Olanzapine versus risperidone - A prospective comparison of clinical and economic outcomes in schizophrenia

Objective: To compare the clinical and economic outcomes associated with ol anzapine and risperidone treatment for schizophrenia. Design and setting: An international, multicentre, double-blind, prospectiv e study. To facilitate economic comparisons, our sample was restricted to p atients enrolled in US sites. 150 patients with a Diagnostic and Statistica l Manual of mental disorders, 4th edition (DSM-IV) diagnosis of schizophren ia, schizoaffective disorder or schizophreniform disorder were randomised t o therapy with either olanzapine 10 to 20 mg/day (n = 75) or risperidone 4 to 12 mg/day (n = 75) for a maximum of 28 weeks. In addition to tolerabilit y and efficacy assessments, use of health services was assessed at baseline and prospectively, at 8-week intervals and at study completion. Clinically important response, defined as a 40% improvement in the Positive and Negat ive Syndrome Scale total score, maintenance of response and rates of treatm ent-emergent extrapyramidal symptoms were compared between groups. Direct m edical costs were estimated by assigning standardised prices to resource un its. Median total, inpatient/outpatient service and medication acquisition costs were compared between treatment groups. Main outcome measures and results: The mean modal dosages for the olanzapin e and risperidone treatment groups were 17.7 +/- 3.4 mg/day and 7.9 +/- 3.2 mg/day, respectively. Olanzapine-treated patients were more likely to main tain response compared with risperidone-treated patients (p = 0.048). In ad dition, a smaller proportion of olanzapine-treated patients required antich olinergic therapy compared with risperidone-treated patients (25.3 vs 45.3% ; p = 0.016). Total per patient medical costs over the study interval were $US2843 (1997 values) [36%] lower in the olanzapine treatment group than in the risperidone treatment group (p = 0.342). Medication costs were signifi cantly higher for olanzapine-treated patients ($US2513 vs $US1581; p < 0.00 1), but this difference was offset by a reduction of $US3774 (52%) in inpat ient/outpatient service costs for olanzapine-treated patients in comparison with risperidone-treated patients ($US3516 vs $US7291, p = 0.083). Median cost findings were consistent with results observed using other robust meas ures of central tendency and provide conservative estimates of potential sa vings that may be obtained from olanzapine therapy. Conclusions: In this study, olanzapine-treated patients experienced clinica l improvements that translated into savings in costs of care for both inpat ient and outpatient services. These savings offset the difference in medica tion acquisition cost between olanzapine and risperidone.