Initiation of Antipsychotics During the First Year After First-Episode Psychosis: A Population-Based Study

Abstract

Background: Antipsychotics are recommended after first-episode psychosis. Knowledge on the current use patterns in real-world settings is thus important to inform clinical practice. We aimed to describe antipsychotic initiation during 1 year after first-episode psychosis and its associated factors.

Methods: Population-based cohort study using linked nationwide health and population registers from Norway. The study population comprised 8052 persons aged 16-45 years with first-episode psychosis diagnosed in secondary care (ICD-10 F20, F22-F29) in the period 2011-2019. Initiation of antipsychotic use was defined as being dispensed antipsychotics (ATC N05A, excl. lithium) at least once from -90 to +365 days from secondary care diagnosis of first-episode psychosis. Antipsychotic polypharmacy during follow-up was defined as having at least 90 days with overlapping drug use periods modeled using the Prescriptions to Drug Use Periods method. Adjusted risk ratios (aRRs) with 95% confidence intervals (CIs) for the association between socioeconomic and clinical factors and initiation of antipsychotic use were calculated using modified Poisson regression.

Results: In total, 4413 persons (54.8%) initiated antipsychotic use after first-episode psychosis with proportions ranging from 45.5% in 2012 to 62.1% in 2019. Oral formulations of olanzapine (34.9%), quetiapine (21.2%), and aripiprazole (11.6%) were most common at initiation, whereas long-acting injectables (LAIs) and clozapine were rarely used. Among the initiators, 13.8% started a polypharmacy period lasting more than 90 days. Factors associated with antipsychotic initiation were lower age (aRR 1.14, 95% CI 1.08-1.21; 26-35 years vs. 36-45 years), higher education (1.11, 1.05-1.18), being employed (1.04, 1.00-1.09), being hospitalized (1.13, 1.09-1.18), being diagnosed late in the study period (1.16, 1.11-1.22; 2017-2019 vs. 2011-2013), or with previously diagnosed bipolar disorder, depression, or anxiety disorders.

Conclusions: The antipsychotic use pattern is largely within the current clinical guideline. Primary non-compliance and disease severity may explain the socioeconomic and clinical differences related to initiation of antipsychotic use.

Keywords: antipsychotics; drug utilization; polypharmacy; psychosis; registry‐linkage.

FIGURE 1

Proportion (%) initiating antipsychotic use within the period from 3 months before to 1 year after first‐episode psychosis. The denominator is the number of individuals with a first‐episode psychosis in the respective years. The dashed lines mark the implementation of the current treatment guideline (in 2013) and the launch of medication‐free treatment alternatives for patients admitted to psychiatric care (in 2015).

FIGURE 2

Distribution (%) of antipsychotic drug initiated within the first year after first‐episode psychosis. The denominator is number of individuals initiating antipsychotics during 2011–2019 (N = 4413). Specific drug substances refer to oral antipsychotics and all long‐acting injectables are categorized as “LAIs.” AP polypharmacy refers to situations when two or more antipsychotics were dispensed on the same day. Also, initiation with oral and LAI formulation of the same drug substance is categorized as AP polypharmacy.

FIGURE 3

Distribution (%) of antipsychotic drug initiated within the first year after first‐episode psychosis according to cohort entry year in the period 2011–2019. The denominator is the number of individuals initiating antipsychotics in the respective years. Specific drug substances refer to oral antipsychotics and all long‐acting injectables are categorized as “LAIs.” AP polypharmacy refers to situations when two or more antipsychotics were dispensed on the same day. Also, initiation with oral and LAI formulation of the same drug substance is categorized as AP polypharmacy.