Article Text

Original research
E-cigarette use and combustible tobacco cigarette smoking uptake among non-smokers, including relapse in former smokers: umbrella review, systematic review and meta-analysis
  1. Olivia Nina Baenziger1,
  2. Laura Ford2,
  3. Amelia Yazidjoglou2,
  4. Grace Joshy2,
  5. Emily Banks2
  1. 1The University of Melbourne School of Population and Global Health, Melbourne, Victoria, Australia
  2. 2The National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australian Capital Territory, Australia
  1. Correspondence to Professor Emily Banks; emily.banks{at}


Objective To 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.

Design Umbrella review, systematic review and meta-analysis.

Data sources PubMed, Scopus, Web of Science, PsychINFO (Ovid), Medline (Ovid) and Wiley Cochrane Library up to April 2020.

Results Of 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 3.19 (95% CI 2.44 to 4.16, I2 85.7%) and among non-smokers at baseline the OR for current smoking was 3.14 (95% CI 1.93 to 5.11, I2 91.0%). 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%).

Conclusions Across 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 number CRD42020168596.

  • epidemiology
  • public health
  • respiratory medicine (see thoracic medicine)

Data availability statement

All data used in the manuscript are from published research.

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:

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Data availability statement

All data used in the manuscript are from published research.

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  • Correction notice This article has been corrected since it was first published. The data in the abstract section has been modified.

  • Contributors ONB, LF and EB all contributed to the study conception and design and interpretation of data. GJ and AY assisted with statistical analysis and interpretation of data. All authors were involved in revising the manuscript.

  • Funding This review was developed as part of an independent programme of work examining the health impacts of e-cigarettes, funded by the Australian Government Department of Health. EB is supported by the National Health and Medical Research Council of Australia (Principal Research Fellowship: 1136128).

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.