Electronic cigarette use in Hong Kong adolescents : prevalence, favourable perceptions, nicotine and flavoured electronic cigarette use, and smoking progression

Abstract

Few Hong Kong adolescents smoke cigarettes, but the potential gateway effect of electronic cigarettes (e-cigarettes) is of great concern. E-cigarettes may attract adolescents, especially those with low risk for smoking (cigarettes), to initiate nicotine use and then smoking. I therefore examined e-cigarette use in Hong Kong adolescents, including (i) the prevalence, (ii) e-cigarette use in relation to smoking susceptibility by background risk for smoking, (iii) favourable perceptions of e-cigarettes versus cigarettes in relation to e-cigarette use susceptibility, and (iv) nicotine e-cigarette use and (v) flavoured e-cigarette use in relation to faster smoking progression.

The data used were mainly from the School-based Smoking Survey among Students 2014/15 and 2016/17. Students completed anonymous questionnaires, reporting e-cigarette use and smoking status, susceptibility to e-cigarette use and smoking, risk factors of smoking, favourable perceptions of e-cigarettes relative to cigarettes, e-cigarette nicotine content, e-cigarette flavours, and age at different e-cigarette use and smoking milestones (e.g. first e-cigarette use and first smoking). Descriptive data, including (i) prevalence of e-cigarette use, were weighted by age, sex and grade. Binary logistic regression analysed the (ii) associations of e-cigarette use with smoking susceptibility by background risk for smoking; (iii) associations of favourable perceptions of e-cigarettes with e-cigarette use susceptibility; (iv) associations of nicotine and non-nicotine e-cigarette use with faster smoking progression; (v) associations of flavoured e-cigarette use with faster smoking progression.

Current (past 30-day) e-cigarette use in adolescents was 0.8% in 2016/17. E-cigarette use was associated with smoking susceptibility in never smokers. When stratified by background risk for smoking, the association was only significant in those with low risk. Almost half (48.8%) the adolescents had favourable perceptions of e-cigarettes versus cigarettes, most commonly perceiving e-cigarettes as less harmful. All the perceptions were associated with e-cigarette use susceptibility in never users, and a stronger association was observed for having more favourable perceptions (p for trend < 0.001).

More than one-fourth (26.4%) of ever e-cigarette users used nicotine e-cigarettes. Nicotine users were more than twice as likely to progress faster from first e-cigarette use to first smoking as non-nicotine users. In ever smokers, both nicotine or non-nicotine e-cigarette users were more likely to progress faster from first to monthly and weekly smoking than never e-cigarette users.

Nearly all (98.3%) ever e-cigarette users used flavoured e-cigarettes, with fruit, menthol and candy flavours being most popular. Only tobacco and alcohol flavours were associated with faster progression to smoking initiation in ever users. In ever smokers, e-cigarette users of any flavours were more likely to progress faster from first to monthly and weekly smoking than never e-cigarette users.

To conclude, e-cigarette use in Hong Kong adolescents was not common, but was associated with smoking susceptibility, especially in those with low background risk for smoking. Favourable perceptions of e-cigarettes were associated with e-cigarette use susceptibility. E-cigarette use even without nicotine and of flavours less appealing to adolescents may promote and accelerate smoking progression. These results support reducing unwarranted favourable perceptions of e-cigarettes and the government’s proposal to ban e-cigarettes in Hong Kong.