Do Electronic Cigarettes Increase Cigarette Smoking in UK Adolescents? Evidence from a 12-month Prospective Study.

Background: In cross-sectional surveys, increasing numbers of adolescents report using both electronic cigarettes (e-cigarettes) and cigarettes. This study assessed whether adolescent e-cigarette use was associated prospectively with initiation or escalation of cigarette use.

Method: Data were from 2,836 adolescents (aged 13-14 years at baseline) in 20 schools in England. At baseline, breath carbon monoxide levels, self-reported e-cigarette and cigarette use, sex, age, friends and family smoking, beliefs about cigarette use, and percentage receiving free school meals (measure of socio-economic status) were assessed. At 12 month follow-up, self-reported cigarette use was assessed and validated by breath carbon monoxide levels.

Results: At baseline, 34.2% of adolescents reported ever using e-cigarettes (16·0% used only e-cigarettes). Baseline ever use of e-cigarettes was strongly associated with subsequent initiation (N = 1,726; OR = 5·38, 95%CI = 4·02 to 7·22; controlling for covariates, OR = 4·06, 95%CI = 2·94 to 5·60) and escalation (N = 318; OR = 1·91, 95%CI = 1·14 to 3·21; controlling for covariates this effect became non-significant, OR = 1·39, 95%CI = 0·97 to 1·82) of cigarette use.

Conclusions: This is the first study to report prospective relationships between ever use of e-cigarettes and initiation and escalation of cigarette use among UK adolescents. Ever use of e-cigarettes was robustly associated with initiation but more modestly related to escalation of cigarette use. Further research with longer follow-up in a broader age-range of adolescents is required.