Gateway effects and electronic cigarettes

Increased e-cigarette use prevalence is associated with decreased smoking prevalence among US adults

BACKGROUND

If US adults who smoke cigarettes are switching to e-cigarettes, the effect may be observable at the population level: smoking prevalence should decline as e-cigarette prevalence increases, especially in sub-populations with highest e-cigarette use. This study aimed to assess such effects in recent nationally-representative data.

METHODS

We updated a prior analysis with the latest available National Health Interview Survey data through 2022. Data were cross-sectional estimates of the yearly prevalence of smoking and e-cigarette use, respectively, among US adults and among specific age, race/ethnicity, and sex subpopulations. Non-linear models were fitted to observed smoking prevalence in the pre-e-cigarette era, with a range of 'cut-off' years explored (i.e., between when e-cigarettes were first introduced to when they became widely available). These trends were projected forward to predict what smoking prevalence would have been if pre-e-cigarette era trends had continued uninterrupted. The difference between actual and predicted smoking prevalence ('discrepancy') was compared to e-cigarette use prevalence in each year in the e-cigarette era to investigate whether the observed decline in smoking was statistically associated with e-cigarette use.

RESULTS

Observed smoking prevalence in the e-cigarette era was significantly lower than expected based on pre-e-cigarette era trends; these discrepancies in smoking prevalence grew as e-cigarette use prevalence increased, and were larger in subpopulations with higher e-cigarette use, especially younger adults aged 18-34. Results were robust to sensitivity tests varying the analysis design.

CONCLUSIONS

Population-level data continue to suggest that smoking prevalence has declined at an accelerated rate in the last decade in ways correlated with increased uptake of e-cigarette use.

Differences in Attentional Bias Toward e-Cigarette Cues Between e-Cigarette Users and Nonusers

ABSTRACT

The use of electronic nicotine delivery systems (ENDS) has increased rapidly in recent years, particularly among young adults. There is a dearth of research on the cognitive factors that contribute to ENDS use. One of the possible cognitive mechanisms involved with addictive behavior is attentional bias (AB). AB can manifest as either facilitated attention engagement toward or delayed attention disengagement from a relevant stimulus. The purpose of this study was to examine the difference in AB toward ENDS-related cues between ENDS users and non-ENDS users. ENDS users (n = 29) and nonusers (n = 24) between the ages of 18 and 29 years participated in the dot-probe and eye-tracking picture-viewing tasks. The results showed that there was a significant difference in the variance of AB between the two groups. In the eye-tracking task, ENDS users displayed significantly greater net dwell time and fixation time at time frames of 6-9, 9-12, and 12-15 seconds, compared to nonusers. It is noteworthy that ENDS users exhibited attentional fluctuation toward ENDS cues as well as difficulties disengaging attention from ENDS cues. The current findings offer insight into the nature of attentional processes associated with ENDS cues and provide useful data to guide the development of a nurse-led cognitive intervention focusing on biased attentional processing related to ENDS cues.

Psychological predictors of vaping uptake among non-smokers: A longitudinal investigation of New Zealand adults

INTRODUCTION

Demographic and health factors are known to predict vaping. Less is known about psychological predictors of vaping uptake, particularly among non-smoking adults using longitudinal designs. We aimed to model how psychological factors related to personality and mental health predicted the likelihood of vaping uptake over time in non-smoking adults ages 18+ using longitudinal data.

METHODS

Longitudinal regression models utilised data from the 2018-2020 waves of the New Zealand Attitudes and Values Study to assess how the Big Five personality traits, mental distress and self-control predicted who began vaping over time among non-users (non-vapers and non-smokers), controlling for gender, age, ethnicity and economic deprivation.

RESULTS

Analyses included 36,309 adults overall (ages 18 to 99; M = 51.0). The number of non-users who transitioned into current vaping was small (transitioned from 2018 to 2019, n = 147; 0.48%; 2019 to 2020, n = 189, 0.63%). Fully adjusted models showed that adults with higher mental distress (adjusted odds ratio [aOR] 1.43; 95% confidence interval [CI] 1.09-1.88), lower self-control (aOR 0.79; 95% CI 0.69-0.89) and higher extraversion (aOR 1.09; 95% CI 1.06-1.13) were more likely to begin vaping at the next time point compared to adults who remained non-users. Higher neuroticism and lower conscientiousness also predicted vaping uptake in initial models, but inclusion of mental distress and self-control superseded these traits.

DISCUSSION AND CONCLUSIONS

Psychological factors related to mental distress, impulse control and sociability predicted who was more likely to begin vaping as non-smoking adults. Harm prevention interventions could target these factors to reduce vaping uptake in non-smokers.

Racial and Ethnic Disparities in Adolescent Combustible Tobacco Smoking From 2014 to 2020: Declines Are Lagging Among Non-Hispanic Black Youth

INTRODUCTION

We quantified the linear trend in combustible tobacco smoking among adolescents in the United States from 2014 to 2020, and then compared these trends across racial and ethnic categories. We also tested the effect of e-cigarette use on these trends for all-youth and across racial and ethnic categories.

AIMS AND METHODS

We pooled and analyzed seven years of National Youth Tobacco Survey data for n = 124 151 middle and high school students from 2014 to 2020. Weighted logistic regression analyses calculated the annual change in combustible tobacco smoking (ie cigarettes, cigars, and hookah) from 2014 to 2020. Stratified analyses examined linear trends for non-Hispanic White (NHW), NH-Black (NHB), Hispanic/Latino, and NH-Other (NHO) youth. All-models controlled for sex, grade level, and past 30-day e-cigarette use.

RESULTS

Combustible tobacco smoking from 2014 to 2020 dropped by more than 50% for NHW youth, more than 40% for Latino and NHO youth, compared to just 16% among NHB youth. From 2014 to 2020, the odds of combustible tobacco smoking declined by 21.5% per year for NHWs, which was significantly greater than Hispanic/Latinos (17% per year; p = .025), NHOs (15.4% per year; p = .01), and NHBs (5.1% per year; p < .001), adjusting for sex, grade, and e-cigarette use. Trends and disparities in trends by race and ethnicity were observed independent of e-cigarette use.

CONCLUSIONS

Combustible tobacco smoking declined for all-youth but at significantly different rates across races and ethnicities. Notably, declines in combustible tobacco smoking are lagging among NHB youth. Interventions are critically needed to address this disparity.

IMPLICATIONS

A direct, evidence-based intervention to reduce combustible tobacco smoking among NHB youth is critically needed. Such tobacco control initiatives should follow the Best Practices for Comprehensive Tobacco Control Framework, incorporating sustainable funding for school-based intervention, public health education, and adult cessation.

A systematic review and meta-analysis of the association between e-cigarette use among non-tobacco users and initiating smoking of combustible cigarettes

INTRODUCTION

The rapid increase in e-cigarette use over the past decade has triggered an important public health question on the potential association between e-cigarette use and combustible cigarette smoking. Following AMSTAR 2 and PRISMA guidelines, this evidence synthesis sought to identify and characterize any associations between e-cigarette use among individuals not smoking cigarettes and initiation of cigarette smoking.

METHODS

The protocol was registered on September 24, 2018 (PROSPERO 2018 CRD42018108540). Three databases were queried from January 01, 2007 to April 26, 2023. Search results were screened using the PICOS review method.

RESULTS

Among 55 included studies (40 "good" and 15 "fair"; evidence grade: "high") that adjusted for gender, age, and race/ethnicity between groups, generally, there was a significant association between non-regular e-cigarette use and initiation of cigarette smoking, further supported by the meta-analytic results (AOR 3.71; 95% CI 2.86-4.81). However, smoking initiation was most often measured as ever/current cigarette smoking. Two studies (quality: 2 "good") evaluated progression to regular cigarette smoking among individuals with regular use of e-cigarettes, and generally found no significant associations. One study ("good") evaluated smoking initiation among individuals with regular use of e-cigarettes, finding an increasing probability of ever smoking cigarettes with increased e-cigarette use. Twelve studies (10 "good" and two "fair") examining progression to regular smoking among individuals with non-regular use of e-cigarettes reported inconsistent findings.

CONCLUSIONS

Numerous methodological flaws in the body of literature limit the generalizability of these results to all individuals who are not smoking cigarettes with few studies measuring established/regular use/smoking of e-cigarettes and cigarettes. Further, studies did not control adequately for specific confounding variables representing common liabilities between e-cigarette use and cigarette smoking, nor did they account for sufficient follow-up durations. Collectively, these flaws limit the generalizability of findings to the question of an association between e-cigarette use and cigarette smoking initiation.

An 8-year longitudinal study of long-term, continuous users of electronic cigarettes

BACKGROUND AND AIMS

E-cigarettes have been available for over 15 years, but relatively little is known about long-term users. Our aim was to describe change over time in behaviours, attitudes and dependence in long-term users.

DESIGN AND PARTICIPANTS

A longitudinal study of 375 e-cigarette users enrolled on the Internet in 2012-2016 and surveyed again in 2021 (8 years later on average), who continuously used e-cigarettes in the interval.

FINDINGS

Fewer people in 2021 (11 %) than at baseline (33 %) had smoked tobacco in the past 31 days. Participants switched from second-generation models at baseline (e.g. Ego) to box mods in 2021 (e.g. iStick), they used larger refill bottles, they used home-made e-liquids twice as often, they used tobacco flavours less often and the nicotine concentration in e-liquids decreased from 12 to 6 mg/mL. There was no change over time in the time to the first e-cigarette puff of the day, but an e-cigarette dependence score of 0-100 decreased from 75 to 60, the frequency and strength of urges to vape decreased (from 31 % to 18 % of "strong" urges) and the proportion of people who said they would be likely to succeed if they tried to stop vaping increased. Compared to baseline, fewer people in 2021 reported vaping to cope with cravings or other smoking cessation symptoms, and fewer people reported vaping to quit smoking, to avoid relapse into smoking, or to reduce their tobacco consumption (p < 0.001 for all differences).

