Cost-effectiveness of clozapine compared with conventional antipsychotic medication for patients in state hospitals

Background: An open-label, randomized controlled trial compared clozapine with physicians'-choice medications among long-term state hospital inpatients in Connecticut. The goal was to examine clozapine's cost-effectiveness in routine practice for people experiencing lengthy hospitalizations. Methods: Long-stay patients with schizophrenia in a state hospital were randomly assigned to begin open-label clozapine (n = 138) or to continue receiving conventional antipsychotic medications (n = 89). We interviewed study participants every 4 months for 2 years to assess psychiatric symptoms and functional status, and we collected continuous measures of prescribed medications, service utilization, and other costs, We used both parametric and nonparametric techniques to examine changes in cost and parametric analyses to examine changes in effectiveness. We used bootstrap techniques to estimate incremental cost-effectiveness ratios and create cost-effectiveness acceptability curves. Results: Both groups incurred similar costs during the 2-year study period, with a trend for clozapine to be less costly than usual care in the second study year. Clozapine was more effective than usual care on many but not all measures. With the use of effectiveness measures that favored clozapine (extrapyramidal side effects, disruptiveness), bootstrap techniques indicated that, even when a payer is unwilling to incur any additional cost for gains in effectiveness, the probability that clozapine is more cost-effective than usual care is at least 0.80. These findings were not as evident when outcomes where clozapine was not clearly superior (psychotic symptoms, weight gain) were examined. Conclusion: Clozapine demonstrated cost-effectiveness on some but not all measures of effectiveness when the alternative was a range of conventional antipsychotic medications.