Switching from cigarettes to electronic nicotine delivery system: rapid systematic review and meta-analysis and economic aspects

Agustín Ciapponi Federico Rodríguez Cairoli Germán Solioz Carlos Rojas-Roque Akram Hernández-Vásquez Alfredo Palacios Ariel Bardach About the authors

ABSTRACT

Objectives.

To assess how and in what extent the electronic nicotine delivery systems (ENDS) use substituted the consumption of traditional combustible cigarettes (c-cigarettes, c-cig).

Materials and Methods.

We performed a systematic review of the literature up to August 2019 in scientific databases. Primary outcomes were proportion of complete or partial substitution of conventional to electronic cigarettes and related economic aspects. Secondary outcomes were odds ratio of substitution and country-wise time trends.

Results.

We retrieved 3,628 references and included 49 studies, providing economic and epidemiological data. Economic studies of cross-price elasticity showed that combustible cigarettes are partially substitutable for electronic cigarettes. Most studies reported that electronic cigarettes consumption prevalence increased over time. Three studies reported a significant reduction of combustible cigarettes consumed per day among dual users (combustible- plus electronic- cigarettes users) versus combustible-cigarettes users. The pooled adjusted odds ratio of quitting combustible cigarettes among electronic cigarettes users versus never or past electronic cigarettes (e-cigarettes, e-cig) users was 1.19 (95% confidence interval 1.09 to 1.30; heterogeneity score 0%). Longitudinal studies showed globally a growing prevalence of electronic cigarettes use, mainly in adolescents. A negative relationship between consumption and price increase of electronic and combustible cigarettes was found.

Conclusion.

The chance of quitting smoking combustible cigarettes among current electronic nicotine delivery systems users was increased with respect to never- or past- electronic nicotine delivery systems users. Economic studies reported that electronic cigarette is partially substitutable for combustible cigarettes.

Keywords:
Electronic Nicotine Delivery Systems; Nicotine; Tobacco Use Disorder; Cigarette Smoking; E-Cigarette Vapor; Systematic Review; Meta-Analysis

INTRODUCTION

Smoking is the second leading risk factor for disability, behind only hypertension 11. Stanaway JD, Afshin A, Gakidou E. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: A systematic analysis for the Global Burden of Disease Stu. Lancet. 2018:1923-1994. doi: 10.1016/S0140-6736(18)32225-6.
https://doi.org/10.1016/S0140-6736(18)32...
. Although its global prevalence has declined over the past fifty years, smoking is estimated to be responsible for approximately seven million deaths each year and about 200 million disability-adjusted life years (DALYs). Exposure to smoking may be higher in high-income countries, although nearly 80% of traditional tobacco users live in low-income countries 11. Stanaway JD, Afshin A, Gakidou E. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: A systematic analysis for the Global Burden of Disease Stu. Lancet. 2018:1923-1994. doi: 10.1016/S0140-6736(18)32225-6.
https://doi.org/10.1016/S0140-6736(18)32...

2. Metrics I of H. Global Burden of Disease Compare I VIZ Hub. 2019. Disponible en: http://ihmeuw.org/4pgv. Published 2017.
http://ihmeuw.org/4pgv. Published 2017...
-33. American Cancer Society. The Cancer Atlas. Disponible en: http://canceratlas.cancer.org/risk-factors/risks-of-tobacco/. Published 2019.
http://canceratlas.cancer.org/risk-facto...
.

The World Health Organization (WHO) launched the Framework Convention on Tobacco Control (FCTC) in 2003, setting a milestone for public health promotion 44. FCTC adopted by the C of the P to the W. WHO Framework Convention on Tobacco Control. Disponible en: https://www.who.int/fctc/text_download/en/. Published 2003.
https://www.who.int/fctc/text_download/e...
. The better cost-effective strategies to combat the global tobacco epidemic were identified in the Centers for Disease Control and Prevention (CDC) MPOWER document 55. Organization WH. The MPOWER Measures. World Health Organization. https://www.who.int/tobacco/mpower/package/es/. Published2008.
https://www.who.int/tobacco/mpower/packa...
. Also, in 2009, the implementation of the Global Adult Tobacco Survey (GAS) started, with the objective of describing smoking behavior with a standard questionnaire for all countries, and indirectly measuring the impact of control measures and public policies 66. Asma S, Mackay J, Song SY, Zhao L, Morton J, Palipudi KM, et al. Global Adults Tobacco Survey. The GATS Atlas. Centers For Disease Control and Prevention Foundation. http://gatsatlas.org/. Published 2015.
http://gatsatlas.org/...
.

The addictive property of nicotine is the key factor used by the tobacco industry to promote the consumption of its products 77. Organization WH. WHO Report On The Global Tobacco Epidemic 2019. World Health Organization. https://www.who.int/tobacco/global_report/en/. Published 2019.
https://www.who.int/tobacco/global_repor...
,88. Malone RE. Tobacco industry shoving its snout under the UN tent flap. Tob Control. 2019;28(5):479 LP - 480. doi: 10.1136/tobaccocontrol-2019-055309.
https://doi.org/10.1136/tobaccocontrol-2...
. By using filters and modifying tar levels, the tobacco industry attempted to argue that these cigarettes were “healthier”; however, studies failed to demonstrate these benefits 99. Frieden TR, Jaffe HW, Richards CL, Iademarco MF. E-Cigarette Use Among Youth and Young Adults. A Report of the Surgeon General. Mmwr.. Electronic nicotine delivery systems (ENDS) are battery-operated devices for inhaling or “vaping” a flavored solution containing a specific concentration of nicotine. The most common types of ENDS are the electronic cigarette, electronic hookah, or vaporizer pens, as nicotine delivery options promoted by their manufacturers as “healthier” replacements for conventional cigarettes and which in recent years have become a disruptive technology in nicotine consumption 1010. Howard K Koh, Clifford E Douglas. The San Francisco Ban and the Future of e-Cigarettes. JAMA Forum. https://newsatjama.jama.com/2019/09/11/jama-forum-the-san-franciscoban-and-the-future-of-e-cigarettes/. Published 2019.
https://newsatjama.jama.com/2019/09/11/j...
. The growth in the use of ENDS has been significant, mainly in the young population, generating a partial replacement or switch to traditional tobacco 1010. Howard K Koh, Clifford E Douglas. The San Francisco Ban and the Future of e-Cigarettes. JAMA Forum. https://newsatjama.jama.com/2019/09/11/jama-forum-the-san-franciscoban-and-the-future-of-e-cigarettes/. Published 2019.
https://newsatjama.jama.com/2019/09/11/j...
,1111. Hajek P, Phillips-Waller A, Przulj D. A Randomized Trial of E-Cigarettes versus Nicotine-Replacement Therapy. N Engl J Med. 2019;380(7):629-637. doi: 10.1056/NEJMoa1808779.
https://doi.org/10.1056/NEJMoa1808779...
. The possibility of adding different flavors and transforming them into vehicles for the consumption of other substances, such as oils based on tetrahydrocannabinol (THC), cannabidiol (CBD) and butane, contributed to the rapid expansion and switch to ENDS 1212. Kimball A, Layer M, Tenforde M. Pulmonary Illness Related to E-Cigarette Use in Illinois and Wisconsin - Preliminary Report. 2019:1-14. doi: 10.1056/NEJMoa1911614.
https://doi.org/10.1056/NEJMoa1911614...
. Recent studies have shown that, in addition to nicotine, there are a large number of substances harmful to health in ENDS associated with cases of lipoid pneumonia with fatal outcomes worldwide 1212. Kimball A, Layer M, Tenforde M. Pulmonary Illness Related to E-Cigarette Use in Illinois and Wisconsin - Preliminary Report. 2019:1-14. doi: 10.1056/NEJMoa1911614.
https://doi.org/10.1056/NEJMoa1911614...
.

The analysis of the economic behavior of markets defines the term substitution as the interaction of two products, where an increase in the price of one would lead to an increase in the purchase of another with a fixed price. This relationship is modeled mathematically using the concept of cross-price elasticity. A substitute is defined as a product that has positive cross-price elasticity, where switching from conventional cigarettes to alternative products would depend on consumer characteristics, as well as the type and number of alternative products 1313. Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
https://doi.org/10.1093/ntr/ntz116...
. In particular, ENDS have shown more switching between potentially less harmful alternative products, depending on the nicotine dose they include 1313. Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
https://doi.org/10.1093/ntr/ntz116...
.

However, there is a knowledge gap on the current status of ENDS as substitute products for conventional cigarettes with debate focusing on the long-term effects of these products and their consequences in the younger population 1010. Howard K Koh, Clifford E Douglas. The San Francisco Ban and the Future of e-Cigarettes. JAMA Forum. https://newsatjama.jama.com/2019/09/11/jama-forum-the-san-franciscoban-and-the-future-of-e-cigarettes/. Published 2019.
https://newsatjama.jama.com/2019/09/11/j...
,1313. Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
https://doi.org/10.1093/ntr/ntz116...
,1414. Fairchild AL, Bayer R, Colgrove J. The Renormalization of Smoking? E-Cigarettes and the Tobacco "Endgame". N Engl J Med. 2013;370(4):293-295. doi: 10.1056/NEJMp1313940
https://doi.org/10.1056/NEJMp1313940...
. The aim of this rapid systematic review is to assess how and to what extent a switch from conventional cigarettes to electronic nicotine delivery systems (ENDS) occurs.

KEY MESSAGES

Motivation for the study: There is little evidence on the current status of electronic nicotine delivery systems as substitutes for traditional tobacco products. The debate is focused on the long-term effects of these products and their consequences in young people.

Main findings: Cessation of conventional cigarette smoking is more likely among e-cigarette users compared to non-users. The prevalence of e-cigarette use is increasing, mainly among teenagers. Increasing prices of conventional and e-cigarettes may be helpful in stopping smoking.

Implications: These findings should be considered in public health strategies for tobacco control.

MATERIALS AND METHODS

A rapid systematic review with meta-analysis was conducted; the report followed the guidelines established in the Cochrane Manual 1515. Higgins J, Green S. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. Cochrane Collab. 2011. and the PRISMA statement 1616. Liberati A, Altman DG, Tetzlaff J. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. In: Journal of Clinical Epidemiology. 2009. doi: 10.1016/j.jclinepi.2009.06.006.
https://doi.org/10.1016/j.jclinepi.2009....
,1717. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol. 2009. doi: 10.1016/j.jclinepi.2009.06.005.
https://doi.org/10.1016/j.jclinepi.2009....
. The review protocol was registered in PROSPERO under number CRD42019142089.

Selection criteria and outcomes

The following study types were included: a) controlled before-and-after trials (CBA); b) uncontrolled before-and-after trials (UBA); c) interrupted time series studies (ITS) with at least three data points before and after the intervention, with or without comparison groups; d) cohort studies; and e) cross-sectional studies. Systematic reviews were considered as a source of studies. Regarding the type of participants, studies should include smokers or ex-smokers of any age, sex, and country of residence who changed their consumption pattern.

The primary outcome was defined as a complete switch when the person started using ENDS and stopped smoking, or partial switch if the person started using ENDS and reduced daily consumption of conventional cigarettes, as well as the economics of this switch (price-demand and other types of elasticity and retail prices). Secondary outcomes were defined as outcome measures: a) Odds ratio (OR) of the switch, b) magnitude of change by country, c) time trends by country.

