Long-acting risperidone compared with oral olanzapine and haloperidol depot in schizophrenia: a Belgian cost-effectiveness analysis

Patients with schizophrenia suffer numerous relapses and rehospitalizations that are associated with high direct and indirect medical expense. Suboptimal therapeutic efficacy and, in particular, problems with compliance are major factors leading to relapse. Atypical antipsychotic agents offer improved efficacy and a lower rate of extrapyramidal adverse effects compared with conventional antipsychotic drugs. Long-acting intramuscular risperidone combines these benefits with improvements in compliance associated with depot injections. To assist decision making regarding the place of long-acting risperidone in therapy, a cost-effectiveness analysis of strategies involving first-line treatment with long-acting risperidone, oral olanzapine or depot haloperidol was performed from the perspective of the Belgian healthcare system. A decision tree model was created to compare the cost effectiveness of three first-line treatment strategies in a sample of young schizophrenic patients who had been treated for I year and whose disease had not been diagnosed for longer than 5 years. The model used a time horizon of 2 years, with health state transition probabilities, resource use and cost estimates derived from clinical trials, expert opinion and published prices. The four health states in the model were derived from an analysis of the literature. The principal efficacy measure was the proportion of patients successfully treated, defined as those who responded to initial treatment and who had none to two episodes of clinical deterioration without needing a change of treatment over the 2-year period. Comprehensive sensitivity analysis was carried out to test the robustness of the model. A greater proportion of patients were successfully treated with long-acting risperidone (82.7%) for 2 years, compared with those treated with olanzapine (74.8%) or haloperidol (57.3%). Total mean costs per patient over 2 years were C 16 406 with long-acting risperidone, 17 074 euro with olanzapine and 21 779 euro with haloperidol (year of costing 2003). The mean cost-effectiveness ratios were 19 839 euro, 22 826 euro and 38 008 euro per successfully treated patient for long-acting risperidone, olanzapine and haloperidol, respectively. Results of the sensitivity analysis confirmed that the rebust to a wide variation of different input variables (effectiveness, dosing distribution, patient status according to healthcare system). Long-acting risperidone was the dominant depot haloperidol. Long-acting risperidone appears to represent a favourable first-line strategy for patients with schizophrenia requiring long-term maintenance treatment.