Health effects in COPD smokers who switch to electronic cigarettes: a retrospective-prospective 3-year follow-up

Assessing the association between e-cigarette use and cardiovascular disease: A meta-analysis of exclusive and dual use with combustible cigarettes

BACKGROUND

Growing evidence highlights the impact of e-cigarette use on cardiovascular health, prompting a crucial examination of its association with cardiovascular disease (CVD) in both exclusive e-cigarette and dual use scenarios with combustible cigarettes. This meta-analysis assessed the association between e-cigarette use and CVD by synthesizing the existing literature.

METHODS

Pertinent observational studies were identified using multiple electronic databases, from August 22nd, 2006, to April 10th, 2024. A meta-analysis was conducted using random-effect models. Risk of bias was assessed using the National Institutes of Health (NIH) Study Quality Assessment Tools.

FINDINGS

A total of 20 observational studies involving 8,499,444 participants were included in the meta-analysis. Dual use (e-cigarettes and combustible cigarette) increased the odds of CVD by 2.56 times (95 % CI: 2.11, 3.11) compared to never use of both. Current e-cigarette use combined with former combustible cigarette increased the odds of CVD by 2.02 times (95 % CI: 1.58, 2.58) compared to never use of either. Exclusive current e-cigarette use did not show a statistically significant association with CVD odds compared to never use of either (OR = 1.24, 95 % CI: 0.93, 1.67).

CONCLUSIONS

Dual use of e-cigarettes and combustible cigarettes was significantly associated with CVD, but results failed to show a significant association between exclusive e-cigarette use and CVD. Robust and longitudinal studies are needed to understand the long-term implications of e-cigarette use and CVD. Public health efforts should focus on awareness, smoking cessation, and regulating both e-cigarettes and combustible cigarettes.

Smoking cessation program preferences of individuals with chronic obstructive pulmonary disease: a qualitative study

AIM

To explore the views of tobacco-smoking chronic obstructive pulmonary disease (COPD) and asthma-COPD overlap (ACO) patients on telehealth-based cessation programs and the role of e-cigarettes as an aid to quit smoking.

BACKGROUND

Tobacco smoking accelerates the progression of COPD. Traditional smoking cessation programs often do not entirely address the unique needs of COPD patients, leading to suboptimal effectiveness for this population. This research is aimed at describing the attitudes and preferences of COPD and ACO patients toward innovative, telehealth-based smoking cessation strategies and the potential application of e-cigarettes as a quitting aid.

METHODS

A qualitative exploratory approach was adopted in this study, employing both focus groups and individual interviews with English-speaking adults with diagnosed COPD or ACO. Participants included both current smokers (≥ 5 cigarettes/day) and recent ex-smokers (who quit < 12 months ago). Data were systematically coded with iterative reliability checks and subjected to thematic analysis to extract key themes.

FINDINGS

A total of 24 individuals participated in this study. The emergent themes were the perceived structure and elements of a successful smoking cessation program, the possible integration of telehealth with digital technologies, and the strategic use of e-cigarettes for smoking reduction or cessation. The participants stressed the importance of both social and professional support in facilitating smoking cessation, expressing a high value for insights provided by ex-smokers serving as mentors. A preference was observed for group settings; however, the need for individualized plans was also highlighted, considering the diverse motivations individuals had to quit smoking. The participants perceived online program delivery as potentially beneficial as it could provide immediate access to support during cravings or withdrawals and was accessible to remote users. Opinions on e-cigarettes were mixed; some participants saw them as a less harmful alternative to conventional smoking, while others were skeptical of their efficacy and safety and called for further research.

Effects of Combustible Cigarettes and Electronic Nicotine Delivery Systems on the Development and Progression of Chronic Lung Inflammation in Mice

INTRODUCTION

Although detrimental effects of combustible cigarettes (CCs) on the progression of lung inflammatory diseases are well known, changes in electronic nicotine delivery systems (ENDS)-exposed lung-infiltrated immune cells are still unrevealed.

AIMS AND METHODS

The analysis of blood gas parameters, descriptive and quantitative histology of lung tissues, determination of serum cytokines, intracellular staining, and flow cytometry analysis of lung-infiltrated immune cells were used to determine the differences in the extent of lung injury and inflammation between mice from experimental (CC and ENDS-exposed animals) and control groups (Air-exposed mice).

RESULTS

Continuous exposition to either CCs or ENDS induced severe systemic inflammatory response, increased activation of NLRP3 inflammasome in neutrophils and macrophages and enhanced dendritic cell-dependent activation of Th1 and Th17 cells in the lungs. ENDS induced less severe immune response than CCs. Serum concentrations of inflammatory cytokines were significantly lower in the samples of ENDS-exposed mice. Compared to CCs, ENDS recruited lower number of circulating leukocytes in injured lungs and had less capacity to induce CD14/TLR2-dependent activation of NLRP3 inflammasome in lung-infiltrated neutrophils and macrophages. ENDS-primed dendritic cells had reduced capacity for the generation of Th1 and Th17 cell-driven lung inflammation. Accordingly, extensive immune cell-driven lung injury resulted in severe respiratory dysfunction in CCs-exposed mice, while ENDS caused moderate respiratory dysfunction in experimental animals.

CONCLUSIONS

Continuous exposition to either CCs or ENDS induced immune cell-driven lung damage in mice. ENDS triggered immune response, which was less potent than inflammatory response elicited by CCs and, therefore, caused less severe lung injury and inflammation.

IMPLICATIONS

This is the first study that compared the effects of CCs and ENDS on lung-infiltrated immune cells. Although both CCs and ENDS elicited systemic inflammatory response, immune cell-driven lung injury and inflammation were less severe in ENDS-exposed than in CC-exposed animals. Continuous exposition to ENDS-sourced aerosols was less harmful for respiratory function of experimental animals than CC-derived smoke.

Documento de consenso sobre tabaquismo y riesgo vascular

Consensus statement on smoking and vascular risk About 22% of the Spanish population are daily smokers. Men are more likely to smoke than women. In Spain, women between 15-25 years of age smoke as much or more than men. Every smoker should be assessed for: physical dependence on nicotine (Fagerström test), social and psychological dependence (Glover Nilsson test), level of motivation to quit (Richmond test), probability of therapy success (Henri-Mondor and Michael-Fiore tests), and stage of behavioral change development (Prochaska and DiClementi). Advice on smoking cessation is highly cost-effective and should always be provided. Smoking is an enhancer of cardiovascular risk because it acts as a pathogen agent in the development of arteriosclerosis and is associated with ischemic heart disease, stroke, and peripheral artery disease. Smoking increases the risk of chronic lung diseases (COPD) and is related to cancers of the lung, female genitalia, larynx, oropharynx, bladder, mouth, esophagus, liver and biliary tract, and stomach, among others. Combined oral contraceptives should be avoided in women smokers older than 35 years of age due to the risk of thromboembolism. In smoking cessation, the involvement of physicians, nurses, psychologists, etc. is important, and their multidisciplinary collaboration is needed. Effective pharmacological treatments for smoking cessation are available. Combined treatments are recommended when smoker's dependence is high. For individuals who are unable to quit smoking, a strategy based on tobacco damage management with a total switch to smokeless products could be a less dangerous alternative for their health than continuing to smoke.