Search strategies

The literature search was conducted in PubMed, Embase, CINAHL, LILACS and Global Health (OVID) on August 30, 2019. The search strategy was created for PubMed and adapted to other electronic databases; no language restrictions were applied (see Supplementary Material Annex 1).

Selection of studies and extraction of results

For studies with multiple published papers, we included the one with the largest data set. Article selection and data extraction were carried out independently by peer reviewers (FRC and GS). Discrepancies were resolved by consensus of the entire team. These phases were completed using Covidence, an online platform designed for the development of systematic reviews 1818. Covidence.org [Internet]. Melbourne VIC: Better systematic review management; 2021. Disponible en: https://www.covidence.org/.
https://www.covidence.org/...
. Authors were contacted when necessary to obtain missing or supplementary information. A predesigned data extraction form was used after pilot testing. The following information was extracted: year of publication, journal name, authors’ names, language, study location (geographic region, country, province, city), study setting (urban vs. rural), study design, including risk of bias assessment domains, participants, selection criteria used, full or partial switch rate, and reasons for switching, among other data of interest.

Quality assessment

The evaluation of the bias risk (quality) of the epidemiological studies identified was carried out using the National Institutes of Health (NIH) quality assessment tool for observational cohort and cross-sectional studies 1919. Study Quality Assessment Tools | National Heart, Lung, and Blood Institute (NHLBI). https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools. Published 2019.
https://www.nhlbi.nih.gov/health-topics/...
. On the other hand, it should be taken into consideration that no specific instrument has been developed to evaluate studies aimed at estimating price elasticities and/or cross-price elasticity of demand. In this regard, to assess the quality of the included economic studies, we developed and proposed an ad hoc instrument, based on two previous systematic reviews that analyzed the elasticities of tobacco products 2020. Jankhotkaew J, Pitayarangsarit S, Chaiyasong S, Markchang K. Price elasticity of demand for manufactured cigarettes and roll-your-owncigarettes across socioeconomic status groups in Thailand. Tob Control. 2020. doi: 10.1136/tobaccocontrol-2019-055480.
https://doi.org/10.1136/tobaccocontrol-2...
,2121. Gallet CA, List JA. Cigarette demand: A meta-analysis of elasticities.Health Econ. 2003. doi: 10.1002/hec.765.
https://doi.org/10.1002/hec.765...
. The items of the instrument include aspects of the studies related to data, methods, evidence, and reporting of results (supplementary material, appendix 2 and 3).

Data analysis

A descriptive analysis was conducted to determine the frequency of total or partial switching (defined as the reduction of conventional cigarettes consumed per day) by country, and year of publication (taking into consideration when ENDS entered the market). The results are described using frequencies and measures of dispersion (median and interquartile range). A meta-analysis of the adjusted ORs was also carried out using Statsdirect software 2222. StatsDirect. Statistal Analysis Software. https://www.statsdirect.com/. Published 2019.
https://www.statsdirect.com/...
. Results were presented with 95% confidence intervals (CI). Intervention heterogeneity was described using the I2 statistic as follows: 1) 0-30% as not important; 30-70% as moderate; and more than 70% as considerable heterogeneity. To assess the impact of statistical heterogeneity, results were compared using fixed- and random-effects models. It was assumed that clinical heterogeneity (populations, interventions) was very likely to occur given the nature of the interventions included, so results from the random-effects model were reported. Overall effects were reported by the inverse variance method. We planned to convert continuous data to mean difference (MD) when necessary.

RESULTS

We found 3,628 studies of which 49 were finally included (Figure 1). Of these, 14 were economic studies and 35 provided epidemiological data on the switch from cigarettes to ENDS or the consumption of both (concurrent).

Figure 1
Flow of study selection according to the PRISMA statement.

Economic studies

Fourteen economic studies were considered, including cost studies and/or economic evaluations 2323. Zheng Y, Zhen C, Dench D, Nonnemaker JM. U.S. Demand for Tobacco Products in a System Framework. Heal Econ (United Kingdom). 2017. doi: 10.1002/hec.3384.
https://doi.org/10.1002/hec.3384...

24. Han MA. The price of tobacco and its effects on smoking behaviors in Korea: The 2015 Korea Community Health Survey. Prev Med (Baltim). 2019;120(July 2018):71-77. doi: 10.1016/j.ypmed.2019.01.010.
https://doi.org/10.1016/j.ypmed.2019.01....

25. Cheng KW, Chaloupka FJ, Shang C. Prices, use restrictions and electronic cigarette use-evidence from wave 1 (2016) US data of the ITC Four Country Smoking and Vaping Survey. Addiction. 2019;1(2016):1-7. doi: 10.1111/add.14562.
https://doi.org/10.1111/add.14562...

26. Liber AC. Heated tobacco products and combusted cigarettes: Comparing global prices and taxes. Tob Control. 2019. doi: 10.1136/tobaccocontrol-2018-054602
https://doi.org/10.1136/tobaccocontrol-2...

27. Liber A, Stoklosa M, Drope J, Huang J, Chaloupka F. Converging combustible and electronic cigarette prices: evidence for Nielsen retail scanner data in the United States from 2011 to 2015. Tob Induc Dis. 2018. doi: 10.18332/tid/83902.
https://doi.org/10.18332/tid/83902...

28. Liber AC, Drope JM, Stoklosa M. Combustible cigarettes cost less to use than e-cigarettes: Global evidence and tax policy implications. Tob Control. 2017. doi: 10.1136/tobaccocontrol-2015-052874.
https://doi.org/10.1136/tobaccocontrol-2...

29. Grace RC, Kivell BM, Laugesen M. Estimating cross-price elasticity of e-cigarettes using a simulated demand procedure. Nicotine Tob Res. 2015. doi: 10.1093/ntr/ntu268.
https://doi.org/10.1093/ntr/ntu268...

30. Quisenberry AJ, Koffarnus MN, Epstein LH, Bickel WK. The Experimental Tobacco Marketplace II: Substitutability and sex effects in dual electronic cigarette and conventional cigarette users. Drug Alcohol Depend. 2017. doi: 10.1016/j.drugalcdep.2017.06.004.
https://doi.org/10.1016/j.drugalcdep.201...

31. Pesko MF, Huang J, Johnston LD, Chaloupka FJ. E-cigarette price sensitivity among middle- and high-school students: evidence from monitoring the future. Addiction. 2018. doi: 10.1111/add.14119.
https://doi.org/10.1111/add.14119...

32. Chen X, Yu B, Chen DG. Probabilistic discrete event systems modeling of nonlinear transitions between electronic and combustible cigarette smoking with the 2014 National Youth Tobacco Survey data. Nonlinear Dynamics Psychol Life Sci. 2018; Jul 22(3):289-312.

33. Johnson MW, Johnson PS, Rass O, Pacek LR. Behavioral economic substitutability of e-cigarettes, tobacco cigarettes, and nicotine gum. J Psychopharmacol. 2017. doi: 10.1177/0269881117711921.
https://doi.org/10.1177/0269881117711921...

34. Rutter L, Britton J, Langley T. Price-Minimizing Behaviors in Response to Increasing Tobacco Price: A Cross-Sectional Study of Students. J Child Adolesc Subst Abus. 2017. doi: 10.1080/1067828X.2017.1306472.
https://doi.org/10.1080/1067828X.2017.13...

35. Stoklosa M, Drope J, Chaloupka FJ. Prices and e-cigarette demand: Evidence from the European Union. Nicotine Tob Res. 2016. doi: 10.1093/ntr/ntw109.
https://doi.org/10.1093/ntr/ntw109...
-3636. Minami H, Teo TK. The impact of e-cigarette price changes on vaping and smoking behaviors. Subst Use Misuse. 2019. doi: 10.1080/10826084.2019.1592195.
https://doi.org/10.1080/10826084.2019.15...
(Table 1), of which eight were from the United States, and the rest from England, New Zealand, and South Korea (one study for each of these countries). Three studies included several countries. Two of them considered data from 20 middle- and low-income countries. Most of the studies were cross-sectional in design (64%) and used a variety of data sources, including retail sales databases, cigarette purchase questionnaires, and online surveys. Nine studies (64%) evaluated health policy interventions. The most frequently evaluated or simulated intervention was price increases for e-cigarettes or conventional cigarettes (89%).

Table 1
Characteristics and main results of the economic studies.

We assessed the quality of the evidence of economic studies (Supplementary Material, Annex 4). Eleven of fourteen studies (79%) used household, retail or individual-level data. Almost all studies reported price/revenue and demand/sales/purchases outcomes. Half of the studies included a set of control variables in the analysis, and eight out of ten studies had an adequate sample size. Nine out of eleven studies estimated an adequate econometric model and are based on microeconomic theory. However, of the nine studies, only six (67%) tested the results for model validation or misspecification. About half of the studies (46.2%) reported results by subgroups. The average positive score across studies was 69.3%, ranging from 33.3% as the lowest value to 87.5% as the highest value. The identified studies suggest a negative relationship between consumption and price increases of e-cigarettes and conventional cigarettes. Four studies reported the price elasticity of the e-cigarette, and two showed that demand for this product is inelastic (elasticity below one, indicating that variations in demand for e-cigarettes are lower than variations in price, ceteris paribus). Overall, with the exception of the study by Zheng et al. that performs an elasticity analysis in different geographic areas in the United States 2323. Zheng Y, Zhen C, Dench D, Nonnemaker JM. U.S. Demand for Tobacco Products in a System Framework. Heal Econ (United Kingdom). 2017. doi: 10.1002/hec.3384.
https://doi.org/10.1002/hec.3384...
, the rest of the studies did not report elasticity estimates for population subgroups by socioeconomic or age characteristics.

Five studies reported the cross-price elasticity of the e-cigarette 2525. Cheng KW, Chaloupka FJ, Shang C. Prices, use restrictions and electronic cigarette use-evidence from wave 1 (2016) US data of the ITC Four Country Smoking and Vaping Survey. Addiction. 2019;1(2016):1-7. doi: 10.1111/add.14562.
https://doi.org/10.1111/add.14562...
,2929. Grace RC, Kivell BM, Laugesen M. Estimating cross-price elasticity of e-cigarettes using a simulated demand procedure. Nicotine Tob Res. 2015. doi: 10.1093/ntr/ntu268.
https://doi.org/10.1093/ntr/ntu268...
,3131. Pesko MF, Huang J, Johnston LD, Chaloupka FJ. E-cigarette price sensitivity among middle- and high-school students: evidence from monitoring the future. Addiction. 2018. doi: 10.1111/add.14119.
https://doi.org/10.1111/add.14119...
,3333. Johnson MW, Johnson PS, Rass O, Pacek LR. Behavioral economic substitutability of e-cigarettes, tobacco cigarettes, and nicotine gum. J Psychopharmacol. 2017. doi: 10.1177/0269881117711921.
https://doi.org/10.1177/0269881117711921...
,3535. Stoklosa M, Drope J, Chaloupka FJ. Prices and e-cigarette demand: Evidence from the European Union. Nicotine Tob Res. 2016. doi: 10.1093/ntr/ntw109.
https://doi.org/10.1093/ntr/ntw109...
(Table 1). The positive values of the cross-price elasticity of e-cigarettes show that e-cigarettes are partially interchangeable with conventional cigarettes, i.e., the demand for e-cigarettes increases when the price of conventional cigarettes increases, ceteris paribus.

