Gateway or common liability? A systematic review and meta‐analysis of studies of adolescent e‐cigarette use and future smoking initiation

Background: A recent meta-analysis of nine cohort studies in youths reported that baseline ever e-cigarette use strongly predicted cigarette smoking initiation in the next 6-18 months, with an adjusted odds ratio of 3.62 (95% confidence interval 2.42-5.41). A recent review of e-cigarettes agreed there was substantial evidence for this “gateway effect”. However, the number of confounders considered in the studies was limited, so we investigated whether the effect might have resulted from inadequate adjustment, using Waves 1 and 2 of the Population Assessment of Tobacco and Health study. Methods: Our main analyses considered Wave 1 never cigarette smokers who, at Wave 2, had information available on smoking initiation. We constructed a propensity score for ever e-cigarette use from Wave 1 variables, using this to predict ever cigarette smoking. Sensitivity analyses accounted for use of other tobacco products, linked current e-cigarette use to subsequent current smoking, or used propensity scores for ever smoking or ever tobacco product use as predictors. We also considered predictors using data from both waves to attempt to control for residual confounding from misclassified responses. Results: Adjustment for propensity dramatically reduced the unadjusted odds ratio (OR) of 5.70 (4.33-7.50) to 2.48 (1.85-3.31), 2.47 (1.79-3.42) or 1.85 (1.35-2.53), whether adjustment was made as quintiles, as a continuous variable or for the individual variables. Additional adjustment for other tobacco products reduced this last OR to 1.59 (1.14-2.20). Sensitivity analyses confirmed adjustment removed most of the gateway effect. Control for residual confounding also reduced the association. Conclusions: We found that confounding is a major factor, explaining most of the observed gateway effect. However, our analyses are limited by small numbers of new smokers considered and the possibility of over-adjustment if taking up e-cigarettes affects some predictor variables. Further analyses are intended using Wave 3 data which should avoid these problems.

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Cardiovascular autonomic effects of electronic cigarette use: a systematic review

Clinical Autonomic Research ◽

10.1007/s10286-020-00683-4 ◽

2020 ◽

Vol 30 (6) ◽

pp. 507-519 ◽

Cited By ~ 6

Author(s):

Phoebe D. Garcia ◽

Jeffrey A. Gornbein ◽

Holly R. Middlekauff

Keyword(s):

Systematic Review ◽

Heart Rate ◽

Electronic Cigarettes ◽

Meta Analysis ◽

Cardiovascular Effects ◽

Tobacco Product ◽

Cigarette Use ◽

Prisma Statement ◽

The Usa ◽

Acute And Chronic Effects

Abstract Purpose Electronic cigarettes (ECs) are the fastest growing tobacco product in the USA, and ECs, like tobacco cigarettes (TCs), have effects on the cardiovascular autonomic nervous system, with clinical implications. The purpose of this review was to collect and synthesize available studies that have investigated the autonomic cardiovascular effects of EC use in humans. Special attention is paid to the acute and chronic effects of ECs, the relative contributions of the nicotine versus non-nicotine constituents in EC emissions and the relative effects of ECs compared to TCs. Methods Using the methodology described in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement, we conducted a literature search of the Ovid PubMed and Embase databases on 6 December 2019 using keywords in titles and abstracts of published literature. Acute (minutes to hours) and chronic (days or longer) changes in heart rate variability (HRV), heart rate (HR) and blood pressure (BP) were used as estimates of cardiovascular autonomic effects. Results Nineteen studies were included in this systematic review, all of which used earlier generation EC devices. Acute EC vaping increased HR and BP less than acute TC smoking. Nicotine but not non-nicotine constituents in EC aerosol were responsible for the sympathoexcitatory effects. The results of chronic EC vaping studies were consistent with a chronic sympathoexcitatory effect as estimated by HRV, but this did not translate into chronic increases in HR or BP. Conclusions Electronic cigarettes are sympathoexcitatory. Cardiac sympathoexcitatory effects are less when vaping using the earlier generation ECs than when smoking TCs. Additional studies of the latest pod-like EC devices, which deliver nicotine similarly to a TC, are necessary.