CONCLUSIONS

In long-term, continuous users, over a period of 8 years, substantial changes were observed in the models of e-cigarettes used, in the flavours and strength of e-liquids, and in the reasons for vaping. Their level of nicotine dependence tended to decrease over time. These users were satisfied with e-cigarettes and vaped mostly because they felt that vaping was less dangerous than smoking, and for enjoyment.

Association between e-cigarette use and susceptibility to tobacco product use: findings from the 2019 China National Youth Tobacco Survey

Background

There is an ongoing debate about whether e-cigarettes act as a gateway to tobacco smoking or contribute to smoking cessation, and relevant studies are limited among Chinese adolescents. This cross-sectional study therefore aimed to explore the relationship between e-cigarette use and susceptibility to tobacco product use among Chinese high school students.

Methods

The study population comprised 107,633 never smokers and 19,377 former smokers, generated from the 2019 China National Youth Tobacco Survey. The primary independent variables of interest were ever e-cigarette use, current e-cigarette use, and the frequency of current e-cigarette use. The main outcome was the susceptibility to tobacco product use. Multilevel logistic regression was used to estimate the association between the primary independent variables of interest and the outcome variable. Moreover, two additional multilevel logistic regression models were fitted using two alternative definitions of the outcome as the sensitivity analyses.

Results

Among never smokers, students who ever used e-cigarettes were more likely to be susceptible to tobacco product use compared to students who never used e-cigarettes (AOR = 2.83, 95%CI = 2.59-3.08). Students who currently used e-cigarettes were more likely to be susceptible to tobacco product use than those who did not currently use e-cigarettes (AOR = 3.89, 95%CI = 3.21-4.72). Among former smokers, with the same settings of modeling, the AORs were 1.76 (95%CI = 1.62-1.91) and 3.16 (95%CI = 2.52-3.97), respectively. Similar results were obtained from the two sensitivity analyses.

Conclusion

Among Chinese high school students, both never smokers and former smokers, e-cigarette use, especially current e-cigarette use, was positively associated with susceptibility to tobacco product use. It is recommended to strengthen the monitoring of e-cigarettes and to provide targeted health education to adolescents.

Clinical impact of vaping on cardiopulmonary function and lung cancer development: an update

The word 'vaping' is used to define the usage of electronic cigarettes or other instruments to inhale a wide variety of heated and aerosolized substances. Although proposed as a less dangerous and oncogenic alternative than standard nicotine products, e-cigarettes and vaping devices are quite far from being considered benign. In fact, although vaping devices do not generate carcinogenic agents as polycyclic aromatic hydrocarbons produced by the combustion of standard cigarettes and their liquids do not present tobacco-related carcinogens like nitrosamines, there is nowadays clear evidence that they produce dangerous products during their use. Several different molecular mechanisms have been proposed for the oncogenic impact of vaping fluids - by means of their direct chemical action or derivative products generated by pyrolysis and combustion ranging from epithelial-mesenchymal transition, redox stress and mitochondrial toxicity to DNA breaks and fragmentation. In this review we focus on vaping devices, their potential impact on lung carcinogenesis, vaping-associated lung injury and other clinical implications on cardiovascular, cerebrovascular and respiratory diseases, as well as on the psychological implication of e-cigarettes both on heavy smokers trying to quit smoking and on younger non-smokers approaching vaping devices because they are considered as a less dangerous alternative to tobacco cigarettes.

Systematic Review and Critical Analysis of Longitudinal Studies Assessing Effect of E-Cigarettes on Cigarette Initiation among Adolescent Never-Smokers

Prospective longitudinal studies mainly conclude on a causal role of e-cigarettes in the initiation of cigarettes in flagrant contradiction with conclusions drawn from epidemiology and other studies showing a sharp decline in cigarette use in parallel with the spread of e-cigarette use. This systematic review explores the reasons for this discrepancy.

METHODS

Among 84 publications on e-cigarette/cigarette association in adolescents identified in the Medline database from 2011 to 2022, 23 concern 22 never-smoker longitudinal sub-cohorts.

RESULTS

A link between e-cigarette experimentation at T1 and cigarette initiation at T2 is reported in sub-cohort analyses of never-smokers (AOR: 1.41 to 8.30). However, studies exclude 64.3% of T1 e-cigarette experimenters (because of dual-use) and 74.1% of T2 cigarette experimenters. With this study design, e-cigarettes contribute only to 5.3% of T2 cigarette experimentation, casting major doubt on the external validity of results and authors' conclusions that e-cigarettes have a significant effect on the initiation of cigarettes (Gateway effect) at the population level. This sub-cohort design prohibits highlighting any Diversion effect, which is the most likely mechanism accounting for the competition between these two products.

CONCLUSIONS

While nicotine abstinence remains the best medical option, over-regulation of e-cigarettes because of misinterpretation of longitudinal study results may be detrimental to public health and tobacco control.

Regional French evolution of tobacco and e-cigarette experimentation and use among adolescents aged 15-16 years: A cross-sectional observational study conducted in the Loire department from 2018 to 2020

Background

We assessed/compared the evolution of tobacco and e-cigarette experimentation and use among French adolescents of the Loire department aged 15-16 years.

Methods

A descriptive, cross-sectional/observational study conducted in 2018-2020 among 7,950 Year 11 pupils attending 27 public secondary schools of the Loire department, France.

Results

From 2018 to 2020, 66.18% of adolescents were "non-vapers and non-smokers", 19.76% were "vapers and smokers", 7.90% were "non-vapers and smokers" and 6.15% were "vapers and non-smokers". E-cigarette experimentation was more prevalent than tobacco experimentation (44.92% vs 41.67%), and daily vaping was less prevalent than daily smoking (5.40% vs 10.24%). More boys than girls were daily vapers or daily smokers. A decrease was observed in tobacco experimentation (from 41.22% in 2018 to 39.73% in 2020) and e-cigarette experimentation (from 50.28% in 2018 to 41.25% in 2020). Current vaping remained stable, with an increase in daily vaping. French adolescent vapers frequently use e-liquids with little or no nicotine or with fruit or sweet flavours.

Conclusions

Adolescents used e-cigarettes mainly for experimental and/or recreational purposes, with no intention of progression to daily smoking. Although the design of this study is not longitudinal and caution must be exercised, from our cross-sectional observational study data, it appears that the proportion of "non-vapers and non-smokers" tended to increase. "Smokers" tended to progress to the dual use of vaping and smoked tobacco, with the likely intention to reduce or quit smoking.

Nicotine dependence and associated factors among persons who use electronic e-cigarettes in Malaysia - an online survey

BACKGROUND

Nicotine dependence, factors associated with dependence, and self-reported side effects among people who use e-cigarettes are scarce in developing countries.

METHODS

A sample of 302 persons who currently use e-cigarettes was recruited from discussion forums on Reddit, Facebook, and the forum 'lowyat'. The online Google form survey collected data on demographics, e-cigarette use, and the reasons, for cigarette smoking, Fagerstorm Test for Nicotine Dependence adapted for e-cigarettes (eFTND), and side effects experienced.

RESULTS

The mean age was 25.5 years (6.5), 60.6% were males and 86% had higher education. About 47% were using e-cigarettes only, 27.8% were currently using dual products (both electronic and conventional cigarettes), and 25.2% had also smoked cigarettes in the past. 'Less harmful than cigarettes' (56.3%), 'because I enjoy it' (46.7%), and 'it has a variety of flavors (40.4%) were the common reasons for e-cigarette use. The mean eFTND score was 3.9 (SD = 2.2), with a median of four side effects (IQR 3-6), sore or dry mouth/throat (41.4%), cough 33.4%, headache (20.5%), dizziness (16.2%) were commonly reported side effects. eFTND score and side effects were higher among persons using dual products. By multiple linear regression analysis, males (β = 0.56 95% CI 0.45, 1.05, p = 0.033), dual-use (β = 0.95 95% CI 0.34, 1.56, p < 0.003), and use of nicotine-containing e-cigarettes (β = 0.66 95% CI 0.07, 1.25 p = 0.024) had higher eFTND score.

CONCLUSION

Our findings of the study call for the placement of disclaimers about possible nicotine addiction and side effects of e-cigarette products.

Youth's exposure to and engagement with e-cigarette marketing on social media: a UK focus group study

OBJECTIVE

Electronic-cigarettes (e-cigarette) are promoted creatively through social media and considering the potential influence of social media marketing on young people, we explored young people's exposure to and engagement with social media marketing of e-cigarettes.

DESIGN

Semistructured discussion groups.

SUBJECTS

Twenty focus groups with 82 young people aged 11-16 living in the Central belt of Scotland.

METHODS

Youths were asked about smoking and vaping behaviours, social media use, vaping advertisement exposure and were shown illustrative examples of social media content (eg, images and videos) about different messages, presentations and contextual features. Transcripts were imported into NVivo V.12, coded thematically and analysed.

RESULTS

Youths highlighted a variety of tactics e-cigarette companies use, including influencer or celebrity endorsement, attractive youth flavours, bright colours and emotional appeal to advertise and promote their products directly to young people. Social media influencers who advertise e-cigarettes were described as portraying e-cigarettes as 'cool' and 'fashionable' to entice viewers to try the products. Youths considered that there is a need for more restrictions on social media content to protect youths while also still allowing smokers to purchase them as a cessation device.