Epidemiological studies

As for epidemiological studies, 35 were useful in assessing the switch from conventional cigarette smoking to ENDS; 24 were from the United States 3737. Zhu SH, Zhuang YL, Wong S, Cummins SE, Tedeschi GJ. E-cigarette use and associated changes in population smoking cessation: Evidence from US current population surveys. BMJ. 2017;358:1-8. doi: 10.1136/bmj.j3262.
https://doi.org/10.1136/bmj.j3262...
,3838. Young-Wolff KC, Klebaner D, Folck B. Documentation of e-cigarette use and associations with smoking from 2012 to 2015 in an integrated healthcare delivery system. Prev Med (Baltim). 2018;109(January):113-118. doi: 10.1016/j.ypmed.2018.01.012.
https://doi.org/10.1016/j.ypmed.2018.01....
,4747. Kasza KA, Borek N, Conway KP. Transitions in tobacco product use by u.S. adults between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2013-2014. doi: 10.3390/ijerph15112515.
https://doi.org/10.3390/ijerph15112515...

48. Hair EC, Romberg AR, Niaura R. Longitudinal tobacco use transitions among adolescents and young adults: 2014-2016. Nicotine Tob Res. 2019. doi: 10.1093/ntr/ntx285.
https://doi.org/10.1093/ntr/ntx285...

49. Giovenco DP, Delnevo CD. Prevalence of population smoking cessation by electronic cigarette use status in a national sample of recent smokers. Addict Behav. 2018;76(April 2017):129-134. doi: 10.1016/j.addbeh.2017.08.002.
https://doi.org/10.1016/j.addbeh.2017.08...

50. Gentzke AS, Creamer ML, Cullen KA. Vital Signs: Tobacco Product Use Among Middle and High School Students - United States, 2011-2018. MMWR Morb Mortal Wkly Rep. 2019;68(6):157-164. doi: 10.15585/mmwr.mm6806e1.
https://doi.org/10.15585/mmwr.mm6806e1...

51. Farsalinos KE, Niaura R. E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz025.
https://doi.org/10.1093/ntr/ntz025...

52. Ekanem US, Cardenas VM, Cen R. Electronic nicotine delivery systems and smoking cessation in Arkansas, 2014. Public Health Rep. 2017;132(2):210-219. doi: 10.1177/0033354916689611.
https://doi.org/10.1177/0033354916689611...

53. Chen JC. Flavored E-cigarette Use and Cigarette Smoking Reduction and Cessation-A Large National Study among Young Adult Smokers.Subst Use Misuse. 2018. doi: 10.1080/10826084.2018.1455704.
https://doi.org/10.1080/10826084.2018.14...

54. Boyle RG, Amato MS, Rode P, Kinney AM, St Claire AW, TaylorK. Tobacco use among Minnesota adults, 2014. Am J Health Behav. 2015;39(5):674-679. doi: 10.5993/AJHB.39.5.9.
https://doi.org/10.5993/AJHB.39.5.9...

55. Berry KM, Reynolds LM, Collins JM. E-cigarette initiation and associated changes in smoking cessation and reduction: The Population Assessment of Tobacco and Health Study, 2013-2015. Tob Control. 2019;28(1):42-49. doi: 10.1136/tobaccocontrol-2017-054108.
https://doi.org/10.1136/tobaccocontrol-2...
-5656. Barrington-Trimis JL, Bello MS, Liu F. Ethnic Differences in Patternsof Cigarette and E-Cigarette Use Over Time Among Adolescents.J Adolesc Heal. 2019. doi: 10.1016/j.jadohealth.2019.04.002.
https://doi.org/10.1016/j.jadohealth.201...
,3939. Wills TA, Knight R, Sargent JD, Gibbons FX, Pagano I, Williams RJ. Longitudinal study of e-cigarette use and onset of cigarette smoking among high school students in Hawaii. Tob Control. 2017;26(1):34-39. doi: 10.1136/tobaccocontrol-2015-052705.
https://doi.org/10.1136/tobaccocontrol-2...
,5757. Barrington-Trimis JL, Kong G, Leventhal AM. E-cigarette use and subsequent smoking frequency among adolescents. Pediatrics. 2018;142(6). doi: 10.1542/peds.2018-0486.
https://doi.org/10.1542/peds.2018-0486...

58. Barrington-Trimis JL, Urman R, Leventhal AM. E-cigarettes, cigarettes, and the prevalence of adolescent tobacco use. Pediatrics. 2016;138(2). doi: 10.1542/peds.2015-3983.
https://doi.org/10.1542/peds.2015-3983...

59. Bao W, Xu G, Lu J, Snetselaar LG, Wallace RB. Changes in Electronic Cigarette Use Among Adults in the United States, 2014-2016. JAMA. 2018. doi: 10.1001/jama.2018.4658.
https://doi.org/10.1001/jama.2018.4658...
-6060. Anic GM, Holder-Hayes E, Ambrose BK, et al. E-cigarette and Smokeless Tobacco Use and Switching Among Smokers: Findings From the National Adult Tobacco Survey. Am J Prev Med. 2018;54(4):539-551. doi: 10.1016/j.amepre.2017.12.010.
https://doi.org/10.1016/j.amepre.2017.12...
,4040. Stanton CA, Bansal-Travers M, Johnson AL. Longitudinal e-Cigarette and Cigarette Use Among US Youth in the PATH Study (2013-2015). JNCI J Natl Cancer Inst. 2019;111:1-9. doi: 10.1093/jnci/djz006.
https://doi.org/10.1093/jnci/djz006...

41. Piper ME, Baker TB, Benowitz NL, Jorenby DE. Changes in Use Patterns Over 1 Year Among Smokers and Dual Users of Combustible and Electronic Cigarettes. Nicotine Tob Res. 2019:1-9. doi: 10.1093/ntr/ntz065.
https://doi.org/10.1093/ntr/ntz065...

42. Park SH, Duncan DT, Shahawy O El. Characteristics of Adults Who Switched From Cigarette Smoking to E-cigarettes. Am J Prev Med. 2017;53(5):652-660. doi: 10.1016/j.amepre.2017.06.033.
https://doi.org/10.1016/j.amepre.2017.06...

43. Niaura R, Rich I, Johnson AL. Young Adult Tobacco and E-cigarette Use Transitions: Examining Stability Using Multistate Modeling. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz030.
https://doi.org/10.1093/ntr/ntz030...

44. Loukas A, Marti CN, Perry CL. Trajectories of Tobacco and Nicotine Use Across Young Adulthood, Texas, 2014-2017. Am J Public Health. 2019;109(3):465-471. doi: 10.2105/AJPH.2018.304850.
https://doi.org/10.2105/AJPH.2018.304850...

45. Carolina N, Tobacco Y, Huang L, Kowitt SD, Sutfin EL, Patel T. School Students and Its Association With Cigarette Use And Smoking Cessation. 2016:1-12.
-4646. Kasza KA, Coleman B, Sharma E. Correlates of transitions in tobacco product use by u.S. adult tobacco users between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2014-2015., three from Italy (6161. Manzoli L, Flacco ME, Ferrante M. Cohort study of electronic cigarette use: Effectiveness and safety at 24 months. Tob Control. 2017;26(3):284-292. doi: 10.1136/tobaccocontrol-2015-052822.
https://doi.org/10.1136/tobaccocontrol-2...

62. Liu X, Lugo A, Davoli E. Electronic cigarettes in Italy: a tool for harm reduction or a gateway to smoking tobacco?. Tob Control. 2019. doi: 10.1136/tobaccocontrol-2018-054726.
https://doi.org/10.1136/tobaccocontrol-2...
-6363. Flacco ME, Ferrante M, Fiore M, et al. Cohort study of electronic cigarette use: Safety and effectiveness after 4 years of follow-up. Eur Rev Med Pharmacol. Sci. 2019;23(1):402-412. doi: 10.26355/eurrev_201901_16789.
https://doi.org/10.26355/eurrev_201901_1...
, three from the United Kingdom 6464. Eastwood B, Dockrell MJ, Arnott D. Electronic cigarette use in young people in Great Britain 2013-2014. Public Health. 2015;129(9):1150-1156. doi: 10.1016/j.puhe.2015.07.009.
https://doi.org/10.1016/j.puhe.2015.07.0...

65. 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. doi: 10.1111/add.12917.
https://doi.org/10.1111/add.12917...
-6666. Beard E, Brown J, McNeill A, Michie S, West R. Has growth in electronic cigarette use by smokers been responsible for the decline in use of licensed nicotine products?. Findings from repeatedcross-sectional surveys. Thorax. 2015;70(10):974-978. doi: 10.1136/thoraxjnl-2015-206801.
https://doi.org/10.1136/thoraxjnl-2015-2...
, and one each from Germany 6767. Orth B, Merkel C. The decline of cigarette smoking among adolescents and young adults in Germany and the rising relevance of waterpipes, e-cigarettes and e-hookahs. Bundesgesundheitsblatt - Gesundheitsforsch - Gesundheitsschutz. 2018;61(11):1377-1387. doi: 10.1007/s00103-018-2820-1.
https://doi.org/10.1007/s00103-018-2820-...
, Czech Republic 6868. Kralikova E, Novak J, West O, Kmetova A, Hajek P. Do e-cigarettes have the potential to compete with conventional cigarettes?: A survey of conventional cigarette smokers' experiences with e-cigarettes. Chest. 2013;144(5):1609-1614. doi: 10.1378/chest.12-2842.
https://doi.org/10.1378/chest.12-2842...
, France 6969. El-Khoury F, Bolze C, Gomajee R, White V, Melchior M. Lower smoking rates and increased perceived harm of cigarettes among French adults one year after comprehensive tobacco control measures. Drug Alcohol Depend. 2019;201(March):65-70. doi: 10.1016/j.drugalcdep.2019.03.025.
https://doi.org/10.1016/j.drugalcdep.201...
, and Poland 7070. Smith DM, Gawron M, Balwicki L, Sobczak A, Matynia M, GoniewiczML. Exclusive versus dual use of tobacco and electronic cigarettes among adolescents in Poland, 2010-2016. Addict Behav. 2019;90(October 2018):341-348. doi: 10.1016/j.addbeh.2018.11.035.
https://doi.org/10.1016/j.addbeh.2018.11...
. Finally, one European study was multi-country 7171. Farsalinos KE, Poulas K, Voudris V, Le Houezec J. Electronic cigarette use in the European Union: analysis of a representative sample of 27 460 Europeans from 28 countries. Addiction. 2016. Nov;111(11):2032-2040. doi: 10.1111/add.13506.
https://doi.org/10.1111/add.13506...
. More than half were cross-sectional studies (55%), while the rest were retrospective cohort studies. Nineteen studies reported outcomes and measures of effect regarding sustainability (Table 2).

Table 2
Epidemiological studies reporting switching outcomes and measures of effect.

