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.