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. 2022 Nov 17;11(11):CD010216.
doi: 10.1002/14651858.CD010216.pub7.

Electronic cigarettes for smoking cessation

Jamie Hartmann-Boyce  1 , Nicola Lindson  1 , Ailsa R Butler  1 , Hayden McRobbie  2 , Chris Bullen  3 , Rachna Begh  1 , Annika Theodoulou  1 , Caitlin Notley  4 , Nancy A Rigotti  5 , Tari Turner  6 , Thomas R Fanshawe  1 , Peter Hajek  7
Affiliations

Electronic cigarettes for smoking cessation

Jamie Hartmann-Boyce et al. Cochrane Database Syst Rev. .

Update in

Abstract

Background: Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol by heating an e-liquid. Some people who smoke use ECs to stop or reduce smoking, although some organizations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit smoking, and if they are safe to use for this purpose. This is a review update conducted as part of a living systematic review.

Objectives: To examine the effectiveness, tolerability, and safety of using electronic cigarettes (ECs) to help people who smoke tobacco achieve long-term smoking abstinence.

Search methods: We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 July 2022, and reference-checked and contacted study authors. SELECTION CRITERIA: We included randomized controlled trials (RCTs) and randomized cross-over trials, in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. Studies had to report abstinence from cigarettes at six months or longer or data on safety markers at one week or longer, or both.

Data collection and analysis: We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months follow-up, adverse events (AEs), and serious adverse events (SAEs). Secondary outcomes included the proportion of people still using study product (EC or pharmacotherapy) at six or more months after randomization or starting EC use, changes in carbon monoxide (CO), blood pressure (BP), heart rate, arterial oxygen saturation, lung function, and levels of carcinogens or toxicants, or both. We used a fixed-effect Mantel-Haenszel model to calculate risk ratios (RRs) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data in meta-analyses.

Main results: We included 78 completed studies, representing 22,052 participants, of which 40 were RCTs. Seventeen of the 78 included studies were new to this review update. Of the included studies, we rated ten (all but one contributing to our main comparisons) at low risk of bias overall, 50 at high risk overall (including all non-randomized studies), and the remainder at unclear risk. There was high certainty that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (RR 1.63, 95% CI 1.30 to 2.04; I2 = 10%; 6 studies, 2378 participants). In absolute terms, this might translate to an additional four quitters per 100 (95% CI 2 to 6). There was moderate-certainty evidence (limited by imprecision) that the rate of occurrence of AEs was similar between groups (RR 1.02, 95% CI 0.88 to 1.19; I2 = 0%; 4 studies, 1702 participants). SAEs were rare, but there was insufficient evidence to determine whether rates differed between groups due to very serious imprecision (RR 1.12, 95% CI 0.82 to 1.52; I2 = 34%; 5 studies, 2411 participants). There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.94, 95% CI 1.21 to 3.13; I2 = 0%; 5 studies, 1447 participants). In absolute terms, this might lead to an additional seven quitters per 100 (95% CI 2 to 16). There was moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 5 studies, 1840 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 1.00, 95% CI 0.56 to 1.79; I2 = 0%; 8 studies, 1272 participants). Compared to behavioural support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.66, 95% CI 1.52 to 4.65; I2 = 0%; 7 studies, 3126 participants). In absolute terms, this represents an additional two quitters per 100 (95% CI 1 to 3). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was some evidence that (non-serious) AEs were more common in people randomized to nicotine EC (RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low certainty; 4 studies, 765 participants) and, again, insufficient evidence to determine whether rates of SAEs differed between groups (RR 1.03, 95% CI 0.54 to 1.97; I2 = 38%; 9 studies, 1993 participants). Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued EC use. Very few studies reported data on other outcomes or comparisons, hence evidence for these is limited, with CIs often encompassing clinically significant harm and benefit.

Authors' conclusions: There is high-certainty evidence that ECs with nicotine increase quit rates compared to NRT and moderate-certainty evidence that they increase quit rates compared to ECs without nicotine. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the effect size. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, with no difference in AEs between nicotine and non-nicotine ECs nor between nicotine ECs and NRT. Overall incidence of SAEs was low across all study arms. We did not detect evidence of serious harm from nicotine EC, but longest follow-up was two years and the number of studies was small. The main limitation of the evidence base remains imprecision due to the small number of RCTs, often with low event rates, but further RCTs are underway. To ensure the review continues to provide up-to-date information to decision-makers, this review is a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.

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Conflict of interest statement

RB holds an NIHR grant, but this did not directly fund this current work. She is principal investigator of an ongoing study listed in this review.

CB was principal investigator on the ASCEND e‐cigarette trial reported in the Cochrane Review and a co‐investigator on the ASCEND II trial and several other studies included in the review. CB has provided consultancy for J&J KK (Japan) on NRT products. CB reports research grants from the Health Research Council of NZ, the Heart Foundation of NZ and the NZ Ministry of Health. He has recently led a project funded by Pfizer (NZ) on chronic disease management.

ARB's work on this review has been supported by Cancer Research UK Project Award funding. This is not deemed a conflict of interest.

TF has no known conflicts of interest.

PH provided consultancy for and received research funding from Pfizer, a manufacturer of stop‐smoking medications. He was principal investigator on one of the trials included in this review and co‐investigator on other relevant studies.

JHB has received support for this work from the Cochrane Review Support Programme and the University of Oxford's Returning Carer's Fund. Neither of these are deemed conflicts of interest.

NL has received payment for lectures on systematic review methodology, and has been an applicant on project funding to carry out priority setting and systematic reviews in the area of tobacco control (NIHR funded). None of this is deemed a conflict of interest.

HM has no known conflicts of interest.

CN has no known conflicts of interest.

NAR has received royalties from UpToDate, Inc., for chapters on electronic cigarettes and occasional fees from academic hospitals or professional medical societies for lectures on smoking cessation that include discussion of electronic cigarettes. NAR was a member of the committee that produced the 2018 National Academies of Science, Engineering, and Medicine's Consensus Study Report on the Public Health Benefits of E‐cigarettes. She was unpaid for this work. Outside the topic of e‐cigarettes, NAR is a consultant for Achieve LifeSciences, which is developing an investigational smoking cessation medication for FDA approval (cytisine) and her institution (MGH) receives a grant from the company as a site for a clinical trial testing the safety and efficacy of cytisine. NAR holds grants from NIH for research work.

AT's work on this review has been supported by the Cochrane Review Support Programme and the University of Oxford's Returning Carer's Fund. Neither of these are deemed conflicts of interest.

TT has no known conflicts of interest.

Figures

1
1
PRISMA diagram for 2022 update
2
2
PRISMA diagram for 2021 update (Autumn update)
3
3
2021 update flow diagram (Spring update)
4
4
2020 update flow diagram
5
5
2016 update flow diagram
6
6
2014 flow diagram
7
7
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
8
8
9
9
Funnel plot for comparison 4.4
1.1
1.1. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 1: Smoking cessation
1.2
1.2. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 2: Adverse events
1.3
1.3. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 3: Serious adverse events
1.4
1.4. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 4: Carbon monoxide (ppm)
1.5
1.5. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 5: Heart rate (bpm)
1.6
1.6. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 6: Systolic blood pressure
1.7
1.7. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 7: Blood oxygen saturation
1.8
1.8. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 8: 3‐HPMA (pmol/mg creatinine)
1.9
1.9. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 9: NNAL (pmol/mg creatinine))
1.10
1.10. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 10: 2‐HPMA (pmol/mg creatinine)
1.11
1.11. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 11: HMPMA (pmol/mg creatinine)
1.12
1.12. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 12: PheT (pmol/mg creatinine)
1.13
1.13. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 13: CEMA (pmol/mg creatinine)
1.14
1.14. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 14: AAMA (pmol/mg creatinine)
1.15
1.15. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 15: FEV1
1.16
1.16. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 16: FEV1/FVC (%)
1.17
1.17. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 17: PEF (L/min)
1.18
1.18. Analysis
Comparison 1: Nicotine EC versus NRT, Outcome 18: Product use at 6+ months
2.1
2.1. Analysis
Comparison 2: Nicotine EC versus varenicline, Outcome 1: Smoking cessation
2.2
2.2. Analysis
Comparison 2: Nicotine EC versus varenicline, Outcome 2: Serious adverse events
3.1
3.1. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 1: Smoking cessation
3.2
3.2. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 2: Adverse events
3.3
3.3. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 3: Serious adverse events
3.4
3.4. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 4: Carbon monoxide (ppm)
3.5
3.5. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 5: Heart rate
3.6
3.6. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 6: Systolic blood pressure
3.7
3.7. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 7: FeNO (ppb)
3.8
3.8. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 8: FEV1 (l)
3.9
3.9. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 9: FEV1/FVC
3.10
3.10. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 10: NNAL (pmol/mg creatinine)
3.11
3.11. Analysis
Comparison 3: Nicotine EC versus non‐nicotine EC, Outcome 11: Product use at 6+ months
4.1
4.1. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 1: Smoking cessation
4.2
4.2. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 2: Adverse events
4.3
4.3. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 3: Serious adverse events
4.4
4.4. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 4: Carbon monoxide (ppm)
4.5
4.5. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 5: Heart rate (bpm)
4.6
4.6. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 6: Systolic blood pressure
4.7
4.7. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 7: Blood oxygen saturation
4.8
4.8. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 8: 3‐HPMA (SMD)
4.9
4.9. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 9: NNAL (SMD)
4.10
4.10. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 10: 2‐HPMA (pmol/mg creatinine)
4.11
4.11. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 11: HMPMA (pmol/mg creatinine)
4.12
4.12. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 12: PheT (pmol/mg creatinine)
4.13
4.13. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 13: CEMA (pmol/mg creatinine)
4.14
4.14. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 14: AAMA (pmol/mg creatinine)
4.15
4.15. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 15: S‐PMA (nanograms)
4.16
4.16. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 16: FEV1 (SMD)
4.17
4.17. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 17: FEF 25‐75 (litres/second))
4.18
4.18. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 18: PEF 25‐75 (litres/minute)
4.19
4.19. Analysis
Comparison 4: Nicotine EC versus behavioural support only/no support, Outcome 19: FEV1/FVC
5.1
5.1. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 1: Smoking cessation
5.2
5.2. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 2: Serious adverse events
5.3
5.3. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 3: Carbon monoxide (ppm)
5.4
5.4. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 4: Heart rate
5.5
5.5. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 5: Systolic blood pressure
5.6
5.6. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 6: FeNO (ppb)
5.7
5.7. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 7: FEV1 (l)
5.8
5.8. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 8: FVC (l)
5.9
5.9. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 9: FEV1/FVC
5.10
5.10. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 10: NNAL (pg/mg creatinine) at 24 weeks
5.11
5.11. Analysis
Comparison 5: Higher versus lower nicotine content, Outcome 11: Product use at 6+ months
6.1
6.1. Analysis
Comparison 6: Tobacco vs. menthol flavour, Outcome 1: Serious adverse events
6.2
6.2. Analysis
Comparison 6: Tobacco vs. menthol flavour, Outcome 2: NNAL (ng/g)
6.3
6.3. Analysis
Comparison 6: Tobacco vs. menthol flavour, Outcome 3: FEV1 (% predicted)
6.4
6.4. Analysis
Comparison 6: Tobacco vs. menthol flavour, Outcome 4: FEV1/FVC
7.1
7.1. Analysis
Comparison 7: Refillable versus cartridge, Outcome 1: Exhaled CO
8.1
8.1. Analysis
Comparison 8: Nicotine salt EC versus free‐base nicotine EC, Outcome 1: Smoking cessation
8.2
8.2. Analysis
Comparison 8: Nicotine salt EC versus free‐base nicotine EC, Outcome 2: Product use at 6+ months
9.1
9.1. Analysis
Comparison 9: Non‐nicotine EC versus behavioural support only/no support, Outcome 1: Smoking cessation
9.2
9.2. Analysis
Comparison 9: Non‐nicotine EC versus behavioural support only/no support, Outcome 2: Adverse events at 12 weeks
9.3
9.3. Analysis
Comparison 9: Non‐nicotine EC versus behavioural support only/no support, Outcome 3: Serious adverse events at 24 weeks
10.1
10.1. Analysis
Comparison 10: Non‐nicotine EC + NRT versus NRT, Outcome 1: Smoking cessation
10.2
10.2. Analysis
Comparison 10: Non‐nicotine EC + NRT versus NRT, Outcome 2: Adverse events
10.3
10.3. Analysis
Comparison 10: Non‐nicotine EC + NRT versus NRT, Outcome 3: Serious adverse events
11.1
11.1. Analysis
Comparison 11: Non‐nicotine EC versus NRT, Outcome 1: Smoking cessation
11.2
11.2. Analysis
Comparison 11: Non‐nicotine EC versus NRT, Outcome 2: Adverse events
11.3
11.3. Analysis
Comparison 11: Non‐nicotine EC versus NRT, Outcome 3: Serious adverse events
12.1
12.1. Analysis
Comparison 12: Advice to use e‐cigarettes compared to no advice to use e‐cigarettes, Outcome 1: Smoking cessation
12.2
12.2. Analysis
Comparison 12: Advice to use e‐cigarettes compared to no advice to use e‐cigarettes, Outcome 2: Adverse events at 3 months
12.3
12.3. Analysis
Comparison 12: Advice to use e‐cigarettes compared to no advice to use e‐cigarettes, Outcome 3: Serious adverse events at 3 months
13.1
13.1. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 1: Smoking cessation
13.2
13.2. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 2: Adverse events
13.3
13.3. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 3: Serious adverse events
13.4
13.4. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 4: Carbon monoxide (ppm)
13.5
13.5. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 5: FeNO (ppb)
13.6
13.6. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 6: FEV1 (%)
13.7
13.7. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 7: FVC (%)
13.8
13.8. Analysis
Comparison 13: Nicotine EC + NRT versus non‐nicotine EC + NRT, Outcome 8: Study product use at 6+ months
14.1
14.1. Analysis
Comparison 14: Nicotine EC + NRT versus NRT, Outcome 1: Smoking cessation
14.2
14.2. Analysis
Comparison 14: Nicotine EC + NRT versus NRT, Outcome 2: Adverse events
14.3
14.3. Analysis
Comparison 14: Nicotine EC + NRT versus NRT, Outcome 3: Serious adverse events
15.1
15.1. Analysis
Comparison 15: Nicotine EC + varenicline vs. varenicline, Outcome 1: Adverse events at 12 weeks
15.2
15.2. Analysis
Comparison 15: Nicotine EC + varenicline vs. varenicline, Outcome 2: Serious adverse events at 12 weeks
See this image and copyright information in PMC

