Antipsychotic utilisation and persistence in Australia: A nationwide 5-year study.

Abstract

To evaluate the utilisation and persistence of antipsychotics for the treatment of schizophrenia in Australia. A retrospective study using the Australian Pharmaceutical Benefits Scheme database of a representative 10% sample. All adults with schizophrenia who were dispensed three or more supplies of oral (including clozapine) or long-acting injectable antipsychotics between 1 June 2015 and 31 May 2020 were included. Persistence time in treatment was evaluated using survival analysis and Cox hazard ratios. In all, 26,847 adults with schizophrenia were studied. Oral second-generation antipsychotics were more frequently dispensed than the other antipsychotic groups studied. Median treatment persistence times were 18.3 months for second-generation antipsychotic long-acting injectables, 10.7 months for oral second-generation antipsychotics and were significantly lower for both formulations of first-generation antipsychotics at 5.2 months (long-acting injectables) and 3.7 months (oral). The median persistence time for clozapine was significantly longer than all other antipsychotics groups. Oral second-generation antipsychotics and second-generation antipsychotic long-acting injectables accounted for over 75% and 13% of all antipsychotics in Australia, respectively. Concerns over medication adherence and subsequent relapse have not translated into increased long-acting injectable usage despite their significantly longer persistence. Clozapine, the single most 'persistent' antipsychotic, was only used in 9% of people, although up to a third of all cases are likely to be treatment-resistant. Our data suggest clinicians should give consideration to the earlier use of second-generation antipsychotic long-acting injectables and clozapine, to ameliorate prognosis in schizophrenia.