After applying the NIH assessment tool for each article, studies with low risk of bias were categorized as “good” (86%), while those with moderate risk were classified as “fair” (14%). No studies with high risk of bias were found (Supplementary Material, Annex 5).

Regarding the complete switch from conventional cigarettes to ENDS, three studies reported the adjusted OR of quitting conventional cigarettes, of current ENDS users versus nonusers or former ENDS users (Figure 2) 3838. Young-Wolff KC, Klebaner D, Folck B. Documentation of e-cigarette use and associations with smoking from 2012 to 2015 in an integrated healthcare delivery system. Prev Med (Baltim). 2018;109(January):113-118. doi: 10.1016/j.ypmed.2018.01.012.
https://doi.org/10.1016/j.ypmed.2018.01....
,5151. Farsalinos KE, Niaura R. E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz025.
https://doi.org/10.1093/ntr/ntz025...
,5555. Berry KM, Reynolds LM, Collins JM. E-cigarette initiation and associated changes in smoking cessation and reduction: The Population Assessment of Tobacco and Health Study, 2013-2015. Tob Control. 2019;28(1):42-49. doi: 10.1136/tobaccocontrol-2017-054108.
https://doi.org/10.1136/tobaccocontrol-2...
. The adjusted OR (with random effects) of the conventional cigarette smoking cessation group among ENDS users (whether daily or otherwise) was 1.19-fold (95% CI 1.09-1.30) compared with never or former ENDS users, with an I2 of 0%. Finally, four included studies were not meta-analyzed and are described narratively because of substantial heterogeneity 4949. Giovenco DP, Delnevo CD. Prevalence of population smoking cessation by electronic cigarette use status in a national sample of recent smokers. Addict Behav. 2018;76(April 2017):129-134. doi: 10.1016/j.addbeh.2017.08.002.
https://doi.org/10.1016/j.addbeh.2017.08...
,5353. Chen JC. Flavored E-cigarette Use and Cigarette Smoking Reduction and Cessation-A Large National Study among Young Adult Smokers.Subst Use Misuse. 2018. doi: 10.1080/10826084.2018.1455704.
https://doi.org/10.1080/10826084.2018.14...
,6161. Manzoli L, Flacco ME, Ferrante M. Cohort study of electronic cigarette use: Effectiveness and safety at 24 months. Tob Control. 2017;26(3):284-292. doi: 10.1136/tobaccocontrol-2015-052822.
https://doi.org/10.1136/tobaccocontrol-2...
,7171. Farsalinos KE, Poulas K, Voudris V, Le Houezec J. Electronic cigarette use in the European Union: analysis of a representative sample of 27 460 Europeans from 28 countries. Addiction. 2016. Nov;111(11):2032-2040. doi: 10.1111/add.13506.
https://doi.org/10.1111/add.13506...
.

Figure 2
Forest plot of total switch of conventional cigarettes for electronic cigarettes.

Manzoli et al. compared abstinence in a prospective cohort conducted in Italy. Data at 24 months were available for 229 e-cigarette users, 480 tobacco smokers, and 223 of those using both 6161. Manzoli L, Flacco ME, Ferrante M. Cohort study of electronic cigarette use: Effectiveness and safety at 24 months. Tob Control. 2017;26(3):284-292. doi: 10.1136/tobaccocontrol-2015-052822.
https://doi.org/10.1136/tobaccocontrol-2...
. Of the e-cigarette users, 61.1% remained abstinent from tobacco (whereas 23.1% and 26.0% of tobacco smokers and users of both achieved abstinence from tobacco). The rate (18.8%) of quitting either product (tobacco and/or e-cigarettes) was not higher for e-cigarette users compared to tobacco smokers or smokers of both.

Giovenco et al. pooled data from the 2014 and 2015 U.S. National Health Interview Survey (NHSIS) and restricted the sample to recent smokers and the analysis to daily e-cigarette users4949. Giovenco DP, Delnevo CD. Prevalence of population smoking cessation by electronic cigarette use status in a national sample of recent smokers. Addict Behav. 2018;76(April 2017):129-134. doi: 10.1016/j.addbeh.2017.08.002.
https://doi.org/10.1016/j.addbeh.2017.08...
. A quarter of the sample (25.2%) were former smokers. The prevalence of quitting smoking was significantly higher among daily e-cigarette users compared with never users (52.2% vs. 28.2%; prevalence ratio: 3.15; 95% CI: 2.66-3.73). Among those with a recent history of smoking, daily use of e-cigarettes had the strongest association with quitting smoking.

Farsalinos et al. assessed changes in smoking status due to e-cigarette use and the correlation with e-cigarette use in European Union (EU) member states in 2014 7171. Farsalinos KE, Poulas K, Voudris V, Le Houezec J. Electronic cigarette use in the European Union: analysis of a representative sample of 27 460 Europeans from 28 countries. Addiction. 2016. Nov;111(11):2032-2040. doi: 10.1111/add.13506.
https://doi.org/10.1111/add.13506...
. Through a survey of 27,460 citizens ≥15 years of age from the 28 EU member states. Researchers found that 31.1% of current smokers, 10.8% of former smokers, and 2.3% of never smokers reported ever using e-cigarettes; and that 35.1% (95% CI: 30.7-39.5) of current e-cigarette users reported quitting smoking conventional cigarettes because of e-cigarettes, while 32.2% (95% CI: 29.9-36.5) reported a reduction in conventional cigarette consumption. Being a smoker (OR: 21.23; 95% CI: 18.32-24.59) or former smoker (OR: 6.49; 95% CI: 5.49-7.67) were the strongest associations with e-cigarette use.

Chet et al. reported that e-cigarette users with one (adjusted OR: 2.5; p < 0.001) or multiple tobacco-free/menthol-free flavors (adjusted OR: 3.0; p < 0.001) were more likely to have reduced or stopped cigarette use during the past year compared with non-users of e-cigarettes5353. Chen JC. Flavored E-cigarette Use and Cigarette Smoking Reduction and Cessation-A Large National Study among Young Adult Smokers.Subst Use Misuse. 2018. doi: 10.1080/10826084.2018.1455704.
https://doi.org/10.1080/10826084.2018.14...
.

To analyze the outcome of conventional cigarette smoking cessation rates, Ekanem et al. included 4,465 participants from the USA 5252. Ekanem US, Cardenas VM, Cen R. Electronic nicotine delivery systems and smoking cessation in Arkansas, 2014. Public Health Rep. 2017;132(2):210-219. doi: 10.1177/0033354916689611.
https://doi.org/10.1177/0033354916689611...
. Most current smokers who reported smoking in the previous 5 years and used ENDS did not quit smoking conventional cigarettes. This study was not included in the meta-analysis because the follow-up period is much longer than in the other included studies. ENDS use was inversely associated with smoking cessation. The odds of quitting smoking among ENDS users were about half those observed for non-users of ENDS (OR: 0.53; 95% CI: 0.34-0.63; n=1,083).

Zhu et al. found that ENDS users had a higher rate of quitting conventional cigarettes than those who did not report using e-cigarettes, with a Relative Risk (RR) of 1.73 3737. Zhu SH, Zhuang YL, Wong S, Cummins SE, Tedeschi GJ. E-cigarette use and associated changes in population smoking cessation: Evidence from US current population surveys. BMJ. 2017;358:1-8. doi: 10.1136/bmj.j3262.
https://doi.org/10.1136/bmj.j3262...
. However, this study was not included in the meta-analysis because it lacked statistical information and used RR instead of OR. Piper et al. reported a confirmed abstinence from conventional cigarettes with a point prevalence of 7 days in the first year among exclusive users of conventional cigarettes versus users of the two products with a p-value of 0.03, but without reporting any measure of association (for that reason it was not considered in the meta-analysis) 4141. Piper ME, Baker TB, Benowitz NL, Jorenby DE. Changes in Use Patterns Over 1 Year Among Smokers and Dual Users of Combustible and Electronic Cigarettes. Nicotine Tob Res. 2019:1-9. doi: 10.1093/ntr/ntz065.
https://doi.org/10.1093/ntr/ntz065...
.

