State-dependent motivational interviewing for people with schizophrenia and substance use. Results of a randomised controlled trial

Comorbid substance use disorder in patients with schizophrenia is associated with poor clinical and social outcome and low compliance with integrated outpatient treatment programs. For the first time the present trial compares the efficacy of four sessions of motivational interviewing (MI) and four sessions of supportive therapy (ST). The primary outcome was compliance with integrated outpatient treatment post-intervention. Secondary outcomes were substance use, psychopathology, compliance with medication and stage of change in psychotherapy. Sixty inpatients with schizophrenia and substance use disorder were randomised to receive either four sessions of MI or four sessions of ST. Masked assessments took place at baseline, post-treatment and 3- and 6-month follow-ups. The integrated outpatient program was attended by 70.0% of the MI (n=30) and 40.0% of the ST patients (n=30; p=0.020). There were no differences regarding secondary outcome between MI and ST groups. The study design allows one for the first time to attribute the findings to the specific effects of MI and thereby emphasizes the effectiveness of this particular treatment approach. In summary, these findings show that the integration of short-term MI for people with both psychosis and substance abuse could significantly improve their chances of attending appropriate outpatient settings and thereby improve their well-being.