Purpose: To compare the characteristics of outpatients who were initiated on olanzapine or risperidone in the naturalistic treatment of schizophrenia in Japan.
Methods: The Japan Medical Data Centre Database (JMDC) was used to identify patients diagnosed with schizophrenia or schizoaffective disorder using ICD-10 codes. Patients were required to be 20-65 years old, to have initiated olanzapine or risperidone therapy at an outpatient setting between January 2004 and July 2008, and to be continuously enrolled during the 6 months prior and 12 months post initiation date. Treatment groups were compared on demographics, medical and psychiatric comorbidities, prior medication use patterns, and prior health care resource utilization. Chi-square tests and t-tests were employed for univariate comparisons. Multivariate logistic regressions were used to assess the independent contribution of the predictors.
Results: In both the multivariate and univariate models, olanzapine-initiated patients (n=334) were more likely than risperidone-initiated patients (n=502) to have a history of treatment with antidepressants (56.6% vs. 43.8%, p < 0.001) and a history of prior manic episodes (59.3% vs. 51.6%, p = 0.03).
Discussion: Current findings suggest that in Japan, olanzapine and risperidone are not used interchangeably. Olanzapine appears to be used more often for schizophrenia patients with comorbid mood symptoms, as reflected by a prior diagnosis of manic episodes and prior treatment with antidepressants. Previous research has found that schizophrenia patients with depressive symptoms have a worse prognosis across a broad range of outcomes including the use of more relapse-related mental health services, higher rates of arrests, and suicidality, as well as poorer quality of life, mental functioning, family relationships, and medication adherence.