Long-term antipsychotic polypharmacy in the VA health system: Patient characteristics and treatment patterns

Objective: Although antipsychotic polypharmacy is being prescribed with increasing frequency, few studies have described patient characteristics and treatment patterns associated with long-term use of this treatment strategy. Methods: By using data from the National Psychosis Registry of the Department of Veterans Affairs, 5,826 patients with schizophrenia or schizoaffective disorder who received long-term antipsychotic polypharmacy (simultaneous treatment with two or more antipsychotics for 90 or more days) during fiscal year 2000 and 39,745 patients who received long-term antipsychotic monotherapy were identified. By using multivariate regression models, patient demographic and clinical characteristics, antipsychotic dosages, and use of antiparkinson and adjunctive psychotropic medications were compared between the two groups. Results: Patients were more likely to receive antipsychotic polypharmacy if they were younger, were unmarried, had a military service-connected disability, had schizophrenia rather than schizoaffective disorder, or had greater use of inpatient and outpatient mental health services. Patients were less likely to receive antipsychotic polypharmacy if they were African American, had concurrent diagnoses of depression or substance use disorder, or had greater medical comorbidity. For most antipsychotics, dosages prescribed for patients receiving polypharmacy were the same or modestly higher than those prescribed for patients receiving monotherapy. Patients given prescriptions for polypharmacy were more likely to receive antiparkinson medications, antianxiety agents, and mood stabilizers and equally likely to receive concurrent treatment with antidepressants. Conclusions: Longterm antipsychotic polypharmacy appears to be reserved for more severely ill patients with psychotic symptoms rather than mood symptoms. These patients may experience increased adverse effects as a result of excess antipsychotic exposure.