Inpatient Hospital Admissions for Mental Health in the United States: Medicaid Compared With Private Insurance

OBJECTIVE: Differences in mental health services covered by U.S. insurance payers are a public health concern. Mental health benefits are required under the Affordable Care Act, and parity laws have long aimed to ensure equitable access across insurance types. The authors examined the association between insurance coverage (Medicaid or private), hospitalization for a principal psychiatric diagnosis, and patient outcomes. METHODS: A retrospective cross-sectional analysis was conducted by using the 2017-2019 Nationwide Inpatient Sample for adults ages 18-64 with Medicaid or private insurance. Mental disorders, length of stay (LOS), hospital charges, and in-hospital mortality rates were analyzed. Survey-weighted multivariable regressions adjusted for demographic characteristics, hospital characteristics (i.e., region and size as number of beds), and somatic comorbid conditions were performed. RESULTS: Among 7,428,110 unweighted hospital discharges (weighted=37.1 million), 11.9% of Medicaid and 5.5% of privately insured hospitalizations (610,394 unweighted and 3,051,969 weighted discharges) involved a principal psychiatric diagnosis (adjusted OR=2.35, 95% CI=2.25-2.44, p<0.001). Compared with private insurance, Medicaid was associated with a longer LOS and higher charges among hospitalizations for a principal psychiatric diagnosis. Subgroup analyses revealed longer LOS and higher charges for major depressive, substance use, and posttraumatic stress disorders. For anxiety disorders, longer LOS under Medicaid was not associated with higher charges. No differences in in-hospital mortality rate were identified. CONCLUSIONS: Compared with private insurance, Medicaid was found to cover a higher proportion of hospitalizations for a principal psychiatric diagnosis, longer LOS, and higher cost. These findings likely reflect differences in patient needs but may also be due to programmatic differences.