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E-cigarette use and combustible tobacco cigarette smoking uptake among non-smokers, including relapse in former smokers: umbrella review, systematic review and meta-analysis

BMJ Open ◽

10.1136/bmjopen-2020-045603 ◽

2021 ◽

Vol 11 (3) ◽

pp. e045603

Author(s):

Olivia Nina Baenziger ◽

Laura Ford ◽

Amelia Yazidjoglou ◽

Grace Joshy ◽

Emily Banks

Keyword(s):

Systematic Review ◽

Cigarette Smoking ◽

Meta Analysis ◽

Current Evidence ◽

Cigarette Use ◽

Umbrella Review ◽

Review Systematic ◽

Former Smokers ◽

Smoking Uptake ◽

Never Smokers

ObjectiveTo review and summarise the current evidence on the uptake of combustible cigarette smoking following e-cigarette use in non-smokers—including never-smokers, people not currently smoking and past smokers—through an umbrella review, systematic review and meta-analysis.DesignUmbrella review, systematic review and meta-analysis.Data sourcesPubMed, Scopus, Web of Science, PsychINFO (Ovid), Medline (Ovid) and Wiley Cochrane Library up to April 2020.ResultsOf 6225 results, 25 studies of non-smokers—never, not current and former smokers—with a baseline measure of e-cigarette use and an outcome measure of combustible smoking uptake were included. All 25 studies found increased risk of smoking uptake with e-cigarette exposure, although magnitude varied substantially. Using a random-effects model, comparing e-cigarette users versus non-e-cigarette users, among never-smokers at baseline the OR for smoking initiation was 3.25 (95% CI 2.61 to 4.05, I2 85.7%) and among non-smokers at baseline the OR for current smoking was 2.87 (95% CI 1.97 to 4.19, I2 90.1%). Among former smokers, smoking relapse was higher in e-cigarette users versus non-users (OR=2.40, 95% CI 1.50 to 3.83, I2 12.3%).ConclusionsAcross multiple settings, non-smokers who use e-cigarettes are consistently more likely than those avoiding e-cigarettes to initiate combustible cigarette smoking and become current smokers. The magnitude of this risk varied, with an average of around three times the odds. Former smokers using e-cigarettes have over twice the odds of relapse as non-e-cigarettes users. This study is the first to our knowledge to review and pool data on the latter topic.PROSPERO registration numberCRD42020168596.

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Prospective association between use of electronic cigarettes and use of conventional cigarettes - a systematic review and meta-analysis

ERJ Open Research ◽

10.1183/23120541.00976-2020 ◽

2021 ◽

pp. 00976-2020

Author(s):

Louise Adermark ◽

Maria Rosaria Galanti ◽

Charlotta Ryk ◽

Hans Gilljam ◽

Linnea Hedman

Keyword(s):

Systematic Review ◽

Cigarette Smoking ◽

Electronic Cigarettes ◽

Meta Analysis ◽

Cochrane Library ◽

Cigarette Use ◽

Study Selection ◽

Prospective Association ◽

Never Smokers

ObjectiveThe aim of this systematic review and meta-analysis was to assess the association between e-cigarette use and subsequent initiation or recurrence of cigarette smoking.Data sourcesA systematic literature search was finalised November 11, 2019 using PubMed incl. Medline, EMBASE, Cochrane Library, Scopus, PubMed Health, NICE evidence search, PROSPERO, CRD, and PsycInfo.Study selectionStudies were included if meeting the following criteria: reporting empirical results; longitudinal observational design with a minimum of 3 months of follow-up; including general population samples; allowing for the comparison between users and non-users of e-cigarettes. Studies rated as having high risk of bias were excluded. Studies were independently assessed by at least two authors. The procedures described by PRISMA were followed, and the quality of evidence was rated using GRADE.Data synthesisThirty longitudinal studies from 22 different cohorts assessing e-cigarette use among non- or never-smokers at baseline, and subsequent use of cigarette smoking at follow-up, were included in this review. A random-effects meta-analysis based on 89 076 participants showed a pooled unadjusted odds ratio (OR) of cigarette smoking among baseline non-smokers e-cigarette users compared with non-users of 4.68 (CI 3.64–6.02), while the adjusted OR was 3.37 (CI 2.68–4.24). These results were consistent irrespective of whether the outcome was measured as ever smoking or as past 30-day smoking. The evidence was graded as moderate.ConclusionsUse of e-cigarettes may predict the initiation or recurrence of cigarette smoking.

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Electronic cigarette use and smoking cessation in cohort studies and randomized trials: A systematic review and meta-analysis

Tobacco Prevention & Cessation ◽

10.18332/tpc/142320 ◽

2021 ◽

Vol 7 (October) ◽

pp. 1-16

Author(s):

Linnea Hedman ◽

Maria Galanti ◽

Lotta Ryk ◽

Hans Gilljam ◽

Louise Adermark

Keyword(s):

Systematic Review ◽

Smoking Cessation ◽

Cohort Studies ◽

Randomized Trials ◽

Meta Analysis ◽

Electronic Cigarette ◽

Cigarette Use

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Association between e-cigarette use and asthma: a systematic review and meta-analysis

Journal of Asthma ◽

10.1080/02770903.2021.1971703 ◽

2021 ◽

pp. 1-10

Author(s):

Benjamin R. Chand ◽

Hassan Hosseinzadeh

Keyword(s):

Systematic Review ◽

Meta Analysis ◽

Cigarette Use

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

10.21203/rs.3.rs-59681/v3 ◽

2021 ◽

Author(s):

Doireann O'Brien ◽

Jean Long ◽

Joan Quigley ◽

Caitriona Lee ◽

Anne McCarthy ◽

...

