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

BACKGROUND Risperidone and olanzapine are thought to have broadly similar clinical effects. This study was designed as a cost analysis study comparing costs and basic clinical outcomes of treatment with risperidone or olanzapine in a naturalistic setting. METHOD The U.K. Risperidone Olanzapine Drug Outcomes Studies in Schizophrenia (RODOS-UK) program consisted of a retrospective review of medical notes and prescription charts for 501 patients with schizophrenia or schizoaffective disorder who had been admitted to the hospital for the treatment of psychosis. The main outcome measure was cost of inpatient drug treatment. Clinical outcomes (clinician-assessed and -documented effectiveness, time to discharge) were also evaluated. Data were collected and verified between June and September 2000. RESULTS Clinical outcomes were similar for risperidone and olanzapine. Clinician-assessed effectiveness was similar for both treatments (78% risperidone, 74% olanzapine; p =.39), but mean time to documented onset of effectiveness was significantly shorter for those treated with risperidone versus olanzapine (17.6 vs. 22.4 days; p =.01). Risperidone-treated patients stayed a mean of 9 fewer days in the hospital compared with olanzapine-treated patients (49 vs. 58 days; p =.007). The possibility that these observed differences were a result of different baseline characteristics could not be entirely discounted. Mean +/- SD doses of risperidone and olanzapine were 5.5 +/- 2.4 mg/day and 14.1 +/- 4.7 mg/day, respectively. The mean daily cost of all inpatient drugs was significantly higher for olanzapine than for risperidone (pound 5.63 vs. pound 3.92; p <.0001). Mean total costs of all inpatient drugs were significantly higher for olanzapine than for risperidone (pound 164 vs. pound 96; p <.0001), which partly reflected the longer mean treatment duration for olanzapine compared with risperidone (44 vs. 37 days). Concomitant antipsychotic use was similar for both groups (66% risperidone, 67% olanzapine). The number of patients documented as experiencing adverse events was not different between groups (22% risperidone, 19% olanzapine; p =.32). CONCLUSION Risperidone and olanzapine produced broadly comparable clinical outcome in this cohort of hospitalized patients, but the use of risperidone was associated with significantly lower drug treatment costs.