Testing messages about comparative risk of electronic cigarettes and combusted cigarettes.

INTRODUCTION: Health agencies are grappling with communicating risks of electronic cigarettes (e-cigarettes) compared with combusted cigarettes. This study examined smokers' responses to two types of comparative risk messages with one type incorporating more negative antismoking elements in the design.

METHODS: In an online experiment, 1400 US adult (18+ years) current smokers and recent quitters were randomised to view one of three comparative risk messages about e-cigarettes (CR messages), one of three comparative risk messages that included more negative antismoking elements in the design (CR- messages) or a control message. Selection of outcomes was guided by the antismoking message impact framework. Multivariate analyses of covariance and logistic regression models analysed effects of messages on message evaluations, e-cigarette-related and cigarette-related beliefs and behavioural intentions.

RESULTS: Both CR and CR- messages decreased smokers' intentions to smoke cigarettes, increased intentions to switch to e-cigarettes completely and increased perceptions that e-cigarettes are less harmful than combusted cigarettes. Neither message type increased dual use intentions relative to exclusive e-cigarettes use or smoking cessation. CR messages decreased perceived absolute risks of e-cigarettes and self-exempting beliefs about smoking, whereas CR- versus CR messages produced higher self-efficacy to quit smoking.

CONCLUSION: Comparative risk communication might encourage smokers to switch to lower-harm tobacco products. Comparative risk messages with more negative antismoking elements in the design might be particularly effective, because they led to higher self-efficacy to quit smoking. Regulatory agencies may consider using comparative risk messages with more negative antismoking elements to educate the public about lower risk of e-cigarettes.