Update of

Comment in

References

References to studies included in this review

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Caponnetto 2013b {published data only}
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Cobb 2021 {published and unpublished data}
    1. Cobb CO, Foulds J, Yen M-S, Veldheer S, Lopez AA, Yingst JM et al. Effect of an electronic nicotine delivery system with 0, 8, or 36 mg/mL liquid nicotine versus a cigarette substitute on tobacco-related toxicant exposure: a four-arm, parallel-group, randomised, controlled trial. Lancet Respiratory Medicine April 2021;9(8):840-50. [DOI: org/10.1016/ S2213-2600(21)00022-9] - PMC - PubMed
    1. Foulds J, Cobb C, Yen M-S, Veldheer S, Brosnan P, Yingst J et al . Effect of electronic nicotine delivery systems on cigarette abstinence in smokers with no plans to quit: exploratory analysis of a randomized placebo-controlled trial. Nicotine Tobacco Research 2022 Jun 15;24(7):955-961. [DOI: 10.1093/ntr/ntab247] - DOI - PMC - PubMed
    1. Lopez AA, Cobb CO, Yingst JM, Veldheer S, Hrabovsky S, Yen MS, et al. A transdisciplinary model to inform randomized clinical trial methods for electronic cigarette evaluation. BMC Public Health 2016;16(1):217. [PMCID:: PMC4778292] [PMID: ] - PMC - PubMed
    1. NCT02342795. Randomized controlled trial methods for novel tobacco products evaluation. clinicaltrials.gov/show/NCT02342795 (accessed 17 February 2016).
    1. Veldheer S, Yingst J, Midya V, Hummer B, Lester C, Krebs N, . Pulmonary and other health effects of electronic cigarette use among adult smokers participating in a randomized controlled smoking reduction trial. Addictive Behaviors 2019;91:95-101. - PMC - PubMed
Czoli 2019 {published and unpublished data}
    1. Czoli CD, Fong GT, Goniewicz ML, Hammond D. Biomarkers of exposure among "dual users" of tobacco cigarettes and electronic cigarettes in Canada. Nicotine and Tobacco Research 2019;21(9):1259-66. - PMC - PubMed
Dawkins 2020 {published and unpublished data}
    1. Dawkins L, Bauld L, Ford A, Robson D, Hajek P, Parrott S, et al. A cluster feasibility trial to explore the uptake and use of e-cigarettes versus usual care offered to smokers attending homeless centres in Great Britain. PLOS One 2020;15(10):e0240968. [ISRCTN14140672] - PMC - PubMed
    1. ISRCTN14140672. Exploring the use and uptake of e-cigarettes for homeless smokers. www.isrctn.com/ISRCTN14140672 (first received 7 November 2018).
Edmiston 2022 {published data only}
    1. Edmiston JS, Webb KM, Wang J, Oliveri D, Liang Q, Sarkar M. Biomarkers of exposure and biomarkers of potential harm in adult smokers who switch to e-vapor products relative to cigarette smoking in a 24-week, randomized, clinical trial. Nicotine & Tobacco Research 2022;24(7):1047–54. [DOI: ] - PMC - PubMed
Eisenberg 2020 {published data only}
    1. Eisenberg MJ, Hébert-Losier M, Windle SB, Greenspoon T, Brandys T, Fülöp T. Effect of e-cigarettes plus counseling vs counseling alone on smoking cessation: a randomized clinical trial. JAMA 2020;324(18):1844-54. - PMC - PubMed
    1. Hebert-Losier A, Filion KB, Windle SB, Eisenberg MJ. A randomized controlled trial evaluating the efficacy of e-cigarette use for smoking cessation in the general population: E3 trial design. Canadian Journal of Cardiology Open 2020;2(3):168-75. [NCT02417467] - PMC - PubMed
    1. NCT02417467. Evaluating the efficacy of e-cigarette use for smoking cessation (E3) trial. clinicaltrials.gov/show/NCT02417467 (accessed 17 February 2016).
Eisenhofer 2015 {published data only}
    1. Eisenhofer J, Makanjuola T, Martinez V, Thompson-Lake DG, Rodgman C, DeBrule DS, et al. Efficacy of electronic cigarettes for smoking cessation in veterans. Drug and Alcohol Dependence 2015;156:e63-e64.
Ely 2013 {published data only}
    1. Ely J. Evaluation of the use of electric cigarettes in a rural smoking cessation program. Available online at: digitalunc.coalliance.org/fedora/repository/cogru:4161 [no longer available] 2013 (accessed 1st November 2014).
Felicione 2019 {published data only}
    1. Felicione NJ, Enlow P, Elswick D, Long D, Sullivan CR, Blank MD. A pilot investigation of the effect of electronic cigarettes on smoking behavior among opioid-dependent smokers. Addictive Behaviors 2019;91:45-50. - PubMed
George 2019 {published data only}
    1. George J, Hussain M, Vadiveloo T, Ireland S, Hopkinson P, Struthers AD, et al. Cardiovascular effects of switching from tobacco cigarettes to electronic cigarettes. Journal of the American College of Cardiology 2019;74(25):3112-20. - PMC - PubMed
    1. NCT02878421. Vascular EffectS of regUlar cigarettes Versus electronIc cigarette USe (VESUVIUS). clinicaltrials.gov/ct2/show/NCT02878421 (first received 25 August 2016).
Goniewicz 2017 {published data only}
    1. Goniewicz ML, Gawron M, Smith DM, Peng M, Jacob P 3rd, Benowitz NL. Exposure to nicotine and selected toxicants in cigarette smokers who switched to electronic cigarettes: a longitudinal within-subjects observational study. Nicotine & Tobacco Research 2017;19(2):160-7. - PMC - PubMed
Guillaumier 2018 {unpublished data only}
    1. ACTRN12617000849392. The QuitNic Study: a pilot study of electronic nicotine devices for smoking cessation with drug and alcohol clients. www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372198 (first received 8 June 2017).
    1. Bonevski B, Manning V, Wynne O, Gartner C, Borland R, Baker A, et al. QuitNic: A pilot randomised controlled trial comparing nicotine vaping products with nicotine replacement therapy for smoking cessation following residential detoxification. Nicotine and Tobacco Research 2021;23(3):462-70. - PMC - PubMed
    1. Guillaumier A, Manning V, Wynne O, Gartner C, Borland R, Baker AL, et al. Electronic nicotine devices to aid smoking cessation by alcohol- and drug-dependent clients: protocol for a pilot randomised controlled trial. Trials 2018;19:415. - PMC - PubMed
Hajek 2015a {published data only}
    1. Hajek P, Corbin L, Ladmore D, Spearing E. Adding e-cigarettes to specialist stop-smoking treatment: City of London pilot project. Journal of Addiction Research & Therapy 2015;6(244):(online ahead of print). [DOI: 10.4172/2155-6105.1000244] - DOI
Hajek 2019 {published and unpublished data}ISRCTN60477608
    1. Hajek P, Phillips-Waller A, Przulj D, Pesola F, Myers Smith K, Bisal N, et al. A randomized trial of e-cigarettes versus nicotine-replacement therapy. New England Journal of Medicine 2019;380(7):629-37. - PubMed
    1. Hajek P, Phillips-Waller A, Przulj D, Pesola F, Smith KM, Bisal N, et al. E-cigarettes compared with nicotine replacement therapy within the UK Stop Smoking Services: the TEC RCT. Health Technology Assessment 2019;23(43):1-82. [ISRCTN60477608] - PMC - PubMed
    1. ISRCTN60477608. The efficacy of e-cigarettes compared with nicotine replacement therapy, when used within the UK stop smoking service. www.isrctn.com/ISRCTN60477608 2014 (first received 2 April 2015).
    1. Li J, Hajek P, Pesola F, Wu Q, Phillips-Waller A, Przulj D, et al. Cost-effectiveness of e-cigarettes compared with nicotine replacement therapy in stop smoking services in England (TEC study): a randomized controlled trial. Addiction 2020;115(3):507-17. - PMC - PubMed
Hajek 2022 {published and unpublished data}
    1. Ford A, Uny I, Lowes J, Naughton F, Cooper S, Coleman T. A qualitative study of factors influencing adherence among pregnant women taking part in a trial of e-cigarettes for smoking cessation. International Journal of Environmental Research and Public Health 2021;18(2):430. - PMC - PubMed
    1. Hajek P, Przulj D, Pesola F, Griffiths C, Walton R, McRobbie H, et al. Electronic cigarettes versus nicotine patches for smoking cessation in pregnancy: a randomized controlled trial. Nature Medicine 2022;28:958-64. [DOI: ] - PMC - PubMed
    1. ISRCTN62025374. Helping pregnant smokers quit: a multi-centre study of electronic cigarettes and nicotine patches. www.isrctn.com/ISRCTN62025374 (first received March 21 2017). [DOI: ]
Halpern 2018 {published data only}
    1. Halpern SD, Harhay MO, Saulsgiver K, Brophy C, Troxel AB, Volpp KG. A pragmatic trial of e-cigarettes, incentives, and drugs for smoking cessation. New England Journal of Medicine 2018;378(24):2302-10. - PubMed
    1. Harhay MO, Troxel AB, Brophy C, Saulsgiver K, Volpp KG, Halpern SD, . Financial incentives promote smoking cessation directly, not by increasing use of cessation aids. Annala of the American Thoracic Society 2019 February;16(2):280-282. [DOI: 10.1513/AnnalsATS.201808-574RL] - DOI - PMC - PubMed
    1. NCT02328794. Randomized clinical trial to reduce harm from tobacco. clinicaltrials.gov/show/NCT02357173 (accessed 17 February 2016).
Hatsukami 2020 {published and unpublished data}
    1. Hatsukami D, Meier E, Lindgren BR, Anderson A, Reisinger S, Norton K, et al. A randomized clinical trial examining the effects of instructions for electronic cigarette use on smoking-related behaviors, and biomarkers of exposure. Nicotine & Tobacco Research 2020;22(9):1524-32. [DOI: 10.1093/ntr/ntz233] - DOI - PMC - PubMed
    1. NCT03111537. Methods Project 4: Clinical Trial - Amended (COMET). https://clinicaltrials.gov/ct2/show/NCT03111537 (Accessed 10 September 2022).
Hickling 2019 {published data only}
    1. Hickling LM, Perez-Iglesias R, McNeill A, Dawkins L, Moxham J, Ruffell T, et al. A pre-post pilot study of electronic cigarettes to reduce smoking in people with severe mental illness. Psychological Medicine 2019;49(6):1033-40. - PubMed
    1. NCT02212041. Acceptability, patterns of use and safety of electronic cigarette in people with mental illness: a pilot study. clinicaltrials.gov/show/NCT02212041 (accessed 17 February 2016).
Holliday 2019 {published data only}
    1. Holliday et al. E-cigarettes for Smoking Cessation in Patients with Periodontitis: Pilot RCT. In: IADR International Association for Dental Research. 2019.
    1. Holliday R, Preshaw PM, Ryan V, Sniehotta FF, McDonald S, Bauld L, et al. A feasibility study with embedded pilot randomised controlled trial and process evaluation of electronic cigarettes for smoking cessation in patients with periodontitis. Pilot and Feasibility Studies 2019;5:74. - PMC - PubMed
    1. ISRCTN17731903. Feasibility study of e-cigarettes in periodontitis. www.isrctn.com/ISRCTN17731903 (first received 27 September 2016).
Humair 2014 {published data only}
    1. Humair J-P, Tango R. Can e-cigarette help patients to reduce or stop smoking in primary care practice? Journal of General Internal Medicine 2014;29:S480.
Ikonomidis 2018 {published data only}
    1. Ikonomidis I, Vlastos D, Kourea K, Kostelli G, Varoudi M, Pavlidis G, et al. Electronic cigarette smoking increases arterial stiffness and oxidative stress to a lesser extent than a single conventional cigarette: an acute and chronic study. Circulation 2018;137(3):303-6. - PubMed
    1. NCT03039920. The effects of electronic cigarette smoking on the arterial wall and endothelial glycocalyx properties of smokers. clinicaltrials.gov/ct2/show/NCT03039920 (first received 1 February 2017).
Ikonomidis 2020a {published data only}
    1. Ikonomidis I, Katogiannis K, Kostelli G, Kourea K, Kyriakou E, Kypraiou A, et al. Effects of electronic cigarette on platelet and vascular function after four months of use. Food and Chemical Toxicology 2020;141:111389. - PubMed
Ikonomidis 2020b {published and unpublished data}
    1. Ikonomidis I, Katogiannis K, Kostelli G, Kourea K, Kyriakou E, Kypraiou A, et al. Effects of electronic cigarette on platelet and vascular function after one month of use. In: European Heart Journal 2020; Conference: European Society of Cardiology Congress, ESC 2020. Suppl 2 edition. Vol. 41. 2020:2359.
Ioakeimidis 2018 {published data only}
    1. Ioakeimidis N, Vlachopoulos C, Georgakopoulos C, Abdelrasoul M, Skliros N, Katsi V, et al. Smoking cessation rates with varenicline and electronic cigarettes in relapsed smokers with a history of acute coronary syndrome. European Heart Journal 2018;39(Suppl_1):242.
Kerr 2020 {published and unpublished data}
    1. Kerr D. Chapter 5: A randomised controlled trial investigating the cardiovascular effects of e-cigaretttes in comparison to nicotine replacement patches [personal communication]. Studies into the Cardiovascular and Respiratory Effects of Electronic Cigarettes (PhD thesis), email to: A Butler 27 September 2020.
