested that states that expanded Medicaid in 2014 experienced larger increases in government-sponsored health insurance coverage among documented farm workers than states that did not expand Medicaid.
- Study findings provided some evidence that Medicaid expansion was associated with increases in the receipt of other public benefits. States that expanded Medicaid in 2014 experienced larger increases in the share of documented workers who reported receiving TANF benefits. However, there was no evidence of a statistically significant association between Medicaid expansion and SNAP receipt, WIC receipt, or housing assistance receipt.
Employer Benefits Receipt
- There was no evidence of a statistically significant relationship between Medicaid expansion and employer-provided health insurance coverage among documented farm workers.
Employment
- Study findings suggested that, on average, documented farm workers in states that expanded Medicaid increased their weekly hours more than farm workers in states that did not expand Medicaid.
- Study findings suggested that rates of non-farm employment among documented farm workers decreased by more in states that expanded Medicaid than in states that did not expand Medicaid.
Earnings and Wages
- There was no evidence of a statistically significant relationship between Medicaid expansion and earnings or wages for documented farm workers.
Considerations for Interpreting the Findings
The authors’ difference-in-differences regression model included controls for a number of individual characteristics to adjust for possible pre-existing or time-varying demographic differences between the treatment and comparison groups. However, the regression model used to estimate the impacts of Medicaid expansion did not adjust for the race or ethnicity of documented farm workers. To receive a moderate evidence rating – the highest available evidence rating for quasi-experimental studies using difference-in-differences designs – CLEAR requires the use of specific control variables, including race and ethnicity. In this case, preexisting or time-varying differences in the racial or ethnic composition of documented farm workers – and not the ACA Medicaid expansion – could explain the observed differences in outcomes. Therefore, the study is not eligible for a moderate causal evidence rating, the highest rating available for nonexperimental designs.
Causal Evidence Rating
The quality of causal evidence presented in this report is low because the authors did not include control variables required to ensure that the groups being compared were similar before the intervention and across the period of study. This means we are not confident that the estimated effects are attributable to the Affordable Care Act (ACA) Medicaid expansion; other factors are likely to have contributed.