Regarding changes in prevalence over time, eighteen articles reported a general population estimate 3939. Wills TA, Knight R, Sargent JD, Gibbons FX, Pagano I, Williams RJ. Longitudinal study of e-cigarette use and onset of cigarette smoking among high school students in Hawaii. Tob Control. 2017;26(1):34-39. doi: 10.1136/tobaccocontrol-2015-052705.
https://doi.org/10.1136/tobaccocontrol-2...
,4040. Stanton CA, Bansal-Travers M, Johnson AL. Longitudinal e-Cigarette and Cigarette Use Among US Youth in the PATH Study (2013-2015). JNCI J Natl Cancer Inst. 2019;111:1-9. doi: 10.1093/jnci/djz006.
https://doi.org/10.1093/jnci/djz006...
,5959. Bao W, Xu G, Lu J, Snetselaar LG, Wallace RB. Changes in Electronic Cigarette Use Among Adults in the United States, 2014-2016. JAMA. 2018. doi: 10.1001/jama.2018.4658.
https://doi.org/10.1001/jama.2018.4658...
,6060. Anic GM, Holder-Hayes E, Ambrose BK, et al. E-cigarette and Smokeless Tobacco Use and Switching Among Smokers: Findings From the National Adult Tobacco Survey. Am J Prev Med. 2018;54(4):539-551. doi: 10.1016/j.amepre.2017.12.010.
https://doi.org/10.1016/j.amepre.2017.12...
,6262. Liu X, Lugo A, Davoli E. Electronic cigarettes in Italy: a tool for harm reduction or a gateway to smoking tobacco?. Tob Control. 2019. doi: 10.1136/tobaccocontrol-2018-054726.
https://doi.org/10.1136/tobaccocontrol-2...
,62,6464. Eastwood B, Dockrell MJ, Arnott D. Electronic cigarette use in young people in Great Britain 2013-2014. Public Health. 2015;129(9):1150-1156. doi: 10.1016/j.puhe.2015.07.009.
https://doi.org/10.1016/j.puhe.2015.07.0...
,6666. Beard E, Brown J, McNeill A, Michie S, West R. Has growth in electronic cigarette use by smokers been responsible for the decline in use of licensed nicotine products?. Findings from repeatedcross-sectional surveys. Thorax. 2015;70(10):974-978. doi: 10.1136/thoraxjnl-2015-206801.
https://doi.org/10.1136/thoraxjnl-2015-2...
,6767. Orth B, Merkel C. The decline of cigarette smoking among adolescents and young adults in Germany and the rising relevance of waterpipes, e-cigarettes and e-hookahs. Bundesgesundheitsblatt - Gesundheitsforsch - Gesundheitsschutz. 2018;61(11):1377-1387. doi: 10.1007/s00103-018-2820-1.
https://doi.org/10.1007/s00103-018-2820-...
,6969. El-Khoury F, Bolze C, Gomajee R, White V, Melchior M. Lower smoking rates and increased perceived harm of cigarettes among French adults one year after comprehensive tobacco control measures. Drug Alcohol Depend. 2019;201(March):65-70. doi: 10.1016/j.drugalcdep.2019.03.025.
https://doi.org/10.1016/j.drugalcdep.201...
,7070. Smith DM, Gawron M, Balwicki L, Sobczak A, Matynia M, GoniewiczML. Exclusive versus dual use of tobacco and electronic cigarettes among adolescents in Poland, 2010-2016. Addict Behav. 2019;90(October 2018):341-348. doi: 10.1016/j.addbeh.2018.11.035.
https://doi.org/10.1016/j.addbeh.2018.11...
,4242. Park SH, Duncan DT, Shahawy O El. Characteristics of Adults Who Switched From Cigarette Smoking to E-cigarettes. Am J Prev Med. 2017;53(5):652-660. doi: 10.1016/j.amepre.2017.06.033.
https://doi.org/10.1016/j.amepre.2017.06...
,4444. Loukas A, Marti CN, Perry CL. Trajectories of Tobacco and Nicotine Use Across Young Adulthood, Texas, 2014-2017. Am J Public Health. 2019;109(3):465-471. doi: 10.2105/AJPH.2018.304850.
https://doi.org/10.2105/AJPH.2018.304850...
,4545. Carolina N, Tobacco Y, Huang L, Kowitt SD, Sutfin EL, Patel T. School Students and Its Association With Cigarette Use And Smoking Cessation. 2016:1-12.,4747. Kasza KA, Borek N, Conway KP. Transitions in tobacco product use by u.S. adults between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2013-2014. doi: 10.3390/ijerph15112515.
https://doi.org/10.3390/ijerph15112515...
,5050. Gentzke AS, Creamer ML, Cullen KA. Vital Signs: Tobacco Product Use Among Middle and High School Students - United States, 2011-2018. MMWR Morb Mortal Wkly Rep. 2019;68(6):157-164. doi: 10.15585/mmwr.mm6806e1.
https://doi.org/10.15585/mmwr.mm6806e1...
,5454. Boyle RG, Amato MS, Rode P, Kinney AM, St Claire AW, TaylorK. Tobacco use among Minnesota adults, 2014. Am J Health Behav. 2015;39(5):674-679. doi: 10.5993/AJHB.39.5.9.
https://doi.org/10.5993/AJHB.39.5.9...
,5656. Barrington-Trimis JL, Bello MS, Liu F. Ethnic Differences in Patternsof Cigarette and E-Cigarette Use Over Time Among Adolescents.J Adolesc Heal. 2019. doi: 10.1016/j.jadohealth.2019.04.002.
https://doi.org/10.1016/j.jadohealth.201...
,5858. Barrington-Trimis JL, Urman R, Leventhal AM. E-cigarettes, cigarettes, and the prevalence of adolescent tobacco use. Pediatrics. 2016;138(2). doi: 10.1542/peds.2015-3983.
https://doi.org/10.1542/peds.2015-3983...
. The prevalence of e-cigarette and conventional cigarette use by country are presented in the supplementary material, annex 6 and supplementary material, annex 7; likewise, the prevalence gap of e-cigarettes/conventional cigarettes by country was estimated (Table 3). In most cases the prevalence of e-cigarettes increased over time. Figure 3A shows the percentage prevalence of e-cigarettes and conventional cigarettes among adolescents in country-representative samples through 2018 (United States, Germany, and United Kingdom), where the prevalence of e-cigarettes among high school students in the US exceeded the prevalence of conventional cigarettes in 2018.

Table 3
Absolute difference in the consumption prevalence of electronic cigarettes and conventional cigarettes (oldest prevalence minus most recent prevalence).

electronic cigarettes
in the United States.

Figure 3B shows the prevalence of e-cigarette and conventional cigarette use among adults in Europe over time, showing, albeit slightly, an increase in the use of e-cigarettes and a decreasing trend in conventional cigarette use. Finally, Figure 3C shows how Park and Anic reported an increase in the prevalence of smokers who may switch from conventional cigarette use exclusively to ENDS over time in the U.S., both results were based on the National Adult Smoking Survey 2012-2013; 2013-2014 4242. Park SH, Duncan DT, Shahawy O El. Characteristics of Adults Who Switched From Cigarette Smoking to E-cigarettes. Am J Prev Med. 2017;53(5):652-660. doi: 10.1016/j.amepre.2017.06.033.
https://doi.org/10.1016/j.amepre.2017.06...
,6060. Anic GM, Holder-Hayes E, Ambrose BK, et al. E-cigarette and Smokeless Tobacco Use and Switching Among Smokers: Findings From the National Adult Tobacco Survey. Am J Prev Med. 2018;54(4):539-551. doi: 10.1016/j.amepre.2017.12.010.
https://doi.org/10.1016/j.amepre.2017.12...
.

Regarding partial exchange, three studies reported a reduction in conventional cigarettes consumed per day among e-cigarette and conventional cigarette users 6363. Flacco ME, Ferrante M, Fiore M, et al. Cohort study of electronic cigarette use: Safety and effectiveness after 4 years of follow-up. Eur Rev Med Pharmacol. Sci. 2019;23(1):402-412. doi: 10.26355/eurrev_201901_16789.
https://doi.org/10.26355/eurrev_201901_1...
,6565. 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. doi: 10.1111/add.12917.
https://doi.org/10.1111/add.12917...
,6868. Kralikova E, Novak J, West O, Kmetova A, Hajek P. Do e-cigarettes have the potential to compete with conventional cigarettes?: A survey of conventional cigarette smokers' experiences with e-cigarettes. Chest. 2013;144(5):1609-1614. doi: 10.1378/chest.12-2842.
https://doi.org/10.1378/chest.12-2842...
. While Kralikova reported a reduction in cigarettes over time in users of both 6868. Kralikova E, Novak J, West O, Kmetova A, Hajek P. Do e-cigarettes have the potential to compete with conventional cigarettes?: A survey of conventional cigarette smokers' experiences with e-cigarettes. Chest. 2013;144(5):1609-1614. doi: 10.1378/chest.12-2842.
https://doi.org/10.1378/chest.12-2842...
, Brose et al. and Flacco et al. reported percentage reductions in conventional cigarettes consumed among users of both and nonusers of ENDS 6363. Flacco ME, Ferrante M, Fiore M, et al. Cohort study of electronic cigarette use: Safety and effectiveness after 4 years of follow-up. Eur Rev Med Pharmacol. Sci. 2019;23(1):402-412. doi: 10.26355/eurrev_201901_16789.
https://doi.org/10.26355/eurrev_201901_1...
,6565. 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. doi: 10.1111/add.12917.
https://doi.org/10.1111/add.12917...
. These three studies found a significant reduction in cigarette consumption between users of both and conventional cigarette users.

Finally, four studies reported transition probabilities in baseline data. Niaura et al. (4343. Niaura R, Rich I, Johnson AL. Young Adult Tobacco and E-cigarette Use Transitions: Examining Stability Using Multistate Modeling. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz030.
https://doi.org/10.1093/ntr/ntz030...
reported transition probability at 6 months and 3 years according to multistate probabilistic models. Hair et al. reported transition probability as a risk index 4848. Hair EC, Romberg AR, Niaura R. Longitudinal tobacco use transitions among adolescents and young adults: 2014-2016. Nicotine Tob Res. 2019. doi: 10.1093/ntr/ntx285.
https://doi.org/10.1093/ntr/ntx285...
. Kasza et al. reported the transition to noncigarette smoking between current daily e-cigarette use and nonusers of e-cigarettes as a relative index 4646. Kasza KA, Coleman B, Sharma E. Correlates of transitions in tobacco product use by u.S. adult tobacco users between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2014-2015.. Barrington-Trimis et al. reported the prevalence of percent transition from the total sample of exclusive users of conventional cigarettes and users of both at baseline to exclusive users of e-cigarettes at follow-up 5757. Barrington-Trimis JL, Kong G, Leventhal AM. E-cigarette use and subsequent smoking frequency among adolescents. Pediatrics. 2018;142(6). doi: 10.1542/peds.2018-0486.
https://doi.org/10.1542/peds.2018-0486...
.

DISCUSSION

The commercial increase and the potential consequences derived from the use of ENDS in the population have transformed these devices into one of the current problems that opened a great debate in public health. Our study evaluated a little-known aspect about the different forms of switching from traditional tobacco by performing a systematic review and meta-analysis. This can be a complete switch to ENDS and also a partial switch as consumers of both products. In the first case, our meta-analysis showed an association between non-current ENDS users (daily or not) and smoking cessation compared to current ENDS users. In the second case, three studies reported a significant reduction in conventional cigarettes consumed per day among dual users (defined as users of conventional and e-cigarettes) and non-users of ENDS. Studies based on state transition models were heterogeneous. In addition, longitudinal studies showed that the prevalence of ENDS use is increasing, mainly in the teenage population, while traditional tobacco use shows a gradual decline.

We also found a negative relationship between consumption and price increases of e-cigarettes and conventional cigarettes. The positive values of the cross-price elasticity of e-cigarettes showed that e-cigarettes are partially interchangeable with conventional cigarettes, which is consistent with our epidemiological findings. To our knowledge, no specific instrument has been developed to evaluate studies aimed at estimating own-price elasticity and/or cross-price elasticity of demand. Therefore, to assess the quality of the included economic studies, we propose an ad hoc instrument, based on two previous systematic reviews that analyzed cigarette elasticities 2121. Gallet CA, List JA. Cigarette demand: A meta-analysis of elasticities.Health Econ. 2003. doi: 10.1002/hec.765.
https://doi.org/10.1002/hec.765...
,7272. Jawad M, Lee JT, Glantz S, Millett C. Price elasticity of demand of non-cigarette tobacco products: A systematic review and meta-analysis. Tob Control. 2018. doi: 10.1136/tobaccocontrol-2017-054056.
https://doi.org/10.1136/tobaccocontrol-2...
.

Given that tobacco is the leading preventable cause of cancer worldwide and that ENDS users are mostly teenagers and young people, some postulate that an alternative involving a “less harmful” option may be useful to avoid the harm caused by tobacco 33. American Cancer Society. The Cancer Atlas. Disponible en: http://canceratlas.cancer.org/risk-factors/risks-of-tobacco/. Published 2019.
http://canceratlas.cancer.org/risk-facto...
,1414. Fairchild AL, Bayer R, Colgrove J. The Renormalization of Smoking? E-Cigarettes and the Tobacco "Endgame". N Engl J Med. 2013;370(4):293-295. doi: 10.1056/NEJMp1313940
https://doi.org/10.1056/NEJMp1313940...
. However, a large number of recent publications highlighted adverse effects related to ENDS, mainly cases of lung injury 1313. Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
https://doi.org/10.1093/ntr/ntz116...
,7373. CDC. Lung Injury Associated with Electronic Cigarettes, or Vaping. https://interactives.nejm.org/ile/cdc_vaping/index.html. Published 2019.
https://interactives.nejm.org/ile/cdc_va...

74. Butt YM, Smith ML, Tazelaar HD. Pathology of Vaping-Associated Lung Injury. N Engl J Med. 2019. doi: 10.1056/nejmc1913069.
https://doi.org/10.1056/nejmc1913069...

