Methods
In this pharmacoepidemiological study, we investigated real-life prescribing trends related to psychotropic drugs in schizophrenia patients at Dokkyo Medical University Hospital and its affiliated hospitals. The study was initiated in April 2021 and was conducted in 15 psychiatric hospitals. To avoid sampling bias, we enrolled up to 70 consecutive patients with schizophrenia attending each hospital from April 1, 2021, whose prescriptions could be traced over the past 20 years; for institutions that did not reach 70 patients, all patients were enrolled. We retrospectively examined all prescriptions as of April 1, 2016, 2011, 2006, and 2001, every 5 years starting in 2021, for this population. Consensus meetings were held at each site prior to the study to discuss issues related to data collection and the uniformity of data entry. The participating patients met the diagnostic criteria for schizophrenia in the International Classification of Diseases, Tenth Edition (ICD-10)18 or the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5).19Patients with clinically significant medical illnesses or active psychotic symptoms related to comorbid substance use disorders were excluded.
The data collected included basic sociodemographic information and information on all prescribed medications. Daily doses of antipsychotic drugs were calculated using the equations in the Inada & Inagaki article as average daily CPeq, imipramine equivalents, and diazepam equivalents.20 This study was approved by the Ethics Committee of Dokkyo Medical University Hospital (Ref. R-54-3J).
Statistical Package for Social Sciences (SPSS) Version 28 (SPSS Inc., Chicago, IL, USA) was used for analysis. The Cochran Q test and repeated-measures analysis of variance (ANOVA) and were used to determine the differences among the five groups. Although statistical significance required a two-sided P<0.05, these were adjusted by Bonferroni’s correction to avoid multiplicity, and P < 2.5 × 10-3 (0.05/20) was defined as significant. Cochran–Armitage trend test and the Pearson correlation test were used to determine the trends. There statistical significances required a two-sided P<0.05