Cost-effectiveness of olanzapine vs. aripiprazole in the treatment of schizophrenia

Information about the cost-effectiveness of aripiprazole relative to other atypical antipsychotics in the treatment of patients with schizophrenia is limited. This information is needed to better inform drug formulary managers and population-based health care decision makers. The objective of this study was to compare the cost-effectiveness of olanzapine to aripiprazole in the treatment of schizophrenia from the perspective of public payers in the United States. Data for this post-hoc analysis came from a 28-week double-blind, randomized trial of individuals with schizophrenia who were treated with olanzapine or aripiprazole (clinicaltrial.gov identifier NCT00088049). Two-thirds (67.7%) of the patients were male and the patients' mean age was 37.6 years. Utilities were calculated based on previously published methods using the Positive and Negative Syndrome Scale (PANSS) and treatment-emergent adverse events. Treatment costs were calculated based on previously published methods and were inflated to 2008 US dollars. A mixed model was used to compare outcomes on utilities. Propensity score-adjusted analysis of covariance was used for the cost analysis. Olanzapine treatment was associated with statistically significantly greater total utility scores relative to aripiprazole (0.78 vs. 0.76; p = 0.024) and lower total treatment costs ($22,831 vs. $24,749; p = 0.013), although medication acquisition cost was significantly higher for olanzapine than aripiprazole ($3524 vs. $2637; p < 0.001). An incremental cost-effectiveness ratio was not calculated because olanzapine was found to be the dominant choice (i.e., greater effectiveness and lower total costs). This cost-effectiveness analysis is the first to use patient-level data from a randomized, double-blind study comparing olanzapine and aripiprazole in the treatment of patients with schizophrenia. Olanzapine was found to be a dominant cost-effective choice, as it was associated with greater effectiveness at lower total costs relative to aripiprazole.