title: Adherence and persistence to typical and atypical antipsychotics in the naturalistic treatment of patients with schizophrenia.
abstract: OBJECTIVE
  To compare adherence and persistence to typical versus atypical antipsychotics and between specific atypical agents in the usual care of schizophrenia and to examine the association between adherence and persistence.
  
  
  METHODS
  Data were drawn from a 3-year prospective, nonrandomized, noninterventional study of schizophrenia conducted during 1997-2003. Initiators on haloperidol, risperidone, olanzapine, quetiapine, and clozapine with at least 1 year of follow-up were included (n = 878). Adherence (Medication Possession Ratio, MPR) and persistence (time to all-cause medication discontinuation) were assessed using medical record prescription information. Analyses employed multivariate statistics adjusted for group differences.
  
  
  RESULTS
  Overall, 58% of the patients were deemed adherent (MPR >80%). Adherence rates were higher: for atypical (59.4%) than typical antipsychotics (34.5%, p < 0.001), for clozapine (77%) than each comparator excluding olanzapine (p < 0.01), and for olanzapine (64%) than risperidone (57%, p = 0.027) and quetiapine (52%, p = 0.019). Differences between risperidone and quetiapine were not statistically significant. Adherence and persistence were highly correlated (r = 0.957, p < 0.001).
  
  
  CONCLUSIONS
  In the usual care of schizophrenia, medication adherence and persistence appear to be highly correlated and to significantly differ between typical and atypical antipsychotics and among atypical agents. The choice of antipsychotic may play a meaningful role in patients' adherence to and persistence with antipsychotic medications.
authors.affiliation: Eli Lilly and Company, Outcomes Research, Indianapolis, IN, USA;
authors.forename: Haya
authors.initials: H
authors.lastname: Ascher-Svanum
authors.forename: Baojin
authors.initials: B
authors.lastname: Zhu
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Faries
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Lacro
authors.forename: Christian R
authors.initials: CR
authors.lastname: Dolder
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Peng