title: Medication nonadherence and treatment outcome in patients with schizophrenia or schizoaffective disorder with suboptimal prior response.
abstract: OBJECTIVE
  To examine the impact of medication nonadherence on treatment outcome in schizophrenia and potential risk factors for nonadherence.
  
  
  METHODS
  A post hoc analysis of a randomized, double-blind, 8-week, fixed-dose study comparing olanzapine 10, 20, and 40 mg/day for patients with schizophrenia or schizoaffective disorder (DSM-IV criteria) with suboptimal response to current treatment (N = 599) was conducted between September 12, 2003, and November 3, 2005, at 55 study centers in the United States. Nonadherence was defined as not taking medication as prescribed based on daily pill counts. Because there was no significant difference in nonadherence between dose groups, effects of nonadherence on efficacy and safety outcomes were examined using all 3 groups combined. Baseline demographics and symptom severity were investigated as potential risk factors for nonadherence.
  
  
  RESULTS
  During the 8-week study, 34.5% of patients were nonadherent at least once. Nonadherent patients had significantly less improvement compared to adherent patients as measured by change in Positive and Negative Syndrome Scale total score (-22.57 vs. -26.84, p = .002). Longer duration of nonadherence was associated with reduced likelihood of treatment response (odds ratio = 0.94, 95% CI = 0.90 to 0.99, p = .008). The early treatment discontinuation rate was higher in nonadherent compared to adherent patients (40.8% vs. 24.5%, p < .001). Adherent and nonadherent patients had comparable outcomes in most safety measures, except for weight change, for which adherent patients had greater weight gain than nonadherent patients (2.63 kg vs. 1.96 kg, p = .02). Greater depression severity at baseline (p = .01) and greater hostility level during the study were significant risk factors for nonadherence (p = .02).
  
  
  CONCLUSIONS
  Medication nonadherence had a significantly negative impact on treatment response, highlighting the importance of adherence to achieve satisfactory treatment outcome. Findings may also help clinicians identify patients at risk for nonadherence and utilize interventions to improve adherence.
  
  
  BACKGROUND
  clinicaltrials.gov Identifier: NCT00100776.
authors.affiliation: New York University School of Medicine, New York, N.Y. 10035, USA. lindenmayer@nki.rfmh.org
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lindenmayer
authors.forename: Hong
authors.initials: H
authors.lastname: Liu-Seifert
authors.forename: Pandurang M
authors.initials: PM
authors.lastname: Kulkarni
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Kinon
authors.forename: Virginia
authors.initials: V
authors.lastname: Stauffer
authors.forename: Sara E
authors.initials: SE
authors.lastname: Edwards
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: David H
authors.initials: DH
authors.lastname: Adams
authors.forename: Haya
authors.initials: H
authors.lastname: Ascher-Svanum
authors.forename: Peter F
authors.initials: PF
authors.lastname: Buckley
authors.forename: Leslie
authors.initials: L
authors.lastname: Citrome
authors.forename: Jan
authors.initials: J
authors.lastname: Volavka
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000627:therapeutic use; D001569:Benzodiazepines / Q000627:therapeutic use; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D055118:Medication Adherence; D000077152:Olanzapine; D010352:Patient Dropouts / Q000706:statistics & numerical data; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000188:drug therapy*; D012008:Recurrence; D012559:Schizophrenia / Q000188:drug therapy*; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D000077152:Olanzapine