Electronic cigarette use and smoking initiation among youth: a longitudinal cohort study

• Published in: Canadian Medical Association journal (CMAJ) Vol. 189; no. 43; pp. E1328 - E1336
• Main Authors: Hammond, David, Reid, Jessica L, Cole, Adam G, Leatherdale, Scott T
• Format: Journal Article
• Language: English
• Published: Canada Joule Inc 30.10.2017; CMA Impact, Inc
• Subjects: Adolescent; Adolescent Behavior - physiology; Alberta - epidemiology; Analysis; Behavior, Addictive - epidemiology; Behavior, Addictive - psychology; Causes of; Cohort analysis; Cohort Studies; Electronic cigarettes; Electronic Nicotine Delivery Systems - psychology; Electronic Nicotine Delivery Systems - statistics & numerical data; Female; Health behavior; Health risk assessment; Humans; Longitudinal Studies; Male; Ontario - epidemiology; Peer Group; Risk Factors; Secondary school students; Self Report; Smoking; Smoking - epidemiology; Smoking - psychology; Teenagers; Tobacco Use Disorder - prevention & control; Vaping; Youth smoking; Canada; Alberta Canada
• ISSN: 0820-3946; 1488-2329
• DOI: 10.1503/cmaj.161002

The influence of e-cigarette use on smoking initiation is a highly controversial issue, with limited longitudinal data available for examining temporal associations. We examined e-cigarette use and its association with cigarette-smoking initiation at 1-year follow-up within a large cohort of Canadian secondary school students. We analyzed data from students in grades 9-12 who participated in 2 waves of COMPASS, a cohort study of purposefully sampled secondary schools in Ontario and Alberta, Canada, at baseline (2013/14) and 1-year follow-up (2014/15). We assessed cigarette smoking and e-cigarette use at baseline and follow-up using self-completed surveys. We used generalized linear mixed-effects models to examine correlates of past 30-day e-cigarette use at baseline and smoking initiation between waves within the longitudinal sample. Past 30-day e-cigarette use increased from 2013/14 to 2014/15 (7.2% v. 9.7%, < 0.001), whereas past 30-day cigarette smoking decreased slightly (11.4% v. 10.8%, = 0.02). Among the 44 163 students evaluated at baseline, past 30-day e-cigarette use was strongly associated with smoking status and smoking susceptibility. In the longitudinal sample ( = 19 130), past 30-day use of e-cigarettes at baseline was associated with initiation of smoking a whole cigarette (adjusted odds ratio [OR] 2.12, 95% confidence interval [CI] 1.68-2.66) and with initiation of daily smoking (adjusted OR 1.79, 95% CI 1.41-2.28) at follow-up. E-cigarette use was strongly associated with cigarette smoking behaviour, including smoking initiation at follow-up. The causal nature of this association remains unclear, because common factors underlying the use of both e-cigarettes and conventional cigarettes may also account for the temporal order of initiation.