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