Hiding negative trials by pooling them: A secondary analysis of pooled-Trials publication bias in FDA-registered antidepressant trials

Ymkje Anna De Vries, Annelieke M. Roest, Erick H. Turner, Peter De Jonge

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Background Previous studies on reporting bias generally examined whether trials were published in stand-Alone publications. In this study, we investigated whether pooled-Trials publications constitute a specific form of reporting bias. We assessed whether negative trials were more likely to be exclusively published in pooled-Trials publications than positive trials and examined the research questions, individual trial results, and conclusions presented in these articles.Methods Data from a cohort of 105 randomized controlled trials of 16 antidepressants were extracted from earlier publications and the corresponding Food and Drug Administration (FDA) reviews. A systematic literature search was conducted to identify pooled-Trials publications.Results We found 107 pooled-Trials publications that reported results of 23 (72%) of 32 trials not published in stand-Alone publications. Only two (3.8%) of 54 positive trials were published exclusively in pooled-Trials publications, compared with 21 (41.1%) of 51 negative trials (p < 0.001). Thirteen (12%) of 107 publications had as primary aim to present data on the trial's primary research question (drug efficacy compared with placebo). Only four of these publications, reporting on five (22%) trials, presented individual efficacy data for the primary research question. Additionally, only five (5%) of 107 pooled-Trials publications had a negative conclusion.Conclusions Compared with positive trials, negative trials of antidepressants for depression were much more likely to be reported exclusively in pooled-Trials publications. Pooled-Trials publications flood the evidence base with often-redundant articles that, instead of addressing the original primary research question, present (positive) results on secondary questions. Therefore, pooled-Trials publications distort the apparent risk-benefit profile of antidepressants. Copyright Cambridge University Press 2018Â This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

Original languageEnglish (US)
Pages (from-to)2020-2026
Number of pages7
JournalPsychological Medicine
Issue number12
StatePublished - Sep 1 2019


  • Antidepressants
  • bias
  • depression
  • pooled-Trials publication bias

ASJC Scopus subject areas

  • Applied Psychology
  • Psychiatry and Mental health


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