Protocol for the "magnitude of cigarette substitution after initiation of e-cigarettes and its impact on biomarkers of exposure and potential harm in dual users" (MAGNIFICAT) study

Introduction

Many smokers who use e-cigarettes (ECs) to quit continue smoking alongside vaping. The impact on health among individuals who simultaneously smoke conventional cigarettes (CCs) and use ECs remains unclear. The varying patterns of dual use present differing levels of overall toxin exposure and relative risks concerning smoking-related diseases. Understanding these complexities is vital to assessing the implications for human health.

Objective

Herein we describe a protocol designed to analyze the impact of different level of substituting CCs with ECs on exposure to toxicants. We'll use biomarkers to measure this exposure and assess harm reduction in dual users through clinical endpoints, harm-related biomarkers, and behavioral correlations. We expect to observe progressive changes with varying patterns of dual use.

Methods and analyses

For this purpose, we planned to recruit a group of 250 smokers who will be asked to reduce their CC consumption by adopting ECs (intervention group). A separate group of 50 smokers will continue to smoke CC (reference group). Study groups will be followed up for 6 months during which biospecimens will be collected for biomarker analyses, and clinical endpoints will be assessed. The trial is structured to characterize subjects' usage patterns over time using robust biomarkers of exposure and a standardized mobile phone application to facilitate the precise categorization of dual users along the risk continuum based on their usage behaviors. Subject recruitment will start in February 2024 and enrolment is expected to be completed by August 2024. Results will be reported early in 2025. Study findings may provide valuable insights into health benefits or risks associated with varying patterns of dual use.

Ethics and dissemination

The study protocol and informed consent forms will be approved by the local Ethical Review Boards. Study results will be disseminated through articles published in reputable, peer-reviewed, open access, scientific journals, presentations at conferences, and the University website.

A multicenter prospective randomized controlled trial investigating the effects of combustion-free nicotine alternatives on cardiovascular risk factors and metabolic parameters in individuals with type 2 diabetes who smoke: the DiaSmokeFree study protocol

Stopping smoking is crucial for public health and especially for individuals with diabetes. Combustion-free nicotine alternatives like e-cigarettes and heated tobacco products are increasingly being used as substitutes for conventional cigarettes, contributing to the decline in smoking prevalence. However, there is limited information about the long-term health impact of those products in patients with diabetes. This randomized controlled trial aims to investigate whether switching from conventional cigarettes to combustion-free nicotine alternatives will lead to a measurable improvement in cardiovascular risk factors and metabolic parameters over a period of 2 years in smokers with type 2 diabetes. The multicenter study will be conducted in seven sites across four countries. A total of 576 smokers with type 2 diabetes will be randomly assigned (1:2 ratio) to either standard of care with brief cessation advice (Control Arm) or combustion-free nicotine alternatives use (Intervention Arm). The primary end point is the change in the proportion of patients with metabolic syndrome between baseline and the 2-year follow-up. Additionally, the study will analyze the absolute change in the sum of the individual factors of metabolic syndrome at each study time point. Patient recruitment has started in September 2021 and enrollment is expected to be completed by December 2023. Results will be reported in 2026. This study may provide valuable insights into cardiovascular and metabolic health benefits or risks associated with using combustion-free nicotine alternatives for individuals with type 2 diabetes who are seeking alternatives to tobacco cigarette smoking. The study protocol, informed consent forms, and relevant documents were approved by seven ethical review boards. Study results will be disseminated through articles published in high-quality, peer-reviewed journals and presentations at conferences.

The online promotion strategies of e-cigarette and heated tobacco product retailers in South Korea following the COVID-19 pandemic: Implications for regulation

INTRODUCTION

The surge in popularity of e-cigarettes and heated tobacco products (HTPs) in South Korea, driven by perceived health benefits and COVID-19-related concerns, has led to increased advertising claims about their safety despite ongoing debates about their health effects. This study explores the marketing strategies of online e-cigarette and HTP retailers in South Korea pre- and post-COVID-19, examining potential misleading claims and providing a foundation for future regulatory measures.

METHODS

We conducted a comprehensive study of eight major e-commerce platforms and three dominant search engines in South Korea to analyze the marketing and advertising strategies of e-cigarettes and heated tobacco products (HTPs) (n=774). Using specific keywords, promotional strategies were identified and categorized, after which statistical analysis was conducted to understand the frequency and proportion of these strategies, highlighting differences between HTP and e-cigarette sellers.

RESULTS

Our analysis reveals a significant rise in the number of online retailers selling e-cigarettes and HTPs following the COVID-19 pandemic, with the promotional strategies 'Stay home and vape' and 'Trendy' being the most prevalent. Trends also indicate a shift in promotional strategies over the years, with a marked increase in health reassurance themes and appeals to trendiness, particularly targeting female consumers, which were used significantly more at HTPs stores.

CONCLUSIONS

The study highlights the need for stricter regulation due to the potential health risks posed by the aggressive marketing strategies of e-cigarette and HTP online retailers in South Korea, amplified by the COVID-19 pandemic.

Varenicline for smoking cessation in individuals who smoke cigarettes and use electronic cigarettes: a double-blind, randomised, placebo-controlled phase 3 trial

Background

The efficacy and safety of varenicline for smoking cessation among individuals who smoke tobacco cigarettes and also use electronic cigarettes (known e-cigarettes or vapes) have not been studied. We aimed to address this knowledge gap and examine predictors for smoking abstinence.

Methods

In this double-blind, placebo-controlled, single-centre randomised trial in Italy, we enrolled adults who had used an e-cigarette daily for at least 12 months and who also smoked at least one tobacco cigarette per day and had a willingness to quit smoking. 155 participants were randomly assigned to receive either varenicline (n = 78) or matched placebo (n = 77). Varenicline (1 mg, administered twice daily for 12 weeks) was given in combination with smoking cessation counseling in dual users with an intention to quit smoking. Participants in both treatment groups received the same smoking cessation counselling throughout the whole duration of the study. The trial consisted of a 12-week treatment phase followed by a 12-week follow-up. The primary efficacy endpoint was continuous abstinence rate (CAR) in weeks 4-12. Secondary efficacy endpoints were the CAR in weeks 4-24 and 7-day point prevalence of smoking abstinence at weeks 12 and 24. This study is registered in EUDRACT, 2016-000339-42.

Findings

Between November 2018, and February 2020, 114 participants (61 in the varenicline group and 53 in the placebo group) completed the intervention phase at week 12 and 88 participants (52 in the varenicline group and 36 in the placebo group) completed the follow-up phase at week 24. CARs were significantly higher for the varenicline vs placebo at each time-point: 50.0% vs 16.9% (OR = 4.9; 95% CI, 2.3-10.4; P < 0.0001) between weeks 4 and 12; and 48.7% vs 14.3% (OR = 5.7; 95% CI, 2.6-12.3; P < 0.0001) between weeks 4 and 24. The 7-day point prevalence of smoking abstinence was also higher for the varenicline than placebo at each time point. Adverse events were rated as mild or moderate and rarely led to treatment discontinuation.

Interpretation

Our findings indicate that inclusion of varenicline in a cessation programme for adults who smoke and use e-cigarettes with an intention to quit smoking could result in smoking abstinence without serious adverse events. In the absence of evidence from other smoking cessation methods, it could be useful to suggest the use of varenicline in cessation programmes specifically designed to help dual users stop smoking. Further research in larger and more generalisable populations is required to strengthen such a suggestion.

Funding

Global Research Award for Nicotine Dependence, an independently reviewed competitive grants programmeme funded by Pfizer.