CONCLUSIONS

Our study highlights that the e-cigarette industry is using previously employed tactics similar to the tobacco industry to advertise and promote its products on social media. These findings suggest the growing need for governments to work together to develop and implement policies to restrict the advertising and marketing of e-cigarettes on social media.

Impact of e-cigarette experimentation and use on smoking behavior among adolescents aged 15-16 years in the Loire department, France

INTRODUCTION

We describe the vaping and smoking habits of French adolescents aged 15-16 years in the Loire department with a view to assess the impact of e-cigarette experimentation and use on their smoking behavior.

METHODS

This quantitative, cross-sectional, single-center and observational study conducted from January to July 2019 targeted 6622 students aged 15-16 years attending public high school in the Loire department, France.

RESULTS

A total of 4937 (74.6%) adolescents were included. Of these, 73.2% were non-vapers and 72.2% non-smokers; 66.0% of adolescents were non-vapers and non-smokers. Slightly less than half of adolescents had experimented with e-cigarettes (44.6%), more than half of whom (26.8%) continued to use vaping products, with 6.02% vaping daily. Likewise, a little less than half of adolescents had experimented with smoked tobacco (42.4%), more than half of whom (27.8%) continued to use smoking products, with 10.3% smoking daily. Vapers and smokers (20.6%) tended to begin with the use of smoked tobacco and to progress to the dual use of vaping and smoked tobacco products. Vaping had a positive effect, as 71.8% of vapers who smoked tobacco before initiating vaping stopped or reduced smoking following their progression to this double use. More than half of tobacco users are daily users while this daily use affects only 1/3 boys and 1/6 girls for vape. Finally, nearly 80.7% of adolescents who had never smoked before vaping did not smoke at the time of the study.

CONCLUSIONS

Our data suggest that vaping has a rather marginal impact on smoking initiation among French adolescents aged 15-16 years in the Loire department. They therefore neither confirm nor completely disprove the gateway effect theory, relating to use of tobacco subsequent to vaping.

Vaping and socioeconomic inequalities in smoking cessation and relapse: a longitudinal analysis of the UK Household Longitudinal Study

BACKGROUND

Smoking is a key cause of socioeconomic health inequalities. Vaping is considered less harmful than smoking and has become a popular smoking cessation aid, and therefore has potential to reduce inequalities in smoking.

METHODS

We used longitudinal data from 25 102 participants in waves 8-10 (2016 to early 2020) of the UK Household Longitudinal Study to examine how vaping affects socioeconomic inequalities in smoking cessation and relapse. Marginal structural models were used to investigate whether vaping mediates or moderates associations between educational attainment and smoking cessation and relapse over time. Multiple imputation and weights were used to adjust for missing data.

RESULTS

Respondents without degrees were less likely to stop smoking than those with a degree (OR: 0.65; 95% CI 0.54-0.77), and more likely to relapse (OR: 1.74; 95% CI 1.37-2.22), but this inequality in smoking cessation was not present among regular vapers (OR: 0.99; 95% CI 0.54-1.82). Sensitivity analyses suggested that this finding did not hold when comparing those with or without any qualifications. Inequalities in smoking relapse did not clearly differ by vaping status.

CONCLUSIONS

Vaping may be especially helpful as a cessation aid for smokers without degree level education and therefore may help reduce inequalities in smoking. Nevertheless, other supports or aids may be needed to reach the most disadvantaged (ie, those with no qualifications) and to help people avoid relapse after cessation, though we did not find clear evidence suggesting that vaping would increase inequalities in relapse.

Exploring the gateway hypothesis of e-cigarettes and tobacco: a prospective replication study among adolescents in the Netherlands and Flanders

BACKGROUND

Studies demonstrated that adolescent e-cigarette use is associated with subsequent tobacco smoking, commonly referred to as the gateway effect. However, most studies only investigated gateways from e-cigarettes to tobacco smoking. This study replicates a cornerstone study revealing a positive association between both adolescent e-cigarette use and subsequent tobacco use; and tobacco and subsequent e-cigarette use in the Netherlands and Flanders.

DESIGN

The longitudinal design included baseline (n=2839) and 6-month (n=1276) and 12-month (n=1025) follow-up surveys among a school-based cohort (mean age: 13.62). Ten high schools were recruited as a convenience sample. The analyses involved (1) associations of baseline e-cigarette use and subsequent tobacco smoking among never smokers; (2) associations of e-cigarette use frequency at baseline and tobacco smoking frequency at follow-up; and (3) the association of baseline tobacco smoking and subsequent e-cigarette use among non-users of e-cigarettes.

FINDINGS

Consistent with prior findings, baseline e-cigarette use was associated with higher odds of tobacco smoking at 6-month (OR=1.89; 95% CI 1.05 to 3.37) and 12-month (OR=5.63; 95% CI 3.04 to 10.42) follow-ups. More frequent use of e-cigarettes at baseline was associated with more frequent smoking at follow-ups. Baseline tobacco smoking was associated with subsequent e-cigarette use (OR=3.10; 95% CI 1.58 to 6.06 at both follow-ups).

CONCLUSION

Our study replicated the positive relation between e-cigarette use and tobacco smoking in both directions for adolescents. This may mean that the gateway works in two directions, that e-cigarette and tobacco use share common risk factors, or that both mechanisms apply.

Associations Between E-cigarettes and Subsequent Cocaine Use in Adolescence: An Analysis of the UK Millennium Cohort Study

INTRODUCTION

Nicotine exposure via early combustible cigarette smoking can prime the adolescent brain for subsequent cocaine use. However, there is limited evidence whether e-cigarette use, a nicotine delivery system that is increasingly popular among youth, is associated with later cocaine use. We examine the association between e-cigarette use by the age of 14 years and cocaine use by the age of 17 years.

AIMS AND METHODS

The Millennium Cohort Study is a nationally representative sample of 18 552 9-month-old children born between September 2000 and January 2002 in the United Kingdom. Follow-up interviews and surveys were collected from children and their caregivers at modal ages 3, 5, 7, 9, 11, 14, and 17 years. Our analytic sample included 340 youth who had used e-cigarettes by age 14 years (exposure variable), matched using coarsened exact matching, to 4867 nicotine naïve youth on childhood common liability confounders and demographics measured from infancy to age 11. The outcome was cocaine use by the modal age of 17 years.

RESULTS

Of the 5207 successfully matched youth, 7.6% of adolescent e-cigarette users by age 14 years used cocaine by age 17 years versus 3.1% of non-e-cigarette users. Multivariable logistic regression in the matched sample indicated that e-cigarette use by age 14 years was associated with 2.7 times higher odds of cocaine use by age 17 years (95% CI, 1.75 to 4.28).

CONCLUSIONS

These findings in a UK sample showed that e-cigarette use in early adolescence is associated with higher odds of cocaine use later in adolescence, similar to risks posed by tobacco cigarette smoking.

IMPLICATIONS

In this large-scale prospective cohort study (n = 5207), youth who had used e-cigarettes by the age of 14 years were matched to nicotine naïve youth on childhood common liability confounders and demographics measured from infancy to age 11 years (e.g. school engagement, risk-taking propensity, delinquency, peer and parental smoking, parental educational attainment). After matching, 7.6% of age 14 years e-cigarette users had subsequently used cocaine by the age of 17 years versus 3.1% of non-e-cigarette users. Although e-cigarettes are promoted as a strategy for nicotine-dependent users to reduce the harms of combustible cigarettes, the evidence here suggests that for nicotine naïve youth, they may increase the risk of subsequent cocaine use.

A Novel Puff Recording Electronic Nicotine Delivery System for Assessing Naturalistic Puff Topography and Nicotine Consumption During Ad Libitum Use: Ancillary Study

BACKGROUND

Assessing the naturalistic puff topography and associated nicotine consumption during e-cigarette use is important as such information will not only unveil how these products are being consumed in real-world conditions, but also enable investigators and regulatory bodies to conduct quantitative, accurate, and realistic harmful exposure and nicotine abuse liability risk assessments based on actual e-cigarette use. Conventional approaches cannot accurately, conveniently, and noninvasively determine e-cigarette puff topography in a natural use environment. Thus, novel technology-enabled systems that do not primarily rely on self-report mechanisms or intrusive measurements to monitor e-cigarette product use behaviors are highly desired.

OBJECTIVE

This study aimed to explore and demonstrate the feasibility of a novel puff recording electronic nicotine delivery system (PR-ENDS) device for measuring naturalistic puff topography and estimating nicotine consumption during the ad libitum use of products among smokers and vapers.

METHODS

An ancillary data analysis based on a completed parent study was conducted. The parent study was a 1-way randomized controlled open-label puff topography and nicotine pharmacokinetic assessment carried out in 24 healthy adults (12 smokers and 12 vapers). Participants were assigned a randomized product use sequence of a PR-ENDS device within 5 site visits for both controlled and ad libitum product use sessions. Blood samples were obtained for plasma nicotine analysis, and questionnaires were administered at various time points. During the ad libitum use session, puff topography was measured using a Clinical Research Support System (CReSS) device as a benchmark, as well as the PR-ENDS device with a built-in puff recording feature.

RESULTS

There were no significant differences in representative puff topography parameters (number of puffs, total puff duration, and average puff duration) between the PR-ENDS and CReSS devices at the populational level across different device powers, e-liquid nicotine strengths, and flavors. The nicotine consumption estimated by the PR-ENDS device suggested that this device can be employed as a convenient monitoring tool for estimating nicotine use without measuring e-liquid weight loss between puffs. The linear relationship between nicotine consumption estimated by the PR-ENDS device and the pharmacokinetic parameter AUC_{ad lib} (plasma concentration-time curve for 1-hour ad libitum use) substantiated the potential of using this device as a pragmatic, noninvasive, and convenient means for estimating nicotine intake in the human body without blood collection.

