Medicaid Expansion Benefits Young Adults

In 2010, Congress passed the Affordable Care Act (ACA), which included extending health insurance to more Americans. Under that law, states were given the option to expand Medicaid coverage to people at a higher income level. A new study supported by NIMHD has found that the Medicaid expansion increased the number of young adults covered by health insurance. It increased the quality of care they receive following traumatic injuries, such as those sustained in a car accident or a fall. The Medicaid expansion also improved outcomes for young adult Black and Hispanic trauma patients, reducing death rates and bringing their injury-related outcomes more in line with those of their White counterparts.

Young adults ages 19-44 are the demographic group most likely to be uninsured or underinsured. That is a burden both on these young adults and on the health care system, especially given the facts that:

  • More than 50% of deaths among young adults are caused by unintentional injury or homicide.
  • Before the ACA became law in 2010, more than 30% of young adult trauma patients did not have health insurance.
  • Young adults experiencing poverty, who do not have health insurance, or who belong to a racial or ethnic minority group are less likely to receive rehabilitation care after hospitalization due to a traumatic injury.

Medicaid is the federal government’s health insurance program for people experiencing poverty. Before the ACA, individuals qualified for this program if they lived at about 64% of the federal poverty level. That meant a single person making less than $12,000 per year would qualify. The ACA allowed states to expand eligibility for Medicaid to 138% of the federal poverty level, about $16,000 per year for a single person. Not every state took advantage of the opportunity to expand eligibility. By the end of 2014, 28 states and the District of Columbia had expanded coverage, while 22 states had not.

Researchers conducting the study looked at the changes in insurance coverage and health outcomes following hospitalization for traumatic injury. They compared data from two time periods: the three years before the ACA Medicaid expansion, 2011 to 2013, and the four years after it, from 2014 to 2017. They also compared data from five states where Medicaid expansion occurred in January 2014 to data from five states that had not yet implemented the expansion by the end of 2017.

Overall, researchers found that the ACA Medicaid expansion has led to improvements in health care and decreases in health disparities, including:

  • Decreasing the number of uninsured patients.
  • Increasing the number of patients discharged to rehabilitation facilities where they could continue to heal from their injuries under professional care.
  • Decreasing the rate at which young Black trauma patients die in the hospital following their injuries, bringing that rate closer to what it is for White patients.

In all, researchers analyzed data for nearly 368,000 patients, with about 119,000 living in states that had expanded Medicaid eligibility under the ACA. The majority of the patients, 73%, were male. The demographics in the Medicaid expansion states and the non-expansion states were about the same, with Black patients comprising about 27% and Hispanic patients making up about 14% of the total number of patients. However, patients from non-expansion states were more likely to live in poorer neighborhoods, while patients from expansion states were more likely to live in higher-income communities. The two groups were similar in terms of the injuries they sustained and how they were treated.

In states that implemented the Medicaid expansion, the uninsured rate dropped by 17% compared to pre-expansion levels. Non-expansion states only saw a 1% decrease in the uninsured rate. The researchers also found that the Medicaid expansion resulted in a 21% increase in young adult trauma patients covered by Medicaid. These improvements, however, were not the same across all racial and ethnic backgrounds. The most significant decrease in the likelihood of being uninsured was seen in Black patients and those living in the poorest neighborhoods. Hispanic patients also saw a reduction, but the magnitude was not as great as it was among White patients.

The researchers also compared the health outcomes by patient race and ethnicity, finding that Medicaid expansion was associated with more Black patients being released to rehabilitation centers and fewer Black patients dying in the hospital. In fact, the disparities between Black patients and White patients and between patients from lower- and higher-income communities were reduced in Medicaid expansion states.

The researchers concluded that the ACA Medicaid expansion improved the quality of care, increased access to care, and, ultimately, reduced health care costs in states that chose to broaden eligibility. The study’s authors also wrote that the expansion likely improved the quality of life and economic stability of the individual patients who would not have had insurance coverage without it. The study suggests expanding Medicaid eligibility has a positive impact on public health.


Metzger, G. A., Asti, L., Quinn, J. P., Chisolm, D. J., Xiang, H., Deans, K. J., & Cooper, J. N. (2021). Association of the Affordable Care Act Medicaid Expansion with Trauma Outcomes and Access to Rehabilitation among Young Adults: Findings Overall, by Race and Ethnicity, and Community Income Level. Journal of the American College of Surgeons, 233(6), 776–793.e16.

Page updated July 26, 2022