75. Hswen Y, Brownstein JS. Real-Time Digital Surveillance of Vaping- Induced Pulmonary Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1912818.
https://doi.org/10.1056/nejmc1912818...
-7676. Henry TS, Kanne JP, Kligerman SJ. Imaging of Vaping-AssociatedLung Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1911995.
https://doi.org/10.1056/nejmc1911995...
. The similarities in risk factors and lung injury caused by SARS-CoV-2 alerts the scientific community that is trying to establish a link between the risk and susceptibility of ENDS users and the COVID-19 pandemic 7777. Kaur G, Lungarella G, Rahman I. SARS-CoV-2 COVID-19 susceptibility and lung inflammatory storm by smoking and vaping. J Inflamm. 2020. doi: 10.1186/s12950-020-00250-8.
https://doi.org/10.1186/s12950-020-00250...
.

In addition, it is important to mention that most studies did not use biochemical parameters such as carbon monoxide (CO) measurement in exhaled air to confirm smoking reduction or cessation, although this method of analysis is currently under discussion 7878. Liu X, Lu W, Liao S. Efficiency and adverse events of electronic cigarettes: A systematic review and meta-analysis (PRISMA-com pliant article). Med (United States). 2018;97(19). doi: 10.1097/MD.0000000000010324.
https://doi.org/10.1097/MD.0000000000010...
. On the other hand, the included studies did not consider adverse effects caused by ENDS use or the transition from ENDS users to conventional cigarettes or from use of both. For example, Wills et al. in a longitudinal study conducted in schools in Hawaii reported that in the teenager population, ENDS use is associated with a nearly threefold increased risk of smoking initiation3939. Wills TA, Knight R, Sargent JD, Gibbons FX, Pagano I, Williams RJ. Longitudinal study of e-cigarette use and onset of cigarette smoking among high school students in Hawaii. Tob Control. 2017;26(1):34-39. doi: 10.1136/tobaccocontrol-2015-052705.
https://doi.org/10.1136/tobaccocontrol-2...
. Khouja et al. 7979. Khouja JN, Suddell SF, Peters SE, Taylor AE, Munafo MR. Is e-cigarette use in non-smoking young adults associated with later smoking? A systematic review and meta-analysis. Tob Control. 2020. doi: 10.1136/tobaccocontrol-2019-055433.
https://doi.org/10.1136/tobaccocontrol-2...
conducted a systematic review on the use of electronic cigarettes in young adult nonsmokers and found a possible association with subsequent consumption of conventional cigarettes.

In 2014, McRobbie et al. published a Cochrane systematic review analyzing the effectiveness of ENDS for smoking cessation and reduction 8080. McRobbie H, Bullen C, Hajek P. Electronic cigarettes for smoking cessation and reduction ( Protocol ). Cochrane Libr. 2014;12(12):CD010216. Disponible en: www.cochranelibrary.com. doi: 10.1002/14651858.CD010216.pub2.
https://doi.org/10.1002/14651858.CD01021...
. With only two randomized controlled trials for each outcome, the authors concluded that despite the low quality of evidence available at the time, ENDS use increased the odds of smoking cessation, which was consistent with the meta-analysis results. Unlike the study by McRobbie et al., this systematic review took into account a wide variety of studies and designs, which allowed conclusions to be drawn including measures of association and longitudinal data, a situation that may be important for its external validity.

According to recent research, ENDS are known to have been designed initially for an audience of teenage non-nicotine users 8181. Reuters Health. Juul disregarded early evidence it was hooking teens. 2019. https://www.reuters.com/investigates/special-report/juul-ecigarette/?utm_source=twitter&utm_medium=Social%0A.
https://www.reuters.com/investigates/spe...
, although nicotine users remain of paramount importance for the natural history of cigarette smoking. Given the amount of nicotine contained in ENDS, the effectiveness of switching products may vary 7878. Liu X, Lu W, Liao S. Efficiency and adverse events of electronic cigarettes: A systematic review and meta-analysis (PRISMA-com pliant article). Med (United States). 2018;97(19). doi: 10.1097/MD.0000000000010324.
https://doi.org/10.1097/MD.0000000000010...
,8282. Hughes JR, Adams EH, Franzon MA, Maguire MK, Guary J. A prospective study of off-label use of, abuse of, and dependence on nicotine inhaler. Tob Control. 2005. doi: 10.1136/tc.2004.008367.
https://doi.org/10.1136/tc.2004.008367...

83. Vansickel AR, Weaver MF, Eissenberg T. Clinical laboratory assessment of the abuse liability of an electronic cigarette. Addiction. 2012. doi: 10.1111/j.1360-0443.2012.03791.x.
https://doi.org/10.1111/j.1360-0443.2012...
-8484. 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. Subst Abus Res Treat. 2013. doi: 10.4137/SART.S12756.
https://doi.org/10.4137/SART.S12756...
. However, the growing wave of reports of adverse effects, mainly at the pulmonary level1313. Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
https://doi.org/10.1093/ntr/ntz116...
,7373. CDC. Lung Injury Associated with Electronic Cigarettes, or Vaping. https://interactives.nejm.org/ile/cdc_vaping/index.html. Published 2019.
https://interactives.nejm.org/ile/cdc_va...

74. Butt YM, Smith ML, Tazelaar HD. Pathology of Vaping-Associated Lung Injury. N Engl J Med. 2019. doi: 10.1056/nejmc1913069.
https://doi.org/10.1056/nejmc1913069...

75. Hswen Y, Brownstein JS. Real-Time Digital Surveillance of Vaping- Induced Pulmonary Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1912818.
https://doi.org/10.1056/nejmc1912818...
-7676. Henry TS, Kanne JP, Kligerman SJ. Imaging of Vaping-AssociatedLung Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1911995.
https://doi.org/10.1056/nejmc1911995...
, accentuates the concern caused by these products, which is why many countries and states prohibit their commercialization, supported by greater control of these products by organizations such as the WHO or FDA, until the causes are clarified 8585. Gottlieb S, Zeller M. A Nicotine-Focused Framework for Public Health. N Engl J Med. 2017;377(12):1111-1114. doi: 10.1056/NEJMp1707409.
https://doi.org/10.1056/NEJMp1707409...
.

The main limitation is inherent to the nature of a rapid systematic review. Therefore, we did not search the gray literature, which could have contributed additional relevant information. Another limitation of our analysis was the heterogeneity among the included studies, which is a common finding when preparing systematic reviews of epidemiological studies 8686. Ciapponi A, Glujovsky D, Virgilio SA, Bardach AE. Conducting and Disseminating Epidemiological Systematic Reviews in Latin America and the Caribbean: Pitfalls and Lessons Learned. Value Heal Reg Issues. 2017. doi: 10.1016/j.vhri.2017.07.011.
https://doi.org/10.1016/j.vhri.2017.07.0...
. Finally, additional studies might exist in bibliographic databases or regional repositories or after the search date (see supplementary material) that were not included in our review. Regarding the strengths of our review, we highlight the enrollment of the protocol in PROSPERO, the exhaustive search strategy used, the assessment of the risk of bias (quality of the studies) and the diversity of designs that we considered (the PRISMA checklist for our review is presented in supplementary material annex 8).

In conclusion, the likelihood of quitting conventional cigarette smoking among current ENDS users increased when compared to never users or ENDS users. However, this found short-term association might be different in the long term, and not directly associated with a positive effect due to the reported adverse events of ENDS, future research is needed to confirm this hypothesis. Economic studies found that the cross-price elasticity of e-cigarettes is partially interchangeable with conventional cigarettes. All these findings should be considered by decision makers to design public health strategies for tobacco control and by researchers to address highlighted evidence gaps.

Acknowledgments:

The librarian of the IECS, Daniel Comandé, for developing the search strategies and providing the required full texts.