Respiratory health effects of e-cigarette substitution for tobacco cigarettes: a systematic review

BACKGROUND

E-cigarettes (electronic nicotine delivery system, ENDS) have been presented as a harm reduction strategy for people who smoke tobacco cigarettes but who cannot achieve abstinence, or for those who wish to continue to enjoy nicotine and the habit of smoking. What are the health effects of the substitution of ENDS for tobacco cigarettes? This systematic review evaluates the evidence of human clinical tests on the respiratory effects of ENDS use in participants who smoke tobacco cigarettes.

METHODS

A registered and published protocol was developed conforming to PRISMA 2020 and AMSTAR2 standards. The literature search was conducted in PubMed, Scopus, and the CENTRAL Cochrane Library and updated to May 2022. Three supplementary searches and a grey literature search were performed. Studies were evaluated with the JBI quality tools and the Oxford Catalogue of Bias. Due to the heterogeneity (diversity) of the studies, a narrative data synthesis was performed on the test findings plus three sub-group analyses.

RESULTS

The review consists of sixteen studies and twenty publications. Spirometry tests comprised the majority of the data. In total, 66 respiratory test measurements were reported, out of which 43 (65%) were not significant. Statistically significant findings were mixed, with 9 tests showing improvements and 14 measuring declines, none of which was clinically relevant. Ten studies were rated at a high risk of bias, and six had some concerns primarily due to inadequate research designs and the conduct of the studies. Reporting bias was documented in thirteen studies.

CONCLUSIONS

Most of the studies showed no difference in respiratory parameters. This indicates that ENDS substitution for smoking likely does not result in additional harm to respiratory health. Due to the low quality of the studies, confidence in the conclusions is rated as low. Robust studies with a longer duration and sufficient power are required to validate any potential benefits or possible harms of ENDS substitution. Registration PROSPERO #CRD42021239094, International Registered Report Identifier (IRRID): DERR1-10.2196/29084.

Cardiopulmonary Impact of Electronic Cigarettes and Vaping Products: A Scientific Statement From the American Heart Association

Vaping and electronic cigarette (e-cigarette) use have grown exponentially in the past decade, particularly among youth and young adults. Cigarette smoking is a risk factor for both cardiovascular and pulmonary disease. Because of their more limited ingredients and the absence of combustion, e-cigarettes and vaping products are often touted as safer alternative and potential tobacco-cessation products. The outbreak of e-cigarette or vaping product use-associated lung injury in the United States in 2019, which led to >2800 hospitalizations, highlighted the risks of e-cigarettes and vaping products. Currently, all e-cigarettes are regulated as tobacco products and thus do not undergo the premarket animal and human safety studies required of a drug product or medical device. Because youth prevalence of e-cigarette and vaping product use was as high as 27.5% in high school students in 2019 in the United States, it is critical to assess the short-term and long-term health effects of these products, as well as the development of interventional and public health efforts to reduce youth use. The objectives of this scientific statement are (1) to describe and discuss e-cigarettes and vaping products use patterns among youth and adults; (2) to identify harmful and potentially harmful constituents in vaping aerosols; (3) to critically assess the molecular, animal, and clinical evidence on the acute and chronic cardiovascular and pulmonary risks of e-cigarette and vaping products use; (4) to describe the current evidence of e-cigarettes and vaping products as potential tobacco-cessation products; and (5) to summarize current public health and regulatory efforts of e-cigarettes and vaping products. It is timely, therefore, to review the short-term and especially the long-term implications of e-cigarettes and vaping products on cardiopulmonary health. Early molecular and clinical evidence suggests various acute physiological effects from electronic nicotine delivery systems, particularly those containing nicotine. Additional clinical and animal-exposure model research is critically needed as the use of these products continues to grow.

Smoking cessation and vaccination

A significant proportion of COPD patients (∼40%) continue smoking despite knowing that they have the disease. Smokers with COPD exhibit higher levels of nicotine dependence, and have lower self-efficacy and self-esteem, which affects their ability to quit smoking. Treatment should be adapted to the needs of individual patients with different levels of tobacco dependence. The combination of counselling plus pharmacotherapy is the most effective cessation treatment for COPD. In patients with severe COPD, varenicline and bupropion have been shown to have the highest abstinence rates compared with nicotine replacement therapy. There is a lack of evidence to support that smoking cessation reduction or harm reduction strategies have benefits in COPD patients. The long-term efficacy and safety of electronic cigarettes for smoking cessation need to be evaluated in high-risk populations; therefore, it is not possible to recommend their use for smoking cessation in COPD. Future studies with the new generation of nicotine vaccines are necessary to determine their effectiveness in smokers in general and in COPD patients.

Perceived Health and Capacity to Cope With Stress in Recent Ex-smokers: Impact of Vaping Versus Quitting All Nicotine

INTRODUCTION

Little is known about the continued use of nicotine following smoking cessation on perceived well-being in comparison to complete cessation of nicotine use.

AIMS AND METHODS

To explore aspects of perceived well-being and coping among recent ex-smokers as a function of vaping status. Ever-daily smokers in the International Tobacco Control 4 country smoking and vaping surveys in 2016 (w1 N = 883) and 2018 (w2 N = 1088). Cross-sectional associations and longitudinal samples for those who quit between waves and those who quit at w1 and maintained abstinence to w2. Main outcome measures were: Past 30 days of depression symptoms, perceived stress, stress management since quitting, and change in perceived day-to-day health.

RESULTS

In the cross-sectional analyses vapers were more likely to report both improved stress management (aOR = 1.71, 95% CI 1.23-2.36) and perceived day-to-day health (aOR = 1.65, 95% CI 1.26-2.16) than nicotine abstainers. In the longitudinal analyses, smokers who switched to vaping between waves (n = 372) were more likely to report depression symptoms at w2 (aOR = 2.00, 95% CI 1.09-3.65) but reported improved perceived health (aOR = 1.92, 95% CI 1.16-3.20). For the past daily smokers who remained quit between waves (n = 382), vapers were more likely to report improved stress management relative to abstainers (RRR = 5.05. 95% CI 1.19-21.40). There were no other significant differences between vapers and nicotine abstainers.

CONCLUSIONS

There is little evidence to support the view that perceptions of well-being deteriorate in vapers compared to complete nicotine abstainers in the immediate years after smoking cessation.

IMPLICATIONS

This study could find no conclusive evidence that the continued use of nicotine via e-cigarettes was detrimental to health compared to completely stopping nicotine intake altogether. Our results would suggest that continuing to use nicotine may even result in some benefits in the short term such as improved stress management, however further longitudinal studies are required to examine if these effects are restricted to the early post-quitting phase and whether other positive or negative effects on psychosocial health emerge in the future.

Update on new forms of tobacco use

Smoking remains the leading cause of morbidity and mortality worldwide. Because of its clear influence on cardiovascular and respiratory diseases, it is an important factor in internal medicine consultations. Although the rate of smoking cessation has been increasing in recent years, there is a percentage of patients who continue to smoke because they are unable or unwilling to quit, despite having tried existing pharmacological and non-pharmacological therapies. For this group of patients there are strategies based on interventions aimed at reducing the negative effects of smoking without the need for complete cessation. In this review it is shown that due to the absence of combustion of organic matter in conventional cigarettes, snus, e-cigarettes and heated tobacco products generate significantly lower levels of toxic substances.

Chronic health effects associated with electronic cigarette use: A systematic review

Introduction

Over the last decade, e-cigarette use has been on the rise but with growing health concerns. The objective of this systematic review was to update findings for chronic health outcomes associated with e-cigarette use from the 2018 National Academies of Sciences, Engineering, and Medicine (NASEM) report.