    1. NCT03358953. The cardiovascular impacts of electronic cigarettes in comparison to the use of nicotine replacement patches (VAPOUR). clinicaltrials.gov/ct2/show/NCT03358953 (first received December 2 2017 ).
Kimber 2021 {published data only}
    1. Kimber CF, Soar K, Dawkins LE . Changes in puffing topography and subjective effects over a 2-week period in e-cigarette naive smokers: effects of device type and nicotine concentrations. Addictive Behaviors 2021;118:106909. [DOI: 10.1016/j.addbeh.2021.106909] - DOI - PubMed
Kumral 2016 {published data only}
    1. Kumral TL, Saltürk Z, Yildirim G, Uyar Y, Berkiten G, Atar Y, et al. How does electronic cigarette smoking affect sinonasal symptoms and nasal mucociliary clearance? B-ENT 2016;12(1):17-21. - PubMed
Lee 2018 {published data only}
    1. Lee SM, Tenney R, Wallace A, Arjojmandi M. The end perioperative smoking pilot study: a randomized trial comparing e-cigarettes versus nicotine patch. Canadian Journal of Anesthesia 2017;64(1 Supplement 1):S48-S49.
    1. Lee SM, Tenney R, Wallace A, Arjomandi M. Exploring the teachable moment: facilitators and barriers to perioperative smoking cessation, a qualitative study,. Canadian Journal of Anesthesia 2017; Conference: 2017 Annual Meeting of the Canadian Anesthesiologists' Society, Canada. 61;1 Supplement:S46-S47.
    1. Lee SM, Tenney R, Wallace AW, Arjomandi M. E-cigarettes versus nicotine patches for perioperative smoking cessation: a pilot randomized trial. PeerJ 2018;6(9):e5609. - PMC - PubMed
    1. NCT02482233. A pilot randomized controlled clinical trial - "Electronic nicotine delivery device (e-cigarette) for perioperative smoking cessation in veterans". clinicaltrials.gov/show/NCT02482233 (accessed 17 February 2016).
Lee 2019 {published data only}
    1. KCT0001277. Effect of an electronic cigarette for smoking reduction and cessation in Korean male smokers: a randomized, controlled study. KCT0001277 2014 (accessed 15 August 2016). - PubMed
    1. Lee SH, Ahn SH, Cheong YS. Effect of electronic cigarettes on smoking reduction and cessation in Korean male smokers: a randomized controlled study. Journal of the American Board of Family Medicine 2019;32(4):567-74. - PubMed
Lucchiari 2020 {published data only}
    1. Lucchiari C, Masiero M, Mazzocco K, Veronesi G, Maisonneauve P, Jemos C, et al. Benefits of e-cigarettes in smoking reduction and in pulmonary health among chronic smokers undergoing a lung cancer screening program at 6 months. Addictive Behaviours 2020;103:106222. - PubMed
    1. Lucchiari C, Masiero M, Veronesi G, Maisonneuve P, Spina S, Jemos C, et al. Benefits of e-cigarettes among heavy smokers undergoing a lung cancer screening program: randomized controlled trial protocol. JMIR Research Protocols 2016;5(1):e21. [PMID: ] - PMC - PubMed
    1. Masiero M, Lucchiari C, Mazzocco K, Veronesi G, Maisonneuve P, Jemos C, et al. E-cigarettes may support smokers with high smoking-related risk awareness to stop smoking in the short run: preliminary results by randomized controlled trial. Nicotine and Tobacco Research 2019;21(1):119-126. [NCT02422914] - PubMed
    1. Masiero M, Lucchiari C, Mazzocco K, Veronesi G, Maisonneuve P Jemos C, et al. Corrigendum: E-cigarettes may support smokers with high smoking-related risk awareness to stop smoking in the short run: preliminary results by randomized controlled trial. Nicotine and Tobacco Research 2020;22(4):594-5. [NCT02422914] - PubMed
    1. NCT02422914. Benefits of tobacco free cigarette among heavy smokers undergoing a lung cancer screening program: a randomized controlled study. clinicaltrials.gov/show/NCT02422914 (accessed 17 February 2016).
Martinez 2021 {published data only}
    1. Byrne M, Simmons V, Martinez U, Sutton S, Brandon K, Brandon T . Cost effectiveness of a smoking cessation intervention for dual users of combustible and electronic cigarettes . In: Society for Research on Nicotine and Tobacco, Annual Meeting, Baltimore USA. March 2022.
    1. Gore LR, Sutton SK, Martinez U, Brandon KO, Simmons VN, Brandon TH. Mediators of initial abstinence for an extended self help smoking cessation intervention with dual users of combustible and electronic cigarettes. In: Society for Research on Nicotine and Tobacco, Annual Meeting, Baltimore USA. Vol. PS3-7. March 2022.
    1. Martinez U, Simmons VN, Brandon KO, Quinn GP, Brandon TH. Examining smoking and vaping behaviors, expectancies, and cessation outcomes between bisexual and heterosexual individuals. Behavioral Medicine Online May 2022;25:1-10. [DOI: 10.1080/08964289.2022.2077295] - DOI - PMC - PubMed
    1. Martinez U, Simmons VN, Sutton SK, Drobes DJ, Meltzer LR, Brandon KO, et al. Targeted smoking cessation for dual users of combustible and electronic cigarettes: a randomised controlled trial. Lancet Public Health 2021;6(7):e500-9. - PMC - PubMed
    1. Meltzer LR, Simmons VN, Sutton SK, Drobes DJ, Quinn GP, Meade CD, et al. A randomized controlled trial of a smoking cessation self-help intervention for dual users of tobacco cigarettes and e-cigarettes: intervention development and research design. Contemporary Clinical Trials 2017;60:56-62. - PMC - PubMed
Martner 2019 {published data only (unpublished sought but not used)}
    1. Martner SG, Dallery J. Technology-based contingency management and e-cigarettes during the initial weeks of a smoking quit attempt. Journal of Applied Behavior Analysis 2019;52(4):928-43. - PMC - PubMed
McRobbie 2015 {published data only}
    1. McRobbie H, Goniewicz M, Phillips A, Myers-Smith K, West O, Hajek P. Effects of the use of electronic cigarettes with and without concurrent smoking on acrolein delivery POS4-33. In: Society for Research on Nicotine and Tobacco, 20th Annual Meeting, Seattle, Washington. 2014:13. [www.srnt.org/conferences/2014/pdf/SRNT_2014_Rapids_C.pdf]
    1. McRobbie H, Phillips A, Goniewicz ML, Smith KM, Knight-West O, Przulj D, et al. Effects of switching to electronic cigarettes with and without concurrent smoking on exposure to nicotine, carbon monoxide, and acrolein. Cancer Prevention Research (Philadelphia, Pa.) 2015;8(9):873-8. - PubMed
    1. NCT01714778. Toxins and Delivery in E-cigarette USers (TADEUS). clinicaltrials.gov/ct2/show/NCT01714778 (first received 26 October 2012).
Meier 2017 {published data only}
    1. Meier E, Wahlquist AE, Heckman BW, Cummings KM, Froeliger B, Carpenter MJ. A pilot randomized crossover trial of electronic cigarette sampling among smokers. Nicotine & Tobacco Research 2017;19(2):176-82. - PMC - PubMed
Morphett 2022a {unpublished data only}
    1. ACTRN12612001210864. Can using nicotine as a long-term substitute enhance smoking cessation over using it only as a cessation aid? [An open-label randomised pragmatic policy trial examining effectiveness of short-term use of Nicotine Replacement Therapy (NRT) vs short- or long-term use of NRT vs short- or long-term use of NRT or electronic nicotine delivery systems for smoking cessation in cigarette smokers.]. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?ACTRN=1261... (first received November 15 2012).
    1. Fraser D, Borland R, Gartner C. Protocol for a randomised pragmatic policy trial of nicotine products for quitting or long-term substitution in smokers. BMC Public Health 2015;15:1026. - PMC - PubMed
    1. Morphett K, Fraser D, Borland R, Hall W, Walker N, Bullen C, et al. A pragmatic randomized comparative trial of e-cigarettes and other nicotine products for quitting or long-term substitution in smokers. Nicotine & Tobacco Research 2022;24(7):1079-88. [DOI: doi: 10.1093/ntr/ntab266] - PubMed
Morphett 2022b {published and unpublished data}
    1. ACTRN12618000408280. Cessation And Relapse Prevention (CARP) trial: nicotine vaporisers compared to standard nicotine replacement therapy for smoking cessation among people with co-morbidities. www.anzctr.org.au/ACTRN12618000408280.aspx (first received 21 March 2018).
    1. Morphett K, Boyd M, Puljevic C, Gilks C, Bonevski B, Borland R, et al. Do nicotine vaping products increase quitting among priority population groups over standard smoking cessation therapy? A pragmatic randomised partial cross-over trial. In: Society for Research on Nicotine and Tobacco (SRNT), Annual Meeting 2022. Vol. SYM17-4. 2022.
Morris 2022 {published data only}
    1. Morris P, McDermott S, Chapman F, Verron T, Cahours X, Stevenson M, et al. Reductions in biomarkers of exposure to selected harmful and potentially harmful constituents following exclusive and partial switching from combustible cigarettes to myblu TM electronic nicotine delivery systems (ENDS). Internal & Emergency Medicine 2022;17(2):397-410. [DOI: 10.1007/s11739-021-02813-w] - DOI - PMC - PubMed
    1. NCT04429932. A study to evaluate nicotine uptake and biomarkers in adult smokers using mybluTM electronic cigarettes. clinicaltrials.gov/ct2/show/NCT04429932 (first received June 7 2021).
    1. NCT04430634 . A study to evaluate nicotine uptake and biomarkers in smokers using mybluTM electronic cigarettes [An open-label, randomized, crossover study to assess nicotine uptake, tobacco-related biomarkers of exposure, biomarkers of potential harm, and puff topography with use of mybluTM electronic cigarettes in adult smokers]. clinicaltrials.gov/ct2/show/NCT04430634 (first received June 7 2021).
Myers‐Smith 2022 {published data only}
    1. ISRCTN13288677. Can electronic cigarettes and nicotine replacement treatment help reduce smoking in smokers who struggle to quit? www.isrctn.com/ISRCTN13288677 (first received 17 March 2017).
    1. Myers Smith K, Phillips-Waller A, Pesola F, McRobbie H, Przulj D, Orzol M, et al. E-cigarettes versus nicotine replacement treatment as harm reduction interventions for smokers who find quitting difficult: randomised controlled trial. Addiction 2022;117(1):224-33. [DOI: ] - PubMed
NCT02648178 {published data only}
    1. NCT02648178. Evaluation of appeal and impact of e-cigarettes among chronic smokers with smoking-related cancers. clinicaltrials.gov/show/NCT02648178 (accessed 17 February 2016).
NCT02918630 {published data only}
    1. NCT02918630. E-cigarettes to promote smoking reduction among individuals with schizophrenia. clinicaltrials.gov/ct2/show/NCT02918630 (first received 5 July 2018).
NCT03492463 {published data only}
    1. NCT03492463. The role of nicotine dose and route of delivery in affecting adoption of e-cigarettes and reducing exposure to toxic combustion products (ENDS-Switch). clinicaltrials.gov/ct2/show/study/NCT03492463 (first received April 10 2018).
Nides 2014 {published data only}
    1. NCT01898169. Evaluation of short-term safety and use patterns of an electronic nicotine delivery system. clinicaltrials.gov/ct2/show/NCT01898169 (first received 12 July 2013).
    1. Nides MA, Leischow SJ, Bhatter M, Simmons M. Nicotine blood levels and short-term smoking reduction with an electronic nicotine delivery system. American Journal of Health Behavior 2014;38(2):265-74. - PubMed
Okuyemi 2022 {published data only}
    1. NCT03084315. Changes in biomarkers associated with use of electronic cigarettes [Changes in biomarkers associated with use of electronic cigarettes among African American menthol and non-menthol smokers]. clinicaltrials.gov/ct2/show/NCT03084315 (first received March 20 2017).
    1. Okuyemi KS, Ojo-Fati O, Aremu TO, Friedrichsen CS, Grude L, Oyenuga M, et al. A randomized trial of nicotine vs. no-nicotine e-cigarettes among African American smokers: changes in smoking and tobacco biomarkers. Nicotine & Tobacco Research 2022;24(4):555-63. [DOI: ] - PubMed
Oncken 2015 {published data only}
    1. NCT01775787. Effects of Electronic Cigarettes on Nicotine Concentrations (ECIG). clinicaltrials.gov/ct2/show/NCT01775787 (first received 25 January 2013).
    1. Oncken CA, Litt MD, McLaughlin LD, Burki NA. Nicotine concentrations with electronic cigarette use: effects of sex and flavor. Nicotine & Tobacco Research 2015;17(4):473-8. - PubMed
    1. Swedeh MA, Oncken C, Burki NK. Acute effects of electronic cigarettes on airway function in human subjects. In: American Thoracic Society International Conference Abstracts. Vol. 189. 2014:A4089.
Ozga‐Hess 2019 {published data only}
    1. Ozga-Hess JE, Felicione NJ, Ferguson SG, Dino G, Elswick D, Whitworth C, et al. Piloting a clinical laboratory method to evaluate the influence of potential modified risk tobacco products on smokers' quit-related motivation, choice, and behaviour. Addictive Behaviors 2019;99:106105. - PMC - PubMed
Pacifici 2015 {published data only}
