AIMS

To systematically review the literature on (i) whether and how various risk messages about nicotine vaping products (NVPs) alter harm perception and behavioural intentions of smokers and non-smokers and (ii) how trust in sources of NVP risk communication affects message reception and behavioural intentions.

METHODS

Seven electronic databases and reference lists of relevant articles were searched for articles published up to April 2020. Experimental and quasi-experimental studies on message effects and cross-sectional studies on source credibility were included. The Newcastle-Ottawa Scale and the Evidence Project Risk of Bias Tool were used to assess the quality of observational and intervention studies, respectively. For each outcome variable, we indicated whether there was an effect (as a 'yes' or 'no') and used effect direction plots to display information on the direction of effects.

RESULTS

Nicotine addiction messages resulted in greater health and addiction risk perceptions, relative risk messages comparing the health risks of NVPs to cigarette smoking increased the perception that NVPs are less harmful than combustible cigarettes, and a nicotine fact sheet corrected misperceptions of nicotine and NVPs. Smokers' intention to purchase, try or switch to NVPs was higher when exposed to a relative risk message and lower when exposed to nicotine addiction warnings. Trust in NVP risk information from public health agencies was associated with lower odds of; (i) NVP use and (ii) perceiving NVPs as less harmful, whereas those who trusted information from NVP companies were more likely to perceive NVPs as less harmful than combustible cigarettes.

CONCLUSIONS

Relative risk messages may help improve the accuracy of harm perceptions of nicotine vaping products and increase smokers' intentions to quit smoking and/or to switch to vaping, although the literature is nascent.