Comparative effectiveness of long-acting injectable antipsychotics in patients with schizophrenia in Japan

Objective: To compare the effectiveness of different long-acting injectable antipsychotics (LAIs) (aripiprazole, paliperidone, risperidone, and fluphenazine/haloperidol) in patients with schizophrenia in Japan. Methods: We conducted a retrospective cohort study using two administrative claims databases. The study population consisted of outpatients with schizophrenia who initiated LAIs between May 1, 2015, and November 30, 2019. We directly compared the risk of psychiatric hospitalization and LAI discontinuation among the LAIs based on hazard ratios (HRs) using Cox proportional hazards regression models. Results: The numbers of eligible patients who initiated aripiprazole, paliperidone, risperidone, and fluphenazine/ haloperidol were 303, 124, 73, and 123, respectively. Regarding psychiatric hospitalization, aripiprazole and paliperidone were associated with significantly lower risk compared to fluphenazine/haloperidol (HR of aripi-prazole: 0.47, 95 % CI: 0.28-0.78, HR of paliperidone: 0.50, 95 % CI: 0.28-0.89); HR of risperidone showed the same trend as the aripiprazole and paliperidone. Regarding LAI discontinuation, aripiprazole and paliperidone were associated with significantly lower risk of LAI discontinuation compared to fluphenazine/haloperidol (HR of aripiprazole: 0.53, 95 % CI: 95 % CI: 0.35-0.80, HR of paliperidone: 0.57, 95 % CI: 0.35-0.92). Aripiprazole was also associated with a significantly lower risk compared to risperidone (HR: 0.56, 95 % CI: 0.32-0.98). Conclusion: Our study suggests that aripiprazole and paliperidone are superior to fluphenazine/haloperidol in the risk of psychiatric hospitalization and LAI discontinuation. Aripiprazole is superior to risperidone in the risk of LAI discontinuation.