Treatment Continuity, Adverse Events and Psychiatric Hospitalization for Incident Users of Second-Generation Antipsychotics Long-Acting Injections in Schizophrenia: One-Year Follow-up Study

OBJECTIVES: Schizophrenia commonly occurs in young adults. Despite the proven benefits of second-generation antipsychotic (SGA) long-acting injections (LAI) for schizophrenia, their utilization in Taiwan is deemed low by professionals. This study aims to assess SGA LAI continuity, adverse events, and psychiatric hospitalization in schizophrenia, with a specific focus on young adults.

METHODS: The study included newly diagnosed cases of schizophrenia and incident users of three second-generation antipsychotic long-acting injections (SGA LAI) – risperidone (RISP), paliperidone (PALP), and aripiprazole (ARIP) – from 2018 to 2019, with a one-year follow-up. Utilization patterns for each SGA LAI were classified as continuous use, switch, withdrawal, or intermittent use. Multinomial logistic regression was conducted to explore influential factors affecting utilization patterns.

RESULTS: The study cohort included 1,189 patients, with 329 on RISP, 706 on PALP, and 244 on ARIP. Withdrawal was the most prevalent utilization pattern, with rates of 48.3% for RISP, 56.1%, PALP and 59.4%, ARIP. Among young adults, the withdrawal rate was 46%. Continuous use was lowest, with rates of 7.6% for RISP, near 20% for PALP, and undetermined for ARIP; young adults had a rate of 21.7%. In young adults, the risk of withdrawal significantly increased with age (OR=1.121). Around 25% was hospitalized within the one-year follow-up, with the lowest incidence of psychiatric hospitalization observed in continuous use for each SGA LAI (0-17.46/100 person-year) and among young adults (14.58/100 person-year). The incidence of extrapyramidal syndrome was highest in the switch category (8.93-22.25/100 person-year) across the three SGA LAIs.

CONCLUSIONS: Approximately two-thirds of LAI users discontinued their treatment, resulting in a negative impact on psychiatric hospitalization. The risk of withdrawal in SGA LAI use increased for individuals in non-public hospitals and with higher age.