Antipsychotic monotherapy and polypharmacy in the naturalistic treatment of schizophrenia with atypical antipsychotics.
BACKGROUND
Antipsychotic monotherapy is recognized as the treatment of choice for patients with schizophrenia. Simultaneous treatment with multiple antipsychotics (polypharmacy) is suggested by some expert consensus guidelines as the last resort after exhausting monotherapy alternatives. This study assessed the annual rate and duration of antipsychotic monotherapy and its inverse, antipsychotic polypharmacy, among schizophrenia patients initiated on commonly used atypical antipsychotic medications.


METHODS
Data were drawn from a large prospective naturalistic study of patients treated for schizophrenia-spectrum disorders, conducted 7/1997-9/2003. Analyses focused on patients (N = 796) who were initiated during the study on olanzapine (N = 405), quetiapine (N = 115), or risperidone (N = 276). The percentage of patients with monotherapy on the index antipsychotic over the 1-year post initiation, and the cumulative number of days on monotherapy were calculated for all patients and for each of the 3 atypical antipsychotic treatment groups. Analyses employed repeated measures generalized linear models and non-parametric bootstrap re-sampling, controlling for patient characteristics.


RESULTS
During the 1-year period, only a third (35.7%) of the patients were treated predominately with monotherapy (> 300 days). Most patients (57.7%) had at least one prolonged period of antipsychotic polypharmacy (> 60 consecutive days). Patients averaged 195.5 days on monotherapy, 155.7 days on polypharmacy, and 13.9 days without antipsychotic therapy. Olanzapine-initiated patients were significantly more likely to be on monotherapy with the initiating antipsychotic during the 1-year post initiation compared to risperidone (p = .043) or quetiapine (p = .002). The number of monotherapy days was significantly greater for olanzapine than quetiapine (p < .001), but not for olanzapine versus risperidone, or for risperidone versus quetiapine-initiated patients.


CONCLUSIONS
Despite guidelines recommending the use of polypharmacy only as a last resort, the use of antipsychotic polypharmacy for prolonged periods is very common during the treatment of schizophrenia patients in usual care settings. In addition, in this non-randomized naturalistic observational study, the most commonly used atypical antipsychotics significantly differed on the rate and duration of antipsychotic monotherapy. Reasons for and the impact of the predominant use of polypharmacy will require further study.
Faries
Douglas
D
Outcomes Research, Eli Lilly and Company, Indianapolis, Indiana, USA. d.faries@lilly.com
Ascher-Svanum
Haya
H
Zhu
Baojin
B
Correll
Christoph
C
Kane
John
J
D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000008:administration & dosage / Q000627:therapeutic use; D003987:Dibenzothiazepines / Q000008:administration & dosage / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D000077152:Olanzapine; D019338:Polypharmacy; D011446:Prospective Studies; D000069348:Quetiapine Fumarate; D012107:Research Design; D018967:Risperidone / Q000008:administration & dosage / Q000627:therapeutic use; D012559:Schizophrenia / Q000188:drug therapy*; D012565:Schizophrenic Psychology; D013997:Time Factors
D014150:Antipsychotic Agents; D003987:Dibenzothiazepines; D001569:Benzodiazepines; D000069348:Quetiapine Fumarate; D018967:Risperidone; D000077152:Olanzapine