The effects of quality of evidence communication on perception of public health information about COVID-19: two randomised controlled trials
Abstract
Background
The quality of evidence about the effectiveness of non-pharmaceutical health interventions is often low, but little is known about the effects of communicating indications of evidence quality to the public.
Methods
In two blinded, randomised, controlled, online experiments, US participants (total n=2140) were shown one of several versions of an infographic illustrating the effectiveness of eye protection in reducing COVID-19 transmission. Their trust in the information, understanding, feelings of effectiveness of eye protection, and the likelihood of them adopting it were measured.
Findings
Compared to those given no quality cues, participants who were told the quality of the evidence on eye protection was ‘low’, rated the evidence less trustworthy (p=.001), and rated it as subjectively less effective (p=.020). The same effects emerged compared to those who were told the quality of the evidence was ‘high’, and in one of the two studies, those shown ‘low’ quality of evidence said they were less likely to use eye protection (p=.005). Participants who were told the quality of the evidence was ‘high’ showed no significant differences on these measures compared to those given no information about evidence quality.
Interpretation
Without quality of evidence cues, participants responded to the evidence about the public health intervention as if it was high quality and this affected their subjective perceptions of its efficacy and trust in the provided information. This raises the ethical dilemma of weighing the importance of transparently stating when the evidence base is actually low quality against evidence that providing such information can decrease trust, perception of intervention efficacy, and likelihood of adopting it.
Funding
The Winton Centre for Risk & Evidence Communication, thanks to the David & Claudia Harding Foundation
Research in Context
Evidence before this study
This is the first quantitative, empirical study, to our knowledge, on the effects of communicating the quality of evidence underlying an effectiveness estimate of a public health intervention on a public audience.
Added value of this study
This study provides novel insights into the effects of quality of evidence communication in a public health context. It is thus of high theoretical as well as translational value.
Implications of all the available evidence
Members of the public may assume that information around the effectiveness of a measure such as wearing eye protection to protect against COVID-19 are based on high quality evidence if they are given no cues to suggest otherwise. Yet, when given a statement of the quality of the evidence, this can (appropriately) affect their feelings of the trustworthiness of the information and their subjective judgement of the effectiveness of the measure. This raises the issue of whether there is an ethical imperative to communicate the quality of underlying evidence, particularly when it is low, albeit with the recognition that this may reduce uptake of a public health measure.
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