    1. Pacifici R, Pichini S, Graziano S, Pellegrini M, Massaro G, Beatrice F. Successful nicotine intake in medical assisted use of e-cigarettes: a pilot study. International Journal of Environmental Research and Public Health 2015;12(7):7638-46. - PMC - PubMed
Polosa 2011 {published data only}
    1. NCT01195597. Smoking cessation and reduction with an electronic nicotine delivery device (ENDD). clinicaltrials.gov/ct2/show/NCT01195597 (first received 6 September 2010).
    1. Polosa R, Caponnetto P, Morjaria JB, Papale G, Campagna D, Russo C. Effect of an electronic nicotine delivery device (e-cigarette) on smoking reduction and cessation: a prospective 6-month pilot study. BMC Public Health 2011;11:786. - PMC - PubMed
    1. Polosa R, Morjaria JB, Caponnetto P, Campagna D, Russo C, Alamo A, et al. Effectiveness and tolerability of electronic cigarette in real-life: a 24-month prospective observational study. Internal and Emergency Medicine 2014;9(5):537-46. - PubMed
Polosa 2014b {published data only}
    1. NCT02124200. High Cessation Rates in Smokers Using Personal Vaporizers (VAPECIG). clinicaltrials.gov/ct2/show/NCT02124200 (first received 28 April 2014).
    1. Polosa R, Caponnetto P, Maglia M, Morjaria JB, Russo C. Success rates with nicotine personal vaporizers: a prospective 6-month pilot study of smokers not intending to quit. BMC Public Health 2014;14:1159. - PMC - PubMed
Polosa 2015 {published data only}
    1. Polosa R, Caponnetto P, Cibella F, Le-Houezec J. Quit and smoking reduction rates in vape shop consumers: a prospective 12-month survey. International Journal of Environmental Research and Public Health 2015;12(4):3428-38. - PMC - PubMed
Pratt 2016 {published data only}
    1. Pratt SI, Sargent J, Daniels L, Santos MM, Brunette M. Appeal of electronic cigarettes in smokers with serious mental illness. Addictive Behaviors 2016;59:30-4. - PubMed
Pratt 2022 {published and unpublished data}
    1. NCT03050853. The appeal and impact of e-cigarettes in smokers with SMI. clinicaltrials.gov/ct2/show/NCT03050853 (first received February 13 2017).
    1. Pratt SI, Brunette MF, Ferron JC, Santos M, Sargent J, Xie H. E-cigarette provision to promote switching in cigarette smokers with serious mental illness - a randomized trial. Nicotine & Tobacco Research 2022;6(24):1405-12. [DOI: doi: 10.1093/ntr/ntac082] - PMC - PubMed
Pulvers 2018 {published data only}
    1. Pulvers K, Emami AS, Nollen NL, Romero DR, Strong DR, Benowitz NL, et al. Tobacco consumption and toxicant exposure of cigarette smokers using electronic cigarettes. Nicotine & Tobacco Research 2018;20(2):206-14. - PMC - PubMed
Pulvers 2020 {published and unpublished data}
    1. Arnold M, Nollen N, Mayo M, Ahluwalia J, Leavens E, Zhang G et al. Dual use of cigarettes and e-cigarettes in African American and LatinX smokers: Secondary analyses from a randomised controlled e-cigarettes switching trial. In: Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meeting. February 24-27 2021 virtual:POD4-2 p31. - PMC - PubMed
    1. Arnold MJ, Nollen NL, Mayo MS, Ahluwalia JS, Leavens EL, Zhang G, Rice M, et al. Harm reduction associated with dual use of cigarettes and e-cigarettes in Black and Latino smokers: secondary analyses from a randomized controlled e-cigarette switching trial. Nicotine & tobacco research 2021;23(11 2021 Oct 7;23(11):192-1876. [DOI: 10.1093/ntr/ntab069] - DOI - PMC - PubMed
    1. Leavens ELS, Nollen N, Ahluwalia J, Mayo M, Rice M, Brett E, et al. Changes in dependence, withdrawal, and craving among adult smokers who switch to nicotine salt pod-based e-cigarettes. In: Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meeting. February 24-27 2021 virtual:POD53-1 p96, C-6 p116. - PMC - PubMed
    1. Leavens ELS, Nollen N, Ahluwalia JS, Mayo MS, Rice M, Brett EI et al. Changes in dependence, withdrawal, and craving among adult smokers who switch to nicotine salt pod-based e-cigarettes. Addiction 2021;117(1):207-215. [DOI: 10.1111/add.15597] - DOI - PMC - PubMed
    1. NCT03511001. Effects Among Smokers Who Use and Do Not Use E-Cigarettes. https://clinicaltrials.gov/ct2/show/NCT03511001.
Russell 2021 {published and unpublished data}
    1. Russell C, McKeganey N, Katsampouris E, Satchwell A, Haseen F. A randomised community-based trial of a closed-system pod e-vapour product and nicotine replacement therapy for cigarette abstinence and reduction. Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meeting February 24-27 2021 virtual:PH-353 p230.
Scheibein 2020 {published and unpublished data}
    1. Scheibein F, McGirr K, Morrison A, Roche, Wells JS. An exploratory non-randomized study of a 3-month electronic nicotine delivery system (ENDS) intervention with people accessing a homeless supported temporary accommodation service (STA) in Ireland. Harm Reduction Journal 2020;17(1):73. - PMC - PubMed
Skelton 2022 {published data only}
    1. ACTRN12617000905369. Smoking reduction interventions for smoking cessation. ncbi.nlm.nih.gov/pmc/articles/PMC6953262/ (first received 9 June 2017). [DOI: 10.1002/14651858.CD013183.pub2] - DOI
    1. Lum A, Skelton E, Robinson M, Guillaumier A, Wynne O, Gartner C, et al. Barriers and facilitators to using vaporised nicotine products as smoking cessation aids among people receiving treatment for substance use disorder. Addictive Behaviors 2021;124:107097. [DOI: 10.1016/j.addbeh.2021.107097] - DOI - PubMed
    1. Skelton E, Lum A, Robinson M, Dunlop A, Guillaumier A, Baker A, et al. A pilot randomised controlled trial of abrupt versus gradual smoking cessation in combination with vaporised nicotine products for people receiving alcohol and other drug treatment. Addictive Behaviors 2022;131:107328. [DOI: doi: 10.1016/j.addbeh.2022.107328] - PubMed
Smith 2020 {published and unpublished data}
    1. Smith TT, Heckman BW, Wahlquist AE, Cummings KM, Carpenter MJ. The impact of e-liquid propylene glycol and vegetable glycerin ratio on ratings of subjective effects, reinforcement value, and use in current smokers. Nicotine & Tobacco Research 2020;22(5):791-7. - PMC - PubMed
Stein 2016 {published data only}
    1. Stein MD, Caviness C, Grimone K, Audet D, Anderson BJ, Bailey GL. An open trial of electronic cigarettes for smoking cessation among methadone-maintained smokers. Nicotine & Tobacco Research 2016;18(5):1157-62. - PMC - PubMed
Strasser 2016 {published data only}
    1. Strasser AA, Souprountchouk V, Kaufmann A, Blazekovic S, Leone F, Benowitz NL, et al. Nicotine replacement, topography, and smoking phenotypes of e-cigarettes. Tobacco Regulatory Science 2016;2(4):352-62. - PMC - PubMed
Tattan‐Birch 2022 {published data only}
    1. Tattan-Birch H, Kock L, Brown J, Beard E, Bauld L, West R, et al. E-cigarettes to augment stop smoking in-person support and treatment with varenicline (E-ASSIST): a pragmatic randomised controlled trial. Nicotine & Tobacco Research June 2022 Epub ahead of print. [DOI: doi: 10.1093/ntr/ntac149] - PMC - PubMed
Tseng 2016 {published data only}
    1. Guttentag A, Tuo-Yen T, Shelley D, Thomas K. Analyzing Trajectories of Acute Cigarette Reduction Post-Introduction of an E-Cigarette Using Ecological Momentary Assessment Data. International Journal of Environmental Research and Public Health 2022;19(12):7452. [DOI: 10.3390/ijerph19127452] - DOI - PMC - PubMed
    1. Guttentag A. Do e-cigarettes "Work" for smokers as a step on the way to cessation? An analysis of the temporal and spatial correlates of switching in a harm reduction trial among adult smokers. Dissertation Abstracts International: Section B: The Sciences and Engineering 2021;82:8-B.
    1. NCT02628964. Assessing the use of electronic cigarettes (e-cigarettes) as a harm reduction strategy. clinicaltrials.gov/show/NCT02628964 (accessed 17 February 2016).
    1. Tseng TY, Ostroff JS, Campo A, Gerard M, Kirchner T, Rotrosen J, et al. A randomized trial comparing the effect of nicotine versus placebo electronic cigarettes on smoking reduction among young adult smokers. Nicotine & Tobacco Research 2016;18(10):1937-43. - PMC - PubMed
Valentine 2018 {published data only}
    1. Valentine GW, Hefner K, Jatlow PI, Rosenheck RA, Gueorguieva R, Sofuoglu M. Impact of e-cigarettes on smoking and related outcomes in veteran smokers with psychiatric comorbidity. Journal of Dual Diagnosis 2018;14(1):2-13. - PMC - PubMed
Van Staden 2013 {published data only}
    1. Van Staden SR, Groenewald M, Engelbrecht R, Becker PJ, Hazelhurst LT. Carboxyhaemoglobin levels, health and lifestyle perceptions in smokers converting from tobacco cigarettes to electronic cigarettes. South African Medical Journal 2013;103(11):865-8. - PubMed
Vickerman 2022 {published data only}
    1. NCT03575468. Enhanced e-cigarette coaching intervention for dual users of cigarettes and e-cigarettes. clinicaltrials.gov/ct2/show/NCT03575468 (first received 2 July 2018).
    1. Vickerman KA, Carpenter KM, Miles LN, Hsu JM, Watt KA, Brandon TH, et al. A randomized pilot of a tailored smoking cessation quitline intervention for individuals who smoke and vape. Nicotine & Tobacco Research 2022;24(11):1811-20. [DOI: ] - PMC - PubMed
    1. Vickerman KA, Carpenter KM, Watt K, Miles L, Hsu J, Brandon T, et al. A behavioral smoking cessation intervention for Quitline callers who also use e-cigarettes. In: Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meeting; February 24-27 2021 (virtual). 2021:POD14-1 p50.
Wadia 2016 {published data only}
    1. Wadia R, Booth V, Yap HF, Moyes DL. A pilot study of the gingival response when smokers switch from smoking to vaping. British Dental Journal 2016;221(11):722-6. - PubMed
Walele 2018 {published data only}
    1. Cravo AS, Bush J, Sharma G, Savioz R, Martin C, Craige S, et al. A randomised, parallel group study to evaluate the safety profile of an electronic vapour product over 12 weeks. Regulatory Toxicology and Pharmacology 2016;81:S1-S14. - PubMed
    1. NCT02029196. A randomised, parallel group, multi-centre study to evaluate the safety profile of the ITG EVP G1 product. clinicaltrials.gov/show/NCT02029196 (accessed 16 July 2014).
    1. NCT02143310. A multi-centre study to evaluate the safety of use of electronic vapour products for two years. clinicaltrials.gov/show/NCT02143310 (accessed 16 July 2014).
    1. Walele T, Bush J, Koch A, Savioz R, Martin C, O'Connell G. Evaluation of the safety profile of an electronic vapour product used for two years by smokers in a real-life setting. Regulatory Toxicology and Pharmacology 2018;92:226-38. - PubMed
Walker 2020 {published data only}
    1. NCT02521662. A randomised-controlled clinical trial to evaluate the effectiveness and safety of combining nicotine patches with e-cigarettes (with and without nicotine) plus behavioural support, on smoking abstinence. clinicaltrials.gov/show/NCT02521662 (accessed 17 February 2016).
    1. Walker N, Parag V, Verbiest M, Laking G, Laugesen M, Bullen C. Nicotine patches used in combination with e-cigarettes (with and without nicotine) for smoking cessation: a pragmatic, randomised trial. Lancet. Respiratory Medicine 2020;8(1):54-64. - PubMed
    1. Walker N, Verbiest M, Kurdziel T, Laking G, Laugesen M, Parag V, et al. Effectiveness and safety of nicotine patches combined with e-cigarettes (with and without nicotine) for smoking cessation: study protocol for a randomised controlled trial. BMJ Open 2019;9(2):e023659. - PMC - PubMed
White 2021 {published and unpublished data}
    1. NCT03185546. Project 2 cigarette and e-cigarette nicotine content and e-liquid flavors. clinicaltrials.gov/ct2/show/NCT03185546 (first received May 14 2021).
    1. White CM, Denlinger-Apte RL, Tessier KM, Koopmeiners JS, Hatsukami DK, Strasser AA. Cigarette nicotine reduction in the presence of an alternative: investigating how cigarette nicotine content and e-liquid content affect smoking. In: Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meetingl February 24-27 2021 (virtual). 2021:SYM2C p2-3.
    1. White CM, Tessier KM, Koopmeiners JS, Denlinger-Apte RL, Cobb CO, Lane T, et al. Preliminary evidence on cigarette nicotine reduction with concurrent access to an e-cigarette: manipulating cigarette nicotine content, e-liquid nicotine content, and e-liquid flavor availability. Preventive Medicine Online 19 August 2022;EPub. [DOI: ] - PMC - PubMed
Yingst 2020 {published data only}
    1. Yingst J, Foulds J, Zurlo J, Steinberg MB, Eissenberg T, Du P. Acceptability of electronic nicotine delivery systems (ENDS) among HIV positive smokers. AIDS Care 2020;32(10):1224-8. - PMC - PubMed

