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Claims of causality in health news: a randomised trial

Adams, Rachel C. ORCID:, Challenger, Aimee, Bratton, Luke, Boivin, Jacky ORCID:, Bott, Lewis ORCID:, Powell, Georgina ORCID:, Williams, Andy, Chambers, Christopher D. ORCID: and Sumner, Petroc ORCID: 2019. Claims of causality in health news: a randomised trial. BMC Medicine 17 , 91. 10.1186/s12916-019-1324-7

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Background Misleading news claims can be detrimental to public health. We aimed to improve the alignment between causal claims and evidence, without losing news interest (counter to assumptions that news is not interested in communicating caution). Methods We tested two interventions in press releases, which are the main sources for science and health news: (a) aligning the headlines and main causal claims with the underlying evidence (strong for experimental, cautious for correlational) and (b) inserting explicit statements/caveats about inferring causality. The ‘participants’ were press releases on health-related topics (N = 312; control = 89, claim alignment = 64, causality statement = 79, both = 80) from nine press offices (journals, universities, funders). Outcomes were news content (headlines, causal claims, caveats) in English-language international and national media (newspapers, websites, broadcast; N = 2257), news uptake (% press releases gaining news coverage) and feasibility (% press releases implementing cautious statements). Results News headlines showed better alignment to evidence when press releases were aligned (intention-to-treat analysis (ITT) 56% vs 52%, OR = 1.2 to 1.9; as-treated analysis (AT) 60% vs 32%, OR = 1.3 to 4.4). News claims also followed press releases, significant only for AT (ITT 62% vs 60%, OR = 0.7 to 1.6; AT, 67% vs 39%, OR = 1.4 to 5.7). The same was true for causality statements/caveats (ITT 15% vs 10%, OR = 0.9 to 2.6; AT 20% vs 0%, OR 16 to 156). There was no evidence of lost news uptake for press releases with aligned headlines and claims (ITT 55% vs 55%, OR = 0.7 to 1.3, AT 58% vs 60%, OR = 0.7 to 1.7), or causality statements/caveats (ITT 53% vs 56%, OR = 0.8 to 1.0, AT 66% vs 52%, OR = 1.3 to 2.7). Feasibility was demonstrated by a spontaneous increase in cautious headlines, claims and caveats in press releases compared to the pre-trial period (OR = 1.01 to 2.6, 1.3 to 3.4, 1.1 to 26, respectively). Conclusions News claims—even headlines—can become better aligned with evidence. Cautious claims and explicit caveats about correlational findings may penetrate into news without harming news interest. Findings from AT analysis are correlational and may not imply cause, although here the linking mechanism between press releases and news is known. ITT analysis was insensitive due to spontaneous adoption of interventions across conditions.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Psychology
Cardiff University Brain Research Imaging Centre (CUBRIC)
Additional Information: This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated
Publisher: BioMed Central
ISSN: 1741-7015
Funders: ESRC
Date of First Compliant Deposit: 3 May 2019
Date of Acceptance: 11 April 2019
Last Modified: 10 May 2023 00:07

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