We included 25 RCTs and found no compelling evidence to support any one psychosocial treatment over another to reduce substance use (or improve mental state) by people with serious mental illnesses. Furthermore, methodological difficulties exist which hinder pooling and interpreting results; high drop out rates, varying fidelity of interventions, varying outcome measures, settings and samples and comparison groups may have received higher levels of treatment than standard care. Further studies are required which address these concerns and improve the evidence in this important area.
Comparison of ACT and standard case management for delivering integrated treatment for co-occurring disorders.
Clients with co-occurring severe mental and substance use disorders are at high risk of institutionalization and other adverse outcomes. Although integrated mental health and substance abuse treatment is becoming a standard clinical approach for such clients, the optimal method for delivering integrated treatment remains unclear.
                This study compared integrated treatment delivered within two different models of community-based case management (assertive community treatment and standard clinical case management). A total of 198 clients in two urban sites who had co-occurring disorders and were homeless or unstably housed were randomly assigned to one of two treatment conditions and were followed for three years.
                Participants in both treatment conditions improved over time in multiple outcome domains, and few differences were found between the two models. Decreases in substance use were greater than would be expected given time alone. At the site that had higher rates of institutionalization, clients who received standard case management were more likely to be institutionalized. However, in the site that had lower rates of institutionalization, no differences in the rate of institutionalization were found between the two treatment conditions.
                Integrated treatment can be successfully delivered either by assertive community treatment or by standard clinical case management.