Correlates and predictors of antipsychotic drug polypharmacy in real-life settings: Results from a nationwide cohort study

Abstract

Reasons for using antipsychotic polypharmacy (APP) in routine clinical practice, despite a potentially unfavorable risk-benefit ratio, are poorly understood. This research aimed to determine (1) if severe courses of schizophrenia were associated with APP and (2) if a schizophrenia-related acute event would predict a switch to APP in the short term. Observational prospective data (at baseline and 6months) were drawn from a French nationwide cohort (“Cohorte Générale Schizophrénie”), which included 1859 inpatients and outpatients with schizophrenia. APP was defined as the prescription of ≥2 antipsychotic drugs (there being different active substances). Early-onset schizophrenia, legal guardianship, higher lifetime maximal severity of illness and comorbid antisocial personality were used as proxies for severe courses of schizophrenia. Schizophrenia-related acute events included hospitalization and recent suicide attempts. Logistic regression models were used to determine (1) whether the use of APP at baseline (vs. monotherapy) was associated with a severe course of schizophrenia or not, independent of acute events, and (2) if a switch to APP at 6months (vs. remaining on monotherapy) was associated with acute events, independent of severe courses of schizophrenia. Increased odds of APP use at baseline were independently associated with legal guardianship (OR=1.6; 95%CI=1.3, 2.0) and higher lifetime maximum severity of illness (OR=1.3; 95%CI=1.2, 1.5). A switch to APP at 6months was predicted by a hospitalization occurring since baseline (OR=6.1; 95%CI=3.9, 9.4). In routine clinical practice, APP is more likely prescribed to patients with severe courses of illness, possibly indicating the difficulty to manage these patients.