CONCLUSIONS

The novel PR-ENDS device was feasible for assessing naturalistic puff topography and estimating nicotine consumption and intake in the human body during ad libitum use. Several key factors can influence users' puff topography, including device power levels, e-liquid nicotine strengths, and flavors. The study results pave the way for further research in the real-time measurement of naturalistic puff topography and puffing behaviors in the real world.

E-cigarette use in global digital youth culture. A qualitative study of the social practices and meaning of vaping among 15-20-year-olds in Denmark, Finland, and Norway

BACKGROUND

The introduction of e-cigarettes on the tobacco market has brought new regulatory challenges, and particular concerns relate to e-cigarette uptake among young people. The aim of this study was to explore the use and social meaning of e-cigarettes among Nordic young people and to discuss this in the context of current legislation.

METHODS

Thirteen focus groups were conducted with 46 Danish, Finnish, and Norwegian young people (24 boys) with vaping experience aged 15-20 years (mean age 17 years).

RESULTS

Young people's vaping stood out as an inherently social practice that was commonly interlinked with experimental use patterns. Relative to smoking, vaping was seen as socially acceptable and less harmful to health. Product innovations like flavour additives and nicotine-free liquid options added to perceptions of low harm, and innovative device design features facilitated new and playful user practices. Finally, digital markets eased the young people's access to e-cigarettes, and the digital world also represented an arena for e-cigarette exposure and self-presentation. They commonly viewed vaping-related content in their social media feeds and also produced such content themselves.

CONCLUSION

Young people's vaping is a social practice interwoven in contemporary digital and global youth culture. Transnational regulations are needed to support individual countries in preventing e-cigarette use and exposure among young people.

A Systematic Review Investigating Associations Between E-Cigarette Use Among Former Cigarette Smokers and Relapse to Smoking Cigarettes

As e-cigarette use has steadily increased over the recent years, the public health interest in the potential implications of e-cigarette use on cigarette smoking has grown in parallel. With strict adherence to PRISMA guidelines, this systematic review examined the potential associations between e-cigarette use and relapse to cigarette smoking among former cigarette smokers. The protocol was registered on November 06, 2018 (PROSPERO 2018 CRD42018115674). Literature searches were executed from January 01, 2007 to August 20, 2022 and search results were screened according to the PICOS review method. One RCT and 10 adjusted studies examined relapse to cigarette smoking (evidence grade "moderate") among regular e-cigarette users, reporting mixed and inconsistent findings according to varying definitions of e-cigarette use and relapse. Findings were similarly inconsistent among the 8 adjusted studies examining relapse to cigarette smoking among non-regular e-cigarette users. The inconsistency in findings among studies evaluating regular measures of e-cigarette use, combined with the numerous methodological flaws in the overall body of literature, limit the generalizability of results associated with a causal association between e-cigarette use and relapse to cigarette smoking. Based on findings from this review, more robust studies are required to determine whether a causal association exists between e-cigarette use and relapse to cigarette smoking. Future studies should apply consistent measures of regular e-cigarette use to examine causality with future use patterns, and sufficiently account for known or suspected confounding variables to support inform determinations related to e-cigarette use and cigarette smoking behaviors.

Intended and unintended effects of e-cigarette taxes on youth tobacco use

Over the past decade, rising youth use of e-cigarettes and other electronic nicotine delivery systems (ENDS) has contributed to aggressive regulation by state and local governments. Between 2010 and mid-2019, ten states and two large counties adopted ENDS taxes. We use two large national surveys (Monitoring the Future and the Youth Risk Behavior Surveillance System) to estimate the impact of ENDS taxes on youth tobacco use. We find that ENDS taxes reduce youth ENDS consumption, with estimated ENDS tax elasticities of -0.06 to -0.21. However, we estimate sizable positive cigarette cross-tax effects, suggesting economic substitution between cigarettes and ENDS for youth. These substitution effects are particularly large for frequent cigarette smoking. We conclude that the unintended effects of ENDS taxation may considerably undercut or even outweigh any public health gains.

Determinants of E-Cigarette and Cigarette Use among Youth and Young Adults in Poland-PolNicoYouth Study

Teen use of tobacco-related products is a significant public health concern. This study evaluated the predictors of e-cigarette use among secondary school students who were never cigarette smokers and ever cigarette smokers in Poland.

METHODS

This study examined a sample of Polish youths aged 13-19 (n = 19,241) attending 200 schools, 12 on average in each county. The study was a part of the National Health Program in Poland for 2016-2020. Logistic regression and multivariable logistic regression models were used to calculate crude and adjusted odds ratios.

RESULTS

Of all participants, 32.5% were ever cigarette users. Among the never cigarette users, 13.6% were deemed susceptible to e-cigarette use. Among the ever cigarette users, 60.6% were deemed susceptible to e-cigarette use. Of those susceptible to e-cigarette use, 68.2% were among the 32.5% ever cigarette users. The profile of e-cigarette use among never e-cigarette users also included: pocket money available per month (more than 150 PLN) (OR = 1.7; p = 0.001), 16-17 years old (OR = 1.9; p = 0.001), parental tobacco smoking and e-cigarette usage (OR = 2.0; p = 0.01 and OR = 1.7; p = 0.001 respectively), maternal secondary education (OR = 1.1; p = 0.04), and living in big cities >500,000 inhabitants (OR = 1.4; p = 0.04). E-cigarette users among ever cigarette users were similar to never cigarette users in their opinion that e-cigarette use is less harmful than traditional smoking (OR = 1.6; p = 0.0012) and living with both parents smoking cigarettes (OR = 1.3; p = 0.02). Additionally, the determinants were: female gender (OR = 1.5; p = 0.009) in the age group less than 15 years of age (OR = 1.3; p = 0.007).

CONCLUSIONS

The major determinant of e-cigarette use in this population was prior smoking. Additionally, the results revealed that fairly obvious predictors such as parental smoking and a belief in the less harmfulness of e-cigarette use are important determinants for smoking among never or ever e-cigarette users.

A Systematic Review and Meta-analysis of the Association between E-cigarette Use among Cigarette Smokers and Quit Attempts Made to Abstain from Cigarette Smoking

Objective: Following AMSTAR 2 and PRISMA guidelines, in this synthesis of evidence we sought to identify and characterize any associations between e-cigarette use among cigarette smokers and cigarette smoking quit attempts. Methods: We queried 3 databases from January 1, 2007 to January 5, 2021. Search results were screened using the PICOS review method. Included studies examined e-cigarette use and cigarette smoking quit attempts across e-cigarette use statuses. Risk of bias was assessed according to the Agency for Healthcare Research and Quality Evidence-Based Practice Center approach. Finally, 4 random-effects models compared e-cigarette users and non- e-cigarette-users in terms of past year and prospective (6 to 12 months) cigarette smoking quit attempts. Results: We qualitatively synthesized 17 adjusted studies for this review. Two meta-analyses showed past year quit attempts were significantly associated with current e-cigarette users and 2 prospective data analyses found no significant association. Conclusions: The results of the meta- analyses emphasize temporality in the association between e-cigarette use and cigarette smoking quit attempts. Numerous methodological limitations, including inadequate definitions of e-cigarette use and non-adjustment for confounding variables, limit the confidence in conclusions that can be drawn on the causal association between e-cigarette use and cigarettes smoking quit attempts.

The Economics of Tobacco Regulation: A Comprehensive Review

Tobacco regulation has been a major component of health policy in the developed world since the UK Royal College of Physicians' and the US Surgeon General's reports in the 1960s. Such regulation, which has intensified in the past two decades, includes cigarette taxation, place-based smoking bans in areas ranging from bars and restaurants to workplaces, and regulations designed to make tobacco products less desirable. More recently, the availability of alternative products, most notably e-cigarettes, has increased dramatically, and these products are just starting to be regulated. Despite an extensive body of research on tobacco regulations, there remains substantial debate regarding their effectiveness, and ultimately, their impact on economic welfare. We provide the first comprehensive review of the state of research in the economics of tobacco regulation in two decades.

Association of quarterly prevalence of e-cigarette use with ever regular smoking among young adults in England: a time-series analysis between 2007 and 2018

AIMS

To assess how changes in the prevalence of e-cigarette use among young adults have been associated with changes in the uptake of smoking in England between 2007 and 2018.

DESIGN

Time-series analysis of population trends with autoregressive integrated moving average with exogeneous input (ARIMAX models).

SETTING

England.

PARTICIPANTS

Data were aggregated quarterly on young adults aged 16-24 years (n = 37 105) taking part in the Smoking Toolkit Study.

MEASURES

In the primary analysis, prevalence of e-cigarette use was used to predict prevalence of ever regular smoking among those aged 16-24. Sensitivity analyses stratified the sample into those aged 16-17 and 18-24. Bayes' factors and robustness regions were calculated for non-significant findings [effect size beta coefficient (B) = 3.1].

FINDINGS

There was evidence for no association between the prevalence of e-cigarette use and ever regular smoking among those aged 16-24 [B = -0.015, 95% confidence interval (CI) = -0.046 to 0.016; P = 0.341; Bayes factor (BF) = 0.002]. Evidence for no association was also found in the stratified analysis among those aged 16-17 (B = 0.070, 95% CI -0.014 to 0.155, P = 0.102; BF = 0.015) and 18-24 (B = -0.021, 95% CI -0.053 to 0.011; P = 0.205; BF = 0.003). These findings were able to rule out percentage point increases or decreases in ever regular smoking prevalence greater than 0.31% or less than -0.03% for 16-17-year-olds and 0.01 or -0.08% for 18-24-year-olds for every 1%-point increase in e-cigarette prevalence.