Keyword(s):

Systematic Review ◽

North America ◽

Cigarette Smoking ◽

Meta Analysis ◽

Electronic Cigarette ◽

Population Characteristics ◽

Primary Study ◽

Cigarette Use ◽

High Quality ◽

Tobacco Cigarette

Abstract Aim: This systematic review of prospective longitudinal primary studies aimed to explore whether electronic cigarette (e-cigarette) use by adolescents who had never smoked conventional tobacco cigarettes (tobacco cigarettes) at baseline was associated with subsequent initiation of tobacco cigarette smoking. Methods: This study followed the principles of a systematic review and meta-analysis. A key word search identified peer-reviewed literature published between 1 January 2005 and 2 October 2019 from seven bibliographic databases and one search engine. Using predefined inclusion/exclusion criteria two authors independently screened abstracts, and subsequently, full text papers. Eligible papers were quality assessed by two authors. Data on population characteristics, exposure and outcome measures were extracted into an adapted Cochrane Data Extraction Form. Statistical analysis was preceded by a feasibility assessment, and included pairwise random effects meta-analyses, and sensitivity and subgroup analyses. Findings: From an initial 6,619 studies, 14 unique primary studies in 21 papers were identified. The studies’ populations ages ranged from 13 to 19 years at baseline and comprised teenagers based in Europe and North America. Nine of the 14 unique studies, with follow-up periods between 4 and 24 months, were eligible 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) times higher odds of initiating tobacco cigarette smoking for those who had ever used e-cigarettes at baseline, although the odds ratio decreased marginally (to 3.71 times odds, 95%CI: 2.83-4. 86) when only the four high-quality studies were analysed. The initial meta-analysis model had a high statistical heterogeneity, sensitivity analysis restricted to high-quality studies had moderate heterogeneity.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 public health harm. Given the widespread availability and use of e-cigarettes, this study further supports urgent action by policymakers to prevent their use by teenagers to reduce direct harms in this vulnerable population group, as well as to protect gains in reducing tobacco cigarette initiation.

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Investigating gateway effects using the PATH study

F1000Research ◽

10.12688/f1000research.18354.2 ◽

2019 ◽

Vol 8 ◽

pp. 264 ◽

Cited By ~ 4

Author(s):

Peter Lee ◽

John Fry

Keyword(s):

Cigarette Smoking ◽

Propensity Scores ◽

Meta Analysis ◽

Smoking Initiation ◽

Continuous Variable ◽

Tobacco Product ◽

Sensitivity Analyses ◽

Cigarette Use ◽

Product Use ◽

Residual Confounding

Background: A recent meta-analysis of nine cohort studies in youths reported that baseline ever e-cigarette use strongly predicted cigarette smoking initiation in the next 6-18 months, with an adjusted odds ratio (OR) of 3.62 (95% confidence interval 2.42-5.41). A recent e-cigarette review agreed there was substantial evidence for this “gateway effect”. As the number of confounders considered in the studies was limited we investigated whether the effect might have resulted from inadequate adjustment, using Waves 1 and 2 of the US PATH study. Methods: Our main analyses considered Wave 1 never cigarette smokers who, at Wave 2, had data on smoking initiation.We constructed a propensity score for ever e-cigarette use from Wave 1 variables, using this to predict ever cigarette smoking. Sensitivity analyses accounted for other tobacco product use, linked current e-cigarette use to subsequent current smoking, or used propensity scores for ever smoking or ever tobacco product use as predictors. We also considered predictors using data from both waves, attempting to reduce residual confounding from misclassified responses. Results: Adjustment for propensity dramatically reduced the unadjusted OR of 5.70 (4.33-7.50) to 2.48 (1.85-3.31), 2.47 (1.79-3.42) or 1.85 (1.35-2.53), whether adjustment was made as quintiles, as a continuous variable or for the individual variables. Additional adjustment for other tobacco products reduced this last OR to 1.59 (1.14-2.20). Sensitivity analyses confirmed adjustment removed most of the gateway effect. Control for residual confounding also reduced the association. Conclusions: We found that confounding is a major factor, explaining most of the observed gateway effect. However, our analyses are limited by small numbers of new smokers considered and the possibility of over-adjustment if taking up e-cigarettes affects some predictor variables. Further analyses are intended using Wave 3 data to try to minimize these problems, and clarify the extent of any true gateway effect.

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