Effects of training community staff in interventions for substance misuse in dual diagnosis patients with psychosis (COMO study): Cluster randomised trial

A cluster randomised controlled trial was used to investigate the effectiveness of training staff in 13 London community mental health teams (CMHTs) to deliver substance misuse interventions to patients with psychosis and comorbid substance misuse ('dual diagnosis'). The primary hypotheses, which were that experimental group patients would spend fewer days in hospital over 18 months of follow-up and show reduced alcohol and drug consumption, were not confirmed, although confidence intervals were wide for some outcomes. Current UK policy guidance advocates training CMHT professionals to deliver dual diagnosis interventions, but the effectiveness of this strategy has not so far been demonstrated.