CONCLUSION

Prevalence of e-cigarette use among the youth population in England does not appear to be associated with substantial increases or decreases in the prevalence of smoking uptake. Small associations cannot be ruled out.

Loot boxes and problem gambling: Investigating the "gateway hypothesis"

Loot boxes are purchasable items in video games with a chance-based outcome. They have attracted substantial attention from academics and legislators over recent years, partly because of associations between loot box engagement and problem gambling. Some researchers have suggested that loot boxes may act as a gateway into subsequent gambling and/or problem gambling. However, such "gateway effects" have not been formally investigated. Using a survey of 1102 individuals who both purchase loot boxes and gamble, we found that 19.87% of the sample self-reported either "gateway effects" (loot boxes causally influencing subsequent gambling) or "reverse gateway effects" (gambling causally influencing subsequent loot box engagement). Both subsets of participants had higher scores for problem gambling, problem video gaming, gambling-related cognitions, risky loot boxes engagement, and impulsivity. These individuals also had a tendency for higher loot box and gambling spend; suggesting that potential gateway effects are related to measurable risks and harms. Moreover, the majority of participants reporting gateway effects were under 18 when they first purchased loot boxes. Content analysis of free text responses revealed several reasons for self-reported gateway effects, the most frequent of which were sensation-seeking, normalisation of gambling-like behaviours, and the addictive nature of both activities. Whilst the cross-sectional nature of our findings cannot conclusively establish directions of causality, thus highlighting the need for longitudinal research, we conclude that there is a case for legislation on loot boxes for harm minimisation purposes.

How Data Security Concerns Can Hinder Natural Experiment Research: Background and Potential Solutions

Health economists conducting cancer-related research often use geocoded data to analyze natural experiments generated by policy changes. These natural experiments can provide causal interpretation under certain conditions. Despite public health benefit of this rigorous natural experiment methodology, data providers are often reluctant to provide geocoded data because of confidentiality concerns. This paper provides an example of the value of natural experiments from e-cigarette research and shows how this research was hindered by security concerns. Although the tension between data access and security will not be resolved overnight, this paper offers 3 recommendations: 1) provide public access to aggregated data at area levels (eg, state) where possible; 2) approve projects with enough time to allow for publication in journals with lengthy peer-review times; and 3) improve communication and transparency between data providers and the research community. The Foundations for Evidence Based Policymaking Act of 2018 also presents a unique opportunity for improving the ability of researchers to use geocoded data for natural experiment research without compromising data security.

Association of Electronic Cigarette Use with Respiratory Symptom Development among U.S. Young Adults

Rationale: Electronic cigarette (e-cigarette) use is highly prevalent among young adults. However, longitudinal data assessing the association between e-cigarette use and respiratory symptoms are lacking. Objectives: To determine whether e-cigarette use is associated with the development of respiratory symptoms in young adults. Methods: Data are derived from the PATH (Population Assessment of Tobacco and Health) study waves 2 (2014-2015), 3 (2015-2016), 4 (2016-2018), and 5 (2018-2019). Young adults aged 18-24 years at baseline with no prevalent respiratory disease or symptoms were included in the analyses. Binary logistic regression models with a generalized estimating equation were used to estimate time-varying and time-lagged associations of e-cigarette use during waves 2-4, with respiratory symptom development approximately 12 months later at waves 3-5. Measurements and Main Results: The per-wave prevalence of former and current e-cigarette use was 15.2% and 5.6%, respectively. Former e-cigarette use was associated with higher odds of developing any respiratory symptom (adjusted odds ratio [aOR], 1.20; 95% confidence interval [CI], 1.04-1.39) and wheezing in the chest (aOR, 1.41; 95% CI, 1.08-1.83) in multivariable adjusted models. Current e-cigarette use was associated with higher odds for any respiratory symptom (aOR, 1.32; 95% CI, 1.06-1.65) and wheezing in the chest (aOR, 1.51; 95% CI, 1.06-2.14). Associations persisted among participants who never smoked combustible cigarettes. Conclusions: In this nationally representative cohort of young adults, former and current e-cigarette use was associated with higher odds of developing wheezing-related respiratory symptoms, after accounting for cigarette smoking and other combustible tobacco product use.

E-cigarette Transitions Among US Youth and Adults: Results from the Population Assessment of Tobacco and Health Study (2013-2018)

Currently, the debate surrounding the regulation of e-cigarettes focuses mainly on the size of e-cigarettes' potentially beneficial effects (i.e., adult cessation) versus their unwarranted effects (i.e., initiation among tobacco-naïve adolescents). Therefore, we investigated the relative scale of e-cigarette use transitions in the United States. We reported cross-sectional weighted prevalence estimates of past-month e-cigarette use by ever cigarette use from Waves 1-4 of the Population Assessment of Tobacco and Health study (2013-2018) among youth (12-17 years) and adults (≥ 18 years). We also examined past-month e-cigarette mono and dual transitions related to cigarette smoking and reported the longitudinal weighted prevalence across waves. Among youth new e-cigarette users, the proportion of never-cigarette smokers increased from 24.1 in Wave 1 (n = 418) to 51.4% in Wave 4 (n = 310) (p < 0.0001 for trend). Of youth past-month e-cigarette mono-users in Wave 1 (n = 151), 15.2% transitioned to cigarette mono-use and 8.2% dual-use at Wave 2 or 3 or 4, compared to 60.2% no tobacco use and 16.4% e-cigarette mono-use. Among young adult past-month dual-users (18-24 years; n = 684), 22.6% transitioned to no tobacco use, 60.1% continued cigarette use, 11.4% dual use, and 5.9% e-cigarette mono-use. Among adult dual-users ≥ 25 years old (n = 1560), 13.6% transitioned to no tobacco use, 71.3% cigarette mono-use, 9.0% dual-use, and 6.1% e-cigarette mono-use. Transition to cigarette mono-use and continued dual-use were common among adult past-month e-cigarette users, while e-cigarette initiation was common among youth never-cigarette smokers. These findings contrast with data from other countries showing limited evidence of e-cigarette initiation among youth never cigarette smokers. Both e-cigarette and cigarette use should be addressed in youth and adults, given the potential for dual use in both populations.

A qualitative analysis of electronic nicotine delivery systems (ENDS) uptake and use among young adult never-smokers in New Zealand

INTRODUCTION

Electronic nicotine delivery systems (ENDS) likely pose fewer health risks than smoking. Yet ENDS uptake has increased among never-smoking young adults, who likely face greater health risks relative to non-users of ENDS. To date, few qualitative studies have explored ENDS uptake and use by never-smokers.

METHODS

We conducted in-depth, semi-structured interviews with 16 current ENDS users from New Zealand aged 18 to 24 years old who reported never having smoked cigarettes regularly. We explored participants' experimentation with conventional tobacco products, trial, uptake and patterns of ENDS use, and their future intentions regarding both ENDS and conventional tobacco products. We managed the data using NVivo12 and used thematic analysis to interpret the transcripts.

RESULTS

ENDS use enhanced connection and belonging by providing communal experiences and facilitating social interactions. Participants' mastery of tricks generated social cachet within friendship groups and counteracted the ENDS-related stigma they experienced. Flavours, clouds and devices' physical attributes provided stimulation and engagement, and some used ENDS for stress or appetite management. Lastly, participants rationalised ENDS uptake by referencing the far greater risks smoking posed.

CONCLUSIONS

ENDS uptake by young adult never-smokers is driven by both psycho-social and functional factors. ENDS provided shared hedonic experiences and physical pleasures, and generated both bonding and bridging social capital, although many participants had also experienced judgement from others for using ENDS. Policies that denormalise ENDS as recreational devices could discourage uptake by never-smokers, though measures will require careful nuancing to avoid deterring smokers from switching to ENDS.

Smoking Susceptibility in Canadian Adolescent Electronic-Cigarette Users

Background: E-cigarette use is increasing among Canadian youth, with experimentation especially prevalent among never-smoking youth. Among this group, there is concern e-cigarette use contributes to future initiation of smoking through a gateway effect. However, e-cigarette use and smoking share many common risk factors; a postulated mechanism to explain the apparent causal pathway from e-cigarette use to smoking initiation in previously smoking-naïve youth. A better understanding of the relationships between smoking susceptibility and e-cigarette use among never-smoking youth is needed. Purpose/objectives: The primary aim of this study was to gain a deeper understanding of the risk factors associated with smoking susceptibility in youth who have recently used e-cigarettes. Methods: This study used data (n = 40,363) from the 2018/2019 Canadian Student Tobacco Alcohol and Drug Use Survey (CSTADS) to compare the risk factor profiles of susceptible and non-susceptible never-smoking e-cigarette users, as well as susceptible and non-susceptible never-smoking youth who have never used an e-cigarette. Results: E-cigarette use, independent of susceptibility status, was associated with a sociodemographic and behavioral risk factor profile likely to confer a higher risk of initiating smoking. Among e-cigarette users, smoking susceptibility was associated with more smoking risk factors. Conclusions/importance: Study findings support a common risk-factor model, rather than e-cigarette use itself, to explain differences in the likelihood of smoking initiation among e-cigarette users. E-cigarette use and smoking initiation may be interchangeable outcomes amongst those with smoking risk factors. The risks of e-cigarette use, and their regulatory status, need to be balanced with their potential as harm reduction tools.

