Long-term combination antipsychotic treatment in VA patients with schizophrenia

Treatment guidelines consider antipsychotic monotherapy the standard of care for patients with schizophrenia. However, previous studies have reported widely varying, and sometimes high, rates of antipsychotic polypharmacy. We identified 61,257 VA patients with schizophrenia in fiscal year 2000 who had >or=90 non-institutionalized days and one or more fills of antipsychotic medications. We used criteria of increasing stringency (>or=30, >or=60, or >or=90 overlapping days' supply of antipsychotic medications) and several cross-sectional criteria from previous studies to compare the prevalence of antipsychotic polypharmacy using these definitions. We also describe specific treatment combinations among patients receiving long-term polypharmacy. The prevalence of antipsychotic polypharmacy was 20.0%, 13.1%, and 9.5% when defined by a >or=30, >or=60, or >or=90-day overlap, respectively. Cross-sectional definitions used in previous studies did not identify 32-89% of patients receiving long-term polypharmacy (>or=90 days). In addition, approximately half of patients identified by cross-sectional criteria had only short-term overlaps of antipsychotic medications. Among patients receiving long-term polypharmacy, 74% received a first- and a second-generation agent, 18% received two second-generation agents, and 6% received two first-generation agents. Definitions of polypharmacy that rely on cross-sectional data or narrow observation periods do not accurately identify patients receiving long-term treatment; in this study, only 10% of patients with schizophrenia received combination treatments for >or=90 days. The most commonly used antipsychotic combinations have little support for safety or efficacy. Further research is needed to understand the impact of these treatments on symptoms, side effects, and costs.