References to studies excluded from this review

Adkison 2013 {published data only}
    1. Adkison SE, O'Connor RJ, Bansal-Travers M, Hyland A, Borland R, Yong HH, et al. Electronic nicotine delivery systems: international tobacco control four-country survey. American Journal of Preventive Medicine 2013;44(3):207-15. - PMC - PubMed
Al‐Delaimy 2015 {published data only}
    1. Al-Delaimy WK, Myers MG, Leas EC, Strong DR, Hofstetter CR. E-cigarette use in the past and quitting behavior in the future: a population-based study. American Journal of Public Health 2015;105(6):1213-9. - PMC - PubMed
    1. Donzelli A. E-cigarettes may impair ability to quit, but other explanations are possible. American Journal of Public Health 2015;105(11):e1. - PMC - PubMed
Anonymous 2019 {published data only}
    1. Anonymous. E-cigarettes best other cessation tools. Cancer Discovery 2019;9(4):OF3. - PubMed
Battista 2013 {published data only}
    1. Battista L, Di Iorio M, Tancredi M, Acconcia MC, Torromeo C, Barilla F, et al. Cardiovascular effects of electronic cigarettes. Circulation 2013;128:A16755.
Bianco 2019 {published data only}
    1. Bianco CL, Pratt SI, Ferron JC, Brunette MF. Electronic cigarette use during a randomized trial of interventions for smoking cessation among Medicaid beneficiaries with mental illness. Journal of Dual Diagnosis 2019;15(3):184-91. - PubMed
Biener 2015 {published data only}
    1. Biener L, Hargraves JL. A longitudinal study of electronic cigarette use among a population-based sample of adult smokers: association with smoking cessation and motivation to quit. Nicotine & Tobacco Research 2015;17(2):127-33. - PMC - PubMed
Biondi‐Zoccai 2019 {published data only}
    1. Biondi-Zoccai G, Sciarretta S, Bullen C, Nocella C, Violi F, Loffredo L, et al. Acute effects of heat-not-burn, electronic vaping, and traditional tobacco combustion cigarettes: the Sapienza University of Rome-Vascular Assessment of Proatherosclerotic Effects of Smoking ( SUR - VAPES ) 2 randomized trial. Journal of the American Heart Association 2019;8(6):e010455. - PMC - PubMed
    1. NCT03301129. Role of Traditional Cigarettes, Electronic and IQOS Cigarettes on Oxidative Stress. https://clinicaltrials.gov/ct2/show/NCT03301129.
Biondi‐Zoccai 2020 {published data only}
    1. Biondi-Zoccai G, Carnevale R, Vitali M, Tritapepe L, Martinelli O, Macrina F, et al. A randomized trial comparing the acute coronary, systemic, and environmental effects of electronic vaping cigarettes versus heat-not-burn cigarettes in smokers of combustible cigarettes undergoing invasive coronary assessment: rationale and design of the SUR-VAPES 3 trial. Minerva Cardioangiologica 2020;68(6):548-55. - PubMed
Borderud 2014 {published data only}
    1. Barton MK. Electronic cigarettes did not help patients with cancer stop smoking. CA: a cancer journal for clinicians 2015;65(2):85-6. - PubMed
    1. Borderud SP, Li Y, Burkhalter JE, Sheffer CE, Ostroff JS. Electronic cigarette use among patients with cancer: characteristics of electronic cigarette users and their smoking cessation outcomes. Cancer 2014;120(22):3527-35. - PMC - PubMed
    1. Fillon M. Electronic cigarettes might not help cancer patients quit smoking. Journal of the National Cancer Institute 2015;107(1):496. - PubMed
Brose 2015 {published data only}
    1. Brose LS, Hitchman SC, Brown J, West R, McNeill A. Is the use of electronic cigarettes while smoking associated with smoking cessation attempts, cessation and reduced cigarette consumption? A survey with a 1-year follow-up. Addiction 2015;110(7):1160-8. - PMC - PubMed
    1. Brown J, West R, Beard E, Michie S, Shahab L, McNeill A. Prevalence and characteristics of e-cigarette users in Great Britain: Findings from a general population survey of smokers. Addictive Behaviors 2014;39(6):1120-5. - PMC - PubMed
    1. Hitchman SC, Brose LS, Brown J, Robson D, McNeill A. Associations between e-cigarette type, frequency of use, and quitting smoking: findings from a longitudinal online panel survey in Great Britain. Nicotine & Tobacco Research 2015;17(10):1187-94. - PMC - PubMed
Brown 2014a {published data only}
    1. Brown J, Beard E, Kotz D, Michie S, West R. Real-world effectiveness of e-cigarettes when used to aid smoking cessation: a cross-sectional population study. Addiction 2014;109(9):1531-40. - PMC - PubMed
Bullen 2010 {published data only}
    1. Bullen C, McRobbie H, Thornley S, Glover M, Lin R, Laugesen M. Effect of an electronic nicotine delivery device (e cigarette) on desire to smoke and withdrawal, user preferences and nicotine delivery: randomised cross-over trial. Tobacco Control 2010;19(2):98-103. - PubMed
Bullen 2018 {published data only}
    1. ACTRN12616001355460. Varenicline alone or with nicotine e-cigarettes for smoking cessation in people with mental illness and drug and/or alcohol dependence. Australian New Zealand Clinical Trials Registry (ACTRN).
    1. Bullen C, Verbiest M, Galea-Singer S, Kurdziel T, Laking G, Newcombe D, et al. The effectiveness and safety of combining varenicline with nicotine e-cigarettes for smoking cessation in people with mental illnesses and addictions: study protocol for a randomised-controlled trial. BMC Public Health 2018;18(1):596. - PMC - PubMed
Caponnetto 2019 {published data only}
    1. Caponnetto P, Maglia M, Polosa R. Efficacy of smoking cessation with varenicline plus counselling for e-cigarettes users (VAREVAPE): a protocol for a randomized controlled trial. Contemporary Clinical Trials Communications 2019;15:100412. - PMC - PubMed
Cavarretta 2019 {published data only}
    1. Cavarretta E, Sciarretta S, Nocella C, Peruzzi M, Marullo AG, Loffredo L, et al. Subjective smoking satisfaction between heat-not-burn, electronic vaping, and traditional tobacco combustion cigarettes: a sub-analysis of the SUR-VAPES 2 trial. European Journal of Preventive Cardiology 2019;26(Supplement 1):S114.
Chaumont 2018 {published data only}
    1. Chaumont M, Becker B, Zaher W, Culie A, Deprez G, Melot C, et al. Differential Effects of E-Cigarette on Microvascular Endothelial Function, Arterial Stiffness and Oxidative Stress: a Randomized Crossover Trial. Scientific reports 2018;8(1):10378. - PMC - PubMed
Chaumont 2019 {published data only}
    1. Chaumont M, El Channan M, Bernard A, Lesage A, Deprez G, Van Muylem A, et al. Short-term high wattage e-cigarette cessation improves cardiorespiratory outcomes in regular users: a randomized crossover trial. Journal of Hypertension 2019;Conference: 29th European Meeting on Hypertension and Cardiovascular Protection, ESH 2019. Italy. 37(Supplement 1):e8-9.
Chausse 2015 {published data only}
    1. Chausse P, Naughton G, Dutheil F. Electronic cigarettes: the resistance value of the heating filament could be the key to lung toxicity. Chest 2015;148(1):e29-30. - PubMed
Choi 2014 {published data only}
    1. Choi K, Forster JL. Beliefs and experimentation with electronic cigarettes: a prospective analysis among young adults. American Journal of Preventive Medicine 2014;6(2):175-8. - PMC - PubMed
    1. Choi K Forster JL. Authors' Response to: Context on use is needed before public health recommendations are made about e-cigarettes. Americal Journal of Preventive Medicine 2014;46(6):e58-59. - PubMed
Chorti 2012 {published data only}
    1. Chorti M, Poulianiti K, Jamurtas A, Kostikas K, Tzatzarakis M, Vynias D, et al. Effects of active and passive electronic and tobacco cigarette smoking on lung function (P08-02). Toxicology Letters 2012;211:S64.
Collins 2019 {published data only}
    1. Collins SE, Nelson LA, Stanton J, Mayberry N, Ubay T, Taylor EM, et al. Harm reduction treatment for smoking (HaRT-S): findings from a single-arm pilot study with smokers experiencing chronic homelessness. Substance Abuse 2019;40(2):229-39. - PubMed
Cook 2019 {published data only}
    1. Cook R, Davidson P, Martin R. E-cigarettes helped more smokers quit than nicotine replacement therapy. BMJ 2019;365:l2036. - PubMed
Cox 2019a {published data only}
    1. Cox S, Dawkins L, Doshi J, Cameron J. Effects of e-cigarettes versus nicotine replacement therapy on short-term smoking abstinence when delivered at a community pharmacy. Addictive Behaviors Reports 2019;10:100202. - PMC - PubMed
Czogala 2012 {published data only}
    1. Czogala J, Cholewinski M, Kutek A, Zielinska-Danch W. Evaluation of changes in hemodynamic parameters after the use of electronic nicotine delivery systems among regular cigarette smokers. Przeglad Lekarski 2012;69(10):841-5. - PubMed
D'Ruiz 2017 {published data only}
    1. D'Ruiz CD, O'Connell G, Graff DW, Yan XS. Measurement of cardiovascular and pulmonary function endpoints and other physiological effects following partial or complete substitution of cigarettes with electronic cigarettes in adult smokers. Regulatory Toxicology and Pharmacology 2017;87:36-53. - PubMed
Dawkins 2012 {published data only}
    1. Dawkins L, Turner J, Hasna S, Soar K. The electronic-cigarette: effects on desire to smoke, withdrawal symptoms and cognition. Addictive Behaviors 2012;37(8):970-3. - PubMed
Dawkins 2013a {published data only}
    1. Dawkins L, Turner J, Crowe E. Nicotine derived from the electronic cigarette improves time-based prospective memory in abstinent smokers. Psychopharmacology 2013;227(3):377-84. - PubMed
Dawkins 2014 {published data only}
    1. Dawkins L, Corcoran O. Acute electronic cigarette use: nicotine delivery and subjective effects in regular users. Psychopharmacology 2014;231(2):401-7. - PubMed
Douptcheva 2013 {published data only}
    1. Douptcheva N, Gmel G, Studer J, Deline S, Etter JF. Use of electronic cigarettes among young Swiss men. Journal of Epidemiology & Community Health 2013;67(12):1075-6. - PubMed
Dutra 2014 {published data only}
    1. Dutra LM, Glantz SA. Electronic cigarettes and conventional cigarette use among U.S. adolescents: a cross-sectional study. JAMA Pediatrics 2014;168(7):610-7. - PMC - PubMed
Eissenberg 2010 {published data only}
    1. Eissenberg T. Electronic nicotine delivery devices: ineffective nicotine delivery and craving suppression after acute administration. Tobacco Control 2010;19(1):87-8. - PMC - PubMed
Etter 2014 {published data only}
    1. Etter JF, Bullen C. A longitudinal study of electronic cigarette users. Addictive Behaviors 2014;39(2):491-4. - PubMed
Farsalinos 2012 {published data only}
    1. Farsalinos K, Tsiapras D, Kyrzopoulos S, Savvopoulou M, Avramidou E, Vasilopoulou D, et al. Acute effects of using an electronic nicotine-delivery device (e-cigarette) on myocardial function: comparison with the effects of regular cigarettes. European Heart Journal 2012;33:203. - PMC - PubMed
    1. Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, Voudris V. Acute effects of using an electronic nicotine-delivery device (electronic cigarette) on myocardial function: comparison with the effects of regular cigarettes. BMC Cardiovascular Disorders 2014;14:78. - PMC - PubMed
Farsalinos 2013a {published data only}
    1. Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, Voudris V. Evaluating nicotine levels selection and patterns of electronic cigarette use in a group of "vapers" who had achieved complete substitution of smoking. Substance Abuse: Research and Treatment 2013;7:139-46. - PMC - PubMed
Farsalinos 2013b {published data only}
    1. Farsalinos KE, Romagna G, Tsiapras D, Kyrzopoulos S, Spyrou A, Voudris V. Impact of flavour variability on electronic cigarette use experience: an internet survey. International Journal of Environmental Research & Public Health 2013;10(12):7272-82. - PMC - PubMed
Farsalinos 2013c {published data only}
    1. Farsalinos K, Tsiapras D, Kyrzopoulos S, Stefopoulos C, Spyrou A, Tsakalou M, et al. Immediate effects of electronic cigarette use on coronary circulation and blood carboxyhemoglobin levels: comparison with cigarette smoking. European Heart Journal 2013;34(Suppl 1):13.
Farsalinos 2013d {published data only}
    1. Farsalinos K, Tsiapras D, Kyrzopoulos S, Spyrou A, Stefopoulos C, Romagna G, et al. Effects of electronic cigarette use on the elastic properties of the ascending aorta in healthy subjects: comparison with the effects of tobacco cigarettes. European Heart Journal Cardiovascular Imaging 2013;14(Suppl 2):ii203.
Flouris 2012 {published data only}
    1. Flouris AD, Poulianiti KP, Chorti MS, Jamurtas AZ, Kouretas D, Owolabi EO, et al. Acute effects of electronic and tobacco cigarette smoking on complete blood count. Food and Chemical Toxicology 2012;50(10):3600-3. - PubMed
Flouris 2013 {published data only}
    1. Flouris AD, Chorti MS, Poulianiti KP, Jamurtas AZ, Kostikas K, Tzatzarakis MN, et al. Acute impact of active and passive electronic cigarette smoking on serum cotinine and lung function. Inhalation Toxicology 2013;25(2):91-101. - PubMed
Gmel 2016 {published data only}
    1. Gmel G, Baggio S, Mohler-Kuo M, Daeppen JB, Studer J. E-cigarette use in young Swiss men: is vaping an effective way of reducing or quitting smoking? Swiss Medical Weekly 2016;146:w14271. - PubMed
Gottlieb 2019 {published data only}
    1. Gottlieb MA. E-cigarettes versus nicotine-replacement therapy for smoking cessation. New England Journal of Medicine 2019;380(20):1974. - PubMed
Grana 2014b {published data only}
