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.
- pooled-Trials publication bias
ASJC Scopus subject areas
- Applied Psychology
- Psychiatry and Mental health