Comparison of the metabolic and economic consequences of long-term treatment of schizophrenia using ziprasidone, olanzapine, quetiapine and risperidone in Canada: a cost-effectiveness analysis.

RATIONALE, AIMS AND OBJECTIVES: Second-generation antipsychotic agents have varying propensities to cause weight gain, elevated lipid levels and associated long-term complications. This study evaluates the cost-effectiveness of four second-generation antipsychotic agents used in Canada for the treatment of schizophrenia (ziprasidone, olanzapine, quetiapine, risperidone) with a focus on their long-term metabolic consequences.

METHOD

Using data from the Clinical Antipsychotic Trials of Intervention Effectiveness Study, a semi-Markov model was developed to predict the incidence and associated costs of type 2 diabetes, cardiovascular complications (e.g. angina, myocardial infarction, stroke, cardiovascular disease death), and acute psychiatric hospitalizations in patients with chronic schizophrenia treated over 5 years. Incremental costs per quality-adjusted life year (QALY) gained were calculated from the perspective of the Canadian provincial ministries of health. Scenario and probabilistic sensitivity analyses were performed.

RESULTS

The total average cost of treatment with ziprasidone was $25,301 versus $28,563 with olanzapine, $26,233 with quetiapine and $21,831 with risperidone. Ziprasidone had the lowest predicted number of type 2 diabetes cases and cardiovascular disease events, and the highest QALY gains. Patients receiving quetiapine had the highest predicted number of hospitalizations. Ziprasidone was less costly and resulted in more QALYs compared with olanzapine and quetiapine. Compared with risperidone, ziprasidone was more costly and had higher QALYs, with an incremental cost per QALY gained of $218,060.

CONCLUSION

Compared with olanzapine and quetiapine, ziprasidone produced savings to the health care system. Although ziprasidone generated incremental expenditures versus risperidone, it resulted in more QALYs. Based on this analysis, ziprasidone treatment possesses cost and therapeutic advantages compared with olanzapine and quetiapine.