Is Adolescent E-Cigarette Use Associated With Subsequent Smoking? A New Look

INTRODUCTION

Prospective studies have consistently reported a strong association between e-cigarette use and subsequent cigarette smoking, but many failed to adjust for important risk factors.

METHODS

Using longitudinal data from the Population Assessment of Tobacco and Health (PATH) Study, we employed multivariable logistic regressions to assess the adolescent vaping-to-smoking relationship, with four regressions (Models 1-4) sequentially adding more risk factors.Our sample included all waves (waves 1-5) of the PATH Study.

RESULTS

The association between ever e-cigarette use and subsequent cigarette smoking decreased substantially in magnitude when adding more control variables, including respondents' sociodemographic characteristics, exposure to tobacco users, cigarette susceptibility, and behavioral risk factors. Using the most recent data (waves 4-4.5 and waves 4.5-5), this association was not significant in the most complete model (Model 4). Using wave 4.5-5 data, the adjusted odds ratio (aOR) for ever e-cigarette use at initial wave and subsequent past 12-month smoking declined from 4.07 (95% confidence interval [CI, 2.86-5.81) in Model 1, adjusting only for sociodemographic characteristics, to 1.35 (95% CI, 0.84-2.16) in Model 4, adjusting for all potential risk factors. Similarly, the aOR of ever e-cigarette use and past 30-day smoking at wave 5 decreased from 3.26 (95% CI, 1.81-5.86) in Model 1 to 1.21 (95% CI, 0.59-2.48) with all covariates (Model 4).

CONCLUSIONS

Among adolescent never cigarette smokers, those who had ever used e-cigarettes at baseline, compared with never e-cigarette users, exhibited modest or non-significant increases in subsequent past 12-month or past 30-day smoking when adjusting for behavioral risk factors.

Smoking and snus use among Norwegian students: Demographic, personality and substance use characteristics

Background and aim:

Smoking rates are decreasing in Norway while the use of snus has increased. We aimed to investigate the co-occurrence of, and the socio-demographics, personality and substance use characteristics associated with, student smoking and snus use.

Methods:

Survey data were collected among students in higher education in Bergen, Norway in 2015 (N = 11,236, response rate 39.4%). Multinomial regression analyses comparing snus users and smokers to non-users and non-smokers, respectively, on demographic, personality and substance use variables were conducted. Regression analyses comparing current dual users to current smokers and current snus users and comparing daily smokers to daily snus users, on demographic, personality and substance use variables were also conducted.

Results:

In total 67.9% of ever snus users identified themselves as non-smokers (past and current). Several demographic, personality and substance use characteristics associated with smoking and snus use were identified (all = p < .05), some of which were common for both (e.g., use of cannabis) and some which were exclusively associated with either smoking (e.g., neuroticism) or snus use (e.g., extroversion).

Conclusion:

The current study contributes with several novel findings regarding traits associated with smoking and snus use. Though limited by a cross-sectional design, the current findings may suggest that the group of students using snus consists of a combination of previous smokers, students who would have smoked if snus was not available and a new segment who may not have used nicotine if snus was not available.

E-cigarette device type and combustible tobacco use: Results from a pooled analysis of 10,482 youth

INTRODUCTION

To understand whether using a certain e-cigarette device is more strongly associated with risk of combustible tobacco use among youth.

METHODS

We conducted multivariable logistic regression analyses using cross-sectional data from 4 samples of youth in Connecticut and California (N = 10,482; ages 13-24), separately for each study using the total sample and the sample of past-month e-cigarette users, to understand the association between e-cigarette device type and past-month combustible tobacco use, while controlling for age, sex, race/ethnicity, socioeconomic status, school, and past-month marijuana use. Then, we conducted meta-analyses to calculate pooled associations for adolescents, young adults, and all individuals combined.

RESULTS

Among the total sample, combustible tobacco use was associated with any e-cigarette device use (vs. no e-cigarette use) in the pooled analysis across all studies. Among past-month e-cigarette users, combustible tobacco use across all studies was 15.8%- 61.5%. Pooled associations among past-month e-cigarette users showed that using disposable devices (vs. pods; AOR=2.83, 95% CI: 1.73-4.61) and multiple devices most frequently (vs. pods; AOR=2.13, 95% CI: 1.16-3.90) was associated with greater odds of combustible tobacco use. Pooled associations also found that using multiple devices (vs. a single device) in the past month was associated with greater odds of combustible tobacco use (AOR 2.33, 95% CI: 1.74, 3.14).

DISCUSSION

Using disposable e-cigarettes and multiple devices is associated with greater likelihood of combustible tobacco use among e-cigarette using youth. Future research should elucidate the trajectory of e-cigarette device used and combustible tobacco use among youth to inform prevention and product regulation.

Adolescent electronic cigarette use and tobacco smoking in the Millennium Cohort Study

AIMS

To evaluate the catalyst, diversion and common liability hypotheses by examining associations between e-cigarette use and tobacco cigarette smoking at modal ages 14 and 17 years, controlling for adolescent and infancy risk factors.

DESIGN

Intergenerational, prospective cohort data from the Millennium Cohort Study (MCS). Nationally representative sample of infants born September 2000 to January, 2002.

SETTING

United Kingdom.

PARTICIPANTS

Parent and child data from 10 625 youth assessed in infancy and modal ages 11, 14 and 17 years.

MEASUREMENTS

Age 14 and 17 e-cigarette and combustible cigarette use (recency, frequency). Potential confounders were age 11 risk factors (e.g. alcohol use, externalizing behaviors, parental tobacco use, permissiveness), infancy risk factors (e.g. maternal smoking during pregnancy, smoke exposure in infancy) and demographic characteristics.

FINDINGS

Among youth who had not smoked tobacco by age 14 (n = 9046), logistic regressions estimated that teenagers who used e-cigarettes by age 14 compared with non-e-cigarette users, had more than five times higher odds of initiating tobacco smoking by age 17 [odds ratio (OR) = 5.25, 95% confidence interval (CI) = 3.28-8.38] and nearly triple the odds of being a frequent tobacco smoker at age 17 (OR = 2.91, 95% CI = 1.56-5.41), net of risk factors and demographics. Among youth who had not used e-cigarettes by age 14 (n = 9078), teenagers who had smoked tobacco cigarettes by age 14 had three times higher odds of initiating e-cigarettes by age 17 (OR = 2.98, 95% CI = 1.74-5.09) compared with non-tobacco smokers and nearly three times higher odds of frequently using e-cigarettes at age 17 (OR = 2.90, 95% CI = 1.21-6.95), net of confounders. Similar links between e-cigarette and tobacco cigarette use were observed in regressions following coarsened exact matching.

CONCLUSIONS

E-cigarette use by age 14 is associated with increased odds of tobacco cigarette initiation and frequent smoking at age 17 among British youth. Similarly, tobacco smoking at age 14 is associated with increased odds of both e-cigarette initiation and frequent use at age 17.

DNA methylation differentiates smoking from vaping and non-combustible tobacco use

Increasing use of non-combusted forms of nicotine such as e-cigarettes poses important public health questions regarding their specific risks relative to combusted tobacco products such as cigarettes. To fully delineate these risks, improved biomarkers that can distinguish between these forms of nicotine use are needed. Prior work has suggested that methylation status at cg05575921 may serve as a specific biomarker of combusted tobacco smoke exposure. We hypothesized combining this epigenetic biomarker with conventional metabolite assays could classify the type of nicotine product consumption. Therefore, we determined DNA methylation and serum cotinine values in samples from 112 smokers, 35 e-cigarette users, 19 smokeless tobacco users, and 269 controls, and performed mass spectroscopy analyses of urine samples from all nicotine users and 22 verified controls to determine urinary levels of putatively nicotine product-specific substances; propylene glycol, 2-cyanoethylmercapturic acid (CEMA), and anabasine. 1) Cigarette smoking was associated with a dose dependent demethylation of cg05575921 and increased urinary CEMA and anabasine levels, 2) e-cigarette use did not demethylate cg05575921, 3) smokeless tobacco use also did not demethylate cg05575921 but was positively associated with anabasine levels 4) CEMA and cg05575921 levels were highly correlated and 5) propylene glycol levels did not reliably distinguish use groups. Cg05575921 assessments distinguish exposure to tobacco smoke from smokeless sources of nicotine including e-cigarettes and smokeless tobacco, neither of which are associated with cg05575921 demethylation. A combination of methylomic and metabolite profiling may allow for accurate classification use status of a variety of nicotine containing products.

Reporting and methodological quality of systematic literature reviews evaluating the associations between e-cigarette use and cigarette smoking behaviors: a systematic quality review

Introduction

Several published systematic reviews have examined the potential associations between e-cigarette use and cigarette smoking, but their methodological and/or reporting quality have not yet been assessed. This systematic quality review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and AMSTAR (A MeaSurement Tool to Assess systematic Reviews) 2 to evaluate the quality of systematic reviews investigating potential associations between e-cigarette use and cigarette smoking.

Materials and methods

PubMed/MEDLINE, Embase, and PsycINFO were searched from 01 January 2007 to 24 June 2020. Methodological quality was assessed using AMSTAR 2, and reporting quality was assessed using PRISMA guidelines.

Results

Of 331 potentially relevant systematic reviews, 20 met predefined inclusion criteria. Most reviews (n = 15; 75%) reported on e-cigarette use and cigarette smoking cessation, while three reported on e-cigarette use and cigarette smoking initiation (15%); and two reported on cigarette smoking initiation and cessation (10%). According to AMSTAR 2 guidelines, 18 of the 20 reviews (90%) were “critically low” in overall confidence of the results, while two were ranked “low.” Additionally, reporting quality varied across the reviews, with only 60% reporting at least half of the PRISMA items.

