Long-acting injectable antipsychotics in schizophrenia management: population-based epidemiological study of longitudinal prescribing practices in Ireland (2014–2024)

BACKGROUND: International guidance recommends that long-acting injectable (LAI) antipsychotics be considered for routine management of first-episode schizophrenia. Reliable national estimates of utilisation are lacking for most countries, including Ireland. AIMS: To determine the prevalence of LAI antipsychotic prescribing in Ireland between 2014 and 2024 and explore the effects of age, sex and socioeconomic status on prescribing trends. METHOD: The annual prescribing prevalence was calculated per 1000 individuals with schizophrenia aged 15-69 using the national pharmacy claims database. The effects of year, age, sex, socioeconomic class and antipsychotic medication on LAI antipsychotic prescribing trends were examined using log-linear regression. RESULTS: The prevalence of LAI antipsychotic prescribing decreased from 327/1000 in 2014 to 281/1000 in 2024, with an average annual change in prescribing rate of -1.49% [95% CI -1.98, -0.79]. In 2024, paliperidone LAIs were most commonly prescribed (40.2%). Prescribing prevalence increased with age, with the lowest prescribing prevalence occurring among those aged 15-24 years (79/1000) and the highest among those aged 65-69 years (434/1000). The prescribing prevalence increased significantly among those aged 25-34 years only (+2.7% [95% CI 1.7, 4.3]). Prescribing rates decreased across all ages between 45 and 69 years; the largest decrease occurred among those aged 65-69 years (-4.3% [95% CI -5.7, -2.9]). Higher rates of prescribing were seen in male compared with female patients across all age bands, with the highest male-to-female ratio (2.94) occurring among those aged 25-34 years. CONCLUSIONS: Approximately 28% of Irish individuals with schizophrenia are prescribed an LAI antipsychotic. Prescribing rates have decreased by 14% since 2014. Priorities for future research include implementation science studies to identify strategies that can effectively increase LAI antipsychotic prescribing.