When the Supreme Court ruled that under the Patient Protection and Affordable Care Act, states could not be compelled to expand Medicaid,¹ it opened an unusual divide for public insurance coverage in the United States. Starting January 1, 2014, adults 19 to 64 years with family income up to 138% of the federal poverty line (133% plus a 5% income disregard) became eligible for Medicaid in 25 states and the District of Columbia (expansion states). In the remaining 25 states (nonexpansion states), while adults with incomes between 100% and 138% of the federal poverty line qualify for subsidized insurance coverage through the new marketplaces, those with income below the poverty line will not qualify and therefore are likely to remain uninsured. Previous estimates indicate that more uninsured adults who could have been made Medicaid eligible live in nonexpansion states (8.5 million) than in expansion states (6.6 million).²

We studied the characteristics of low-income (income no more than 138% of the poverty line) citizens aged 19 to 64 years in expansion and nonexpansion states before the 2014 expansion. We included noncitizens who have been in the United States at least 5 years since some may also be Medicaid eligible.³ We used data from the National Health Interview Survey, 2010–2012,⁴ the conduct of which was approved by the ethics review board of the National Center for Health Statistics. To describe possible health care needs of low-income adults in the 2 groups of states, we compared several measures of health status and the use of and access to health care reported by respondents to the National Health Interview Survey. Analyses were weighted to the civilian noninstitutionalized population, and SEs accounted for the complex design of the survey (Stata version 12; StataCorp LP). We used t tests (dichotomous variables) and the χ² test (categorical variables) to infer statistical significance of differences between groups.

Around 46.0% (95% CI, 44.6%–47.3%) of low-income adults were uninsured in nonexpansion states compared with 37.3% (95% CI, 36.0%–38.6%) in expansion states (P < .001) (Table 1). In nonexpansion states, the low-income uninsured were more likely to have delayed or not received health care in the past year due to cost than were the low-income uninsured in expansion states. The low-income uninsured in nonexpansion states were more likely to have had an emergency department visit in the past year (27.6%; 95% CI, 25.8%–29.4%) compared with those in expansion states (20.9%; 95% CI, 19.0%−22.8%; P < .001). The low-income uninsured in nonexpansion states were also more likely to smoke, to be in fair or poor health, and to have several health conditions (Table 2) than those in expansion states. For example, 22.4% (95% CI, 20.6%–24.2%) in nonexpansion states had diagnosed hypertension compared with 16.8% (95% CI, 15.1%–18.6%) in expansion states.

This analysis suggests that low-income adults in nonexpansion states could have more to gain from a Medicaid expansion than those in expansion states. However, these adults will not receive any direct benefit from the expansion unless their state decides to expand Medicaid. Although the expansion would be financed by the federal government from 2014 through2016,¹state policy makers are concerned about the costs when their contribution increases to 10% in years after 2016 if they choose to maintain the expansion. To the extent that the Medicaid expansion is successful at increasing health insurance coverage and access to care for low-income adults in expansion states, disparities between expansion and nonexpansion states in access to care and in the financial burden of paying for health care (for patients and providers providing charity care to uninsured patients) could widen in the coming years.