Discussion

Methodological limitations were identified across reviews examining potential associations between e-cigarette use and cigarette smoking behaviors, indicating that findings from these reviews should be interpreted with caution.

Conclusions

Future systematic reviews in this field should strive to adhere to AMSTAR 2 and PRISMA guidelines, to provide high quality syntheses of the available data with transparent and complete reporting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12954-021-00570-9.

"That's the whole thing about vaping, it's custom tasty goodness": a meta-ethnography of young adults' perceptions and experiences of e-cigarette use

BACKGROUND

E-cigarettes are increasing in popularity, particularly among young adults. With public health organisations contesting the possible benefits of e-cigarettes, research is required to explore young adults' use of e-cigarettes as a smoking cessation and recreational tool. This study examined existing qualitative data to understand how transition into adulthood and issues of identity affect young adults' perceptions and experiences of e-cigarette use.

METHODS

A meta-ethnography was conducted to examine how young adults perceive and use e-cigarettes. Data were synthesised using Noblit and Hare's (1988) meta-ethnographic approach. Bronfenbrenner's socio-ecological model (1979) was used to conceptualise themes and map findings.

RESULTS

A total of 34 studies were included in the review. Young adults viewed e-cigarettes as a safer alternative to traditional cigarette smoking and perceived e-cigarettes as an effective cessation tool. Users were able to personalise their e-cigarette use due to the variety of flavours and devices available. E-cigarettes were found to be a sociable tool as they allowed users to align themselves with their peers who used e-cigarettes and facilitated use within smoke-free environments. Young adults demonstrated high levels of self-efficacy with regards to obtaining e-cigarettes from various retailers and were active consumers of e-cigarette marketing.

CONCLUSION

This meta-ethnography provides an in-depth insight into social norms around e-cigarette use and beliefs that e-cigarettes could be a safer alternative to traditional cigarettes. As young adults increasingly engage with e-cigarettes, there is a need for informed policy decisions regarding appropriate use. Engagement with e-cigarettes is often reflected within social media, so this medium could be a key platform for creating tailored interventions which inform young adults about the appropriate use of these products.

Waterpipe smoking and subsequent cigarette and e-cigarette use: a cohort study

Aim

We tested the hypothesis that waterpipe smoking increases the likelihood to try conventional and electronic cigarettes.

Methods

In 2017 and 2018, 2752 German adolescents (mean age: 14.9 years), who had never tried conventional cigarettes or e-cigarettes, took part in a longitudinal survey with a 6-month observational period. Multiple regression analyses tested the association between waterpipe use at baseline and first experimentation with e-cigarettes at follow-up. The models adjusted for risk-taking propensity (sensation seeking and experimentation with alcohol and marijuana), age, sex, migration background, type of school and peer substance use.

Results

Some 381 adolescents (12.5% of the survey population) reported waterpipe smoking at baseline. The overall initiation rate during the 6 months was 4.9% (n=134) for conventional cigarettes and 10.5% (n=288) for e-cigarettes. Prior waterpipe smoking significantly predicted cigarette use (adjusted relative risk (ARR)=1.81, 95% CI 1.19-2.76), as well as e-cigarette use (ARR=3.29, 95% CI 2.53-4.28). In addition, a significant interaction between waterpipe use and sensation seeking was found (ARR=0.56, 95% CI 0.33-0.95), with waterpipe use being more predictive of later e-cigarette initiation for lower sensation-seeking individuals.

Discussion

Waterpipe use predicted both later cigarette and e-cigarette use independent of all other assessed risk factors, indicating that waterpipe use might be a risk factor on its own. The results suggest that the association was stronger for adolescents with a lower risk-taking propensity, which brings this group into focus for prevention efforts. However, further research is needed to understand whether these associations are causal.

Balancing Consideration of the Risks and Benefits of E-Cigarettes

The topic of e-cigarettes is controversial. Opponents focus on e-cigarettes' risks for young people, while supporters emphasize the potential for e-cigarettes to assist smokers in quitting smoking. Most US health organizations, media coverage, and policymakers have focused primarily on risks to youths. Because of their messaging, much of the public-including most smokers-now consider e-cigarette use as dangerous as or more dangerous than smoking. By contrast, the National Academies of Science, Engineering, and Medicine concluded that e-cigarette use is likely far less hazardous than smoking. Policies intended to reduce adolescent vaping may also reduce adult smokers' use of e-cigarettes in quit attempts. Because evidence indicates that e-cigarette use can increase the odds of quitting smoking, many scientists, including this essay's authors, encourage the health community, media, and policymakers to more carefully weigh vaping's potential to reduce adult smoking-attributable mortality. We review the health risks of e-cigarette use, the likelihood that vaping increases smoking cessation, concerns about youth vaping, and the need to balance valid concerns about risks to youths with the potential benefits of increasing adult smoking cessation.

Developing a novel e-cigarette regulatory and policy control scale: results from the European Union

Background

E-cigarette regulations vary considerably between countries though a standard approach for comparing regulatory frameworks does not exist. Additionally, there is no evidence on whether regulatory variations are associated with differences in e-cigarette use and smoking cessation. This study aims to develop a regulatory scale to measure and compare e-cigarette regulations between European Union countries and investigate whether scores are associated with e-cigarette use and smoking cessation.

Methods

Data from a range of sources, such as ECigIntelligence, were used to develop a scale and score countries in the respective areas of e-cigarette scale. We used correlation analysis to investigate association between scale scores and e-cigarettes market, e-cigarette prevalence and use of e-cigarettes for smoking cessation.

Results

An e-cigarette scale consisting of 10 domains was developed. Our analysis suggests that higher e-cigarette scale scores were associated with significantly greater use of e-cigarettes within countries, and greater increases in the prevalence of former smoking smokers between 2014 and 2017.

Conclusions

Whilst further work is needed to develop the scale in line with rapidly changing regulatory landscape and product development, the current findings suggest that countries that have implemented e-cigarette regulations might be more successful in obtaining public health gains such as increase in the proportion of former smokers compared to countries where e-cigarette market and sales is not regulated.

Trends in Nicotine Product Use Among US Adolescents, 1999-2020

IMPORTANCE

With increasing e-cigarette use among US adolescents and decreasing use of other tobacco products, it is unclear how total use of nicotine products, and its long-term health risks, have changed. The Centers for Disease Control and Prevention's standard measure-any tobacco product use in the past 30 days-considers neither frequency of use nor product risk implications.

OBJECTIVE

To investigate how nicotine product use, including frequency of use, and its associated risks have changed among middle school and high school students since 1999.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used data from the 1999-2020 National Youth Tobacco Survey, an in-school survey of a nationally representative sample of students in grades 6 through 12; each survey recruited between 15 000 and 36 000 participants.

EXPOSURES

Nicotine product use in the past 30 days.

MAIN OUTCOMES AND MEASURES

Use of nicotine products assessed by nicotine product days (NPDs), the number of days that the average student consumed these products in the past 30 days. Risk-adjusted NPDs account for differential long-term health risks of various products.

RESULTS

This study included 16 years of cross-sectional survey data. Each survey recruited between 15 000 and 36 000 participants in grades 6 through 12 (male students: mean, 50.4% [minimum, 48.5%; maximum, 58.4%]; mean age, 14.5 years [minimum, 14.0 years; maximum, 14.7 years]). Nationally representative cross-sectional data for high school students showed that NPDs decreased steadily from 5.6 days per month in 1999 (95% CI, 5.0-6.2 days per month) to 2.2 days per month in 2017 (95% CI, 1.9-2.6 days per month), increased to 4.6 days per month in 2019 (95% CI, 4.1-5.1 days per month), and then decreased to 3.6 days per month in 2020 (95% CI, 3.0-4.1 days per month). For a risk weight of 0.1 for e-cigarettes, compared with combustible products, risk-adjusted NPDs decreased from 2.5 days per month in 2013 (95% CI, 2.2-2.9 days per month) (prior to the popularity of e-cigarettes) to 2.0 days per month in 2019 (95% CI, 1.6-2.5 days per month) and 1.4 days per month in 2020 (95% CI, 1.0-1.8 days per month). However, with a risk weight of 1.0 for e-cigarettes (identical to that of combustible products), risk-adjusted NPDs increased to 5.3 days per month in 2019 (95% CI, 4.4-6.2 days per month) and 3.9 days per month in 2020 (95% CI, 3.1-4.7 days per month). Similar trends were found for middle school students.

CONCLUSIONS AND RELEVANCE

This study suggests that NPDs represent an improvement, albeit an imperfect one, compared with any 30-day tobacco product use by incorporating the frequency of use of various products. By distinguishing products, NPDs permit consideration of the health consequences associated with different mixes of products over time. Health risks of adolescent nicotine product use could have decreased during vaping's popularity if assessment of the long-term risks associated with vaping compared with those of smoking is low. There is a need to closely monitor youth nicotine and tobacco product use patterns.

Adolescent Use of and Susceptibility to Heated Tobacco Products

BACKGROUND AND OBJECTIVES

A leading brand of heated tobacco products (HTPs), IQOS, was authorized to be sold in the United States in 2019. Researchers have examined the awareness and use of HTPs among US adults. In this study, we examined high school students' awareness, use, and susceptibility pertaining to HTPs.

METHODS

A large, cross-sectional population survey of randomly sampled 10th- and 12th-graders in California (N = 150 516) was conducted online during school hours from September 2019 to March 2020.

