Homelessness, justice involvement, and publicly funded substance use treatment after Medicaid expansion.

Introduction: People experiencing homelessness (PEH) and individuals referred through the criminal-justice (CJ) system face high rates of substance use disorders (SUD) and persistent barriers to treatment. Although Medicaid expansion increased insurance coverage among low-income adults with SUD, it remains unclear how these reforms affected entry into publicly funded treatment for individuals experiencing both homelessness and justice involvement. Methods: We analyzed 32.9 million specialty SUD treatment admissions reported to the Treatment Episode Data Set-Admissions (TEDS) from 2006 to 2023. Multinomial logistic regression estimated demographic, socioeconomic, clinical, and insurance correlates across pathways. Comparative interrupted time series (CITS) models with state and year fixed effects assessed changes in admissions involving PEH-CJ following Medicaid expansion. Results: Of all admissions, PEH-CJ admissions showed the highest levels of socioeconomic instability, repeated treatment episodes, and stimulant involvement. Multinomial models identified elevated relative risk among American Indian/Alaska Native, Black, unemployed individuals, those with low educational attainment, and prior treatment episodes. CITS analyses showed no significant post-expansion change in PEH-CJ admission probability. Conclusion: Medicaid expansion did not alter reliance on publicly funded safety-net treatment for PEH-CJ. Continued dependence on the SUPTRS-BG highlights the need to align Medicaid reforms with strengthened safety-net financing and cross-sector support.