    1. Grana RA, Popova L, Ling PM. A longitudinal analysis of electronic cigarette use and smoking cessation. JAMA Internal Medicine 2014;174(5):812-3. - PMC - PubMed
James 2016 {published data only}
    1. James SA, Meier EM, Wagener TL, Smith KM, Neas BR, Beebe LA. E-Cigarettes for immediate smoking substitution in women diagnosed with cervical dysplasia and associated disorders. International Journal of Environmental Health Research 2016;13(3):E288. [DOI: 10.3390/ijerph13030288] - DOI - PMC - PubMed
    1. NCT01989923. Smoking Cessation in Women With Gynecological Conditions. https://clinicaltrials.gov/ct2/show/NCT01989923 (Accessed 9 September 2022).
Kasza 2013 {published data only}
    1. Kasza KA, Bansal-Travers M, O'Connor RJ, Compton WM, Kettermann A, Borek N, et al. Cigarette smokers' use of unconventional tobacco products and associations with quitting activity: findings from the ITC-4 U.S. cohort. Nicotine & Tobacco Research 2013;16(6):672-81. - PMC - PubMed
Kouretas 2012 {published data only}
    1. Kouretas D, Poulianiti K, Chorti M, Jamurtas A, Kostikas K, Tzatzarakis M, et al. Effects of electronic cigarette and tobacco cigarette smoking on complete blood count (P08-03). Toxicology Letters 2012;211:S64. - PubMed
Kousta 2019 {published data only}
    1. Kousta S. E-cigarettes for smoking cessation. Nature Human Behaviour 2019;3:322. - PubMed
Lechner 2015 {published data only}
    1. Lechner WV, Meier E, Wiener JL, Grant DM, Gilmore J, Judah MR, et al. The comparative efficacy of first- versus second-generation electronic cigarettes in reducing symptoms of nicotine withdrawal. Addiction 2015;110(5):862-7. - PubMed
Lee 2014 {published data only}
    1. Lee S, Grana RA, Glantz SA. Electronic cigarette use among Korean adolescents: a cross-sectional study of market penetration, dual use, and relationship to quit attempts and former smoking. Journal of Adolescent Health 2014;54(6):684-90. - PMC - PubMed
Manzoli 2015 {published data only}
    1. Manzoli L, Flacco ME, Fiore M, La Vecchia C, Marzuillo C, Gualano MR, et al. Electronic cigarettes efficacy and safety at 12 months: cohort study. PLOS One 2015;10(6):e0129443. - PMC - PubMed
    1. Manzoli L, La Vecchia C, Flacco ME, Capasso L, Simonetti V, Boccia S, et al. Multicentric cohort study on the long-term efficacy and safety of electronic cigarettes: study design and methodology. BMC Public Health 2013;13(1):883. - PMC - PubMed
    1. NCT01785537. The efficacy and safety of electronic cigarettes: a 5-year follow-up study. clinicaltrials.gov/ct2/show/NCT01785537 (first received 7 February 2013).
Marini 2014 {published data only}
    1. Marini S, Buonanno G, Stabile L, Ficco G. Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide. Toxicology and Applied Pharmacology 2014;278(1):9-15. - PubMed
Mayor 2019 {published data only}
    1. Mayor S. E-cigarettes help twice as many smokers quit as nicotine replacement therapy, trial finds. BMJ 2019;364:l473. - PubMed
Miura 2015 {published data only}
    1. Miura N, Yuki D, Minami N, Kakehi A, Futama Y. A study to investigate changes in the levels of biomarkers of exposure to selected cigarette smoke constituents in Japanese adult male smokers who switched to a non-combustion inhaler type of tobacco product. Regulatory Toxicology and Pharmacology 2015;71(3):498-506. - PubMed
NCT02487953 {published data only}
    1. NCT02487953. Electronic Nicotine Delivery Systems (ENDS) as a smoking cessation treatment. clinicaltrials.gov/ct2/show/NCT02487953 (first received 2 July 2015).
NCT02527980 {published data only}
    1. NCT02527980. E-cigarettes: dynamic patterns of use and health effects. clinicaltrials.gov/show/NCT02527980 (first received August 19 2015).
NCT03036644 {published data only}
    1. NCT03036644. Comparison of electronic cigarettes and tobacco cigarettes on cardiovascular function and oxidative stress. clinicaltrials.gov/ct2/show/NCT03036644 (first received 30 January 2017).
NCT03575468 {published data only}
    1. NCT03575468. Enhanced E-cigarette Coaching Intervention for Dual Users of Cigarettes and E-cigarettes. https://clinicaltrials.gov/ct2/show/NCT03575468 (first received 2 July 2018).
NCT04107779 {published data only}
    1. NCT04107779. Changes in biomarkers of cigarette smoke exposure after switching either exclusively or partly to JUUL ENDS. clinicaltrials.gov/ct2/show/NCT04107779 (first received 27 September 2019).
Nolan 2016 {published data only}
    1. Nolan M, Leischow S, Croghan I, Kadimpati S, Hanson A, Schroeder D, et al. Feasibility of electronic nicotine delivery systems in surgical patients. Nicotine & Tobacco Research 2016;18(8):1757-62. - PMC - PubMed
NTR6224 {published data only}
    1. NTR6224. Electronic cigarettes: an intervention for dual-users. www.who.int/trialsearch/Trial2.aspx?TrialID=NTR6224 (first received 12 January 2017).
Palamidas 2014 {published data only}
    1. Palamidas A, Gennimata SA, Kaltsakas G, Tsikrika S, Vakali S, Gratziou C, et al. Acute effect of an e-cigarette with and without nicotine on lung function. Tobacco Induced Diseases 2014;12(Suppl 1):A34.
Pearson 2012 {published data only}
    1. Pearson JL, Richardson A, Niaura RS, Vallone DM, Abrams DB. E-cigarette awareness, use, and harm perceptions in US adults. American Journal of Public Health 2012;102(9):1758-66. - PMC - PubMed
Pokhrel 2013 {published data only}
    1. Pokhrel P, Fagan P, Little MA, Kawamoto CT, Herzog TA. Smokers who try e-cigarettes to quit smoking: findings from a multiethnic study in Hawaii. American Journal of Public Health 2013;103(9):e57-62. - PMC - PubMed
Polosa 2014a {published data only}
    1. Polosa R, Morjaria J, Caponnetto P, Caruso M, Strano S, Battaglia E, et al. Effect of smoking abstinence and reduction in asthmatic smokers switching to electronic cigarettes: evidence for harm reversal. International Journal of Environmental Research & Public Health 2014;11(5):4965-77. - PMC - PubMed
Popova 2013 {published data only}
    1. Ling PM, Popova L. Novel "Tobacco" product use and association with smoking cessation: a national study. Journal of General Internal Medicine 2012;27(2 Suppl):S254.
    1. Popova L, Ling PM. Alternative tobacco product use and smoking cessation: a national study. American Journal of Public Health 2013;103(5):923-30. - PMC - PubMed
Prochaska 2014 {published data only}
    1. Prochaska JJ, Grana RA. E-cigarette use among smokers with serious mental illness. PLOS One 2014;9(11):e113013. - PMC - PubMed
Russo 2018 {published data only}
    1. Russo C, Cibella F, Mondati E, Caponnetto P, Frazzetto E, Caruso M, et al. Lack of substantial post-cessation weight increase in electronic cigarettes users. International Journal of Environmental Research and Public Health 2018;15(4):581. - PMC - PubMed
Schober 2014 {published data only}
    1. Schober W, Szendrei K, Matzen W, Osiander-Fuchs H, Heitmann D, Schettgen T, et al. Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers. International Journal of Hygiene and Environmental Health 2014;217(6):628-37. - PubMed
Siegel 2011 {published data only}
    1. Siegel MB, Tanwar KL, Wood KS. Electronic cigarettes as a smoking-cessation tool: results from an online survey. American Journal of Preventive Medicine 2011;40(4):472-5. - PubMed
Song 2020 {published data only}
    1. NCT02596685. Effects of Electronic Cigarette Use on the Lungs. https://www.clinicaltrials.gov/ct2/show/NCT02596685 (Accessed 8 September 2022).
    1. Song M-A, Reisinger SA, Freudenheim JL, Brasky TM, Mathe EA, McElroy JP, et al. Effects of electronic cigarette constituents on the human lung: a pilot clinical trial. Cancer Prevention Research 2020;13(2):145-52. - PMC - PubMed
St.Helen 2020 {published data only}
    1. StHelen G, Nardone N, Addo N, Dempsey D, Havel C, Jacob P, et al. Differences in nicotine intake and effects from electronic and combustible cigarettes among dual users. Addiction 2020;115(4):757-67. - PMC - PubMed
Stein 2019 {published data only}
    1. Stein JH, Korcarz CE. E-cigarettes versus nicotine-replacement therapy for smoking cessation. New England Journal of Medicine 2019;380(20):1973-4. - PubMed
Stower 2019 {published data only}
    1. Stower H. E-cigarettes to help smoking cessation. Nature Medicine 2019;25(3):358. - PubMed
Tsikrika 2014 {published data only}
    1. Tsikrika S, Vakali S, Gennimata SA, Palamidas A, Kaltsakas G, Koulouris N, et al. Short term use of an e-cig: influence on clinical symptoms, vital signs and eCO levels. Tobacco Induced Diseases 2014;12(Suppl 1):A30.
Tucker 2018 {published data only}
    1. Tucker MR, Laugesen M, Bullen C, Grace RC. Predicting short-term uptake of electronic cigarettes: effects of nicotine, subjective effects, and simulated demand. Nicotine & Tobacco Research 2018;20(10):1265-71. - PubMed
Tzatzarakis 2013 {published data only}
    1. Tzatzarakis MN, Tsitoglou KI, Chorti MS, Poulianiti KP, Jamurtas AZ, Koutedakis Y, et al. Acute and short term impact of active and passive tobacco and electronic cigarette smoking on inflammatory markers. Toxicology Letters 2013;221(Suppl):S86.
Vakali 2014 {published data only}
    1. Vakali S, Tsikrika S, Gennimata SA, Kaltsakas G, Palamidas A, Koulouris N, et al. E-cigarette acute effect on symptoms and airway inflammation: comparison of nicotine with a non-nicotine cigarette. Tobacco Induced Diseases 2014;12(Suppl 1):A35.
Valentine 2016 {published data only}
    1. Valentine GW, Jatlow PI, Coffman M, Nadim H, Gueorguieva R, Sofuoglu M. The effects of alcohol-containing e-cigarettes on young adult smokers. Drug and Alcohol Dependence 2016;159:272-6. - PMC - PubMed
Van Heel 2017 {published data only}
    1. Van Heel M, Van Gucht D, Vanbrabant K, Baeyens F. The importance of conditioned stimuli in cigarette and e-cigarette craving reduction by e-cigarettes. International Journal of Environmental Research and Public Health 2017;14(2):193. - PMC - PubMed
Vansickel 2010 {published data only}
    1. Vansickel AR, Cobb CO, Weaver MF, Eissenberg TE. A clinical laboratory model for evaluating the acute effects of electronic "cigarettes": nicotine delivery profile and cardiovascular and subjective effects. Cancer Epidemiology, Biomarkers & Prevention 2010;19(8):1945-53. - PMC - PubMed
Vansickel 2012 {published data only}
    1. Vansickel AR, Weaver MF, Eissenberg T. Clinical laboratory assessment of the abuse liability of an electronic cigarette. Addiction 2012;107(8):1493-500. - PMC - PubMed
Vansickel 2013 {published data only}
    1. Vansickel AR, Eissenberg T. Electronic cigarettes: effective nicotine delivery after acute administration. Nicotine & Tobacco Research 2013;15(1):267-70. - PMC - PubMed
Vardavas 2012 {published data only}
    1. Vardavas CI, Anagnostopoulos N, Kougias M, Evangelopoulou V, Connolly GN, Behrakis PK. Short-term pulmonary effects of using an electronic cigarette: Impact on respiratory flow resistance, impedance, and exhaled nitric oxide. Chest 2012;141(6):1400-6. - PubMed
Vickerman 2013 {published data only}
    1. Vickerman KA, Carpenter KM, Altman T, Nash CM, Zbikowski SM. Use of electronic cigarettes among state tobacco cessation quitline callers. Nicotine & Tobacco Research 2013;15(10):1787-91. - PubMed
Voos 2019 {published data only}
    1. Voos N, Kaiser L, Mahoney MC, Bradizza CM, Kozlowski LT, Benowitz NL, et al. Randomized within-subject trial to evaluate smokers' initial perceptions, subjective effects and nicotine delivery across six vaporized nicotine products. Addiction 2019;114(7):1236-48. - PMC - PubMed
Voos 2020 {published data only}
    1. Voos N, Smith D, Kaiser L, Mahoney MC, Bradizza CM, Kozlowski LT, et al. Effect of e-cigarette flavors on nicotine delivery and puffing topography: results from a randomized clinical trial of daily smokers. Psychopharmacology 2020;237(2):491-502. - PMC - PubMed
Wagener 2014 {published data only}
    1. Wagener TL, Meier E, Hale JJ, Oliver ER, Warner ML, Driskill LM, et al. Pilot investigation of changes in readiness and confidence to quit smoking after e-cigarette experimentation and 1 week of use. Nicotine & Tobacco Research 2014;16(1):108-14. - PubMed
Walele 2016a {published data only}
    1. Walele T, Sharma G, Savioz R, Martin C, Williams J. A randomised, crossover study on an electronic vapour product, a nicotine inhalator and a conventional cigarette. Part A: Pharmacokinetics. Regulatory Toxicity 2016;74:187-92. - PubMed
Walele 2016b {published data only}
    1. Walele T, Sharma G, Savioz R, Martin C, Williams J. A randomised, crossover study on an electronic vapour product, a nicotine inhalator and a conventional cigarette. Part B: Safety and subjective effects. Regulatory Toxicity 2016;74:193-9. - PubMed
Yan 2015 {published data only}
    1. Yan XS, D'Ruiz C. Effects of using electronic cigarettes on nicotine delivery and cardiovascular function in comparison with regular cigarettes. Regulatory Toxicology and Pharmacology 2015;71(1):24-34. - PubMed
Yuki 2017 {published data only}
    1. Yuki D, Sakaguchi C, Kikuchi A, Futamura Y. Pharmacokinetics of nicotine following the controlled use of a prototype novel tobacco vapor product. Regulatory Toxicology and Pharmacology 2017;87(2):30-5. - PubMed
Zhang 2019 {published data only}
    1. Zhang Y, Upson D. E-cigarettes versus nicotine-replacement therapy for smoking cessation. New England Journal of Medicine 2019;380(20):1973. - PubMed

