Antipsychotic switching: results from a one-year prospective, observational study of patients with schizophrenia

ABSTRACT

Objective: The Health Outcomes of a Canadian Community Cohort (HOCCC) study is a 1-year prospective observational study of outpatients with schizophrenia or related psychotic disorders. The purpose of the study was to compare effectiveness of antipsychotic treatment as measured by 1-year treatment completion rates.

Design and methods: Patients (N = 929) were enrolled if in the course of usual clinical practice they switched to a second-generation antipsychotic (SGA). Observational data were collected for up to 1 year. The primary analysis compared 1-year treatment-completion rates for the olanzapine cohort with the other SGA cohort (quetiapine, risperidone, clozapine), using a chi-squared test.

Results: Of 929 patients enrolled, 64.8% (516/796) of evaluable patients completed 1 year of treatment. There was no statistically significant difference in the proportion of treatment completers between the olanzapine cohort (67.4%, 256/380) and the other SGA cohort (62.5%, 260/416). Treatment-completion rates were risperidone 62.0% (127/205), quetiapine 63.7% (123/193) and clozapine 55.6% (10/18). Antipsychotic polypharmacy was common. Patients treated with olanzapine or risperidone had significantly higher increases in BMI than quetiapine-treated patients. There were no major differences between olanzapine monotherapy and pooled other SGA monotherapy groups in status of extrapyramidal symptoms from baseline to endpoint.

Conclusions: Olanzapine and other SGAs exhibited similar rates of 1-year treatment completion. Further study of medication combinations is needed, given their perceived clinical value, and the high frequency of antipsychotic polypharmacy in clinical practice.

Limitations: As most patients received several psychotropics and power was reduced in monotherapy analyses, comparisons between cohorts must be interpreted cautiously. Comparisons between individual antipsychotics were post hoc and not powered a priori. Accuracy and completeness of adverse event information for drugs other than olanzapine is limited.

Keywords: :

• Antipsychotics
• Polypharmacy
• Schizophrenia
• Treatment outcome

Transparency

Declaration of funding

This study was supported by a research grant from Eli Lilly and Company.

Declaration of financial/other relationships

J.K., R.D. and N.M. have disclosed that they are employed by Lilly. L.D. has disclosed that she is a former employee of Lilly and served as a consultant at the time of the study. J.K. and R.D. have disclosed that they are shareholders of Lilly. R.W. has disclosed that he has received speaker and consulting fees from AstraZeneca, Janssen-Ortho, Novartis, Lilly, Pfizer, Genpharm and Prestwick. R.P. has disclosed that he has received consulting or advisory board fees and lecture fees from AstraZeneca, GlaxoSmithKline, Janssen and Lilly. J.H. has disclosed that he has received speakers’ fees from Astra Zeneca, Janssen-Ortho, Lilly, and Pfizer. R.C. and A.T. report no conflict of interest.

All peer reviewers receive honoraria from CMRO for their review work. Reviewer 1 has disclosed that he/she has received grant monies from Lilly and Takeda. The other reviewer has disclosed that he/she has no relevant financial relationships.

Acknowledgment

The authors acknowledge Dr. Tara Moroz, formerly of Lilly, and Dr. Alan Yoshioka, AY's Edit, for technical editing and medical writing assistance in preparing this manuscript.

Statistical analyses were performed by L.D. and N.M.; the protocol is available from [email protected].

R.C., R.W. and A.T. were participants in the HOCCC study.

Portions of this study were presented as a poster at the 28th Annual Meeting of the Canadian College of Neuropsychopharmacology, St. John's, NF, Canada, July 2005; the Canadian Psychiatric Association Meeting, Vancouver, BC, Canada, November 2005; and the Canadian Psychiatric Association Meeting, Toronto, ON, Canada, November 2006. Interim results from this study were presented at the Canadian Psychiatric Association Annual meeting in Montreal, PQ, Canada, October 2004; the International Congress on Schizophrenia Research Savannah, GA, USA, April 2005; and the American Psychiatric Association Annual Meeting, Atlanta, GA, USA, May 2005.