Association of the Affordable Care Act Medicaid Expansion With Secondary Overtriage among Young Adult Trauma Patients.

BACKGROUND: Previous work has shown that the Affordable Care Act (ACA) Medicaid expansion decreased the uninsured rate and improved some trauma outcomes among young adult trauma patients, but no studies have investigated the impact of ACA Medicaid expansion on secondary overtriage, namely the unnecessary transfer of non-severely injured patients to tertiary trauma centers. METHODS: Statewide hospital inpatient and emergency department discharge data from two Medicaid expansion and one non-expansion state were used to compare changes in insurance coverage and secondary overtriage among trauma patients aged 19-44 y transferred into a level I or II trauma center before (2011-2013) to after (2014-quarter 3, 2015) Medicaid expansion. Difference-in-difference (DD) analyses were used to compare changes overall, by race/ethnicity, and by ZIP code-level median income quartiles. RESULTS: Medicaid expansion was associated with a decrease in the proportion of patients uninsured (DD: -4.3 percentage points; 95% confidence interval (CI): -7.4 to -1.2), an increase in the proportion of patients insured by Medicaid (DD: 8.2; 95% CI: 5.0 to 11.3), but no difference in the proportion of patients who experienced secondary overtriage (DD: -1.5; 95% CI: -4.8 to 1.8). There were no differences by race/ethnicity or community income level in the association of Medicaid expansion with secondary overtriage. CONCLUSIONS: In the first 2 y after ACA Medicaid expansion, insurance coverage increased but secondary overtriage rates were unchanged among young adult trauma patients transferred to level I or II trauma centers.