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John M. Davis, MD; Nancy Chen, MS; Ira D. Glick, MD

Arch Gen Psychiatry. 2003;60:553-564.

Background  Consensus panel recommendations regarding choice of an antipsychotic agent for schizophrenia differ markedly, but most consider second-generation antipsychotics (SGAs) as a homogeneous group. It has been suggested that SGAs seem falsely more efficacious than first-generation antipsychotics (FGAs) as a result of reduced efficacy due to use of a high-dose comparator, haloperidol. We performed (1) a meta-analysis of randomized efficacy trials comparing SGAs and FGAs, (2) comparisons between SGAs, (3) a dose-response analysis of FGAs and SGAs, and (4) an analysis of the effect on efficacy of an overly high dose of an FGA comparator.

Methods  Literature search of clinical trials between January 1953 and May 2002 of patients with schizophrenia from electronic databases, reference lists, posters, the Food and Drug Administration, and other unpublished data. We included 124 randomized controlled trials with efficacy data on 10 SGAs vs FGAs and 18 studies of comparisons between SGAs. Two of us independently extracted the sample sizes, means, and standard deviation of the efficacy data.

Results  Using the Hedges-Olkin algorithm, the effect sizes of clozapine, amisulpride, risperidone, and olanzapine were 0.49, 0.29, 0.25, and 0.21 greater than those of FGAs, with P values of 2 x 10^-8, 3 x 10^-7, 2 x 10^-12, and 3 x 10^-9, respectively. The remaining 6 SGAs were not significantly different from FGAs, although zotepine was marginally different. No efficacy difference was detected among amisulpride, risperidone, and olanzapine. We found no evidence that the haloperidol dose (or all FGA comparators converted to haloperidol-equivalent doses) affected these results when we examined its effect by drug or in a 2-way analysis of variance model in which SGA effectiveness is entered as a second factor.

Conclusion  Some SGAs are more efficacious than FGAs, and, therefore, SGAs are not a homogeneous group.

From the Psychiatric Institute, University of Illinois at Chicago (Dr Davis and Ms Chen); and the Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif (Dr Glick). This study received no direct or indirect support from the pharmaceutical industry.

RELATED LETTERS

Subjecting Meta-analyses to Closer Scrutiny: Little Support for Differential Efficacy Among Second-Generation Antipsychotics at Equivalent Doses
Rajiv Tandon and Henry A. Nasrallah
Arch Gen Psychiatry. 2006;63(8):935-937.
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Subjecting Meta-analyses to Closer Scrutiny: Little Support for Differential Efficacy Among Second-Generation Antipsychotics at Equivalent Doses—Reply
John M. Davis, Nancy Chen, and Ira D. Glick
Arch Gen Psychiatry. 2006;63(8):937-939.
EXTRACT | FULL TEXT