Methods

Three bibliographic databases were searched to identify studies comparing the chronic health effects of e-cigarette users (ECU) to non-smokers (NS), smokers, and/or dual users indexed between 31 August 2017 and 29 January 2021. Two independent reviewers screened abstracts and full texts. Data were extracted by one reviewer and verified by a second one. Outcomes were synthesized in a narrative manner using counts and based on statistical significance and direction of the association stratified by study design and exposure type. Risk of bias and certainty of evidence was assessed. The protocol was prospectively registered on Open Science Framework https://osf.io/u9btp.

Results

A total of 180 articles were eligible. This review focused on 93 studies for the 11 most frequently reported outcomes and from which 59 reported on daily e-cigarette use. The certainty of evidence for all outcomes was very low because of study design (84% cross-sectional) and exposure type (27% reported on exclusive ECU, i.e., never smoked traditional cigarettes). Overall, the summary of results for nearly all outcomes, including inflammation, immune response, periodontal and peri-implant clinical parameters, lung function, respiratory symptoms, and cardiovascular disease, suggested either non-significant or mixed results when daily ECU was compared to NS. This was also observed when comparing exclusive ECU to NS. The only notable exception was related to oral health where most (11/14) studies reported significantly higher inflammation among daily ECU vs. NS. Compared to the smokers, the exclusive-ECUs had no statistically significant differences in inflammation orperiodontal clinical parameters but had mixed findings for peri-implant clinical parameters.

Conclusions

This review provides an update to the 2018 NASEM report on chronic health effects of e-cigarette use. While the number of studies has grown, the certainty of evidence remains very low largely because of cross-sectional designs and lack of reporting on exclusive e-cigarette exposure. There remains a need for higher quality intervention and prospective studies to assess causality, with a focus on exclusive e-cigarette use.

Association of tobacco product use with chronic obstructive pulmonary disease (COPD) prevalence and incidence in Waves 1 through 5 (2013-2019) of the Population Assessment of Tobacco and Health (PATH) Study

BACKGROUND

We examined the association of non-cigarette tobacco use on chronic obstructive pulmonary disease (COPD) risk in the Population Assessment of Tobacco and Health (PATH) Study.

METHODS

There were 13,752 participants ≥ 40 years with Wave 1 (W1) data for prevalence analyses, including 6945 adults without COPD for incidence analyses; W1-5 (2013-2019) data were analyzed. W1 tobacco use was modeled as 12 mutually-exclusive categories of past 30-day (P30D) single and polyuse, with two reference categories (current exclusive cigarette and never tobacco). Prevalence and incidence ratios of self-reported physician-diagnosed COPD were estimated using weighted multivariable Poisson regression.

RESULTS

W1 mean (SE) age was 58.1(0.1) years; mean cigarette pack-years was similar for all categories involving cigarettes and exclusive use of e-cigarettes (all > 20), greater than exclusive cigar users (< 10); and COPD prevalence was 7.7%. Compared to P30D cigarette use, never tobacco, former tobacco, and cigar use were associated with lower COPD prevalence (RR = 0.33, (95% confidence interval-CI) [0.26, 0.42]; RR = 0.57, CI [0.47, 0.70]; RR = 0.46, CI [0.28, 0.76], respectively); compared to never tobacco use, all categories except cigar and smokeless tobacco use were associated with higher COPD prevalence (RR former = 1.72, CI [1.33, 2.23]; RR cigarette = 3.00, CI [2.37, 3.80]; RR e-cigarette = 2.22, CI [1.44, 3.42]; RR cigarette + e-cigarette = 3.10, CI [2.39, 4.02]; RR polycombusted = 3.37, CI [2.44, 4.65]; RR polycombusted plus noncombusted = 2.75, CI]1.99, 3.81]). COPD incidence from W2-5 was 5.8%. Never and former tobacco users had lower COPD risk compared to current cigarette smokers (RR = 0.52, CI [0.35, 0.77]; RR = 0.47, CI [0.32, 0.70], respectively). Compared to never use, cigarette, smokeless, cigarette plus e-cigarette, and polycombusted tobacco use were associated with higher COPD incidence (RR = 1.92, CI [1.29, 2.86]; RR = 2.08, CI [1.07, 4.03]; RR = 1.99, CI [1.29, 3.07]; RR = 2.59, CI [1.60, 4.21], respectively); exclusive use of e-cigarettes was not (RR = 1.36, CI [0.55, 3.39]).

CONCLUSIONS

E-cigarettes and all use categories involving cigarettes were associated with higher COPD prevalence compared to never use, reflecting, in part, the high burden of cigarette exposure in these groups. Cigarette-but not exclusive e-cigarette-use was also strongly associated with higher COPD incidence. Compared to cigarette use, only quitting tobacco was protective against COPD development.

What Are the Effects of Electronic Cigarettes on Lung Function Compared to Non-Electronic Cigarettes? A Systematic Analysis

Objective: The effects of e-cigarettes on lung function were compared between the e-cigarette and the non-e-cigarette group, as well as self-changes after inhaling e-cigarettes.

Method: From March 1st, 2022, relevant literature was selected from four databases through a predefined retrieval strategy. Strict literature screening and quality evaluation were conducted. The study followed PRISMA guidelines.

Results: Our results showed that CO (SMD: −1.48, 95%: −2.82–0.15) and FeNO (SMD: −0.66, 95%: −1.32, −0.01) were significantly decreased after e-cigarette usage. Only asthmatic smokers showed a statistically significant increase in flow resistance after inhaling e-cigarettes. Conversely, the decrease of FEV1/FVC% in the non-e-cigarette groups exceeded that in the e-cigarette group (SMD:1.18, 95%: 0.11–2.26). The degree of O₂ saturation decrease was also less than that for the cigarette groups (SMD:0.32, 95%: 0.04–0.59), especially when compared to the conventional cigarette group (SMD:0.56, 95%: 0.04–1.08).

Conclusion: The current findings indicate that short-term e-cigarette inhalation has a similar (but not significant) effect on lung function, as compared with non-e-cigarettes. More clinical studies are needed to explore the safety of inhaling e-cigarettes, especially in vulnerable populations.

Developments in smoking cessation interventions for patients with chronic obstructive pulmonary disease in the past 5 years: a scoping review

INTRODUCTION

Smoking cessation is the most effective strategy for slowing the progression of chronic obstructive pulmonary disease (COPD). However, COPD patients find it difficult to quit smoking with standard cessation interventions.

AREAS COVERED

A scoping review of smoking cessation for COPD patients was conducted by searching the MEDLINE, Embase, and Cochrane Library databases for all studies published between 1 January 2016 and 22 September 2021. Four themes were set up and 47 studies were included eventually. The majority of the included studies (61.7%, 29/47) investigated efficacy and effectiveness, including new strategies for extended treatment and mobile health (mHealth) delivery approach. Studies examining accessibility and utilization (31.9%, 15/47), safety (10.6%, 5/47), and health economics (6.4%, 3/47) were also reviewed. The quality of the included randomized controlled trials was also evaluated.

EXPERT OPINION

Pharmacotherapy combined with behavioral interventions delivered via mHealth may be a promising strategy to help COPD smokers quit. However, the overall quality of the current studies is poor, making it challenging for clinicians to make informed decisions. Future high-quality studies are needed to provide conclusive evidence on the optimal pharmacotherapies and the most cost-effective comprehensive smoking cessation interventions, particularly those integrated into disease management for smokers with COPD.

