The effect of referral to expedited Medicaid on substance use treatment utilization among people with serious mental illness released from prison.

Adults released from incarceration are at high risk of death from drug-related causes, pointing to the importance of connecting individuals to healthcare services after release from prison. Though Medicaid plays an important role in financing behavioral health treatments for vulnerable groups, many states terminate individuals' Medicaid coverage during incarceration. A significant risk factor for substance use disorders (SUD) among incarcerated individuals is serious mental illness (SMI). In January 2006, Washington State began a program of expedited Medicaid enrollment for individuals with mental illnesses being discharged from state prisons, jails, and psychiatric hospitals. Prior literature has shown this program to be effective in increasing Medicaid enrollment and use of mental health services for people with SMI. The current paper examined the effect of referral to expedited Medicaid on use of SUD treatment for people with SMI released from prison. Our sample consisted of 3086 individuals with a diagnosis of SMI who were released from prison from January 1, 2006 to December 31, 2007. Of the sample we identified, 871 individuals received referrals for expedited Medicaid and 2215 did not. To control for selection bias on observed characteristics for referral, we used inverse probability weights (IPW) to balance the referred and not-referred groups on more than 50 baseline covariates. We used doubly-robust IPW models to estimate the effect of referral to expedited Medicaid on use of SUD treatments following prison release. Approximately 12% of our sample used any SUD treatment by 3 months after release, with this percentage rising to 28% at 12 months. When controlling for baseline differences, referral to expedited Medicaid enrollment was associated on average with a 6.7 (SE 2.9, p < .05) percentage point increase in the predicted probability of using any SUD treatment in the 3 months following release as compared to those not referred to the program. This effect size represents a 61% increase in the probability of using any treatment by 3 months. The result was similar for the 6-month follow-up period and persisted at the 12-month follow-up though the magnitude of the effect decreased somewhat. Overall, our results suggest that expedited Medicaid enrollment for people with SMI released from prison can increase use of SUD services.