Characterising trusted spokespeople in noncommunicable disease prevention: A systematic scoping review.

Noncommunicable diseases (NCD) are an increasing global threat. Utilising public policy to address NCDs can reduce incidence and prevalence. However, NCD-relevant public policy action is minimal in many countries as changing public policy is difficult and multifactorial. Two factors that may influence this process is the message people receive and the messenger delivering it. To date, much health communication research has focused on message content, with limited research on messengers that are trusted by policymakers and the public to communicate NCD matters. We aimed to review the literature to characterise who the public and policymakers consider to be trustworthy and/or credible for NCD messaging, and why this might be the case. Arksey and O'Malley's scoping review methodology guided the review. A systematic search of three databases up to June 2021 combined with hand searching of review reference lists was undertaken. Nineteen articles were included. Data extraction focused on study design, issue being influenced, spokesperson studied, and measures of trust. Results showed health professionals were the most-frequently trusted sources of information. Other spokespeople, such as government sources or religious leaders, were only trustworthy in some contexts, and even distrusted in others. Reasons why spokespeople were trusted included technical expertise, strategic engagement with stakeholders, and reputation. However, we also found the nature of trust and credibility of spokespeople is dependent on the studied population and context. Overall, characteristics of influential messengers were nonspecific. Thus, trusted messengers and their characteristics in NCD-messaging must be better understood to develop and maintain the trust of the public and policymakers.