Impact of Medicaid expansion on young adult firearm and motor vehicle crash trauma patients

The Affordable Care Act Medicaid expansion has increased insurance coverage and reduced some disparities in care and outcomes among trauma patients, but its impact on subsets of trauma patients with particular mechanisms of injury are unclear. This study evaluated the association of the Affordable Care Act Medicaid expansion with insurance coverage, trauma care, and outcomes among young adults hospitalized for firearm- or motor vehicle crash–related injuries. We used statewide hospital discharge data from 5 Medicaid expansion and 5 nonexpansion states to compare changes in insurance coverage and outcomes among firearm and motor vehicle crash trauma patients aged 19–44 from before (2011–2013) to after (2014–2017) Medicaid expansion. We examined difference in differences overall, by race/ethnicity, and by zip-code-level median income quartile. Medicaid expansion was associated with a decrease in the proportion of young adult motor vehicle crash and firearm trauma patients who were uninsured (motor vehicle crash: difference in differences −12.7 percentage points, P