Cost-effectiveness of olanzapine long-acting injection in the treatment of patients with schizophrenia in the United States: a micro-simulation economic decision model

Abstract

Objective:

To compare, from the perspective of third-party payers in the United States health care system, the cost-effectiveness of olanzapine long-acting injection (LAI, depot) with alternative antipsychotic agents including risperidone-LAI, paliperidone-LAI, haloperidol-LAI, and oral olanzapine, in the treatment of patients with schizophrenia who have been non-adherent or partially adherent with oral antipsychotics.

Research design and methods:

A 1-year micro-simulation economic decision model was developed to simulate the dynamics of usual care of patients with schizophrenia who continue, discontinue, switch, or restart their medication. The model uses a range of clinical and cost parameters including adherence levels, relapse with and without hospitalization, quality-adjusted life years (QALYs), treatment discontinuation rates by reason, treatment-emergent adverse events, suicide, health care resource utilization, and direct health care costs. Published medical literature and a clinical expert panel were used to develop baseline model assumptions.

Outcome measures:

Key model outputs include annual total direct cost (US$) per treatment and incremental cost-effectiveness values per additional QALY gained.

Results:

Model results found that the olanzapine-LAI treatment strategy was more effective (greater QALYs) and less costly than risperidone-LAI, paliperidone-LAI, and haloperidol-LAI. In addition, olanzapine-LAI was both more effective and more costly, with an estimated incremental cost/QALY of $26,824 compared to oral olanzapine. The base-case and multiple sensitivity analyses found olanzapine-LAI to remain within acceptable cost-effective ranges (<$50,000) in terms of incremental cost/QALY gained.

Conclusions:

This micro-simulation model finds the olanzapine-LAI treatment strategy to result in better effectiveness and to be a cost-effective alternative compared to oral olanzapine and the LAI formulations of risperidone, paliperidone, and haloperidol in the treatment of non-adherent and partially adherent patients with schizophrenia in the United States. A key limitation is the assumption how LAI therapies compare to oral counterparts due to sparse head-to-head data. Further research is needed to verify baseline assumptions.

Key words::

• Cost effectiveness
• Depot
• Long-acting injection
• Olanzapine
• Schizophrenia

Transparency

Declaration of funding

The study was funded by Eli Lily and Company, the manufacturer of oral olanzapine and olanzapine long-acting injection. The sponsor actively participated in the design, execution and writing of this study.

Declaration of financial/other relationships

H.A.-S., A.H.L., W.M., and R.R.C. are all full-time employees and minor shareholders of Eli Lilly and Company. N.M.F., R.W.K., and L.J.S. have consulting agreements with Eli Lilly and Company.

Peer reviewers may receive honoraria from CMRO for their review work. The peer reviewers have disclosed no relevant financial relationships.

Acknowledgments

The authors thank Steven D. Culler, PhD of Emory University for his assistance with review of the model and Megha Bansal, MA of Medical Decision Modeling Inc. for assistance with the analyses and manuscript preparation.

Prior versions of this paper has been previously presented in poster form at the Institute on Psychiatric Services 61st Annual Meeting (Oct 8–11 2009, New York, NY, USA), the American Psychiatric Association 162nd Annual Meeting (May 16–21 2009, San Francisco, CA, USA), the International Society for Pharmacoeconomics and Outcomes Research – 14th International Meeting (2009, Orlando, FL, USA), the International Center for Mental Health Policy and Economics – 9th Workshop on Costs and Assessment in Psychiatry (March 27–29 2009, Venice, Italy).