Treatment Pathway and Patterns of Clozapine Prescribing for Schizophrenia in New Zealand

Abstract

OBJECTIVE: To describe the treatment pathway and patterns of clozapine use in patients with schizophrenia, including coprescribed psychotropic medications, and compare the extent of coprescribing of clozapine with that of non-clozapine schizophrenia treatment in community mental health services in the Auckland and Northland regions of New Zealand. METHODS: A retrospective chart review was conducted for adult outpatients receiving care from community mental health services on October 31, 2004. Data collected for all patients prescribed an antipsychotic included demographics (sex, age, ethnicity); principal diagnosis (Diagnostic and Statistical Manual of Mental Disorders, 4th edition); comorbid conditions; duration of mental illness; psychiatric admissions; and treatment information (psychotropic medications, with dose and route of administration). If clozapine had been started after the introduction of full government prescription subsidy (February 1999), additional data, including year of initiation and prior antipsychotic history, were collected. Analysis included all outpatients with a diagnosis of schizophrenia (including schizoaffective disorder). RESULTS: Antipsychotics were prescribed for 2796 schizophrenia patients; 32.8% were prescribed clozapine, with a mean dose of 372 mg/day and an average duration of illness of 9.7 years before starting clozapine. Patients who had started treatment after clozapine was funded by the government (59.3%) had received a median of 3 antipsychotic drugs prior to starting clozapine; most of the treatment regimens included 1 second-generation antipsychotic (91.2%). Clozapine patients were less likely to be coprescribed another antipsychotic compared with non-clozapine patients (11.7% vs 17.6%; p < 0.001). Both the clozapine and non-clozapine groups had a low total number of psychotropic medications prescribed (median 2); for clozapine patients, the second drug was most likely to be for treatment of hypersalivation. CONCLUSIONS: Outpatients with treatment-resistant schizophrenia were prescribed clozapine at expected rates; however, treatment was delayed longer than recommended. There is some evidence that access to clozapine for treatment-resistant schizophrenia has improved, possibly as the result of the introduction of government subsidy, guideline dissemination, or increasing experience of clinicians with use of clozapine. In this real-world environment, the number of concomitant psychotropic medications for outpatients with schizophrenia was found to be low; when used concomitantly with clozapine, they were most commonly used to manage adverse effects.