A cohort of smokers and ex-smokers was followed over a period of two years.
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Perceived harm of electronic cigarettes relative to cigarettes increased over time.
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Smoking cessation ande-cigarette use predicted subsequent perceived relative harm.
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Perceived relative harm predicted subsequent use of e-cigarettes in non-users.
Abstract
Introduction
Media presentations of e-cigarettes may affect perception of the devices which may influence use.
Objectives
To assess in a cohort of past-year smokers (1) if perceived harm of e-cigarettes relative to cigarettes changed over time, (2) predictors of perceived relative harm, (3) if perceived relative harm predicted subsequent e-cigarette use among never-users.
Methods
Longitudinal web-based survey of a general population sample of British smokers and ex-smokers, waves in 2012 (n = 4553), 2013 and 2014 (44%, 31% response rate, respectively). Changes over time were assessed using Friedman and McNemar tests, n = 1204. Perceived relative harm at wave 3 was regressed onto perceived relative harm at waves 1 and 2, while adjusting for socio-demographics and change in smoking and e-cigarette status, n = 1204. Wave 2 e-cigarette use among 1588 wave 1 never-users was regressed onto wave 1 socio-demographics, smoking status and perceived relative harm.
Results
Perceived relative harm changed (χ2 = 20.67, p < 0.001); the proportion perceiving e-cigarettes to be less harmful than cigarettes decreased from 2013 to 2014 (χ2 = 16.55, p < 0.001). Previous perception of e-cigarettes as less harmful, having tried e-cigarettes and having stopped smoking between waves predicted perceiving e-cigarettes as less harmful than cigarettes. Perceiving e-cigarettes to be less harmful than cigarettes predicted subsequent use, adjusting for other characteristics (OR = 1.39; 95% CI: 1.08–1.80, p = 0.011).
Conclusion
Among a cohort of smokers and ex-smokers, accurately perceiving e-cigarettes as less harmful than smoking predicted subsequent e-cigarette use in never-users; this perception declined over time. Clear information on the relative harm of cigarettes and e-cigarettes is needed.