References to ongoing studies

ACTRN12617001324303 {published data only}
    1. ACTRN12617001324303. Vaporised nicotine products versus oral forms of nicotine replacement therapy (NRT) products for tobacco smoking cessation among low-socioeconomic status (low-SES) smokers. anzctr.org.au/ACTRN12617001324303.aspx (first received 15 September 2017).
ACTRN12619001787178 {published data only}
    1. ACTRN12619001787178. Project NEAT: nicotinE as treatment for tobacco smoking following discharge from residential withdrawal services. www.who.int/trialsearch/Trial2.aspx?TrialID=ACTRN12619001787178 (first received 18 November 2019).
ACTRN12621000076875 {published data only}
    1. ACTRN12621000076875. Vaporised nicotine products versus nicotine replacement therapy for tobacco smoking cessation among low-socioeconomic status smokers: a randomised controlled trial. trialsearch.who.int/Trial2.aspx?TrialID=ACTRN12621000076875 (first received January 29 2021). [CENTRAL: www.cochranelibrary.com/es/central/doi/10.1002/central/CN-02240824/full]
ACTRN12621000148875 {published data only}
    1. ACTRN12621000148875. HARMONY: harm reduction for opiates, nicotine and you. www.who.int/trialsearch/Trial2.aspx?TrialID=ACTRN12621000148875 (first received February 12 2021). [CENTRAL: www.cochranelibrary.com/central/doi/10.1002/central/CN-02240640/full]
Berlin 2019 {published data only}
    1. Berlin I, Dautzenberg B, Lehmann B, Palmyre J, Liégey E, De Rycke Y, et al. Randomised, placebo-controlled, double-blind, double-dummy, multicentre trial comparing electronic cigarettes with nicotine to varenicline and to electronic cigarettes without nicotine: the ECSMOKE trial protocol. BMJ Open 2019;9(5):e028832. - PMC - PubMed
    1. NCT03630614. Randomized trial of electronic cigarettes with or without nicotine in smoking cessation (ECSMOKE). clinicaltrials.gov/ct2/show/NCT03630614 (first received 15 August 2018).
Caponnetto 2014 {published data only}
    1. Caponnetto P, Polosa R, Auditore R, Minutolo G, Signorelli M, Maglia M, et al. Smoking cessation and reduction in schizophrenia (SCARIS) with e-cigarette: study protocol for a randomized control trial. Trials [electronic resource] 2014;15:88. - PMC - PubMed
    1. NCT01979796. Antismoking effects of electronic cigarettes in subjects with schizophrenia and their potential influence on cognitive functioning: design of a randomized trial. Smoking Cessation And Reduction In Schizophrenia (The SCARIS Study). clinicaltrials.gov/show/NCT01979796 (accessed 16 July 2014).
Caponnetto 2020 {published data only}
    1. Caponnetto P, Caruso M, Maglia M, Emma R, Saitta D, Busa B, et al. Non-inferiority trial comparing cigarette consumption, adoption rates, acceptability, tolerability, and tobacco harm reduction potential in smokers switching to Heated Tobacco Products or electronic cigarettes: study protocol for a randomized controlled trial. Contemporary Clinical Trials Communications 2020;8:17. - PMC - PubMed
    1. NCT03569748 . Heated tobacco products vs electronic cigarettes. clinicaltrials.gov/ct2/show/NCT03569748 (first received June 25 2021).
Cox 2022 {published data only}
    1. Cox S, Bauld L, Brown R, Carlise M, Ford A, Hajek P. Evaluating the effectiveness of e-cigarettes compared with usual care for smoking cessation when offered to smokers at homeless centres: protocol for a multi-centre cluster-randomized controlled trial in Great Britain. Addiction 2022;117(7):2096-2107. [DOI: ] - PMC - PubMed
    1. ISRCTN18566874. E-cigarettes vs usual care for smoking cessation when offered at homeless centres. isrctn.com/ISRCTN18566874 (Accessed 8 September 2022) (first received October 12 2021). [DOI: ]
El‐Khoury  2021 {published data only}
    1. El-Khoury F, El Aarbaoui T, Heron M, Hejblum G, Metadieu B, Le Faou AL, et al. Smoking cessation using preference-based tools among socially disadvantaged smokers: study protocol for a pragmatic, multicentre randomised controlled trial. BMJ Open 2021;11(6):e048859. [DOI: 10.1136/bmjopen-2021-048859] - DOI - PMC - PubMed
    1. Heron M, Le Faou AL, Ibanez G, Metadieu B, Melchior M, El-Khoury L, et al . Smoking cessation using preference-based tools: a mixed method pilot study of a novel intervention among smokers with low socioeconomic position.. Addiction Science & Clinical Practice 2021;16(1):43. [DOI: ] - PMC - PubMed
    1. NCT04654585. Preference-based tools for smoking cessation among disadvantaged smokers, a pragmatic randomised controlled trial [Sevrage tabagique à l'aide des outils dédiés selon la préférence, un essai randomisé contrôlé pragmatique]. clinicaltrials.gov/ct2/show/NCT04654585 (first received December 4 2020).
Elling 2021 {published data only}
    1. Elling JM, Crutzen R, Talhout R, DeVries H. Effects of providing tailored information about e-cigarettes in a web-based smoking cessation intervention: protocol for a randomised control trial ,. Journal of Medical Internet Research, Research Protocols 2021;10(5):e27088. [DOI: 10.2196/27088] - DOI - PMC - PubMed
ISRCTN13158982 {published data only}
    1. ISRCTN13158982. Enhancing dental health advice. isrctn.com/ISRCTN13158982 (first received May 10 2022). [DOI: ]
ISRCTN17691451 {published data only}
    1. ISRCTN17691451. ESCAPE: E-cigarettes for smoking cessation and reduction in people with mental illness [E-cigarettes for smoking cessation and reduction in people with mental illness - a randomised pilot feasibility trial]. isrctn.com/ISRCTN17691451 (first received September 30 2021). [DOI: ]
ISRCTN61193406 {published data only}
    1. ISRCTN61193406. Do e-cigarettes help smokers quit when not accompanied by intensive behavioural support? who.int/trialsearch/Trial2.aspx?TrialID=ISRCTN61193406 2020 (first received 11 August 2020).
Klonizakis 2017 {published data only}
    1. Jones G, McIntosh E, Brose LS, Klonizakis M. Participant experiences of a quit smoking attempt through either Nicotine Replacement Therapy (NRT) methods or the use of an e-cigarette. Journal of Addiction Medicine 2022;16(3):272-7. - PubMed
    1. Klonizakis M, Crank H, Gumber A, Brose LS. Smokers making a quit attempt using e-cigarettes with or without nicotine or prescription nicotine replacement therapy: impact on cardiovascular function (ISME-NRT) - a study protocol. BMC Public Health 2017;17(1):293. - PMC - PubMed
    1. Klonizakis M, Gumber A, McIntosh E, Brose LS. Short-term cardiovascular effects of e-cigarettes in adults making a stop-smoking attempt: a randomized controlled trial. Biology 2021;10(11):1208. [DOI: 10.3390/biology10111208] - DOI - PMC - PubMed
    1. NCT03061253. E-cigarettes and cardiovascular function (ISME-NRT). clinicaltrials.gov/ct2/show/NCT03061253 (first received 23 February 2017).
Krysinski 2021 {published data only}
    1. Krysinski A, Russo C, John S, Belsey JD, Campagna D, Caponnetto P, et al. International randomised controlled trial evaluating metabolic syndrome in type 2 diabetic cigarette smokers following switching to combustion-free nicotine delivery systems: the DIASMOKE protocol. BMJ Open 2021;11(4):e045396. [DOI: 10.1136/bmjopen-2020-045396] - DOI - PMC - PubMed
    1. NCT04231838. Metabolic syndrome in diabetic smokers using cigarettes & combustion-free nicotine delivery systems (DIASMOKE). clinicaltrials.gov/ct2/show/NCT04231838 (first received January 18 2020).
Murray 2020 {published data only}
    1. Murray RL, Brain K, Britton J, Quinn-Scoggins HD, Lewis S, McCutchan GM, et al. Yorkshire Enhanced Stop Smoking (YESS) study: a protocol for a randomised controlled trial to evaluate the effect of adding a personalised smoking cessation intervention to a lung cancer screening programme. BMJ Open 2020;10(9):e037086. - PMC - PubMed
NCT01842828 {published data only}
    1. NCT01842828. E-cigarettes as an addition to multi-component treatment for tobacco dependence: a pilot study. clinicaltrials.gov/show/NCT01842828 (first received 16 July 2014).
NCT01989923 {published data only}
    1. NCT01989923. Immediate smoking cessation for patients at risk for cervical dysplasia, cervical cancer and lower genital tract dysplasia and cancer - a feasibility study comparing nicotine replacement therapy with the electronic nicotine delivery system. clinicaltrials.gov/show/NCT01989923 (first received November 21 2013).
NCT02004171 {published data only}
    1. NCT02004171. Electronic nicotine delivery devices (ENDDs) or nicotine inhaler for smoking cessation. clinicaltrials.gov/show/NCT02004171 (first received December 2013).
NCT02124187 {published data only}
    1. NCT02124187. Smoking cessation and reduction in depression (SCARID). clinicaltrials.gov/show/NCT02124187 (first received April 28 2014).
NCT02398487 {published data only}
    1. NCT02398487. Personal Vaporizer vs Cigalike (VAPECIG 2) [Head-to-head comparison of personal vaporizers versus cigalike: prospective 6-month randomized control design study]. clinicaltrials.gov/show/NCT02398487 (first received March 25 2015).
NCT02590393 {published data only}
    1. NCT02590393. The role of nicotine and non-nicotine alkaloids in e-cigarette use and dependence. clinicaltrials.gov/show/NCT02590393 (first received 17 February 2016).
NCT03113136 {published data only}
    1. NCT03113136. Examination of low wattage and high wattage e-cigarettes (SWITCH). clinicaltrials.gov/ct2/show/study/NCT03113136 (first received April 13 2017).
NCT03249428 {published data only}
    1. NCT03249428. E-cigarette inner city RCT [A community-based participatory action pragmatic randomized controlled trial using electronic-cigarette for tobacco dependence in the inner city population with a holistic approach]. clinicaltrials.gov/ct2/show/NCT03249428 (first received August 15 2017).
NCT03277495 {published data only}
    1. NCT03277495. Predictors and consequences of combustible cigarette smokers' switch to standardized research e-cigarettes. clinicaltrials.gov/ct2/show/NCT03277495 (first received September 11 2017).
