Many inmates with serious mental illness leave prisons without health insurance, which reduces their access to health care and therefore places them at risk of relapse and rearrest. This study assessed the effectiveness of a discharge planning program implemented in three Oklahoma state prisons to assist inmates with serious mental illness to enroll in Medicaid on the day of release or soon thereafter.

Administrative data containing demographic characteristics, Medicaid enrollment status, and mental health service use were collected for 686 inmates with serious mental illness released from Oklahoma state prisons between 2004 and 2008. Regression-adjusted difference-in-difference estimates were used to compare postrelease Medicaid enrollment and service use of 77 inmates eligible for program services with those of inmates with mental illness of similar severity in three comparison groups.

In facilities implementing the program, the percentage of inmates with serious mental illness who enrolled in Medicaid on the day of release increased from 8% during the baseline period to 25% after program implementation. The difference-in-difference estimates, which adjusted for trends in Medicaid enrollment and inmate demographic and prison stay characteristics, indicated that the program increased Medicaid enrollment by 15 percentage points (p=.012) and increased Medicaid mental health service use by 16 percentage points (p=.009).

Although additional research is needed to assess the program's long-term effects on health care utilization and rearrest, this study illustrated that with careful planning, interagency collaboration, and dedicated staff, states can successfully increase Medicaid coverage among inmates with serious mental illness on their release from prison. (Psychiatric Services 62:73–78, 2011)