The impact of olanzapine, risperidone, or haloperidol on the cost of schizophrenia care in a Medicaid population

Objectives: The objective of this study was to assess the impact of medication treatment on Medicaid costs for persons with schizophrenia. Methods: Michigan Medicaid claims from January 1995 through September 1998 were analyzed for persons with schizophrenia diagnoses who initiated olanzapine (n = 458), risperidone (n = 481), or haloperidol (n = 252) treatment between January 1996 and September 1997. Total and component Medicaid payments were compared for the year after treatment initiation, with simultaneous adjustment for patient demographics, comorbid conditions, prior medication use, prior service use, and prior year costs. Results: Significant baseline differences existed between the groups in prior medication and service use. Adherence to index medication varied between the groups (O = 60%; R = 54%; H = 37%; P < = .01 for each pairwise comparison). Average postperiod costs were $14,512 per subject. After baseline adjustment, there were no significant differences in mean total cost. Excluding index medication costs, the olanzapine group's average cost was significantly lower than risperidone (-$1,791, P = .002) and haloperidol (-$2,080, P = .003), whereas the risperidone and haloperidol groups were not significantly different. The differences were driven by significantly lower cost for inpatient services for other medications among the olanzapine group. Conclusion: Total costs of schizophrenia care associated with olanzapine, risperidone, or haloperidol were similar, but component costs differed. Relative to risperidone or haloperidol, olanzapine may have a higher acquisition cost, but may decrease inpatient costs and be associated with more optimal medication use patterns. Use of risperidone may also increase pharmacy costs and be associated with greater persistence, relative to haloperidol.