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

Hammond and colleagues recent Canadian Medical Association Journal (CMAJ) longitudinal cohort study is a valuable contribution to electronic cigarette related public health problems for adolescents (1). It is based on a large sample of Canadian high school student (grades 9-12) survey data. The objective of their study is to explore whether electronic cigarette use was associated with cigarette-smoking initiation at a 1-year follow-up. The study methodology is strong, and study authors were able to adjust for the known wide range of demographic and behavioral risk factors. In addition, the real strength of this study is that they were also able to control susceptibility to cigarette smoking.

The study found that, adolescents who initiated electronic cigarette use are more likely to be:
(1). smoking conventional cigarettes a year later and
(2). more likely to have become daily smokers.

The recent systematic review and meta-analysis published in the Journal of the American Medical Association (JAMA) Pediatrics also suggests that adolescents and young children who start with electronic cigarette are more likely to be smoking cigarettes later (2). This systematic review and meta-analysis of 9 longitudinal studies found consistent and strong evidence that electronic cigarette use is associated with increased odds of subsequent cigarette smoking initiation and current cigarette smoking among adolescents.

Despite their strong methodology and accumulative evidence from a recent systematic review, Hammond et al., (1) mentioned that they did not find “causality:” We are very (pleasantly) surprised and puzzled why the study authors attempted to avoid the obvious conclusion from their data even though the survey data very well confirmed the following: “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 (n = 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.”
A most recent US study is also providing preliminary evidence that use of electronic cigarette with higher nicotine concentrations by adolescents and young adults may increase subsequent frequency and intensity of smoking and vaping (3).

In order to minimize the potential public health harm from electronic cigarette use, the Government of Canada, Health Canada, Canadian Medical Association (CMA) as well as respective provinces, will need to launch evidence based prevention efforts to discourage initiation of electronic cigarette use as well as adolescents’ transition from electronic cigarettes to other combustible tobacco products.

REFERENCE:

(1). Hammond D, Reid JL, Cole AG, Leatherdale ST. Electronic cigarette use and smoking initiation among youth: a longitudinal cohort study. CMAJ. 2017 Oct 30;189(43):E1328-E1336. doi: 10.1503/cmaj.161002.

(2). Soneji S, Barrington-Trimis JL, Wills TA, Leventhal AM, Unger JB, Gibson LA, Yang J, Primack BA, Andrews JA, Miech RA, Spindle TR, Dick DM, Eissenberg T, Hornik RC, Dang R, Sargent JD. Association Between Initial Use of e-Cigarettes and Subsequent Cigarette Smoking Among Adolescents and Young Adults: A Systematic Review and Meta-analysis.JAMAPediatr. 2017 Aug 1;171(8):788-797. doi: 10.1001/jamapediatrics.2017.1488.

(3). Goldenson NI, Leventhal AM, Stone MD, McConnell RS, Barrington-Trimis JL. Associations of Electronic Cigarette Nicotine Concentration With Subsequent Cigarette Smoking and Vaping Levels in Adolescents. JAMA Pediatr.2017 Oct 23.doi: 10.1001/jamapediatrics.2017.3209. [Epub ahead of print]
Acknowledgement: We acknowledge Prof. Stanton Glantz-Professor of university of California, San Francisco, School of Medicine for his valuable feedback on the first draft of this letter.

AUTHORS:
Aki Nilanga Bandara-Founding Chair-Global coalition to increase awareness for potential harmful therapies for adolescents’ unique tobacco addictions related issues.

Rashmi Thalagala- Founding Co-Chair-Global coalition to increase awareness for potential harmful therapies for adolescents’ unique tobacco addictions related issues.

Disara Samayawardhena- Founding C0-Chair-Global coalition to increase awareness for potential harmful therapies for adolescents’ unique tobacco addictions related issues.