A cost-effectiveness clinical decision analysis model for treatment of Schizophrenia.

BACKGROUND: Schizophrenia afflicts approximately 0.7% of Mexican citizens during their lifetime. This study explored whether the difference in clinical efficacy and safety between atypical antipsychotics and conventional neuroleptics results in decreases in use and cost of medical services in Mexico, offsetting the higher price of atypical antipsychotics.

METHODS: A U.S. decision analytic Markov model was adapted for use in Mexico to determine cost-effectiveness of treatments and outcomes that Mexican patients with schizophrenia may experience over a 5-year period when treated with olanzapine, haloperidol, or risperidone. Model parameter estimates were based on clinical trial data, published medical literature, and where needed, clinician judgment. Direct medical costs were incorporated into the model and outcomes were estimated using lack of relapse and clinical outcomes based on the Brief Psychiatric Rating Scale (BPRS) as effectiveness indicators. All costs are reported in Mexican pesos.

RESULTS: Over a 5-year period, the cost of treating schizophrenia ranged from 196,620 pesos per patient initiating therapy with haloperidol to 226,670 pesos per patient beginning therapy with risperidone. Olanzapine was estimated to have slightly better non-relapse and BPRS-based effectiveness outcomes, but comparative total medical costs compared to risperidone. Patients receiving olanzapine experienced 13 and 2% fewer relapses compared with patients on haloperidol and risperidone, respectively. The 5-year incremental cost-effectiveness ratio of olanzapine compared with haloperidol was 52,740 pesos per improved patient, BPRS-based outcome and 212,540 pesos per avoided relapse. Sensitivity analyses indicated the model was sensitive only to changes in drug costs.

CONCLUSIONS: Compared with haloperidol, olanzapine therapy results in improved symptoms, fewer relapses, and is cost-effective, even with conservative values for key model parameters. Olanzapine results in slightly improved patient outcomes and comparable costs compared with risperidone.