Effects of a brief intervention for substance use on tobacco smoking and family relationship functioning in schizophrenia and related psychoses: a randomised controlled trial.

Surveys indicate that substance use is prevalent in populations with schizophrenia. Family members may be able to support brief interventions (BI). We conducted a randomised controlled trial with 6-month follow-up among adult patients with schizophrenia and related psychoses who were referred to two hospitals in southern Thailand. Patients with psychosis were screened using the Alcohol Smoking and Substance Involvement Screening Test (ASSIST). 169 participants (all at moderate substance risk on the ASSIST) were randomised to receive simple advice (the clinics' treatment-as-usual, TAU condition), or single-session brief intervention (BI), or a single-session BI with family support (BI-FS). Given observed substance use, the primary outcome was the ASSIST tobacco smoking involvement score (SIS). Secondary outcomes were cigarettes smoked per day, change motivation (Taking Steps from the Stages of Change and Treatment Eagerness Scale), and DSM-IV Axis V Global Assessment of Relational Functioning (GARF). At follow-up, BI-FS participants reported a lower SIS (mean difference, -2.82, 95% confidence interval [CI] -4.84 to -0.81; Glass' effect size [Δ] = 0.57, 95% CI 0.19 to 0.95), smoked fewer cigarettes per day (mean difference -3.10, 95% CI -5.45 to -0.74; Δ = 0.56, 95% CI 0.18 to 0.94), had greater change motivation (mean difference 3.05, 95% CI 0.54 to 5.57; Δ = 0.41, 95% CI 0.03 to 0.79) and GARF (mean difference 6.75, 95% CI 1.57 to 11.93; Δ = 0.54, 95% CI 0.16 to 0.92). The BI-FS group also had better relational functioning in comparison to those receiving BI only (mean difference 5.44, 95% CI 0.20 to 10.67; Δ = 0.46, 95% CI 0.08 to 0.84). In schizophrenia and related psychoses, a brief intervention supported by a family member reduces smoking involvement, cigarette smoking intensity, and increases change motivation and relational functioning.