ObjectivesTo assess the impact of switching atypical antipsychotic treatment [fromrisperidone to olanzapine orolanzapine to risperidone] on medication use patterns and treatment costs for individuals with schizophrenia.In contrast, after switching from olanzapine to risperidone there was no significant change in treatment patterns for any of the medications assessed or in healthcare costs (mental healthcare-related or total), despite a significant decrease in mental health-related pharmaceutical costs.MethodsUsing a large, integrated medical service and pharmacy claims database, 244 individuals diagnosed with schizophrenia (International Classification of Diseases [9th revision]: 295.xx) who switched treatment from risperidone to olanzapine (n = 202) or from olanzapine to risperidone (n = 42) were identified. Changes in medication use patterns and treatment costs (1999 values) per patient from the pre- to the post-switch period were evaluated. McNemar’s tests were used to compare changes in use of antiparkinsonian, antidiabetic and antihyperlipidaemic agents and typical antipsychotics, while the Wilcoxon signed rank tests were applied to examine changes in treatment costs.In contrast, after switching from olanzapine to risperidone there was no significant change in treatment patterns for any of the medications assessed or in healthcare costs (mental healthcare-related or total), despite a significant decrease in mental health-related pharmaceutical costs.ResultsAfter switching from risperidone to olanzapine, the percentage of patients using concomitant antiparkinsonian agents and typical antipsychotics decreased significantly from 30.20% to 21.29% (p = 0.0094) and from 30.69% to 18.32% (p = 0.0006), respectively. There was no significant change in the use of antidiabetic or antihyperlipidaemic drugs. For mental health-related treatment, annualised pharmaceutical costs increased by $US1761 (from $US1829 to $US3590, p < 0.0001) but medical service costs decreased by $US3511 (from $US11 292 to $US7781, p = 0.0036), driven primarily by significantly lower emergency room care and hospital outpatient costs. This resulted in no significant change in overall mental healthcare costs. Similar results were observed with total healthcare costs.In contrast, after switching from olanzapine to risperidone there was no significant change in treatment patterns for any of the medications assessed or in healthcare costs (mental healthcare-related or total), despite a significant decrease in mental health-related pharmaceutical costs.ConclusionsSwitching from risperidone to olanzapine was associated with improved medication use patterns for antiparkinsonian and typical antipsychotic agents. While both mental health and total healthcare pharmaceutical costs increased significantly, this was not associated with a significant increase in overall mental health and total healthcare costs. These outcomes, however, were not evidenced in patients switched from olanzapine to risperidone.