Factors associated with high-dose antipsychotic prescriptions in outpatients with schizophrenia: An analysis of claims data from a Japanese prefecture

Background Antipsychotics are commonly prescribed in high doses in combination with multiple psychotropic drugs. This study focused on the high-dose antipsychotic prescriptions in patients with schizophrenia, while aiming to identify their associations with patients' characteristics and concurrent psychotropic prescriptions. Methods This cross-sectional study used claims data from a prefecture in Japan, between October 2014 and March 2015, to investigate antipsychotic prescriptions in adult outpatients with schizophrenia. The objective variable was the presence/absence of a high-dose prescription. The explanatory variables included sex, age (category), presence of comorbid conditions, and the use of psychiatrist's therapy. Results After exclusion, a total of 13 471 patients with schizophrenia were analyzed. The frequency of high-dose prescriptions was higher in men, with chlorpromazine-equivalent values highest in the age ranges of 45-54 and 35-44 years for men and women, respectively. Patients aged below 65 years with cerebrovascular diseases showed a decrease in high-dose prescriptions. There was a high frequency of polypharmacy psychotropic drug use in combination with a high-dose antipsychotic prescription in patients aged below 65 years. Conclusion High-dose antipsychotics are often used in combination with several psychotropic agents in patients with schizophrenia. Our findings emphasize the need to evaluate the prescribing behavior of physicians to avoid high-dose antipsychotic prescriptions for improved patient care.