Author(s): Thaler KJ, Morgan LC, Van Noord M, Jonas DE, McDonagh MS,
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Abstract OBJECTIVES: Pooled-studies publications (PSPs) present statistical analyses of multiple randomized controlled trials without a systematic literature search or critical appraisal. We explored the characteristics of PSPs and their potential impact on a systematic review (SR). STUDY DESIGN AND SETTING: We systematically evaluated PSPs excluded from an SR of second-generation antidepressants. We analyzed their basic characteristics, risk of bias, and the effect of new data on review conclusions. RESULTS: We identified 57 PSPs containing a median of five trials (range, 2-11) and 1,233 patients (range, 117-2,919). Ninety-six percent of PSPs were industry funded, and 49\% of PSPs contained unpublished data. The median number of citations for PSPs was 29 (range, 0-549). Only 7\% planned pooling a priori, and 19\% combined trials with identical protocols. Fifty-nine percent of PSPs eligible for general efficacy provided no new data. For some subgroups and accompanying symptoms (e.g., anxiety, insomnia, melancholia, fatigue, sex, and race), more than 30\% of PSPs presented entirely new data or data that could alter the strength of the evidence available in the SR. CONCLUSION: In this case study, PSPs provided new information on subgroups and secondary outcomes; however, guidance for reviewers and development of a system to assess their susceptibility to bias are required. Copyright © 2013 Elsevier Inc. All rights reserved.
This article was published in J Clin Epidemiol
and referenced in Evidence based Medicine and Practice