References

  • 1
    Stanaway JD, Afshin A, Gakidou E. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990-2017: A systematic analysis for the Global Burden of Disease Stu. Lancet. 2018:1923-1994. doi: 10.1016/S0140-6736(18)32225-6.
    » https://doi.org/10.1016/S0140-6736(18)32225-6
  • 2
    Metrics I of H. Global Burden of Disease Compare I VIZ Hub. 2019. Disponible en: http://ihmeuw.org/4pgv. Published 2017
    » http://ihmeuw.org/4pgv. Published 2017
  • 3
    American Cancer Society. The Cancer Atlas. Disponible en: http://canceratlas.cancer.org/risk-factors/risks-of-tobacco/. Published 2019
    » http://canceratlas.cancer.org/risk-factors/risks-of-tobacco/. Published 2019
  • 4
    FCTC adopted by the C of the P to the W. WHO Framework Convention on Tobacco Control. Disponible en: https://www.who.int/fctc/text_download/en/ Published 2003.
    » https://www.who.int/fctc/text_download/en/
  • 5
    Organization WH. The MPOWER Measures. World Health Organization. https://www.who.int/tobacco/mpower/package/es/ Published2008.
    » https://www.who.int/tobacco/mpower/package/es/
  • 6
    Asma S, Mackay J, Song SY, Zhao L, Morton J, Palipudi KM, et al. Global Adults Tobacco Survey. The GATS Atlas. Centers For Disease Control and Prevention Foundation. http://gatsatlas.org/ Published 2015.
    » http://gatsatlas.org/
  • 7
    Organization WH. WHO Report On The Global Tobacco Epidemic 2019. World Health Organization. https://www.who.int/tobacco/global_report/en/ Published 2019.
    » https://www.who.int/tobacco/global_report/en/
  • 8
    Malone RE. Tobacco industry shoving its snout under the UN tent flap. Tob Control. 2019;28(5):479 LP - 480. doi: 10.1136/tobaccocontrol-2019-055309.
    » https://doi.org/10.1136/tobaccocontrol-2019-055309
  • 9
    Frieden TR, Jaffe HW, Richards CL, Iademarco MF. E-Cigarette Use Among Youth and Young Adults. A Report of the Surgeon General. Mmwr.
  • 10
    Howard K Koh, Clifford E Douglas. The San Francisco Ban and the Future of e-Cigarettes. JAMA Forum. https://newsatjama.jama.com/2019/09/11/jama-forum-the-san-franciscoban-and-the-future-of-e-cigarettes/ Published 2019.
    » https://newsatjama.jama.com/2019/09/11/jama-forum-the-san-franciscoban-and-the-future-of-e-cigarettes/
  • 11
    Hajek P, Phillips-Waller A, Przulj D. A Randomized Trial of E-Cigarettes versus Nicotine-Replacement Therapy. N Engl J Med. 2019;380(7):629-637. doi: 10.1056/NEJMoa1808779.
    » https://doi.org/10.1056/NEJMoa1808779
  • 12
    Kimball A, Layer M, Tenforde M. Pulmonary Illness Related to E-Cigarette Use in Illinois and Wisconsin - Preliminary Report. 2019:1-14. doi: 10.1056/NEJMoa1911614.
    » https://doi.org/10.1056/NEJMoa1911614
  • 13
    Pope DA, Poe L, Stein JS, Kaplan BA, DeHart WB, Mellis AM, et al. The Experimental Tobacco Marketplace: Demand and Substitutability as a Function of Cigarette Taxes and e-Liquid Subsidies. Nicotine Tob Res. 2020;22(5):782-790. doi: 10.1093/ntr/ntz116.
    » https://doi.org/10.1093/ntr/ntz116
  • 14
    Fairchild AL, Bayer R, Colgrove J. The Renormalization of Smoking? E-Cigarettes and the Tobacco "Endgame". N Engl J Med. 2013;370(4):293-295. doi: 10.1056/NEJMp1313940
    » https://doi.org/10.1056/NEJMp1313940
  • 15
    Higgins J, Green S. Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. Cochrane Collab. 2011.
  • 16
    Liberati A, Altman DG, Tetzlaff J. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. In: Journal of Clinical Epidemiology. 2009. doi: 10.1016/j.jclinepi.2009.06.006.
    » https://doi.org/10.1016/j.jclinepi.2009.06.006
  • 17
    Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. J Clin Epidemiol. 2009. doi: 10.1016/j.jclinepi.2009.06.005.
    » https://doi.org/10.1016/j.jclinepi.2009.06.005
  • 18
    Covidence.org [Internet]. Melbourne VIC: Better systematic review management; 2021. Disponible en: https://www.covidence.org/
    » https://www.covidence.org/
  • 19
    Study Quality Assessment Tools | National Heart, Lung, and Blood Institute (NHLBI). https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools Published 2019.
    » https://www.nhlbi.nih.gov/health-topics/study-quality-assessment-tools
  • 20
    Jankhotkaew J, Pitayarangsarit S, Chaiyasong S, Markchang K. Price elasticity of demand for manufactured cigarettes and roll-your-owncigarettes across socioeconomic status groups in Thailand. Tob Control. 2020. doi: 10.1136/tobaccocontrol-2019-055480.
    » https://doi.org/10.1136/tobaccocontrol-2019-055480
  • 21
    Gallet CA, List JA. Cigarette demand: A meta-analysis of elasticities.Health Econ. 2003. doi: 10.1002/hec.765.
    » https://doi.org/10.1002/hec.765
  • 22
    StatsDirect. Statistal Analysis Software. https://www.statsdirect.com/ Published 2019.
    » https://www.statsdirect.com/
  • 23
    Zheng Y, Zhen C, Dench D, Nonnemaker JM. U.S. Demand for Tobacco Products in a System Framework. Heal Econ (United Kingdom). 2017. doi: 10.1002/hec.3384.
    » https://doi.org/10.1002/hec.3384
  • 24
    Han MA. The price of tobacco and its effects on smoking behaviors in Korea: The 2015 Korea Community Health Survey. Prev Med (Baltim). 2019;120(July 2018):71-77. doi: 10.1016/j.ypmed.2019.01.010.
    » https://doi.org/10.1016/j.ypmed.2019.01.010
  • 25
    Cheng KW, Chaloupka FJ, Shang C. Prices, use restrictions and electronic cigarette use-evidence from wave 1 (2016) US data of the ITC Four Country Smoking and Vaping Survey. Addiction. 2019;1(2016):1-7. doi: 10.1111/add.14562.
    » https://doi.org/10.1111/add.14562
  • 26
    Liber AC. Heated tobacco products and combusted cigarettes: Comparing global prices and taxes. Tob Control. 2019. doi: 10.1136/tobaccocontrol-2018-054602
    » https://doi.org/10.1136/tobaccocontrol-2018-054602
  • 27
    Liber A, Stoklosa M, Drope J, Huang J, Chaloupka F. Converging combustible and electronic cigarette prices: evidence for Nielsen retail scanner data in the United States from 2011 to 2015. Tob Induc Dis. 2018. doi: 10.18332/tid/83902.
    » https://doi.org/10.18332/tid/83902
  • 28
    Liber AC, Drope JM, Stoklosa M. Combustible cigarettes cost less to use than e-cigarettes: Global evidence and tax policy implications. Tob Control. 2017. doi: 10.1136/tobaccocontrol-2015-052874.
    » https://doi.org/10.1136/tobaccocontrol-2015-052874
  • 29
    Grace RC, Kivell BM, Laugesen M. Estimating cross-price elasticity of e-cigarettes using a simulated demand procedure. Nicotine Tob Res. 2015. doi: 10.1093/ntr/ntu268.
    » https://doi.org/10.1093/ntr/ntu268
  • 30
    Quisenberry AJ, Koffarnus MN, Epstein LH, Bickel WK. The Experimental Tobacco Marketplace II: Substitutability and sex effects in dual electronic cigarette and conventional cigarette users. Drug Alcohol Depend. 2017. doi: 10.1016/j.drugalcdep.2017.06.004.
    » https://doi.org/10.1016/j.drugalcdep.2017.06.004
  • 31
    Pesko MF, Huang J, Johnston LD, Chaloupka FJ. E-cigarette price sensitivity among middle- and high-school students: evidence from monitoring the future. Addiction. 2018. doi: 10.1111/add.14119.
    » https://doi.org/10.1111/add.14119
  • 32
    Chen X, Yu B, Chen DG. Probabilistic discrete event systems modeling of nonlinear transitions between electronic and combustible cigarette smoking with the 2014 National Youth Tobacco Survey data. Nonlinear Dynamics Psychol Life Sci. 2018; Jul 22(3):289-312.
  • 33
    Johnson MW, Johnson PS, Rass O, Pacek LR. Behavioral economic substitutability of e-cigarettes, tobacco cigarettes, and nicotine gum. J Psychopharmacol. 2017. doi: 10.1177/0269881117711921.
    » https://doi.org/10.1177/0269881117711921
  • 34
    Rutter L, Britton J, Langley T. Price-Minimizing Behaviors in Response to Increasing Tobacco Price: A Cross-Sectional Study of Students. J Child Adolesc Subst Abus. 2017. doi: 10.1080/1067828X.2017.1306472.
    » https://doi.org/10.1080/1067828X.2017.1306472
  • 35
    Stoklosa M, Drope J, Chaloupka FJ. Prices and e-cigarette demand: Evidence from the European Union. Nicotine Tob Res. 2016. doi: 10.1093/ntr/ntw109.
    » https://doi.org/10.1093/ntr/ntw109
  • 36
    Minami H, Teo TK. The impact of e-cigarette price changes on vaping and smoking behaviors. Subst Use Misuse. 2019. doi: 10.1080/10826084.2019.1592195.
    » https://doi.org/10.1080/10826084.2019.1592195
  • 37
    Zhu SH, Zhuang YL, Wong S, Cummins SE, Tedeschi GJ. E-cigarette use and associated changes in population smoking cessation: Evidence from US current population surveys. BMJ. 2017;358:1-8. doi: 10.1136/bmj.j3262.
    » https://doi.org/10.1136/bmj.j3262
  • 38
    Young-Wolff KC, Klebaner D, Folck B. Documentation of e-cigarette use and associations with smoking from 2012 to 2015 in an integrated healthcare delivery system. Prev Med (Baltim). 2018;109(January):113-118. doi: 10.1016/j.ypmed.2018.01.012.
    » https://doi.org/10.1016/j.ypmed.2018.01.012
  • 39
    Wills TA, Knight R, Sargent JD, Gibbons FX, Pagano I, Williams RJ. Longitudinal study of e-cigarette use and onset of cigarette smoking among high school students in Hawaii. Tob Control. 2017;26(1):34-39. doi: 10.1136/tobaccocontrol-2015-052705.
    » https://doi.org/10.1136/tobaccocontrol-2015-052705
  • 40
    Stanton CA, Bansal-Travers M, Johnson AL. Longitudinal e-Cigarette and Cigarette Use Among US Youth in the PATH Study (2013-2015). JNCI J Natl Cancer Inst. 2019;111:1-9. doi: 10.1093/jnci/djz006.
    » https://doi.org/10.1093/jnci/djz006
  • 41
    Piper ME, Baker TB, Benowitz NL, Jorenby DE. Changes in Use Patterns Over 1 Year Among Smokers and Dual Users of Combustible and Electronic Cigarettes. Nicotine Tob Res. 2019:1-9. doi: 10.1093/ntr/ntz065.
    » https://doi.org/10.1093/ntr/ntz065
  • 42
    Park SH, Duncan DT, Shahawy O El. Characteristics of Adults Who Switched From Cigarette Smoking to E-cigarettes. Am J Prev Med. 2017;53(5):652-660. doi: 10.1016/j.amepre.2017.06.033.
    » https://doi.org/10.1016/j.amepre.2017.06.033
  • 43
    Niaura R, Rich I, Johnson AL. Young Adult Tobacco and E-cigarette Use Transitions: Examining Stability Using Multistate Modeling. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz030.
    » https://doi.org/10.1093/ntr/ntz030
  • 44
    Loukas A, Marti CN, Perry CL. Trajectories of Tobacco and Nicotine Use Across Young Adulthood, Texas, 2014-2017. Am J Public Health. 2019;109(3):465-471. doi: 10.2105/AJPH.2018.304850.
    » https://doi.org/10.2105/AJPH.2018.304850
  • 45
    Carolina N, Tobacco Y, Huang L, Kowitt SD, Sutfin EL, Patel T. School Students and Its Association With Cigarette Use And Smoking Cessation. 2016:1-12.
  • 46
    Kasza KA, Coleman B, Sharma E. Correlates of transitions in tobacco product use by u.S. adult tobacco users between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2014-2015.
  • 47
