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Cochrane Database of Systematic Reviews

Electronic cigarettes for smoking cessation and reduction

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Information

DOI:
https://doi.org/10.1002/14651858.CD010216.pub2Copy DOI
Database:
  1. Cochrane Database of Systematic Reviews
Version published:
  1. 17 December 2014see what's new
Type:
  1. Intervention
Stage:
  1. Review
Cochrane Editorial Group:
  1. Cochrane Tobacco Addiction Group

Copyright:
  1. Copyright © 2014 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

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Authors

  • Hayden McRobbie

    Correspondence to: Wolfson Institute of Preventive Medicine, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK

    [email protected]

  • Chris Bullen

    National Institute for Health Innovation, University of Auckland, Auckland, New Zealand

  • Jamie Hartmann‐Boyce

    Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK

  • Peter Hajek

    Wolfson Institute of Preventive Medicine, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK

Contributions of authors

All authors contributed to the writing of this review.
JHB and HM extracted data, with discrepancies and disagreements referred to PH.
As principal investigator of one of the included trials, CB was not involved with data extraction or assessment of study quality.

Sources of support

Internal sources

  • Queen Mary University of London, UK.

    provides salary, office space and library resources for HM and PH

  • The University of Auckland, New Zealand.

    provides salary, office space and library resources for CB

External sources

  • No sources of support supplied

Declarations of interest

Within the last three years HM has undertaken educational sessions sponsored by Pfizer and Johnson & Johnson, manufacturers of smoking cessation medications.
Within the last three years PH has provided consultancy to GSK, Pfizer, and Johnson & Johnson, manufacturers of smoking cessation medications.
Due to these two interests, this review is not compliant with the Cochrane commercial sponsorship policy, as updated in 2014. At the time the protocol was published it was compliant.

Two authors (HM, CB) have additional declarations:
CB and HM were investigators on a study of ECs from an EC manufacturer (Ruyan Group, Beijing and Hong Kong). Ruyan supplied the ECs used in the trial and contracted with Health NZ Ltd. to undertake the study. Health New Zealand Ltd funded The University of Auckland to conduct the trial, independently of Ruyan Group (Holdings) Ltd. The trial design conduct, analysis and interpretation of results were conducted independently of the sponsors.
CB and HM were investigators on the ASCEND EC trial funded by the Health Research Council of New Zealand that used product supplied at no charge from PGM international, a retailer of ECs.

JHB has no conflicts of interest to declare.

Acknowledgements

JHB is funded by the National Institute of Health Research School for Primary Care Research.

Version history

Published

Title

Stage

Authors

Version

2024 Jan 08

Electronic cigarettes for smoking cessation

Review

Nicola Lindson, Ailsa R Butler, Hayden McRobbie, Chris Bullen, Peter Hajek, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Jonathan Livingstone-Banks, Tom Morris, Jamie Hartmann-Boyce

https://doi.org/10.1002/14651858.CD010216.pub8

2022 Nov 17

Electronic cigarettes for smoking cessation

Review

Jamie Hartmann-Boyce, Nicola Lindson, Ailsa R Butler, Hayden McRobbie, Chris Bullen, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Thomas R Fanshawe, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub7

2021 Sep 14

Electronic cigarettes for smoking cessation

Review

Jamie Hartmann-Boyce, Hayden McRobbie, Ailsa R Butler, Nicola Lindson, Chris Bullen, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Thomas R Fanshawe, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub6

2021 Apr 29

Electronic cigarettes for smoking cessation

Review

Jamie Hartmann-Boyce, Hayden McRobbie, Ailsa R Butler, Nicola Lindson, Chris Bullen, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Thomas R Fanshawe, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub5

2020 Oct 14

Electronic cigarettes for smoking cessation

Review

Jamie Hartmann-Boyce, Hayden McRobbie, Nicola Lindson, Chris Bullen, Rachna Begh, Annika Theodoulou, Caitlin Notley, Nancy A Rigotti, Tari Turner, Ailsa R Butler, Thomas R Fanshawe, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub4

2016 Sep 13

Electronic cigarettes for smoking cessation

Review

Jamie Hartmann‐Boyce, Hayden McRobbie, Chris Bullen, Rachna Begh, Lindsay F Stead, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub3

2014 Dec 17

Electronic cigarettes for smoking cessation and reduction

Review

Hayden McRobbie, Chris Bullen, Jamie Hartmann‐Boyce, Peter Hajek

https://doi.org/10.1002/14651858.CD010216.pub2

2012 Nov 14

Electronic cigarettes for smoking cessation and reduction

Protocol

Hayden McRobbie, Chris Bullen, Peter Hajek

https://doi.org/10.1002/14651858.CD010216

Differences between protocol and review

Originally, the protocol did not specify a minimum follow‐up period for data on adverse events. The Methods section has been changed to clarify that we will exclude follow‐up data at less than a week.

