Absence of conflict of interest.
Citation
Highlights
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The study’s objective was to examine the impact of Medicaid expansion under the Affordable Care Act (ACA) on individuals’ reasons for working part-time (due to health issues or to other factors) and on the duration of working part-time due to health.
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The study used a difference-in-differences design to compare outcomes for individuals in states that expanded Medicaid eligibility versus those in states that did not, before and after the ACA was implemented. Most study data came from the 2009 – 2016 Current Population Survey, which periodically surveys individuals for up to 18 months.
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The study suggested that there was no evidence of an association between residing in a state that expanded Medicaid access and the likelihood of attributing the reason for working part-time to health. The study also suggested there was no evidence of an association between Medicaid expansion and the duration of working part-time due to health.
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The quality of causal evidence presented in this report is low because the author did not ensure that the individuals being compared were similar on important characteristics before the intervention. This means we could not be confident that any estimated effects were attributable to Medicaid expansion and not to other factors. However, the study did not find statistically significant effects.
Intervention Examined
Medicaid Expansion under the Affordable Care Act
Features of the Intervention
Prior to the Affordable Care Act (ACA), adults without dependent children who were not pregnant or disabled were ineligible for Medicaid. The ACA allowed states to expand Medicaid access, primarily to individuals whose household income was no greater than 138 percent of the federal poverty line. States differed in whether they chose to expand access, including in the timing of expansion and to whom. For example, in January 2014, 23 states expanded Medicaid eligibility to childless adults with family incomes no greater than 138 percent of the federal poverty line while two other states plus the District of Columbia expanded eligibility at the same time but set different income thresholds. Seven more states expanded Medicaid eligibility for childless adults later in 2014 or in 2015 or 2016. State-level timing and income thresholds differed for adults with dependent children.
Features of the Study
The study used a difference-in-differences design to compare outcomes for individuals in states that expanded Medicaid access to those of individuals in states that did not expand access, while also comparing outcomes for other individuals in the same states at earlier points in time. Data on state-level Medicaid-eligibility criteria come from the Henry Kaiser Family Foundation. All other data come from the Current Population Survey (CPS) and its associated Annual Social and Economic Supplement. The CPS is a monthly survey of about 60,000 households. Each sampled household is interviewed monthly for four months, not interviewed for eight months, and then interviewed again for four months. Accordingly, each household’s total participation in the CPS spans a period of 16 months. Because of the CPS’s format, the study’s analysis relies on a changing sample of individuals prior to and after Medicaid expansion.
The study examined individuals ages 16-64 who were first interviewed between January 2009 and April 2016 and whose household income would potentially meet the Medicaid eligibility criteria. One analysis focused on individuals who worked part-time at any point at which they were interviewed while another analysis focused on individuals who worked full-time when they were first interviewed but later reported working part-time due to health issues. For the first analysis, the analytic sample was 3,335 people in non-expansion states and 4,949 people in expansion states. For the second analysis, the analytic sample was 166 people in non-expansion states and 245 people in expansion states. Among the larger sample used in the first analysis, the average age of participants was around 39 years old, about 58-60 percent identified as women, and about 47-55 percent identified as non-Hispanic White. Demographics for the smaller sample used in the second analysis were not provided.
Findings
Employment
- The study suggested that, among individuals who worked part-time, there was no evidence of an association between Medicaid expansion and attributing the reason for part-time work to health issues rather than to other factors. The study also suggested that, among individuals who worked full-time when they were first interviewed but switched to part-time employment due to health sometime during the interview period, there was no evidence of an association between Medicaid expansion and the duration of part-time employment due to health.
Considerations for Interpreting the Findings
The study accounted for some preexisting differences between the groups, using statistical models that controlled for individual characteristics like age, sex, and race/ethnicity as well as regional characteristics like the state’s annual health insurance rate. However, the study did not control for individuals’ prior history of part-time work or demonstrate that the groups were comparable at the individual level on pre-intervention measures of the outcomes. Therefore, preexisting differences between the groups—and not Medicaid expansion—could explain any observed differences in outcomes.
Causal Evidence Rating
The quality of causal evidence presented in this report is low because the author did not ensure that the individuals being compared were similar on important characteristics before the intervention. This means we could not be confident that any estimated effects were attributable to Medicaid expansion and not to other factors. However, the study did not find statistically significant effects.