Prescribing pattern of antipsychotic medication for first-episode psychosis: a retrospective cohort study

Objective: Guidelines for antipsychotic use in first-episode psychosis (FEP) recommend that medication be chosen initially on the basis of side effect profile with doses at the lower end of the range. Our objective was to describe the pattern of antipsychotic use in FEP over a period of 21 years in the context of changing clinical guidelines and the development of specialist early intervention in psychosis (EIP) services.

Setting: A community-based mental health service in South County Dublin (population 187 000) and a large private hospital.

Participants: Participants included 465 patients with FEP (146 from an epidemiological study (1995-1999) and 319 from a specialist EIP service (2005-2016)). Treatment with antipsychotic medication did not exceed 30 days at study entry.

Outcome measures: This is a descriptive study of prescribing practices in the context of service development and changing guidelines.

Results: First-generation antipsychotics were prescribed for 65% of the early cohort compared with 4.3% of the EIP cohort. Olanzapine was initially prescribed for 79.7% of EIP patients. Initial doses of medication were frequently low (≤50% British National Formulary (BNF) maximum) in both cohorts (71% and 78.6%). The demographic and clinical factors investigated did not influence the initial choice of antipsychotic medication significantly. Univariate logistic regression analysis suggested inpatient treatment setting was associated with a higher initial dose (>50% BNF maximum) of antipsychotic medication. Increasing dose requirements over the first month of engagement with an EIP service was associated with poorer global functioning at baseline, greater positive symptoms at baseline and the inpatient treatment setting. However, these associations were not seen in the multivariable model.

Conclusions: Second-generation antipsychotic prescribing predominates, but guidelines are often overlooked when choosing olanzapine notwithstanding lower initial dosages. EIP services should include proactive support for optimising medicines in line with evidence-based guidelines.