This year long study carried out by Medical Decision Modeling in Indianapolis set out to measure the cost-effectiveness of the olanzapine long-acting injection with other antipsychotic long-acting injections and oral olanzapine in treating patients with schizophrenia who had trouble adhering to oral drug treatment.

The study used a micro-simulation economic decision model to replicate usual care.  The model used a number of parameters including adherence levels, relapse with and without hospitalisation, treatment discontinuation rates by reason, treatment-emergent adverse events, suicide, health care resource utilization, and direct health care costs.

Key outcomes were the direct cost of treatment and the cost effectiveness as measured by quality-adjusted life years (QALYs):

• The olanzapine long-acting injection was more effective and cheaper than other antipsychotic injections (risperidone, paliperidone and haloperidol)
• The olanzapine long-acting injection was more effective and most costly than oral olanzapine (estimated incremental cost/QALY of $26,824 compared to oral olanzapine)
• The olanzapine long-acting injection remained within acceptable cost-effective ranges (<$50,000) in terms of incremental cost/QALY gained.

The authors concluded:

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.

Furiak NM, Ascher-Svanum H, Klein RW, Smolen LJ, Lawson AH, Montgomery W, Conley RR. Cost-effectiveness of olanzapine long-acting injection in the treatment of patients with schizophrenia in the United States: a micro-simulation economic decision model. Curr Med Res Opin. 2011 Apr;27(4):713-30. Epub 2011 Jan 25.