CapOpus did not reduce the frequency, but possibly the amount, of cannabis use. This is similar to the findings of previous trials in this population. Implementation of CapOpus-type interventions is thus not warranted at present but subgroup analyses call for further trials.

Timeline follow-back (TLFB)-assisted self-report of cannabis use correlates highly with plasma-delta-9-tetrahydrocannabinol in patients with comorbid cannabis use disorder and psychosis. Sensitivity and specificity of timeline follow-back appear to be optimized with 19 days as the cut-off point. As such, timeline follow-back may be superior to analysis of blood when going beyond 19 days of recall.

Insufficient evidence exists on treating this form of dual-diagnosis patients. Studies grouping several types of substances as a single outcome may overlook differential effects. Future RCTs should investigate combinations of psychosocial, pharmacological, and contingency management.

The implementation of this guideline in daily clinical practice can facilitate good treatment outcomes within the population of patients with schizophrenia and complex mental health needs. The guideline does not cover all available interventions and should be used in conjunction with other relevant guidelines.

Psychosocial interventions appear moderately efficacious in reducing quantity of cannabis-use and positive symptoms.