Time to Rehospitalization for Different Oral Risperidone Dosing Frequencies in Patients With Schizophrenia: A 17-Year Retrospective Cohort Study.

PURPOSE: This retrospective cohort study aimed at determining whether the daily administration pattern of risperidone influences time to rehospitalization in patients with schizophrenia. Previous studies have related more frequent dosing to poor medication adherence. This causes suboptimal disease control, which entails shorter times between hospital admissions.

METHODS: We investigated admission records from 1 tertiary psychiatric hospital in Taiwan. Patients were included if they had a main diagnosis of schizophrenia or schizoaffective disorder and were receiving oral risperidone. The enrollment period was July 2001 to December 2016; we observed whether rehospitalization would occur in subsequent periods of 3-month, 6-month, and 1-year follow-ups.

RESULTS: There were 1504 patients grouped by daily dosing frequency of oral risperidone. Most patients (95.9%) received 6 mg or less of risperidone per day. After adjustment for covariates, including daily total dosages of risperidone, it showed an independent association that more frequent dosing frequency of risperidone had higher hazard ratios (HRs) of rehospitalizations (in 1-year follow-up: 2 vs 1 dosing a day: HR, 1.566; 3 vs 1 dosing a day: HR, 3.010; 4 vs 1 dosing a day: HR, 4.305) and a significant trend of more possible rehospitalizations (Cochran-Armitage test for trend: P < 0.001) in 3-month, 6-month, and 1-year follow-up.

CONCLUSIONS: Patients receiving more doses of risperidone per day are more likely to be readmitted within 1 year following last discharge, indicating poorer treatment outcomes for patients who receive more frequent doses.