A Swiss retrospective naturalistic outcome study comparing risperidone and olanzapine in the treatment of schizophrenic inpatients

Atypical anti-psychotics such as clozapine, risperidone and more recently olanzapine have become the cornerstone of the treatment of schizophrenia. These drugs have superior efficacy and tolerability and a better compliance than conventional anti-psychotics, translating into lower relapse and rehospitalisation rates. The RODOS program (Risperidone Olanzapine Drugs Outcome studies in Schizophrenia) was designed to provide outcomes data for risperidone and olanzapine used in a naturalistic clinical setting. This international retrospective study was conducted on 1901 inpatients. The present paper compares the drug-usage pattern and the costs and outcomes associated with the treatment of schizophrenia or schizo-affective disorders with either risperidone or olanzapine in Switzerland. Retrospective chart reviews were carried out in five Swiss hospitals, for inpatients for whom either risperidone or olanzapine was the drug of first intention for long-term treatment. Patients selected were aged ≤65 years and diagnosed with schizophrenia or schizo-affective disorder. Sociodemographic data and clinical information were collected in patients' files, as well as hospitalisation information and usage pattern of all drugs used during the stay in hospital. Treatment efficacy was recorded, as well as time to efficacy, time to discharge, treatment discontinuation and spontaneously reported side effects. Treatment was rated as "effective" or "ineffective" according to the patient's file as noted by the treating physician. Drug prices (including concomitant medication) were calculated and expressed in local currency at the level of the hospital pharmacy purchasing price. The total population comprised 312 patients, 154 receiving risperidone and 158 receiving olanzapine. The two treatment groups did not have significant differences regarding sociodemographic characteristics, history of schizophrenia and use of previous anti-psychotics. The risperidone and olanzapine groups were comparable in terms of number of days before efficacy was established, proportion of patients with effective treatment (83 vs 85%, p = 0.67), number of patients with symptom improvement, discontinuation rate and time to discharge (median 31 vs 41 days, p = 0.32). Mean dosage at the end of treatment for those patients who were discharged was 3.8 mg for risperidone and 14.9 mg for olanzapine. The average daily cost of the study medication was significantly higher for olanzapine than for risperidone (geometric mean: 11.33 vs 4.15 CHF, p <0.0001). The total cost of the treatment drug was also significantly higher for olanzapine compared to risperidone (geometric mean: 289.0 vs 92.0 CHF, respectively, p <0.0001). During the treatment period, 47 patients (31%) treated with risperidone and 49 patients (31%) treated with olanzapine experienced adverse events. These results show that both treatments have comparable efficacy and short-term side-effect profile, with an almost three times lower cost for risperidone. This is true in all comparisons: all inpatients drugs or study medication only, total population or responding patients, whole hospitalisation or treatment period only. Thus, assuming the same effectiveness for risperidone and olanzapine, but higher costs for the latter drug, the cost-effectiveness ratio of risperidone is to be considered more favourable.