Young adolescent smokers who also vape could be at a higher risk of persistent and heavier tobacco smoking in later teenage years than those smokers who did not also vape, according to a study, which recommended further steps should be taken to reduce young people's access to e-cigarettes.
Researchers for the study, published in the journal Tobacco Control, drew on UK and US data and found that, despite national differences in e-cigarette regulation and marketing between the two countries, vaping could entrench early patterns of smoking.
Despite a reduction in tobacco use among teenagers in the past decades, it remains unclear what role vaping might have in reinforcing or reversing the trend. Previous studies have concentrated on how use of vapes by young people translated into later tobacco smoking behaviour. The latest research, conducted by Pennsylvania State University and Purdue University in the US, aimed to answer the question of whether e-cigarette use might steer teenagers who were already smoking away from later tobacco use or entrench smoking behaviour.
UK and US Population Studies
To explore the topic, they looked at 1893 early teenage smokers, of whom 1090 were enrolled in the UK Millennium Cohort Study and 803 in the US Population Assessment of Tobacco and Health study. Participants in both cohorts were regularly surveyed about their use of vapes and how often they smoked tobacco before they reached the age of 18 years.
Among the young smokers, 57% in the UK and 58% in the US reported that they also 'vaped'.
Results of the study, found that those who concurrently vaped and smoked in their early teens were more likely to continue smoking. Before their 18th birthday, 61% of the early vapers in the UK were smoking tobacco compared with 50% of those who had not vaped. For the US cohort, the equivalent figures were 42% compared with 24%.
More nuanced results showed that in both data sets, early smoking young people who did not use e-cigarettes were more likely to report no nicotine use of either type in late adolescence. By late teens, frequent smoking – defined as more than six cigarettes per week – was almost twice as common among UK early vapers (37%) as it was among non-vapers (23%). Similarly, frequent smoking was nearly three times as common among US early teenage vapers (20%) than it was among non-vapers (7%), the results suggested.
The study, which referred to today's adolescents as the "guinea pig generation", on account of them being the first group of teenagers to be exposed to e-cigarettes, concluded: "Among youth who started smoking early in adolescence, early e-cigarette adopters were more likely to become entrenched into tobacco use and in heavier smoking than those who smoked but had not used e-cigarettes." The authors suggested that tobacco control measures "should incorporate the risks posed by e-cigarettes for early smoking youth".
The researchers highlighted some limitations to their study, including the observational nature of their investigation which did not allow them to infer that e-cigarette use combined with smoking played a causal role in entrenching smoking behaviour.
Scepticism from Experts
The implications of the findings were met with some scepticism among UK experts. Dr Jamie Hartmann-Boyce, associate professor in evidence-based policy and practice at the University of Oxford, commented to the Science Media Centre that it "cannot prove that vaping causes young people to start smoking or to smoke more than they would have in the absence of e-cigarettes". He added: "If vaping does cause young people to smoke, we would expect to see youth smoking rates increase as youth vaping rates rise – there is as of yet no clear evidence of this happening."
Professor Peter Hajek, director of the Tobacco Dependence Research Unit at Queen Mary University of London, said: "If vaping led to smoking, we would see an increase in smoking rates among young people since vaping came along. In reality, the decline in smoking among young people has accelerated."
Lion Shahab, professor of health psychology and co-director of the Tobacco and Alcohol Research Group at University College London, said it was "unclear whether e-cigarette use started before or after initiation with cigarettes", whilst Caitlin Notley, professor of addiction sciences at the University of East Anglia, said that "a more appropriate conclusion would be that early reported tobacco smoking is associated with trying an e-cigarette, which is also associated with later continued tobacco smoking".
John Britton, emeritus professor of epidemiology at the University of Nottingham, commented that "most adolescent vaping is transient" and that "those who persist with it are likely to be the most addicted smokers and hence those who are least likely to quit".
Most of the experts who offered their views on the research agreed that the issue was an important public health matter in need of further investigation.
This work was supported by the National Institute on Drug Abuse. This research is based on analyses of data from the UK Millennium Cohort Study, which received core funding from the Economic and Social Research Council UK and a consortium of UK government departments, as well as the Population Assessment of Tobacco and Health, which received funding from the USA by the National Institutes of Health and the Food and Drug Administration. The authors declared no conflicts of interest.