Temporal trends in clozapine use at time of discharge among people with schizophrenia at two public psychiatric hospitals in Taiwan, 2006–2017

Clozapine treatment remains the gold standard for treatment-resistant schizophrenia. This study aimed to describe temporal trends in clozapine use at discharge among patients with schizophrenia at two of the largest public psychiatric hospitals in Taiwan over a twelve-year period. Patients with schizophrenia discharged from the two study hospitals between 2006 and 2017 (n = 24,101) were included in the analysis. Antipsychotic augmentation was defined as concomitant use of a second antipsychotic as augmentation to clozapine treatment. Changes in the rate of clozapine use and antipsychotic augmentation at discharge over time were analyzed using the Cochran-Armitage trend test. Patients discharged on clozapine had significantly longer hospital stays than other patients. The rate of clozapine use at discharge increased from 13.8% to 20.0% over time (Z = 6.88, p < .0001). Concomitant use of anticholinergic medication was more common in patients receiving antipsychotic augmentation than clozapine antipsychotic monotherapy. Among patients discharged on clozapine, the rate of augmentation with a second antipsychotic increased from 19.1% to 36.2% over time (Z = 6.58, p < .0001). Among patients receiving antipsychotic augmentation, use of another second-generation antipsychotic as the augmentation agent grew from 32.6% to 65.5% over time (Z = 8.90, p < .0001). The increase in clozapine use was accompanied by an increase in concomitant use of a second antipsychotic as augmentation during the study period. Further studies are warranted to clarify the risk/benefit of this augmentation strategy. Clozapine may still be underutilized, and educational programs are needed to promote clinical use of clozapine.