Antipsychotic polypharmacy in patients with schizophrenia: a multicentre comparative study in East Asia.

AIMS: Previous studies of the prescription patterns of psychotropic medications in patients with schizophrenia have highlighted a high rate of antipsychotic polypharmacy, but data in Asia are sparse. This study seeks to examine the prevalence of antipsychotic polypharmacy in patients with schizophrenia and compare the differences between patients receiving one vs. those receiving more than one antipsychotic. METHODS: Antipsychotic prescription for a sample of 2399 patients with schizophrenia from six countries and territories was evaluated. Daily doses of antipsychotic medications were converted to standard chlorpromazine equivalents (CPZ). RESULTS: Antipsychotic polypharmacy was found in 45.7% (n = 1097) of the patients with wide intercountry variations. Polypharmacy was associated with male gender [odds ratio (OR) 1.24, 95% confidence interval (CI) 1.06, 1.46, P < 0.01], advanced age (t = -7.81, d.f. = 2396, P < 0.001), psychiatric hospital setting (OR 1.34, 95% CI 1.11, 1.62) as well as higher daily CPZeq doses (411.47 vs. 983.10 CPZeq day(-1), z = -25.94, P < 0.001), anticholinergic use (OR 3.17, 95% CI 2.65, 3.79, P < 0.001) and less use of an atypical antipsychotic drug (OR 0.83, 95% CI 0.71, 0.98, P < 0.05). On multivariate analysis, country, age and duration of illness were significantly associated with antipsychotic polypharmacy. CONCLUSION: This study highlighted the wide intercountry variations of antipsychotic polypharmacy which are likely to be influenced by a complex combination of clinical, setting, cultural and personal practice factors, requiring more research.

Antipsychotic drug prescription for schizophrenia in East Asia: rationale for change.

The purpose of this international collaborative study was to investigate the prescription patterns of antipsychotic drugs for schizophrenia in East Asia and to analyze factors that affect these patterns. Prescription patterns for patients admitted for treatment of schizophrenia were surveyed using a standardized protocol from six East-Asian region/countries: China, Hong Kong, Japan, Korea, Singapore and Taiwan. Patients' social and clinical characteristics, psychiatric symptoms, course of illness, and adverse effects of medications were systematically assessed and recorded. Prescriptions of the first- and second-generation antipsychotic drugs were compared. A total of 2399 patients were recruited. The second-generation drugs comprised 28.1% of all prescribed antipsychotics, and 46% of the antipsychotic prescriptions were in the context of polypharmacy. The mean dosage of antipsychotics for the whole sample was 675.3 + 645.1 mg chlorpromazine equivalents. Japan had a high frequency of prescribing high doses and polypharmacy; Singapore had a high utilization of depot injections while China had a higher prescription of clozapine. Using multiple logistic regression analysis, distinctions in the prescription patterns of antipsychotic drugs were found: first-generation drugs were mainly for controlling aggressive behavior, while second-generation drugs were targeted at the alleviation of positive, negative psychotic symptoms as well as disruptive behavior in schizophrenia. The present collaborative study highlighted differences in the prescription patterns, especially the under-utilization of second-generation antipsychotic drugs in East Asia. The pattern of antipsychotic medication use varied from country to country and is likely to be influenced by the prevailing health-care system, the availability and cost of the drugs.