Factors predicting high-dose and combined antipsychotic prescribing in New Zealand: High-dose antipsychotic prescribing

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Psychiatry Research


Objective: Guidelines recommend using antipsychotic monotherapy at the lowest effective dose, however high-dose and antipsychotic polypharmacy prescribing (APP) remain commonplace. The aim of this study was to determine the prevalence and patterns of high-dose antipsychotic prescribing and APP among mental health service users in New Zealand (NZ). Methods: A retrospective audit of service users discharged from inpatient (n=657), or registered with community (n=1560), mental health services at Auckland District Health Board was undertaken. Case notes were reviewed and data on demographics, antipsychotic routes and doses were collected. Outcomes measures included: frequency of total high-dose prescribing, high-dose monotherapy, APP, high-dose APP, and factors associated with these prescribing practices. Logistic regression models were used to examine the relationships between explanatory and outcome variables. Results: Of the service users prescribed an antipsychotic (n = 2217), 14% were prescribed a high-dose antipsychotic. The frequency of high-dose monotherapy, APP, and high-dose APP was 3%, 26% and 11%, respectively. Being male, Māori, on compulsory treatment, having a schizophrenia diagnosis, or being prescribed polypharmacy were associated with high-dose antipsychotics. Olanzapine was most frequently prescribed in both high dosing (55%) and APP (40%). Conclusions: There is a high prevalence of high-dose prescribing and APP in this NZ setting.



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