Electronic cigarette liquids impair metabolic cooperation and alter proteomic profiles in V79 cells

Background

Although still considered a safer alternative to classical cigarettes, growing body of work points to harmful effects of electronic cigarettes (e-cigarettes) affecting a range of cellular processes. The biological effect of e-cigarettes needs to be investigated in more detail considering their widespread use.

Methods

In this study, we treated V79 lung fibroblasts with sub-cytotoxic concentration of e-cigarette liquids, with and without nicotine. Mutagenicity was evaluated by HPRT assay, genotoxicity by comet assay and the effect on cellular communication by metabolic cooperation assay. Additionally, comprehensive proteome analysis was performed via high resolution, parallel accumulation serial fragmentation-PASEF mass spectrometry.

Results

E-cigarette liquid concentration used in this study showed no mutagenic or genotoxic effect, however it negatively impacted metabolic cooperation between V79 cells. Both e-cigarette liquids induced significant depletion in total number of proteins and impairment of mitochondrial function in treated cells. The focal adhesion proteins were upregulated, which is in accordance with the results of metabolic cooperation assay. Increased presence of posttranslational modifications (PTMs), including carbonylation and direct oxidative modifications, was observed. Data are available via ProteomeXchange with identifier PXD032071.

Conclusions

Our study revealed impairment of metabolic cooperation as well as significant proteome and PTMs alterations in V79 cells treated with e-cigarette liquid warranting future studies on e-cigarettes health impact.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02102-w.

Transcriptomic Evidence That Switching from Tobacco to Electronic Cigarettes Does Not Reverse Damage to the Respiratory Epithelium

The health benefits of switching from tobacco to electronic cigarettes (ECs) are neither confirmed nor well characterized. To address this problem, we used RNA-seq analysis to compare the nasal epithelium transcriptome from the following groups (n = 3 for each group): (1) former smokers who completely switched to second generation ECs for at least 6 months, (2) current tobacco cigarette smokers (CS), and (3) non-smokers (NS). Group three included one former cigarette smoker. The nasal epithelial biopsies from the EC users vs. NS had a higher number of differentially expressed genes (DEGs) than biopsies from the CS vs. NS and CS vs. EC sets (1817 DEGs total for the EC vs. NS, 407 DEGs for the CS vs. NS, and 116 DEGs for the CS vs. EC comparison). In the EC vs. NS comparison, enriched gene ontology terms for the downregulated DEGs included cilium assembly and organization, whereas gene ontologies for upregulated DEGs included immune response, keratinization, and NADPH oxidase. Similarly, ontologies for cilium movement were enriched in the downregulated DEGs for the CS vs. NS group. Reactome pathway analysis gave similar results and also identified keratinization and cornified envelope in the upregulated DEGs in the EC vs. NS comparison. In the CS vs. NS comparison, the enriched Reactome pathways for upregulated DEGs included biological oxidations and several metabolic processes. Regulator effects identified for the EC vs. NS comparison were inflammatory response, cell movement of phagocytes and degranulation of phagocytes. Disease Ontology Sematic Enrichment analysis identified lung disease, mouth disease, periodontal disease and pulmonary fibrosis in the EC vs. NS comparison. Squamous metaplasia associated markers, keratin 10, keratin 13 and involucrin, were increased in the EC vs. NS comparison. Our transcriptomic analysis showed that gene expression profiles associated with EC use are not equivalent to those from non-smokers. EC use may interfere with airway epithelium recovery by promoting increased oxidative stress, inhibition of ciliogenesis, and maintaining an inflammatory response. These transcriptomic alterations may contribute to the progression of diseases with chronic EC use.

Vaping-Associated Lung Injury: A Review

Since commercial development in 2003, the usage of modern electronic cigarette (e-cigarette) continues to increase amongst people who have never smoked, ex-smokers who have switched to e-cigarettes, and dual-users of both conventional cigarettes and e-cigarettes. With such an increase in use, knowledge of the irritative, toxic and potential carcinogenic effects on the lungs is increasing. This review article will discuss the background of e-cigarettes, vaping devices and explore their popularity. We will further summarise the available literature describing the mechanism of lung injury caused by e-cigarette or vaping use.

Electronic cigarettes as a harm reduction strategy among patients with COPD: protocol for an open-label two arm randomized controlled pilot trial

BACKGROUND

Smoking cessation is the most effective means of slowing the decline of lung function associated with chronic obstructive pulmonary disease (COPD). While effective smoking cessation treatments are available, they are underutilized and nearly half of people with COPD continue to smoke. By addressing both nicotine and behavioral dependence, electronic cigarettes (EC) could help people with COPD reduce the harm of combustible cigarettes (CC) through reductions in number of Cigarettes per Day (CPD) or quitting CC completely. The purpose of this pilot study is to identify barriers and facilitators to the use of and assess the preliminary effectiveness of EC as a harm reduction strategy among people with COPD.

METHODS

In an open-label two-arm randomized controlled trial pilot study, 60 patients identified as smokers with a COPD diagnosis via electronic health records from a large urban health center are randomized in a 1:1 ratio to either standard care [counseling + nicotine replacement therapy (NRT)] or counseling + EC. The NRT arm will receive nicotine patches and nicotine lozenges for 12 weeks. The EC arm will receive EC for 12 weeks. Both cohorts will receive counseling from a licensed mental health counselor. Using ecological momentary assessment, participants will report their use of CC in both arms and EC use in the EC arm daily via text message. Primary outcomes will be feasibility and acceptability of intervention, and secondary outcomes will be reduction in CPD and change in COPD symptoms as measured by COPD Assessment Tool (CAT) score at 12-weeks. EC displacement of CC. To explore attitudes towards the use of EC as a harm-reduction strategy for patients with COPD, interviews will be performed with a sample of participants from both study arms.

DISCUSSION

Despite decades of availability of smoking cessation medications, nearly half of people with COPD still smoke. This study aims to address the unmet need for feasible and effective strategies for reducing CC use among those with COPD, which has the potential to significantly improve the health of people with COPD who smoke. Trial Registration ClinicalTrials.gov Identifier: NCT04465318.

A scoping review of studies on the health impact of electronic nicotine delivery systems

We conducted a scoping review of studies on health outcomes from electronic nicotine delivery systems (ENDS). The objective was to identify, narratively synthesize, assess the strength and quality of evidence and critically appraise studies that have reported disease end points associated with the use of ENDS. We included published literature on the health impact of ENDS from 01/01/2015 until 01/02/2020 following the PRISMA guidelines using PubMed, Embase, Scopus and Google Scholar. The database search identified 755 studies, and other sources 265; 37 studies met final eligibility criteria. Levels of evidence included 24(65%) cross-sectional, one (2.7%) case-control and six (16%) case studies, four (11%) cohort studies, one (2.7%) randomized controlled trial (RCT) and one (2.7%) meta-analysis; 27(73%) studies reported only on harms, eight (22%) reported on benefits, two (2%) on benefits and harms. Quality ratings were poor in 20 (54%), fair in 9(24%) and good in 8(22%) of studies. In our review, ENDS was not shown to be causative for harmful cardiovascular disease (CVD) outcomes and shown to be beneficial for hypertensive patients. Switching from cigarettes to e-cigarettes resulted in reduced exacerbations of chronic obstructive pulmonary disease (COPD), with no evidence of long-term deterioration in lung function. Mental Health, cancer and mortality were not adequately studied to form any consensus. Our review has not demonstrated ENDS to be causative of harmful CVD outcomes; furthermore switching from cigarettes to e-cigarettes was associated with improved hypertensive control and reduced exacerbations of COPD, with no evidence of increased asthma risk or long-term respiratory harm. Mental health, cancer and mortality outcomes have not been adequately studied to form a conclusion. Overall, the findings of our review did not provide evidence to counter the consensus held by many that ENDS use is safer than the risks posed from smoking cigarettes.

