Risperidone compared with olanzapine in a naturalistic clinical study in Ireland: a cost analysis.

BACKGROUND: Risperidone and olanzapine are thought to have similar clinical effects. This study was designed to compare costs of treatment. AIM: To compare costs of treatment with risperidone or olanzapine in a naturalistic setting.
METHOD: The Irish Risperidone Olanzapine Drug Outcomes studies in Schizophrenia (RODOS) programme was a retrospective review of medical notes and prescription charts in 396 inpatients with schizophrenia or schizoaffective disorder. The main outcome measure was cost of inpatient drug treatment.
RESULTS: There was no statistical difference in length of hospital stay between risperidone-treated and olanzapine-treated patients (mean duration of stay 37.8 and 40.5 days, p=0.90). Mean+/-SD doses of risperidone and olanzapine were 4.2+/-2.1 mg/day and 12.9+/-5.0 mg/day, respectively. Average daily cost of all inpatient drugs was significantly higher for olanzapine than for risperidone (i.e. IEP5.61 [7.12] vs IEP3.38 [4.29]; p<0.0001), as was mean total costs of all inpatient drugs (i.e. IEP114.8 [145.8] vs IEP62.0 [78.7]; p<0.0001). This partly reflected the mean, non-significant, longer treatment duration for olanzapine compared with risperidone (mean 30.0 vs 26.4 days; p=0.27). Concomitant neuroleptic use was similar for both groups (71% risperidone, 73% olanzapine; p=0.54).
CONCLUSION: Risperidone was associated with significantly lower drug treatment costs.