Risperidone, haloperidol and clozapine in the South Carolina Medicaid program - A comparative analysis of utilisation and expenditure

Objective: To determine whether the increased acquisition costs associated with the atypical antipsychotic risperidone are offset by reductions in oth er mental health care utilisation and expenditure. Design and setting: The study was population-based and used South Carolina Medicaid claims data to determine changes in mental healthcare utilisation and expenditures related to schizophrenia. Changes in mental health-related utilisation and expenditures over time were calculated; total mental healt h-related expenditures and utilisation were disaggregated into pharmaceutic als, inpatient hospitalisations, and ambulatory and inpatient physician ser vices [Health Care Financing Administration (HCFA) 1500 claims]. Groups of patients were compared for two 6-month periods preceding the initial prescr iption (pre1 and pre2), and two 6-month periods following the initial presc ription (post1 and post2). Costs were discounted to the index date. Perspective: Payor (South Carolina Medicaid). Patients: Those patients with schizophrenia who received initial prescripti ons for risperidone (n = 862), haloperidol (n = 325) or clozapine (n = 66) between February 1994 and June 1995 tinder date). Main outcome measures and results: The mean increase in level of expenditur e per person for pharmaceuticals from the pre- to the post-treatment period was significantly greater in the risperidone [751 US dollars ($US)I and cl ozapine ($US1423) groups than in the haloperidol group ($US6). However, the change in mean level of total mental healthcare expenditure per person was not significantly different fur the risperidone group ($US832) compared wi th the haloperidol group ($US540) over the same time period, but the increa se in the clozapine group was significantly higher ($US2500.23; p < 0.0001 for clozapine vs risperidone and clozapine vs haloperidol). As the difference between the risperidone and haloperidol groups in pharmac eutical expenditures was not reflected in total mental healthcare expenditu res, the remaining component costs were investigated to identify where the difference was offset. Compared with haloperidol, risperidone had a signifi cantly smaller change in per person mean level of ambulatory and inpatient physician services claims for expenditure ($US692 vs $US269, p = 0.01) and utilisation (+1.70 vs -0.21, p < 0.0001). Conclusions: Based on these findings, we conclude that, in this population of patients with schizophrenia increased costs associated with risperidone were offset by decreases in other mental healthcare utilization. Risperidon e is a technical substitute for ambulatory healthcare services.