title: Comparing the cost effectiveness of risperidone and olanzapine in the treatment of schizophrenia using the net-benefit regression approach.
abstract: To estimate the cost effectiveness of olanzapine and risperidone for the treatment of schizophrenia in Belgium. Data were retrieved from a prospective, observational, non-randomized, follow-up survey. Clinical investigators assigned 265 patients with schizophrenia to either olanzapine (n = 136) or risperidone (n = 129). Patients were followed up for 2 years. Total healthcare costs were determined from the public payer perspective and calculated by multiplying resource use with official tariffs; effectiveness of the drugs was measured with the EQ-5D. This study uses a net-benefit regression approach to accommodate for baseline differences between treatment groups and uncertainty. Total 2-year costs were very similar for patients receiving risperidone and olanzapine (euro20 915.33 and euro20 569.69, respectively; p = 0.925) [year 2002 values]. The health condition of the patients receiving risperidone was better than that of patients receiving olanzapine but not significantly so (1.46 and 1.41, respectively; p = 0.191). Simple ordinary least squares (OLS) regressions indicated that, for lambda = euro40 000, we could not reject the null hypothesis that the drugs provide similar net monetary benefits to the patient (risperidone vs olanzapine euro2046.95; p = 0.656). When we controlled for several patient characteristics, risperidone moved further away from olanzapine but the difference did not reach statistical significance (risperidone vs olanzapine euro3198.07; p = 0.595). Numerous sensitivity analyses confirmed the robustness of the results. Results of this study suggest that it is important to control for baseline patient characteristics when performing a cost-effectiveness analysis. No significant difference in net monetary benefit was found between risperidone and olanzapine.
authors.affiliation: Department of Mathematics, Statistics and Actuarial Sciences, Faculty of Applied Economics, University of Antwerp, Antwerp, Belgium. annemieke.deridder@ua.ac.be
authors.forename: Annemieke
authors.initials: A
authors.lastname: De Ridder
authors.forename: Diana
authors.initials: D
authors.lastname: De Graeve
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000191:economics* / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000191:economics* / Q000627:therapeutic use*; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D008297:Male; D000077152:Olanzapine; D011446:Prospective Studies; D012044:Regression Analysis; D018967:Risperidone / Q000191:economics* / Q000627:therapeutic use*; D012559:Schizophrenia / Q000188:drug therapy / Q000191:economics*
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D018967:Risperidone; D000077152:Olanzapine