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Efficacy of olanzapine in comparison with clozapine for treatment-resistant schizophrenia: evidence from a systematic review and meta-analyses

Published online by Cambridge University Press:  20 December 2012

Juliano S Souza ,
Monica Kayo ,
Ivson Tassell ,
Camila Bertini Martins  and
Helio Elkis
Juliano S Souza*
Affiliation:
Schizophrenia Program, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil Department and Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
Monica Kayo
Affiliation:
Schizophrenia Program, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
Ivson Tassell
Affiliation:
Schizophrenia Program, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
Camila Bertini Martins
Affiliation:
Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil
Helio Elkis
Affiliation:
Schizophrenia Program, Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil Department and Institute of Psychiatry, University of São Paulo Medical School, São Paulo, Brazil
*
*Address for correspondence: Juliano Santos Souza, University of São Paulo Medical School, Projesq–Schizophrenia Program, Rua Ovidio Pires de Campos 785, São Paulo SP-05403-010, Brazil. Email Juliano.s.souza@gmail.com
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Abstract

Introduction

Clozapine is considered the gold standard for the treatment of patients with treatment-resistant schizophrenia (TRS); however, randomized controlled trials (RCT) of olanzapine showed efficacy similar to clozapine in patients with TRS.

Methods

A systematic review was conducted comparing clozapine with olanzapine in patients with TRS. Meta-analyses were performed for single outcome measures. Response to treatment was measured by the percentage of responders, or mean change or endpoint values of psychotic symptoms scales. Effect sizes were shown as relative risks (RR), or standardized mean differences, with 95% confidence intervals.

Findings

Seven RCT were included, comprising 648 patients. Five meta-analyses were performed. Olanzapine and clozapine had similar effects on dropout rates (RR = 0.93, CI95% = 0.77–1.12), PANSS total endpoints (SMD = 0.21, CI95% = –0.04–0.46), and PANSS total mean changes (SMD = 0.08, CI95% = –0.01–0.027). Clozapine was superior to olanzapine for PANSS positive (SMD = 0.51, CI95% = 0.17–0.86) and negative (SMD = 0.50, CI95% = 0.16–0.85) subscales. There was a trend toward high doses of olanzapine producing higher effect sizes for this drug.

Conclusions

The results of this study suggest that clozapine is significantly more efficacious than olanzapine in improving positive and negative symptoms in TRS patients.

Keywords

clozapineolanzapinetreatment-resistant schizophreniameta-analysissystematic reviewschizophrenia
Type
Original Research
Information
CNS Spectrums , Volume 18 , Issue 2 , April 2013 , pp. 82 - 89
Copyright
Copyright © Cambridge University Press 2012

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Footnotes

*

The authors would like to thank Dr. Carlos B. Pereira, Dr. Ricardo Moreno, and Dr. Orestes Forlenza for their valuable critical comments and suggestions for the manuscript, and also Carolina Rehem, for her library assistance.

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