RESULTS

Overall, 8.9% (95% confidence interval [CI], 8.7%-9.1%) of California high school students had heard of HTPs. Approximately 0.67% (95% CI, 0.61%-0.73%) had ever tried HTPs, and 0.20% (95% CI, 0.17%-0.23%) were current users (ie, ∼30% of ever users continued to use HTPs at the time of survey). Among those who never tried HTPs, 18.3% (95% CI, 17.9%-18.8%) were susceptible to future use. The susceptibility to HTP use was greater among users of cigarettes or e-cigarettes than among nonusers.

CONCLUSIONS

The awareness of HTPs among adolescents was remarkable given the low availability of products at the time of survey. Only a small percentage of adolescents experimented with HTPs. However, almost a third of those who had experimented with HTPs continued to use them. This high ratio and the fact that almost 1 out of 5 never users were susceptible to future HTP use should put the public health community on high alert as more HTP products are coming into the market, with promotion of these products likely to increase.

The emerging norms of e-cigarette use among adolescents: A meta-ethnography of qualitative evidence

While qualitative research has indicated that adolescents' motivation for e-cigarette use is different than adults', this body of literature has not yet been brought together and synthesised. We reviewed qualitative evidence on perceptions and uses of e-cigarettes in order to explore the emerging norms of vaping among adolescents. We searched five databases for qualitative research in October 2019 with no restrictions on date of publication or data collection. We identified fifteen papers from thirteen studies. Using a meta-ethnographic approach, we identified a spectrum of descriptive and injunctive norms of vaping across the themes of addiction; perceptions of comparative harm; parental perceptions and peer perceptions. We found addiction and perceptions of comparative harm to reflect descriptive norms, while we found clearer evidence explaining the use and non-use of e-cigarettes through parental and peer approval of vaping. However, these norms were fluid, diverse and sometimes contradictory. This review provides a resource for researchers, policymakers and practitioners to better understand the ways that emerging norms could be influenced through policy and practice.

An investigation of factors encouraging and deterring EC use: a thematic analysis of accounts from UK adults

OBJECTIVE

This study aimed to explore E-cigarette (EC) accounts from a small sample of UK adults with varied smoking/EC experiences. This was to contribute to existing knowledge of adult perceptions and understand the factors that encourage or deter use to inform health messaging aimed at professionals, policy makers and the general public.

DESIGN

Twelve participants, five men and seven women aged 23-55 years (mean age 32.43) with mixed smoking/EC backgrounds took part in face-to-face interviews, analysed using semantic-level inductive thematic analysis.

RESULTS

The analysis identified three key themes. Social influence (1) relates to the understanding of the social representations of ECs. Representation and knowledge (2) captures the impact of varied EC related communication on perception. Aspects of addiction (3) conveys aspects of nicotine addiction and how this influences EC use.

CONCLUSION

ECs were generally perceived as more socially acceptable than cigarettes by non-smokers, although there were varying levels of acceptability depending on the type of EC device used. There was also unanimity concerning uncertainty surrounding the devices. Behavioural/sensory elements and personal enjoyment of ECs were consistent elements that encouraged or deterred use. Although non-smokers/vapers did not use the devices, they expressed similar apprehensions to those who did.

From gateways to multilinear connections: A qualitative longitudinal investigation of the relationships between vaping and smoking among adolescent users

BACKGROUND

The international growth of e-cigarette use has been accompanied by a corresponding concern that e-cigarettes will act as a 'gateway' to smoking and the use of other drugs. Taking these concerns as our point of departure, we explore the relationships between vaping and smoking among a cohort of young people.

METHODS

Qualitative longitudinal methods with a diverse sample of 36 14-18-year olds from the UK city of Leicester. A total of 66 depth interviews conducted across two phases separated by 6-12 months. The interviews were recorded, transcribed verbatim and thematically analysed.

FINDINGS

We highlight a complex 'tangle' of connections between substances/risk behaviours recounted to us by our adolescent study participants, including multiple and multilinear relationships between vaping and smoking. These findings problematise some of the core axioms of the notion of gateways as an explanatory model of causality and sequential connection between smoking and vaping. They also throw into question gateway logics more fundamentally. While many of our study participants themselves consciously invoked ideas of 'gateway effects', the accounts they produced repeatedly disrupted the logics of connection (between e-cigarettes and smoking; one set of behaviours and another) presupposed in gateway theory and our own early lines of questioning. Accordingly, we explore how cultural understandings of gateway effects are invoked by users in accounting for their vaping and smoking behaviours, noting the potential influence of these ideas upon the very processes they are understood to apprehend.

CONCLUSION

Our findings suggest there is a case to be made to reinforce the distinctiveness of tobacco and e-cigarettes in the life-worlds of young people to avoid naturalising a 'gateway' logic of connection that might ultimately inform the associative logic of young users themselves, and potentially the development of their usage careers.

Consensus on connected hearing health technologies and service delivery models in the UK: a Delphi review

OBJECTIVE

To develop a consensus among hearing healthcare professionals in the UK on connected hearing health technologies and service delivery models.

DESIGN

A three-round, electronic Delphi review was developed using a participatory-design approach. This included ten open-ended questions (round one) that informed 69 Likert-scaled statements (rounds two and three).

STUDY SAMPLE

An expert panel of 34 hearing health professionals representing all geographic regions of the UK from either the publicly funded National Health Service (n = 22) or independent sector (n = 12).

RESULTS

The majority of statements (61%) showed ≥80% consensus, highlighting that there was broad agreement amongst professionals on connected hearing health technologies. For example, there was consensus that adults who report communication difficulties and have no medical contraindications would be ideal candidates. Furthermore, it was unanimously agreed that connected technologies could result in delays in diagnosis of treatable medical conditions, as well as result in inadequate amplification. Overall, the expert panel concurred that connected technologies could serve as "gateway products" that lead to earlier hearing aid uptake.

CONCLUSIONS

This Delphi review identified overarching areas of agreement that may serve as a blueprint for future implementation of connected hearing health technologies through either conventional or new service delivery models in the UK.

A conceptual framework for assessing the public health effects from snus and novel non-combustible nicotine products

Objective:

The tobacco industry plans to base their future earnings on the production of non-combustible nicotine products. These might replace or come in addition to the more harmful cigarettes that historically have dominated the nicotine market in the Nordic countries. The authorities in each country must decide whether the products should have market access and, in that case, how strictly they should be regulated. Our aim is to present a framework that can assist the health authorities to make a regulation where benefits will outweigh the harms.

Method:

In a public health perspective, health gains from substitution must be weighed against the health loss from additional use. The main elements of the weighing will be based on the information about the absolute risk of the products, their relative risk compared to conventional cigarettes and how the users are composed according to smoking status. We apply the framework on snus as used in Norway – a product with an established usage pattern and epidemiologically assessed health risks.

Results:

The framework consists of (i) a comprehensive set of specific user patterns that may result in health deterioration and user patterns that may result in health benefits, (ii) an estimation of the number of people with health-augmenting and health-impairing user patterns, respectively, and (iii) an estimation of the degree of health deterioration or health benefit that will affect the persons with the different user patterns.

Conclusion:

The net effect on public health will appear as an overall result of the number of people with positive and negative user patterns, respectively, in combination with the magnitude of the change in health status these people will experience. The use of an explicit framework highlights how a political decision may affect nicotine use and health-related outcomes. The framework breaks open a large and complex question into smaller pieces and requires the authorities to expose and explain the kind of evidence and reasoning behind regulations of novel nicotine products.

Association between electronic cigarette use and tobacco cigarette smoking initiation in adolescents: a systematic review and meta-analysis

BACKGROUND

This systematic review of prospective longitudinal primary studies sought to determine whether electronic cigarette (e-cigarette) use by teenagers who had never smoked conventional tobacco cigarettes (tobacco cigarettes) at baseline was associated with subsequently commencing tobacco cigarette smoking.

METHODS

The review followed the principles of a systematic review and meta-analysis. A key word search identified peer-reviewed articles published between 1 January 2005 and 2 October 2019 from seven bibliographic databases and one search engine. Using pre-prepared inclusion/exclusion criteria two researchers independently screened abstracts, and subsequently, full text papers. Selected articles were quality assessed in duplicate. Data on study participants characteristics, exposure and outcome measures were recorded in an adapted Cochrane Data Extraction Form. Feasibility assessment was done to detect clinical heterogeneity and choose an approach to meta-analysis. Analysis comprised pairwise random effects meta-analyses, and sensitivity and subgroup analyses.

RESULTS

From the 6619 studies identified, 14 one-off primary studies in 21 articles were suitable for inclusion. The participants ages ranged from 13 to 19 years and comprised teenagers based in Europe and North America. Nine of the 14 one-off studies, with follow-up periods between 4 and 24 months, met the criteria for inclusion in a meta-analysis of the association between ever use of e-cigarettes and subsequent initiation of tobacco cigarette use. Based on primary study adjusted odds ratios, our meta-analysis calculated a 4.06 (95% confidence interval (CI): 3.00-5.48, I2 68%, 9 primary studies) times higher odds of commencing tobacco cigarette smoking for teenagers who had ever used e-cigarettes at baseline, though the odds ratio were marginally lower (to 3.71 times odds, 95%CI: 2.83-4. 86, I2 35%, 4 primary studies) when only the four high-quality studies were analysed.

CONCLUSION

The systematic review found that e-cigarette use was associated with commencement of tobacco cigarette smoking among teenagers in Europe and North America, identifying an important health-related harm. Given the availability and usage of e-cigarettes, this study provides added support for urgent response by policymakers to stop their use by teenagers to decrease direct harms in this susceptible population group, as well as to conserve achievements in diminishing tobacco cigarette initiation.