Has Medicaid expansion improved health outcomes in US states?

The Patient Protection and Affordable Care Act (ACA) sought to reduce the number of uninsured Americans through federal government subsidies of Medicaid coverage expansion. This Medicaid expansion was made optional to states, and as of October 2021 there were 12 U.S. states that have not yet implemented it. A study comparing outcomes of expansion vs. non-expansion states found a significant reduction in mortality in states that expanded Medicaid. Individuals aged 55 to 64 with either less than a high school degree or income under the threshold (138% of the Federal Poverty Level) experienced a 9.4% drop in mortality after expansion as compared to non-expansion states. Furthermore, research on states that already expanded Medicaid found no clear change in overall spending from state funds due to offsetting savings in health care costs.