Perceived relative harm of electronic cigarettes over time and impact on subsequent use. A survey with 1-year and 2-year follow-ups.
BACKGROUND
Media presentations of e-cigarettes may affect perception of the devices which may influence use.


OBJECTIVE
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 (χ(2)=20.67, p<0.001); the proportion perceiving e-cigarettes to be less harmful than cigarettes decreased from 2013 to 2014 (χ(2)=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).


CONCLUSIONS
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.
Department of Addictions, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 4 Windsor Walk, London SE5 8BB, UK; UK Centre for Tobacco and Alcohol Studies (UKCTAS), UK. Electronic address: leonie.brose@kcl.ac.uk.
Leonie S
LS
Brose
UK Centre for Tobacco and Alcohol Studies (UKCTAS), UK; Department of Clinical, Educational and Health Psychology, University College London, 1-19 Torrington Place, London WC1E 7HB, UK.
Jamie
J
Brown
Department of Addictions, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 4 Windsor Walk, London SE5 8BB, UK; UK Centre for Tobacco and Alcohol Studies (UKCTAS), UK.
Sara C
SC
Hitchman
Department of Addictions, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 4 Windsor Walk, London SE5 8BB, UK; UK Centre for Tobacco and Alcohol Studies (UKCTAS), UK.
Ann
A
McNeill
D000293:Adolescent; D000328:Adult; D001294:Attitude to Health; D066300:Electronic Nicotine Delivery Systems / Q000009:adverse effects / Q000523:psychology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D010465:Perception; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology / Q000523:psychology*; D016540:Smoking Cessation / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
Behavior; Electronic cigarettes; Harm; Nicotine; Tobacco