Study Design and Setting

We conducted a telephone survey to compare changes in outcomes before and after implementation of the work requirements in Arkansas among persons 30 to 49 years of age, as compared with Arkansans 19 to 29 years of age and those 50 to 64 years of age (who were not subject to the requirement in 2018) and with adults in three comparison states — Kentucky, Louisiana, and Texas. Kentucky, like Arkansas, expanded Medicaid under the Affordable Care Act (ACA) in 2014 and planned to introduce work requirements in 2018, but the requirements were blocked by a federal judge before implementation. Neither Louisiana (which expanded Medicaid in 2016) nor Texas (which has not expanded Medicaid) has implemented work requirements. All four study states are in the Southern census region and have poverty rates in the highest quartile of the United States. We used baseline data from 2016 (before the implementation of work requirements) for these states from a previous survey conducted by our team that has been validated against government data sources.16-18 This project was approved by the institutional review board of the Harvard T.H. Chan School of Public Health.

Sample and Survey

Our survey was conducted by means of cellular and landline telephones, in English or Spanish, between November 8 and December 30, 2018. The sample comprised U.S. citizens 19 to 64 years of age who reported family incomes in 2017 below 138% of the federal poverty level (e.g., $16,600 for a single adult or $33,900 for a family of four), which corresponds to the income limit for the ACA Medicaid expansion. This inclusion criterion was based on the respondent’s income in the previous year in order to prevent any potential employment response to the policy from biasing the sample composition.

We contacted potential survey participants in Arkansas, Kentucky, Louisiana, and Texas primarily by means of random-digit dialing. The study also included respondents from different surveys that had been previously conducted by our survey vendor who were recontacted for this survey; this facilitated oversampling in the age group subject to work requirements in Arkansas. We combined the 2018 data with baseline data from November and December 2016, which had been obtained from a different set of respondents.17,18 Further details on the survey design are provided in the Methods section in the Supplementary Appendix, available with the full text of this article at NEJM.org.

Outcomes

Our study had three primary outcomes: the percentage of respondents with Medicaid, the percentage of respondents who were uninsured, and the percentage of respondents reporting any employment. Secondary outcomes were the number of hours worked per week, the percentage of respondents satisfying any category of community engagement requirement (described below), the percentage of respondents with employer-sponsored insurance, and two measures of access to care — the percentages of respondents having a personal physician and reporting any cost-related delays in care. We also examined Arkansas respondents’ experience with work requirements: whether they had heard “a lot,” “a little,” or “nothing” about the requirements; whether they thought they were (or would be) subject to the requirements; and their reporting activities to the state.

Health insurance was categorized into mutually exclusive categories (see the Methods section in the Supplementary Appendix). The 2014 expansion in Arkansas used Medicaid funds to purchase ACA marketplace plans for most newly eligible adults (sometimes called the “private option”).19 In contrast, most low-income adults in the other expansion states in our study (Kentucky and Louisiana) were eligible for Medicaid but not ACA marketplace plans. Because of the blurred boundary between Medicaid and marketplace coverage in Arkansas, coverage with Medicaid alone or marketplace coverage alone in Arkansas as compared with the other states would be misleading. Accordingly, we combined Medicaid and marketplace coverage into a single category.

Activities meeting the Arkansas work requirements included 80 hours per month of employment, job search, job training, or community service. Populations of adults who were eligible for exemptions included pregnant women, persons with disabilities or medical frailty, full-time students, persons caring for a child or other household member, and anyone receiving treatment for substance abuse. Since our baseline survey did not assess employment-related activities, our 2018 survey asked respondents about their activities 12 months earlier (during 2017) and then assessed their current activities. The survey questions are shown in the Supplementary Appendix; the 2018 survey questions used identical wording to our baseline survey whenever possible.

Statistical Analysis

Our approach was a difference-in-difference-in-differences (or triple-difference) model, which used comparisons according to year, state, and age group to identify changes in outcomes associated with the policy. Our model tested whether the change among respondents 30 to 49 years of age in Arkansas, relative to the change in other age groups in Arkansas, was larger than the comparable relative changes in other states. This method filters out time trends common to all four states and any state-specific factors influencing employment and coverage in Arkansas that were not due to work requirements. For instance, the waiver in Arkansas increased cost sharing and premiums for some enrollees in addition to work requirements, but these features were not specific to age.20 We implemented this model with adjustment for state, year, and age group (19 to 29 years, 30 to 39 years, 40 to 49 years, 50 to 59 years, and 60 to 64 years) and with pairwise interaction terms between those variables. The policy estimate came from the three-way interaction among indicator variables for Arkansas, the 30-to-49–year-old age group, and the year 2018; the regression equations are shown in the Supplementary Appendix.

For outcomes regarding insurance coverage and health care access, which were measured in separate samples from 2016 and 2018, we used a linear model with standard errors clustered according to age group and state (20 state–age group clusters); we used linear models for ease of interpretation of interaction terms, as is standard practice in difference-in-differences analyses.21 For community engagement outcomes, which were measured in the 2018 sample on the basis of questions regarding activities in the previous year and current year, we used a multilevel mixed model with random effects for age groups in each state and for each respondent.

All models adjusted for sex, respondent-reported race and ethnic group, educational level, interview language (English or Spanish), marital status, and residence area (urban or rural). All analyses used survey weights to reflect the target population in each state (see the Supplementary Appendix).

To assess awareness of and experiences with work requirements in Arkansas, we calculated survey-weighted means. We estimated a multivariate logistic model to identify demographic predictors of awareness of work requirements.

We conducted several sensitivity analyses: a difference-in-differences model that was limited to respondents 30 to 49 years of age, comparing Arkansas with the other states; models for community engagement that adjusted directly for baseline employment (before the implementation of a work requirement), with the use of a single observation per person; and an analysis of the U.S. Census Bureau American Community Survey for 2016 and 2017 to test whether trends in coverage and employment were similar across our study states and age groups before the implementation of work requirements. We report P values (unadjusted and post hoc family-wise adjusted; see the Supplementary Appendix) only for our three primary outcomes, and we report results with 95% confidence intervals (without adjustment for multiple comparisons) for the primary and secondary outcomes.