Treatment for co-occurring mental and substance use disorders in five state Medicaid programs

This study described the locations and patterns of psychiatric and substance abuse treatment for Medicaid beneficiaries with co-occurring mental and substance use disorders in five states.

Medicaid beneficiaries aged 21 to 65 with psychiatric or substance use disorders were identified with claims and encounter records. Groups were further divided into those with and those without a diagnosed substance use disorder. Adjusted odds of treatment in community-based settings, inpatient facilities, emergency departments, and hospital outpatient departments were calculated.

A total of 92,355 persons had a psychiatric disorder, 34,158 had a substance use disorder, and 14,256 had co-occurring psychiatric and substance use disorders. In all five states, beneficiaries with severe mental illness (schizophrenia, bipolar disorder, or major depression) and a substance use disorder had higher odds of inpatient, emergency department, and hospital-based outpatient psychiatric treatment, compared with those with severe mental illness alone. In four of five states, both severe and less severe mental illness and a co-occurring substance use disorder were associated with lower odds of community-based treatment compared with those with the respective mental illness alone. Compared with those with less severe mental illness alone, individuals with less severe psychiatric disorders and a co-occurring substance use disorder had higher odds of inpatient treatment in all states and of emergency department use in three of five states. Odds of inpatient and outpatient hospital use and emergency department use for substance abuse treatment were higher for persons with severe mental illness and a co-occurring substance use disorder in most states, compared with odds for those with a substance use disorder alone.

Heavy inpatient and emergency department use by Medicaid beneficiaries with co-occurring substance use disorders is a consistent cross-state problem. Co-occurring disorders may decrease the likelihood of community-based treatment for those with less severe mental disorders and for those with severe mental illness, suggesting that policies focusing only on these settings may miss a significant proportion of people with these co-occurring disorders.