Clinical Pharmacology of Electronic Nicotine Delivery Systems (ENDS): Implications for Benefits and Risks in the Promotion of the Combusted Tobacco Endgame

Electronic nicotine delivery systems (ENDS) such as e-cigarettes and heated tobacco products are novel battery-operated devices that deliver nicotine without combustion of tobacco. Because cigarette smoking is sustained by nicotine addiction and the toxic combustion products are mainly responsible for the harmful effects of smoking, ENDS could be used to promote smoking cessation while exposing users to lower levels of toxicants compared with conventional cigarettes. The currently available evidence from clinical and observational studies indicates a potential role of e-cigarettes as smoking cessation aids, although many continue to use e-cigarettes long after quitting smoking. Nicotine and toxicant delivery vary considerably by device and depend on the characteristics of the e-liquid formulation. Because smokers tend to titrate their nicotine intake to maintain their desired pharmacologic effects, device and liquid characteristics need to be considered when using ENDS as an aid to quit smoking. Factors potentially limiting their use are the currently still unknown long-term safety of these products and concerns regarding widespread use among youth. Implications of clinical pharmacology data on ENDS for the cigarette endgame and regulation by the U.S. Food and Drug administration are discussed.

A 6-month inhalation toxicology study in Apoe-/- mice demonstrates substantially lower effects of e-vapor aerosol compared with cigarette smoke in the respiratory tract

Cigarette smoking is the major cause of chronic obstructive pulmonary disease. Considerable attention has been paid to the reduced harm potential of nicotine-containing inhalable products such as electronic cigarettes (e-cigarettes). We investigated the effects of mainstream cigarette smoke (CS) and e-vapor aerosols (containing nicotine and flavor) generated by a capillary aerosol generator on emphysematous changes, lung function, and molecular alterations in the respiratory system of female Apoe-/- mice. Mice were exposed daily (3 h/day, 5 days/week) for 6 months to aerosols from three different e-vapor formulations-(1) carrier (propylene glycol and vegetable glycerol), (2) base (carrier and nicotine), or (3) test (base and flavor)-or to CS from 3R4F reference cigarettes. The CS and base/test aerosol concentrations were matched at 35 µg nicotine/L. CS exposure, but not e-vapor exposure, led to impairment of lung function (pressure-volume loop area, A and K parameters, quasi-static elastance and compliance) and caused marked lung inflammation and emphysematous changes, which were confirmed histopathologically and morphometrically. CS exposure caused lung transcriptome (activation of oxidative stress and inflammatory responses), lipidome, and proteome dysregulation and changes in DNA methylation; in contrast, these effects were substantially reduced in response to the e-vapor aerosol exposure. Compared with sham, aerosol exposure (carrier, base, and test) caused a slight impact on lung inflammation and epithelia irritation. Our results demonstrated that, in comparison with CS, e-vapor aerosols induced substantially lower biological and pathological changes in the respiratory tract associated with chronic inflammation and emphysema.

International randomised controlled trial evaluating metabolic syndrome in type 2 diabetic cigarette smokers following switching to combustion-free nicotine delivery systems: the DIASMOKE protocol

INTRODUCTION

Reducing exposure to cigarette smoke is an imperative for public health and for patients with diabetes. Increasingly, combustion-free nicotine delivery systems (C-F NDS) such as e-cigarettes and heated tobacco products are substituting conventional cigarettes and accelerating the downward trends in smoking prevalence. However, there is limited information about the long-term health impact in patients with diabetes who use C-F NDS. This randomised trial of type 2 diabetic cigarette smokers will test the hypothesis that following a switch from conventional cigarettes to C-F NDS a measurable improvement in metabolic syndrome (MetS) factors will be shown over the course of 2 years.

METHODS AND ANALYSIS

The study is multicentre and thus will take place in five locations in four countries in an ambulatory setting. A total of 576 patients with diabetes will be randomised (1:2 ratio) to either a control arm (Study Arm A), in which they will be offered referral to smoking cessation programmes or to an intervention arm (Study Arm B) assigned to C-F NDS use. Participants will be at least 23 years old and of any gender. Patient recruitment will start in February 2021 and is expected to be completed by December 2021. Primary outcome measures include fasting plasma glucose, blood pressure, triglycerides, high-density lipoprotein and waist circumference, while secondary feature absolute change in the sum of the individual factors of MetS and change in each individual factor of MetS measured at each study time point.

ETHICS AND DISSEMINATION

The approval of research ethics committee (REC) regarding the trial protocol, informed consent forms and other relevant documents is required to commence the study. Substantial amendments to the study protocol cannot be implemented until the REC grants a favourable opinion. The results of the study are intended to be published as articles in high quality peer-reviewed journals and disseminated through conference papers.

TRIAL REGISTRATION NUMBER

NCT04231838. Pre-results stage.

Health outcomes in COPD smokers using heated tobacco products: a 3-year follow-up

Given that many patients with chronic obstructive pulmonary disease (COPD) smoke despite their symptoms, it is important to understand the long-term health impact of cigarette substitution with heated tobacco products (HTPs). We monitored health parameters for 3 years in COPD patients who substantially attenuated or ceased cigarette consumption after switching to HTPs. Changes in daily cigarette smoking, annualized disease exacerbations, lung function indices, patient-reported outcomes (CAT scores) and 6-minute walk distance (6MWD) from baseline were measured in COPD patients using HTPs at 12, 24 and 36 months. These were compared to a group of age- and sex-matched COPD patients who continued smoking. Complete data sets were available for 38 patients (19 in each group). Subjects using HTPs had a substantial decrease in annualized COPD exacerbations within the group mean (± SD) from 2.1 (± 0.9) at baseline to 1.4 (± 0.8), 1.2 (± 0.8) and 1.3 (± 0.8) at 12-, 24- and 36-month follow-up (p < 0.05 for all visits). In addition, substantial and clinically significant improvements in CAT scores and 6MWD were identified at all three time points in the HTP cohort. No significant changes were observed in COPD patients who continued smoking. This study is the first to describe the long-term health effects of HTP use in COPD patients. Consistent improvements in respiratory symptoms, exercise tolerance, quality of life, and rate of disease exacerbations were observed in patients with COPD who abstained from smoking or substantially reduced their cigarette consumption by switching to HTP use.

