Time-to-therapy discontinuation in patients newly diagnosed with schizophrenia initiated on long-acting injectable versus oral dopamine receptor blocking agents.

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The purpose of this project is to assess the time-to-therapy discontinuation and hospital readmission rate among patients newly diagnosed with schizophrenia who are prescribed long-acting injectable versus oral dopamine receptor blocking agents. A retrospective review of medical records was performed for adult patients admitted to an 80-bed inpatient behavioural health facility with a new diagnosis of schizophrenia. The primary outcome studied was time to therapy discontinuation within 1 year of discharge, while secondary outcomes assessed were time-to-therapy discontinuation within 90 days and readmission rate at 30-days, 6 months, and 1 year. Multivariate Cox proportional hazard and linear regression modelling were used for statistical analysis. A total of 425 patients were included in the analysis, with 66.4% (n=282) discharged on oral and 33.6% (n=143) on long-acting injectable dopamine receptor blocking agents. At 1 year post-discharge, the rates of discontinuation were 49.7% for those prescribed long-acting injectable and 55.7% for those prescribed oral formulations (adjusted hazard ratio=0.54, p=.012). There was no statistically significant difference in readmission rate between the patients prescribed long-acting injectable and oral dopamine receptor blocking agents at any timepoint tested. The use of long-acting injectable dopamine receptor blocking agents was associated with longer time-to-discontinuation compared to oral agents when prescribed to patients newly diagnosed with schizophrenia in the inpatient setting. However, this was not associated with significant reductions in rehospitalization, calling into question the clinical impact. Future studies will seek to confirm these findings using a prospective study design.