Antipsychotic prescribing pathways, polypharmacy, and clozapine use in treatment of schizophrenia

To ensure optimal care for patients with schizophrenia, antipsychotic medications must be appropriately prescribed and used. Therefore, the primary objectives of this study were to identify and describe pathways for antipsychotic prescribing, assess the consistency of observed pathways with treatment guidelines, and describe variability across facilities.

Data from Veterans Affairs administrative data sets from fiscal year (FY) 2003 to FY 2007 were gathered for analysis in this retrospective cohort study of antipsychotic prescribing pathways among 13 facilities across two regional networks. Patients with a new episode of care for schizophrenia or schizoaffective disorder in FY 2005 were identified, and antipsychotic prescribing history was obtained for two years before and after the index diagnosis. Demographic characteristics and distribution of comorbidities were assessed. Median medical center rates of polypharmacy were calculated and compared with Fisher's exact test.

Of 1,923 patients with a new episode of schizophrenia care, 1,003 (52%) had complete data on prescribing pathways. A majority (74%) of patients were prescribed antipsychotic monotherapy, and 19% received antipsychotic polypharmacy. Of patients receiving antipsychotic polypharmacy, 65% began polypharmacy within 90 days of starting any antipsychotic treatment. There was a fourfold difference in polypharmacy across facilities. Antipsychotic polypharmacy was not associated with geographic location or medical center patient volume. Clozapine utilization was low (0%-2%).

Retrospective examination of longitudinal prescribing patterns identified multiple antipsychotic prescribing pathways. Although most patients received guideline-concordant care, antipsychotic polypharmacy was commonly used as initial treatment, and there was substantial variability among facilities. Study findings suggest the utility of secondary data to assess treatment adaptation or switching for practical clinical trials.