NCT03589989 {published data only}
    1. NCT03589989. The ESTxENDS trial - electronic nicotine delivery systems (ENDS/vaporizer/e-cigarette) as an aid for smoking cessation (ESTxENDS). clinicaltrials.gov/ct2/show/record/NCT03589989 (first received 18 July 2018).
    1. NCT03603340. The ESTxENDS trial - effects of using Electronic Nicotine Delivery Systems (ENDS/Vaporizer/E-cig) on depression (ESTxENDS). clinicaltrials.gov/show/NCT03603340 (first received 27 July 2018).
    1. NCT03603353. The ESTxENDS trial - effects of using Electronic Nicotine Delivery Systems (ENDS/Vaporizer/E-cig) on sleep quality (ESTxENDS). clinicaltrials.gov/show/NCT03603353 (first received 27 July 2018).
    1. NCT03612336. The ESTxENDS trial - metabolic effects of using Electronic Nicotine Delivery Systems (ENDS/Vaporizer/E-cig) (ESTxENDS). clinicaltrials.gov/show/NCT03612336 (first received 2 August 2018).
    1. NCT03612375. ESTxENDS trial - oxidative stress induced by Electronic Nicotine Delivery Systems (ENDS/Vaporizer/E-cig) measured in urine (ESTxENDS). clinicaltrials.gov/show/NCT03612375 (first received 2 August 2018).
NCT03625986 {published data only}
    1. NCT03625986. Does switching to nicotine containing electronic cigarettes reduce health risk markers. clinicaltrials.gov/ct2/show/NCT03625986 (first received August 10 2018).
NCT03700112 {published data only}
    1. NCT03700112. Clinical study comparing 7 ENDS products and 1 combustible cigarette using 2 delivery methods. clinicaltrials.gov/ct2/show/NCT03700112 (first received 7 December 2018).
NCT03962660 {published data only}
    1. NCT03962660. Harm Reduction for Tobacco Smoking with support of Tobacco-Replacing Electronic Nicotine Delivery Systems (HaRTS-TRENDS). clinicaltrials.gov/ct2/show/record/NCT03962660 (first received 24 May 2019).
NCT04003805 {published data only}
    1. NCT04003805. Biomarkers of exposure and effect in standardized research e-cigarette (SREC) users. clinicaltrials.gov/ct2/show/NCT04003805 (first received July 1 2019).
NCT04058717 {published data only}
    1. NCT04058717. Low nicotine cigarettes plus electronic cigarettes [Randomized trial of low nicotine cigarettes plus electronic cigarettes in smokers]. clinicaltrials.gov/ct2/show/NCT04058717 (first received August 15 2019).
NCT04063267 {published data only}
    1. NCT04063267. Electronic cigarettes as a harm reduction strategy in individuals with substance use disorder. clinicaltrials.gov/ct2/show/NCT04063267 (first received 21 August 2019).
NCT04084210 {published data only}
    1. NCT04084210. Impact of alternative nicotine-delivery products on combustible cigarette use [Understanding the real-world impact of the use of three alternate nicotine-delivery products on combustible cigarette use]. clinicaltrials.gov/ct2/show/NCT04084210 (first received September 10 2019).
NCT04090879 {published data only}
    1. DeAtley T, Harrison A, Camacho B, Cassidy R, Kuo C, Higgins ST, et al. Subjective experiences, contexts, and risk perceptions of very low content cigarettes and electronic cigarettes among people with affective disorders who smoke. In: Society for Research on Nicotine and Tobacco Annual Meeting, 2022 March; Baltimore USA. 2022.
    1. NCT04090879. Low nicotine content cigarettes in vulnerable populations: affective disorders. clinicaltrials.gov/ct2/show/NCT04090879 (first received September 16 2019).
NCT04092101 {published data only}
    1. NCT04092101 . Low nicotine content cigarettes in vulnerable populations: opioid use disorder. clinicaltrials.gov/ct2/show/NCT04092101 (first received September 17 2019).
NCT04092387 {published data only}
    1. NCT04092387. Low nicotine content cigarettes in vulnerable populations: women of reproductive age. clinicaltrials.gov/ct2/show/NCT04092387 (first received September 17 2019).
NCT04218708 {published data only}
    1. NCT04218708. Electronic cigarettes as a harm reduction strategy among people living with HIV/AIDS. clinicaltrials.gov/ct2/show/NCT04218708 (first received January 6 2020).
NCT04238832 {published data only}
    1. NCT04238832. Salt-based e-cigarette and IQOS Study. clinicaltrials.gov/show/NCT04238832 (first received 18 January 2020).
NCT04452175 {published data only}
    1. NCT04452175. Cigarette consumption after switchinG to high or low nicotine strENght E-cigaretteS In Smokers With Schizophrenia (GENESIS). clinicaltrials.gov/show/NCT04452175 (first received 30 June 2020).
NCT04465318 {published data only}
    1. NCT04465318. Electronic cigarettes as a harm reduction strategy among patients with COPD. clinicaltrials.gov/ct2/show/NCT04465318 (first received July 10 2020).
    1. Stevens ER, Lei L, Cleland CM, Berger KM, Sherman SE, Vojjala M. Electronic cigarettes as a harm reduction strategy among patients with COPD: protocol for an open-label two arm randomized controlled pilot trial. Addiction Science & Clinical Practice 2022;17(1):2. [DOI: 10.1186/s13722-021-00284-0] - DOI - PMC - PubMed
NCT04521647 {published data only}
    1. NCT04521647. Effects of menthol in e-cigarettes on smoking behaviors. clinicaltrials.gov/ct2/show/NCT04521647 (first received August 20 2020).
NCT04649645 {published data only}
    1. NCT04649645. International randomized controlled trial evaluating changes in oral health in smokers after switching to combustion-free nicotine delivery systems. clinicaltrials.gov/show/NCT04649645 (first received 02 December 2020).
NCT04708106 {published data only}
    1. NCT04708106. Characterization of product use in smokers switching from cigarettes to a RELX electronic nicotine delivery system. clinicaltrials.gov/ct2/show/NCT04708106 (first posted 13 January 2021).
NCT04709471 {published data only}
    1. NCT04709471. E-cigarette nicotine study. clinicaltrials.gov/ct2/show/NCT04709471 (first posted 14 January 2021).
NCT04725656 {published data only}
    1. NCT04725656. Concentration Impact Nicotine Salt (CINS). clinicaltrials.gov/ct2/show/NCT04725656 (first posted January 27 2021).
NCT04854616 {published data only}
    1. NCT04854616. Cessation of Smoking Trial in the Emergency Department (CoSTED). clinicaltrials.gov/ct2/show/NCT04854616 (date first received April 22 2021).
NCT04946825 {published data only}
    1. NCT04946825. Quit smoking study for people who use e-cigarettes [ A randomized controlled trial of smoking cessation treatment for young adult dual users of combustible and electronic cigarettes]. clinicaltrials.gov/ct2/show/NCT04946825 (first received July 1 2021).
NCT05023096 {published data only}
    1. NCT05023096. Potential effects of electronic nicotine delivery system flavor regulations on African American menthol smokers (RVA flavors) [Effects of electronic nicotine delivery system flavor regulations on tobacco behavior, toxicity, and abuse liability among African American menthol smokers]. clinicaltrials.gov/ct2/show/NCT05023096 (first received August 26 2021).
NCT05144542 {published data only}
    1. NCT05144542. Risk and benefits of electronic cigarettes to older smokers at high risk for lung cancer. www.clinicaltrials.gov/ct2/show/NCT05144542 (first received December 3 2021).
NCT05199480 {published data only}
    1. NCT05199480. Understanding the impact of cartridge-based electronic cigarettes and generated aerosols on cardiopulmonary health. clinicaltrials.gov/ct2/show/NCT05199480 (first received January 20 2022).
NCT05205811 {published data only}
    1. NCT05205811. The effects of combination zonisamide and bupropion on switching to an electronic cigarette [A randomized controlled trial to determine the effects of combination zonisamide and bupropion on switching to an electronic cigarette]. clinicaltrials.gov/ct2/show/NCT05205811 (first received January 25 2022).
NCT05206435 {published data only}
    1. NCT05206435. Methadone-maintained smokers switching to e-cigarettes (SHINE). clinicaltrials.gov/ct2/show/NCT05206435 (first received January 25 2022).
NCT05257629 {published data only}
    1. NCT05257629. Aggressive smoking cessation therapy post-acute coronary syndrome (ASAP) trial. www.clinicaltrials.gov/ct2/show/NCT05257629 (first received February 25 2022).
NCT05278065 {published data only}
    1. NCT05278065. E-cigarettes for harm reduction in adult with asthma (SWAP) [Complimentary electronic cigarettes for harm reduction among adult smokers with asthma]. clinicaltrials.gov/ct2/show/NCT05278065 (first received March 14 2022).
NCT05311085 {published data only}
    1. NCT05311085. Cytisine and e-cigarettes with supportive text-messaging for smoking cessation (Cess@Tion). clinicaltrials.gov/ct2/show/NCT05311085 (first received April 5 2022).
NCT05327439 {published data only}
    1. NCT05327439. Using alternative nicotine delivery systems (ANDS) to reduce harm for low SES cigarette smokers (Tri-PEC study). clinicaltrials.gov/ct2/show/NCT05327439 (first received April 14 2022).

Additional references

Akiyama 2021
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Amato 2020
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ASH 2019
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ASH 2022
    1. Action on Smoking and Health. Use of e-cigarettes (vapes) among adults in Great Britain. ash.org.uk/resources/view/use-of-e-cigarettes-among-adults-in-great-brit... (accessed 23 September 2022).
Balfour 2004
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Banks 2022
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Barbeau 2013
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Barrett 2010
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Benowitz 2010
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Besaratinia 2019
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Bjurlin 2021
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