Service use and costs of people with dual diagnosis in South London

Objective: To compare the service use and costs of individuals who have a d ual diagnosis of psychosis and substance abuse with those who have a diagno sis of psychosis but no substance abuse. Method: Patients with psychosis were identified and a representative sample were interviewed. Six-month service use was measured and costs calculated, Regression models were developed to predict costs from background characte ristics and dual diagnosis status. Results: A greater proportion of the patients with dual diagnosis used comm unity psychiatric nurses, in-patient care and the emergency clinic. The reg ression analysis revealed that dual diagnosis patients had significantly hi gher 'core' psychiatric service costs (a difference of pound 1362) and non- accommodation service costs (pound 1360) than non-dual-diagnosis patients. The difference when all services were analysed was pound 1046, but this was not statistically significant. Conclusion: Specific interventions for dual diagnosis patients should be in troduced and assessed in terms of individual outcomes, service use and cost s.