Choice of atypical antipsychotic therapy for patients with schizophrenia: An analysis of a Medicaid population

Background: In patients treated at Veterans Affairs facilities, demographic and clinical characteristics have been found to influence the choice of atypical antipsychotic drugs. However, little is known about the influences on the choice between olanzapine and risperidone in patients with schizophrenia enrolled in Medicaid. Objective: The aim of this study was to determine whether demographic and/or clinical characteristics and/or medical-service utilization before treatment were related to the choice of olanzapine versus risperidone therapy using data from a Medicaid population with schizophrenia. Methods: The study sample was identified in the North Carolina (NC) Medicaid claims database. Data were included from patients aged 18 to 64 years who were diagnosed with schizophrenia; had initiated treatment with olanzapine or risperidone between July 1, 1998, and October 31, 2000; had not used atypical antipsychotics during the 6 months before the start of treatment; and were continuously eligible in the NC Medicaid program during the 6 months before the start of treatment. Multivariate logistic regression models were used to estimate the likelihood of the choice of olanzapine or risperidone associated with patients' demographic and clinical characteristics and medical-service utilization during the 6 months before the initiation of treatment. Results: A total of 764 patients (383 women, 381 men; mean age, 42.1 years) were included in the analysis: 420 were initially prescribed olanzapine and 344 were prescribed risperidone. Men were more likely than women to be prescribed olanzapine compared with risperidone. Patients who had a hospitalization related to a psychiatric condition during the pretreatment period were more likely to be prescribed olanzapine compared with risperidone (OR = 1.530; P = 0.043). Significant regional variation in the likelihood of prescribing olanzapine or risperidone was found, with patients being prescribed risperidone at a higher rate compared with olanzapine in 2 counties with the largest schizophrenic populations. Conclusions: In this study of data from patients with schizophrenia identified in the NC Medicaid claims database, sex, a history of psychiatric-related hospitalization, and geographic residence were found to be correlated with the selection of treatment with olanzapine versus risperidone. These findings need to be confirmed in large, randomized, prospective studies.