Keywords

MeSH

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Study flow diagram.
Figures and Tables -
Figure 1

Study flow diagram.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Figures and Tables -
Figure 2

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Comparison 1 Smoking cessation, Outcome 1 Nicotine EC versus placebo EC.
Figures and Tables -
Analysis 1.1

Comparison 1 Smoking cessation, Outcome 1 Nicotine EC versus placebo EC.

Comparison 1 Smoking cessation, Outcome 2 Nicotine EC versus nicotine replacement therapy.
Figures and Tables -
Analysis 1.2

Comparison 1 Smoking cessation, Outcome 2 Nicotine EC versus nicotine replacement therapy.

Comparison 2 Smoking reduction, Outcome 1 Nicotine EC versus placebo EC (quitters excluded).
Figures and Tables -
Analysis 2.1

Comparison 2 Smoking reduction, Outcome 1 Nicotine EC versus placebo EC (quitters excluded).

Comparison 2 Smoking reduction, Outcome 2 Nicotine EC versus nicotine replacement therapy (quitters excluded).
Figures and Tables -
Analysis 2.2

Comparison 2 Smoking reduction, Outcome 2 Nicotine EC versus nicotine replacement therapy (quitters excluded).

Comparison 3 Adverse Events, Outcome 1 Proportion of participants reporting adverse events: Nicotine EC versus placebo EC.
Figures and Tables -
Analysis 3.1

Comparison 3 Adverse Events, Outcome 1 Proportion of participants reporting adverse events: Nicotine EC versus placebo EC.

Comparison 3 Adverse Events, Outcome 2 Proportion of participants reporting adverse events: nicotine EC versus nicotine replacement therapy.
Figures and Tables -
Analysis 3.2

Comparison 3 Adverse Events, Outcome 2 Proportion of participants reporting adverse events: nicotine EC versus nicotine replacement therapy.

Summary of findings for the main comparison. Electronic cigarettes for smoking cessation and reduction

Electronic cigarettes (EC) for smoking cessation and reduction

Patient or population: people defined as current smokers at enrolment into trials, motivated or unmotivated to quit
Intervention: nicotine‐containing electronic cigarettes

Comparison: placebo electronic cigarettes or nicotine replacement therapy

Outcomes

Illustrative comparative risks* (95% CI)

Relative effect
(95% CI)

No of Participants
(studies)

Quality of the evidence
(GRADE)

Comments

Assumed risk1

Corresponding risk

Control

Electronic cigarettes

Cessation: Nicotine EC versus placebo EC2
assessed with exhaled CO
Follow‐up: 6 ‐ 12 months

40 per 1000

93 per 1000
(42 to 201)

RR 2.29
(1.05 to 4.96)

662
(2 studies)

⊕⊕⊝⊝
low3,4

Only RCTs reported here. Some cohort data also available (see full review) but only RCTs provide efficacy data

Cessation: Nicotine EC versus nicotine replacement therapy
assessed with exhaled CO
Follow‐up: 6 months

58 per 1000

73 per 1000
(39 to 135)

RR 1.26
(0.68 to 2.34)

584
(1 study)

⊕⊝⊝⊝
very low3,5

As above

Reduction: Nicotine EC versus placebo EC
proportion of participants who achieved ≥ 50% reduction in baseline cigarette consumption
Follow‐up: 6 ‐ 12 months

271 per 1000

355 per 1000
(277 to 455)

RR 1.31
(1.02 to 1.68)

612
(2 studies)

⊕⊕⊝⊝
low3,4

As above. Analysis excludes quitters

Reduction: Nicotine EC versus nicotine replacement therapy
proportion of participants who achieved ≥ 50% reduction in baseline cigarette consumption
Follow‐up: 6 months

435 per 1000

614 per 1000
(522 to 727)

RR 1.41
(1.20 to 1.67)

546
(1 study)

⊕⊝⊝⊝
very low3,5

As above. Analysis excludes quitters

Adverse events (AEs)

Follow‐up: 6 ‐ 12 months

Summary data not available. None of the studies reported any serious AEs that were related to EC use. Neither RCT detected a significant difference in AEs between intervention and control groups. Cohort studies found mouth and throat irritation, dissipating over time, to be the most frequently reported AEs in EC users

1090

(8 studies (2 RCTs, 6 cohort))

⊕⊕⊝⊝
low6,7

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

1 'Assumed risk' calculated as risk in control groups.

