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

Abstract

Objective:

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.

Methods:

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.

Results:

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).

Conclusions:

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.

Key words::

• Aripiprazole
• Cost-effectiveness analysis
• Olanzapine
• Schizophrenia

Transparency

Declaration of funding

This study was funded by Eli Lilly and Company.

Declaration of financial/other relationships

H.A.-S., X.P., D.F., V.S. and O.O. have disclosed that they are full-time employees and minor stockholders of Lilly. M.S. has disclosed that he was an employee of Lilly during the development and data analysis. J.K. has disclosed that he serves as a consultant and is on the Speakers Bureau for the following commercial organizations: Astra-Zeneca (speaker), Bristol Meyer Squibb (speaker), Cephalon, Dainippon Sumitomo, GlaxoSmithKline, Intracellullar Therapeutics, Janssen (speaker), Johnson & Johnson, Lilly (speaker), Otsuka America Pharmaceutical, Inc. (speaker), Pfizer, PGxHealth, Proteus, Takeda, Vanda and Wyeth.

Acknowledgments

Technical writing support was provided by Susan L. Dennett, PhD of Strategic Health Outcomes, Inc.

The data in this paper were presented as a poster at the American Psychiatric Association’s 61st Institute on Psychiatric Services, October 8–11, 2009, New York, NY, USA. ‘Stensland MD, Peng X, Ascher-Svanum H, Faries DE, Stauffer VL, Osuntokun OO, Kane JM. The cost-utility of olanzapine versus aripiprazole in the treatment of schizophrenia.’