A 7-month inhalation toxicology study in C57BL/6 mice demonstrates reduced pulmonary inflammation and emphysematous changes following smoking cessation or switching to e-vapor products

Cigarette smoking causes serious diseases, including lung cancer, atherosclerotic coronary artery disease, peripheral vascular disease, chronic bronchitis, and emphysema. While cessation remains the most effective approach to minimize smoking-related disease, alternative non-combustible tobacco-derived nicotine-containing products may reduce disease risks among those unable or unwilling to quit. E-vapor aerosols typically contain significantly lower levels of smoke-related harmful and potentially harmful constituents; however, health risks of long-term inhalation exposures are unknown. We designed a 7-month inhalation study in C57BL/6 mice to evaluate long-term respiratory toxicity of e-vapor aerosols compared to cigarette smoke and to assess the impact of smoking cessation (Cessation group) or switching to an e-vapor product (Switching group) after 3 months of exposure to 3R4F cigarette smoke (CS). There were no significant changes in in-life observations (body weights, clinical signs) in e-vapor groups compared to the Sham Control. The 3R4F CS group showed reduced respiratory function during exposure and had lower body weight and showed transient signs of distress post-exposure. Following 7 months of exposure, e-vapor aerosols resulted in no or minimal increase in pulmonary inflammation, while exposure to 3R4F CS led to impairment of lung function and caused marked lung inflammation and emphysematous changes. Biological changes observed in the Switching group were similar to the Cessation group. 3R4F CS exposure dysregulated the lung and nasal tissue transcriptome, while these molecular effects were substantially lower in the e-vapor group. Results from this study demonstrate that in comparison with 3R4F CS, e-vapor aerosols induce substantially lower biological responses including pulmonary inflammation and emphysematous changes, and that complete switching from CS to e-vapor products significantly reduces biological changes associated with CS in C57BL/6 mice.

Pulmonary Health Effects of Electronic Cigarettes: A Scoping Review

BACKGROUND

There is global concern regarding the public health impact of electronic cigarettes (ECs). ECs are commonly promoted as safer than conventional cigarettes (CCs), however there is limited knowledge of the long-term health effects. This scoping review examined the pulmonary health effects of ECs reported in the literature from 2009 to 2019.

METHOD

PubMed, CINAHL, and Science Direct databases were used. Search terms included "vaping, electronic nicotine delivery systems, electronic cigarettes, lung diseases, respiratory diseases, and pulmonary." Original research articles in English that used human subjects between January 1, 2009 and January 31, 2020 and reported pulmonary outcomes were included.

RESULTS

Forty-five studies met the inclusion criteria. There were 14 (31.1%) randomized experimental, 7 (15.6%) nonrandomized experimental, 6 (13.3%) cohort, and 18 (40.0%) cross-sectional studies. Sixteen (35.6%) studies were conducted in the United States; the rest were conducted across 11 other countries. The total number of subjects was 1,465,292 and ages ranged from 12 to 99 years across studies. Eligible studies demonstrated an association between EC use and pulmonary symptoms, asthma and chronic obstructive pulmonary disease diagnosis and exacerbations. The degree of this association varied based on the use of additional tobacco products. EC use resulted in worse outcomes than nonsmoking, but resulted in improved outcomes when compared with CC use or dual use of CC and EC.

CONCLUSION

Evidence indicates that EC use, especially dual use, leads to negative pulmonary effects and adverse outcomes. Education on the potential risks and publishing of EC ingredients on labels could help improve public health safety communication and reduce EC use.

Acute electronic vapour product whole aerosol exposure of 3D human bronchial tissue results in minimal cellular and transcriptomic responses when compared to cigarette smoke

The use of electronic vapour products (EVPs) continues to increase worldwide and with advances in cell culture systems, molecular biology and the computational sciences there is also accumulating evidence of their potential reduced toxicity and reduced potential harm when compared to cigarette smoke. To further understand the potential risks and health effects associated with exposure to EVP aerosols we have assessed the cellular and transcriptomic response from a commercially available lung tissue culture system (MucilAirTM) following a single sub-cytotoxic exposure to cigarette smoke and the equivalent nicotine delivered dose of EVP aerosol. The transcriptomic, cellular (cilia beat frequency (CBF) and percent active area (%AA), trans epithelial electrical resistance (TEER), histology) and cytokine release were assessed at 4- and 48- hours following recovery from air, EVP aerosol (8.4% V/V: mybluTM blueberry flavour, 2.4% nicotine) and 3R4F smoke (3.5% V/V: exposure). No pathological changes were observed at either recovery time point from any exposure. Air and EVP aerosol exposure had no effect on CBF, %AA nor TEER at 48 hours. Exposure to cigarette smoke resulted in a decrease in TEER, an increase in CBF and the release of proinflammatory cytokines at both recovery time points. Although the number of significantly expressed genes was minimal following exposure to EVP aerosol, exposure to 3R4F smoke resulted in a significant upregulation of several disease relevant pathways. These data provide evidence that following an acute exposure to EVP aerosol there is significantly less damage to lung cells in culture than the equivalent, nicotine based, dose of cigarette smoke.

Multi-endpoint analysis of human 3D airway epithelium following repeated exposure to whole electronic vapor product aerosol or cigarette smoke

Smoking is a cause of serious diseases in smokers including chronic respiratory diseases. This study aimed to evaluate the tobacco harm reduction (THR) potential of an electronic vapor product (EVP, myblu™) compared to a Kentucky Reference Cigarette (3R4F), and assessed endpoints related to chronic respiratory diseases. Endpoints included: cytotoxicity, barrier integrity (TEER), cilia function, immunohistochemistry, and pro-inflammatory markers. In order to more closely represent the user exposure scenario, we have employed the in vitro 3D organotypic model of human airway epithelium (MucilAir™, Epithelix) for respiratory assessment. The model was repeatedly exposed to either whole aerosol of the EVP, or whole 3R4F smoke, at the air liquid interface (ALI), for 4 weeks to either 30, 60 or 90 puffs on 3-exposure-per-week basis. 3R4F smoke generation used the ISO 20778:2018 regime and EVP aerosol used the ISO 20768:2018 vaping regime. Exposure to undiluted whole EVP aerosol did not trigger any significant changes in the level of pro-inflammatory mediators, cilia beating function, barrier integrity and cytotoxicity when compared with air controls. In contrast, exposure to diluted (1:17) whole cigarette smoke caused significant changes to all the endpoints mentioned above. To our knowledge, this is the first study evaluating the effects of repeated whole cigarette smoke and whole EVP aerosol exposure to a 3D lung model at the ALI. Our results add to the growing body of scientific literature supporting the THR potential of EVPs relative to combustible cigarettes and the applicability of the 3D lung models in human-relevant product risk assessments.

Clearing the Haze: What Do We Still Need to Learn about Electronic Nicotine Delivery Systems?

Electronic nicotine delivery systems (ENDS; i.e., electronic cigarettes, e-cigarettes, vaping devices, vape pens) were introduced to the U.S. market in 2007 as a potential harm reduction alternative for people who smoked combustible cigarettes. Since that time, ENDS popularity grew very quickly, particularly among individuals who smoke cigarettes. However, young people and never smokers also started using ENDS, cohorts for whom these products were not intended. There are now a broad range of devices and e-liquid constituents. ENDS devices vary considerably in their design and generation of potentially toxic chemicals, with higher power devices likely much more hazardous than lower power devices. This landscape may further change after September 9, 2020, when all ENDS manufacturers are required to submit a premarket tobacco product application to the FDA to obtain authorization for marketing. Research has not kept pace with this rapidly changing technology and important questions remain regarding the relative benefits versus risks of ENDS. In light of these challenges, we propose key ENDS research priorities to address these gaps.

Use of Electronic Cigarettes and Self-Reported Chronic Obstructive Pulmonary Disease Diagnosis in Adults

INTRODUCTION

Electronic cigarette (e-cigarette) use (vaping) has increased in recent years. Chronic obstructive pulmonary disease (COPD) is the third leading cause of death associated with smoking.

AIMS AND METHODS

Based on 2016 and 2017 Behavioral Risk Factor Surveillance System national survey data on 891 242 adult participants who indicated their smoking and vaping status, the cross-sectional association of vaping with self-reported COPD diagnosis was investigated, using univariable and multivariable weighted logistic regression models.