2 'Placebo EC' refers to ECs which do not contain nicotine.

3 Downgraded one level due to indirectness. The electronic cigarette used in Bullen 2013 was not very effective at delivering nicotine
4 Downgraded one level due to imprecision. Only two included studies, small number of events (< 300) in each arm
5 Downgraded two levels due to imprecision. Only one included study, with small number of events in each arm

6 Downgraded due to risk of bias. 6/8 included studies (cohort studies) judged to be at high risk of bias

7 Downgraded due to imprecision. Only one trial provided data for nicotine EC versus nicotine replacement therapy

Figures and Tables -
Summary of findings for the main comparison. Electronic cigarettes for smoking cessation and reduction
Table 1. Summary of proportion of participants abstinent from smoking at follow‐up: cohort studies

Study

Smokers motivated or unmotivated to quit?

Intervention vs relevant Control

% abstinent

Cohort studies

6 month

12 months

18 months

24 months

Notes

Caponnetto 2013b

Unmotivated to quit

Nicotine EC

14% (2/14)

Ely 2013

Motivated to quit

Nicotine EC¹

44% (21/48)

Polosa 2011

Unmotivated to quit

Nicotine EC

23% (9/40)

15% (6/40)

13% (5/40)

Cohort studies not allowing inclusion of non‐responders

Etter 2014

Not defined

Daily EC users at baseline

46% (16/35)

Response rate: 47% (367/773) completed follow‐up survey

Grana 2014b

Not defined

Used EC in the past 30 days (even once) at baseline

10% (9/88)

Response rate: 81% completed follow‐up

Abtsinence rate was 14% (119/861) in non‐EC users

Choi 2014

Not defined

Used EC for ≥ 1 day in the past 30 days at baseline

11%

Response rate: unknown

Abstinence rate was 17% in non‐EC users

1 All participants (N = 48) used an EC, but 16 also used bupropion and 2 used varenicline

Figures and Tables -
Table 1. Summary of proportion of participants abstinent from smoking at follow‐up: cohort studies
Table 2. Summary of proportion of participants achieving a ≥ 50% reduction of baseline cigarette consumption: cohort studies

Study

Smokers motivated or unmotivated to quit?

Intervention vs. Control

% reduced by ≥ 50% of baseline cigarette consumption

6 month

12 months

18 months

24 months

Caponnetto 2013b

Unmotivated to quit

Nicotine EC

50% (7/14)

Ely 2013

Motivated to quit

Nicotine EC¹

27% (13/48)

Polosa 2011

Unmotivated to quit

Nicotine EC

33% (13/40)

28% (11/40)

28% (11/40)

1 All participants (N = 48) used an EC, but 16 also used bupropion and 2 used varenicline

Figures and Tables -
Table 2. Summary of proportion of participants achieving a ≥ 50% reduction of baseline cigarette consumption: cohort studies
Comparison 1. Smoking cessation

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Nicotine EC versus placebo EC Show forest plot

2

662

Risk Ratio (M‐H, Fixed, 95% CI)

2.29 [1.05, 4.96]

2 Nicotine EC versus nicotine replacement therapy Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 1. Smoking cessation
Comparison 2. Smoking reduction

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Nicotine EC versus placebo EC (quitters excluded) Show forest plot

2

612

Risk Ratio (M‐H, Fixed, 95% CI)

1.31 [1.02, 1.68]

2 Nicotine EC versus nicotine replacement therapy (quitters excluded) Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 2. Smoking reduction
Comparison 3. Adverse Events

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Proportion of participants reporting adverse events: Nicotine EC versus placebo EC Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

2 Proportion of participants reporting adverse events: nicotine EC versus nicotine replacement therapy Show forest plot

1

Risk Ratio (M‐H, Fixed, 95% CI)

Totals not selected

Figures and Tables -
Comparison 3. Adverse Events