    Kasza KA, Borek N, Conway KP. Transitions in tobacco product use by u.S. adults between 2013-2014 and 2014-2015: Findings from the path study wave 1 and wave 2. Int J Environ Res Public Health. 2018;15(11):2013-2014. doi: 10.3390/ijerph15112515.
    » https://doi.org/10.3390/ijerph15112515
  • 48
    Hair EC, Romberg AR, Niaura R. Longitudinal tobacco use transitions among adolescents and young adults: 2014-2016. Nicotine Tob Res. 2019. doi: 10.1093/ntr/ntx285.
    » https://doi.org/10.1093/ntr/ntx285
  • 49
    Giovenco DP, Delnevo CD. Prevalence of population smoking cessation by electronic cigarette use status in a national sample of recent smokers. Addict Behav. 2018;76(April 2017):129-134. doi: 10.1016/j.addbeh.2017.08.002.
    » https://doi.org/10.1016/j.addbeh.2017.08.002
  • 50
    Gentzke AS, Creamer ML, Cullen KA. Vital Signs: Tobacco Product Use Among Middle and High School Students - United States, 2011-2018. MMWR Morb Mortal Wkly Rep. 2019;68(6):157-164. doi: 10.15585/mmwr.mm6806e1.
    » https://doi.org/10.15585/mmwr.mm6806e1
  • 51
    Farsalinos KE, Niaura R. E-cigarettes and Smoking Cessation in the United States According to Frequency of E-cigarette Use and Quitting Duration: Analysis of the 2016 and 2017 National Health Interview Surveys. Nicotine Tob Res. 2020. doi: 10.1093/ntr/ntz025.
    » https://doi.org/10.1093/ntr/ntz025
  • 52
    Ekanem US, Cardenas VM, Cen R. Electronic nicotine delivery systems and smoking cessation in Arkansas, 2014. Public Health Rep. 2017;132(2):210-219. doi: 10.1177/0033354916689611.
    » https://doi.org/10.1177/0033354916689611
  • 53
    Chen JC. Flavored E-cigarette Use and Cigarette Smoking Reduction and Cessation-A Large National Study among Young Adult Smokers.Subst Use Misuse. 2018. doi: 10.1080/10826084.2018.1455704.
    » https://doi.org/10.1080/10826084.2018.1455704
  • 54
    Boyle RG, Amato MS, Rode P, Kinney AM, St Claire AW, TaylorK. Tobacco use among Minnesota adults, 2014. Am J Health Behav. 2015;39(5):674-679. doi: 10.5993/AJHB.39.5.9.
    » https://doi.org/10.5993/AJHB.39.5.9
  • 55
    Berry KM, Reynolds LM, Collins JM. E-cigarette initiation and associated changes in smoking cessation and reduction: The Population Assessment of Tobacco and Health Study, 2013-2015. Tob Control. 2019;28(1):42-49. doi: 10.1136/tobaccocontrol-2017-054108.
    » https://doi.org/10.1136/tobaccocontrol-2017-054108
  • 56
    Barrington-Trimis JL, Bello MS, Liu F. Ethnic Differences in Patternsof Cigarette and E-Cigarette Use Over Time Among Adolescents.J Adolesc Heal. 2019. doi: 10.1016/j.jadohealth.2019.04.002.
    » https://doi.org/10.1016/j.jadohealth.2019.04.002
  • 57
    Barrington-Trimis JL, Kong G, Leventhal AM. E-cigarette use and subsequent smoking frequency among adolescents. Pediatrics. 2018;142(6). doi: 10.1542/peds.2018-0486.
    » https://doi.org/10.1542/peds.2018-0486
  • 58
    Barrington-Trimis JL, Urman R, Leventhal AM. E-cigarettes, cigarettes, and the prevalence of adolescent tobacco use. Pediatrics. 2016;138(2). doi: 10.1542/peds.2015-3983.
    » https://doi.org/10.1542/peds.2015-3983
  • 59
    Bao W, Xu G, Lu J, Snetselaar LG, Wallace RB. Changes in Electronic Cigarette Use Among Adults in the United States, 2014-2016. JAMA. 2018. doi: 10.1001/jama.2018.4658.
    » https://doi.org/10.1001/jama.2018.4658
  • 60
    Anic GM, Holder-Hayes E, Ambrose BK, et al. E-cigarette and Smokeless Tobacco Use and Switching Among Smokers: Findings From the National Adult Tobacco Survey. Am J Prev Med. 2018;54(4):539-551. doi: 10.1016/j.amepre.2017.12.010.
    » https://doi.org/10.1016/j.amepre.2017.12.010
  • 61
    Manzoli L, Flacco ME, Ferrante M. Cohort study of electronic cigarette use: Effectiveness and safety at 24 months. Tob Control. 2017;26(3):284-292. doi: 10.1136/tobaccocontrol-2015-052822.
    » https://doi.org/10.1136/tobaccocontrol-2015-052822
  • 62
    Liu X, Lugo A, Davoli E. Electronic cigarettes in Italy: a tool for harm reduction or a gateway to smoking tobacco?. Tob Control. 2019. doi: 10.1136/tobaccocontrol-2018-054726.
    » https://doi.org/10.1136/tobaccocontrol-2018-054726
  • 63
    Flacco ME, Ferrante M, Fiore M, et al. Cohort study of electronic cigarette use: Safety and effectiveness after 4 years of follow-up. Eur Rev Med Pharmacol. Sci. 2019;23(1):402-412. doi: 10.26355/eurrev_201901_16789.
    » https://doi.org/10.26355/eurrev_201901_16789
  • 64
    Eastwood B, Dockrell MJ, Arnott D. Electronic cigarette use in young people in Great Britain 2013-2014. Public Health. 2015;129(9):1150-1156. doi: 10.1016/j.puhe.2015.07.009.
    » https://doi.org/10.1016/j.puhe.2015.07.009
  • 65
    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. doi: 10.1111/add.12917.
    » https://doi.org/10.1111/add.12917
  • 66
    Beard E, Brown J, McNeill A, Michie S, West R. Has growth in electronic cigarette use by smokers been responsible for the decline in use of licensed nicotine products?. Findings from repeatedcross-sectional surveys. Thorax. 2015;70(10):974-978. doi: 10.1136/thoraxjnl-2015-206801.
    » https://doi.org/10.1136/thoraxjnl-2015-206801
  • 67
    Orth B, Merkel C. The decline of cigarette smoking among adolescents and young adults in Germany and the rising relevance of waterpipes, e-cigarettes and e-hookahs. Bundesgesundheitsblatt - Gesundheitsforsch - Gesundheitsschutz. 2018;61(11):1377-1387. doi: 10.1007/s00103-018-2820-1.
    » https://doi.org/10.1007/s00103-018-2820-1
  • 68
    Kralikova E, Novak J, West O, Kmetova A, Hajek P. Do e-cigarettes have the potential to compete with conventional cigarettes?: A survey of conventional cigarette smokers' experiences with e-cigarettes. Chest. 2013;144(5):1609-1614. doi: 10.1378/chest.12-2842.
    » https://doi.org/10.1378/chest.12-2842
  • 69
    El-Khoury F, Bolze C, Gomajee R, White V, Melchior M. Lower smoking rates and increased perceived harm of cigarettes among French adults one year after comprehensive tobacco control measures. Drug Alcohol Depend. 2019;201(March):65-70. doi: 10.1016/j.drugalcdep.2019.03.025.
    » https://doi.org/10.1016/j.drugalcdep.2019.03.025
  • 70
    Smith DM, Gawron M, Balwicki L, Sobczak A, Matynia M, GoniewiczML. Exclusive versus dual use of tobacco and electronic cigarettes among adolescents in Poland, 2010-2016. Addict Behav. 2019;90(October 2018):341-348. doi: 10.1016/j.addbeh.2018.11.035.
    » https://doi.org/10.1016/j.addbeh.2018.11.035
  • 71
    Farsalinos KE, Poulas K, Voudris V, Le Houezec J. Electronic cigarette use in the European Union: analysis of a representative sample of 27 460 Europeans from 28 countries. Addiction. 2016. Nov;111(11):2032-2040. doi: 10.1111/add.13506.
    » https://doi.org/10.1111/add.13506
  • 72
    Jawad M, Lee JT, Glantz S, Millett C. Price elasticity of demand of non-cigarette tobacco products: A systematic review and meta-analysis. Tob Control. 2018. doi: 10.1136/tobaccocontrol-2017-054056.
    » https://doi.org/10.1136/tobaccocontrol-2017-054056
  • 73
    CDC. Lung Injury Associated with Electronic Cigarettes, or Vaping. https://interactives.nejm.org/ile/cdc_vaping/index.html Published 2019.
    » https://interactives.nejm.org/ile/cdc_vaping/index.html
  • 74
    Butt YM, Smith ML, Tazelaar HD. Pathology of Vaping-Associated Lung Injury. N Engl J Med. 2019. doi: 10.1056/nejmc1913069.
    » https://doi.org/10.1056/nejmc1913069
  • 75
    Hswen Y, Brownstein JS. Real-Time Digital Surveillance of Vaping- Induced Pulmonary Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1912818.
    » https://doi.org/10.1056/nejmc1912818
  • 76
    Henry TS, Kanne JP, Kligerman SJ. Imaging of Vaping-AssociatedLung Disease. N Engl J Med. 2019. doi: 10.1056/nejmc1911995.
    » https://doi.org/10.1056/nejmc1911995
  • 77
    Kaur G, Lungarella G, Rahman I. SARS-CoV-2 COVID-19 susceptibility and lung inflammatory storm by smoking and vaping. J Inflamm. 2020. doi: 10.1186/s12950-020-00250-8.
    » https://doi.org/10.1186/s12950-020-00250-8
  • 78
    Liu X, Lu W, Liao S. Efficiency and adverse events of electronic cigarettes: A systematic review and meta-analysis (PRISMA-com pliant article). Med (United States). 2018;97(19). doi: 10.1097/MD.0000000000010324.
    » https://doi.org/10.1097/MD.0000000000010324
  • 79
    Khouja JN, Suddell SF, Peters SE, Taylor AE, Munafo MR. Is e-cigarette use in non-smoking young adults associated with later smoking? A systematic review and meta-analysis. Tob Control. 2020. doi: 10.1136/tobaccocontrol-2019-055433.
    » https://doi.org/10.1136/tobaccocontrol-2019-055433
  • 80
    McRobbie H, Bullen C, Hajek P. Electronic cigarettes for smoking cessation and reduction ( Protocol ). Cochrane Libr. 2014;12(12):CD010216. Disponible en: www.cochranelibrary.com. doi: 10.1002/14651858.CD010216.pub2.
    » https://doi.org/10.1002/14651858.CD010216.pub2
  • 81
    Reuters Health. Juul disregarded early evidence it was hooking teens. 2019. https://www.reuters.com/investigates/special-report/juul-ecigarette/?utm_source=twitter&utm_medium=Social%0A
    » https://www.reuters.com/investigates/special-report/juul-ecigarette/?utm_source=twitter&utm_medium=Social%0A
  • 82
    Hughes JR, Adams EH, Franzon MA, Maguire MK, Guary J. A prospective study of off-label use of, abuse of, and dependence on nicotine inhaler. Tob Control. 2005. doi: 10.1136/tc.2004.008367.
    » https://doi.org/10.1136/tc.2004.008367
  • 83
    Vansickel AR, Weaver MF, Eissenberg T. Clinical laboratory assessment of the abuse liability of an electronic cigarette. Addiction. 2012. doi: 10.1111/j.1360-0443.2012.03791.x.
    » https://doi.org/10.1111/j.1360-0443.2012.03791.x
  • 84
    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. Subst Abus Res Treat. 2013. doi: 10.4137/SART.S12756.
    » https://doi.org/10.4137/SART.S12756
  • 85
    Gottlieb S, Zeller M. A Nicotine-Focused Framework for Public Health. N Engl J Med. 2017;377(12):1111-1114. doi: 10.1056/NEJMp1707409.
    » https://doi.org/10.1056/NEJMp1707409
  • 86
    Ciapponi A, Glujovsky D, Virgilio SA, Bardach AE. Conducting and Disseminating Epidemiological Systematic Reviews in Latin America and the Caribbean: Pitfalls and Lessons Learned. Value Heal Reg Issues. 2017. doi: 10.1016/j.vhri.2017.07.011.
    » https://doi.org/10.1016/j.vhri.2017.07.011

  • Cite as:

    Ciapponi A, Cairoli FR, Solioz G, Rojas-Roque C, Hernández- Vásquez A, Palacios A, et al. Switching from cigarettes to electronic nicotine delivery system: Rapid systematic review and meta-analysis and economic aspects. Rev Peru Med Exp Salud Publica. 2021;38(4):537-50. doi: https://doi. org/10.17843/rpmesp.2021.384.7776.

  • Sources of funding:

    Self-funded.

  • Supplementary material:

    Available in the electronic version of the RPMESP.

Publication Dates

  • Publication in this collection
    01 Apr 2022
  • Date of issue
    Oct-Dec 2021

History

  • Received
    31 Mar 2021
  • Accepted
    17 Nov 2021
Instituto Nacional de Salud Lima - Lima - Peru
E-mail: revmedex@ins.gob.pe