title: Antipsychotic patterns of use in patients with schizophrenia: polypharmacy versus monotherapy.
abstract: BACKGROUND
  The objective of this study was to characterize real-world treatment patterns in the prescription of antipsychotic polypharmacy (≥ 2 concurrent antipsychotics) compared with antipsychotic monotherapy for patients with schizophrenia.
  
  
  METHODS
  This study was a retrospective claims-based analysis of patients (aged 13-64 years) with schizophrenia belonging to an employer-based health plan. Duration of therapy was measured as the number of treatment days over one year following the initial date of antipsychotic therapy. Discontinuation was defined as a 90-day gap in antipsychotic treatment (or in at least one antipsychotic for the polypharmacy group). Logistic regression analyses were used to predict discontinuation within one year. Ordinary Least Squares (OLS) regressions were used to predict duration of therapy (by type of therapy) when controlling for gender, region, number of somatic and psychiatric comorbidities, Deyo-Charlson comorbidity score, and number of psychiatric and somatic medications.
  
  
  RESULTS
  Of the 4,156 patients, 3,188 received monotherapy and 968 received polypharmacy. Mean age was 40 years (37.8 years for polypharmacy vs 40.3 years for monotherapy, p < 0.001). Within one year, 77% of the polypharmacy group and 54% of the monotherapy group discontinued treatment. The average duration of therapy was 163 [SD = 143] days in the polypharmacy group vs 253 [SD = 147] days in the monotherapy group. In both cohorts, patients <25 years had a higher frequency of discontinuations than those ≥ 26 years. Age and polypharmacy were independent predictors of treatment duration and discontinuation prior to one year.
  
  
  CONCLUSIONS
  One quarter of patients with schizophrenia received antipsychotic polypharmacy. Discontinuation was higher in the polypharmacy group. Age and polypharmacy were significant predictors of treatment discontinuation.
authors.forename: Maxine D
authors.initials: MD
authors.lastname: Fisher
authors.forename: Kathleen
authors.initials: K
authors.lastname: Reilly
authors.forename: Keith
authors.initials: K
authors.lastname: Isenberg
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Villa
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019338:Polypharmacy; D012189:Retrospective Studies; D012559:Schizophrenia / Q000188:drug therapy*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents