Antipsychotic utilization patterns among patients with schizophrenic disorder: a cross-national analysis in four countries.

PURPOSE: The aim of the present study was to describe antipsychotic utilization patterns among patients with schizophrenic disorder in Italy, Spain, the UK, and the USA. METHODS: A retrospective cohort study was conducted. Patients aged 15 and over with schizophrenic disorder were identified in the Caserta claims database (Italy), the Valencia electronic medical record (EMR) database (Spain), in The Health Improvement Network EMR database (UK), and in databases of publicly and privately insured populations in the United States (US). RESULTS: The frequency of first-generation or second-generation antipsychotic use and of long-acting or other formulations was described. Persistence to antipsychotics was estimated. Overall, 1,403,240 patients with schizophrenic disorder having a total of 765,573 new antipsychotic treatment episodes were identified. The median follow-up time ranged from 0.8 (IQR 0.2-1.9) years in the US commercially-insured population to 1.2 (IQR 0.1-1.7) years in the Spanish population. Second-generation antipsychotics were more frequently used than first-generation antipsychotics in all countries (on average, from 64.4% in the UK to 87% in US): the use of this class increased over time in Italy, Spain, and US (Medicaid). The use of long-acting formulations was heterogeneous across countries, but generally much lower than other formulations. Persistence to antipsychotic treatment at 1 year was low in all countries, ranging from 40 in Spain to 30% in Italy. CONCLUSIONS: Antipsychotic utilization was heterogeneous among persons with schizophrenic disorder. Nevertheless, low persistence was an issue in all the countries, as less than half of the patients continued their treatment beyond 1 year.