RESULTS

Compared to never users, while dual users showed the highest association with self-reported COPD diagnosis (adjusted odds ratio [aOR] = 4.39; 95% confidence interval [CI] = 3.98 to 4.85), current vapers who were either ex-smokers or never smoked showed significantly higher association with self-reported COPD diagnosis (aOR = 3.24; 95% CI = 2.78 to 3.78 and aOR = 1.47; 95% CI = 1.01 to 2.12, respectively). Current vapers who were ex-smokers showed higher association with self-reported COPD diagnosis than ex-smokers who do not vape (aOR = 1.27; 95% CI = 1.09 to 1.48). Dual users showed higher association with self-reported COPD diagnosis than current smokers who do not vape (aOR = 1.16; 95% CI = 1.05 to 1.27). Ex-smokers showed significantly less association with self-reported COPD diagnosis (aOR = 0.67; 95% CI = 0.64 to 0.71) than current smokers. Current vapers who were either ex-smokers or never smoked had less association with self-reported COPD diagnosis compared to current smokers, with aOR = 0.85 (95% CI = 0.73 to 0.99) and aOR = 0.39 (95% CI = 0.27 to 0.56).

CONCLUSIONS

Vaping is significantly associated with self-reported COPD diagnosis in adults, even among vapers who never smoked. Whether there is a benefit for COPD of switching from smoking to vaping requires study of the long-term effects of vaping.

IMPLICATIONS

With the increase of e-cigarette use in recent years, the health effects of e-cigarettes need to be investigated. While several studies have examined the association of vaping with respiratory symptoms among adolescents, little is known about the association of vaping with susceptibility to COPD among US adults. Using cross-sectional national survey data in adults, our study showed that vaping was significantly associated with self-reported COPD diagnosis. Although our data did not establish the causal relationship between vaping and self-reported COPD diagnosis, this study raises concerns about the observed association between vaping and self-reported COPD diagnosis.

Real-World Evidence of Differences in Biomarkers of Exposure to Select Harmful and Potentially Harmful Constituents and Biomarkers of Potential Harm Between Adult E-Vapor Users and Adult Cigarette Smokers

INTRODUCTION

Real-world evidence regarding likely long-term health effects of e-vapor products (EVP) under actual use conditions relative to cigarette smoking is not well studied.

METHODS

In this cross-sectional, observational study, biomarkers of exposure (BOE) to select harmful and potentially harmful constituents and biomarkers of potential harm (BOPH) relevant to smoking-related diseases were measured in exclusive adult EVP users (AEVP, n = 144) and exclusive adult cigarette smokers (AS, n = 73). AEVP used their own brand of EVP for 6+ months following 10+ years of cigarette smoking and AS smoked own brand of cigarettes for 10+ years. Subject recruitment and informed consent were obtained online and urine/blood samples were collected at local clinical laboratories, representing a new paradigm for collecting real-world evidence.

RESULTS

The levels of total NNAL (NNK metabolite), 3-hydroxypropyl mercapturic acid (acrolein metabolite), and carboxyhemoglobin (carbon monoxide measure) were 46% to 86% lower in AEVP compared with AS (p ≤ .0001) as was nicotine equivalents (nicotine and its five metabolites; 36%, p < .01). The levels of some BOPH were significantly lower in AEVP compared with AS for 11-dehydrothromboxane-B2 (29%, p = .04; platelet activation), 8-epi-prostaglandin F2α (23%, p = .02; oxidative stress) and soluble intercellular adhesion molecule-1 (16%, p = .02; endothelial function).

CONCLUSIONS

This study demonstrates the feasibility of a new approach for collecting real-world evidence. Substantially lower levels of BOEs (NNK, nicotine, acrolein, carbon monoxide) and favorable differences in BOPHs (platelet activation, oxidative stress, endothelial function) suggest EVP users may have lower health risks than cigarette smokers.

IMPLICATIONS

Cigarette smoking causes serious diseases. Switching from a combustible tobacco product to a noncombustible product is a potential harm reduction pathway for adult smokers unable or unwilling to quit. Real-world evidence regarding the relative risk of EVP use compared with cigarettes is not well established. This study provides data specific to BOE to tobacco smoke constituents and biomarkers of potential harm collected under actual use conditions in a real-world setting. The totality of evidence suggests that exclusive EVP use may present lower health risk compared with smoking cigarettes.

Electronic cigarette use and subjective cognitive complaints in adults

INTRODUCTION

Electronic cigarette use (vaping) has become popular in recent years. The number of Americans with a variety of cognitive deficits has been increasing dramatically. This study aimed to examine the potential association of vaping with subjective cognitive complaints in US adults.

METHODS

A combined 2016 and 2017 Behavioral Risk Factor Surveillance System (BRFSS) national survey dataset yielded 886,603 adults who indicated their smoking and vaping status, as well as whether they had subjective cognitive complaints. With this dataset, the cross-sectional association of electronic cigarette use with subjective cognitive complaints was examined using multivariable weighted logistic regression models.

RESULTS

Both dual users (adjusted Odds Ratio [aOR] = 2.07; 95% Confidence Interval [CI] = 1.66 to 2.60) and current vapers who were either ex-smokers (aOR = 1.94; 95% CI = 1.40 to 2.71) or never smoked (aOR = 1.96; 95% CI = 1.16 to 3.30) showed a significantly higher association with subjective cognitive complaints than never users. Current smokers (aOR = 1.49; 95% CI = 1.32 to 1.69) and ex-smokers (aOR = 1.25; 95% CI = 1.11 to 1.41) had a significantly higher association with subjective cognitive complaints compared to never users. Compared to current smokers, the ex-smokers showed a lower association with subjective cognitive complaints (aOR = 0.84; 95% CI = 0.73 to 0.96). Finally, the association of vaping with subjective cognitive complaints was not statistically significant in individual age group.

CONCLUSION

Similar to smoking, vaping is associated with subjective cognitive complaints in US adults. These results provide preliminary evidence for a cross-sectional association of vaping with potential cognitive health effects in adults.

COPD smokers who switched to e-cigarettes: health outcomes at 5-year follow up

BACKGROUND AND AIMS

The long-term health effects of the use of electronic cigarettes (ECs) in patients with chronic obstructive pulmonary disease (COPD) are largely unexplored. We present findings from a 5-year prospective assessment of respiratory parameters in a cohort of COPD patients who substantially reduced conventional smoking or achieved abstinence by switching to ECs.

METHODS

Patients were evaluated prospectively for their measurements of respiratory exacerbations, spirometric indices, quality of life using the COPD assessment tool (CAT), 6-min walk distance (6MWD), as well as conventional cigarette consumption. Baseline measurements prior to switching to EC use were compared with follow-up visits at 12-, 24-, 48- and 60-months. Age- and sex-matched COPD patients reporting to be regular smokers (not using ECs) were the reference group for the analysis.

RESULTS

Complete data were available from 39 patients. Those in the EC user group achieved a marked decline in cigarette smoking or abstinence. COPD EC users had a significant diminution in COPD exacerbations; with the mean (±SD) exacerbation rate falling from 2.3 (±0.9) at baseline to 1.1 (±1.0) at 5 years (p < 0.001), whereas no significant changes were observed in the control group.Significant and constant improvements in lung function, CAT scores and 6MWD were reported in the EC user group over the 5-year observation period compared with the reference group (p < 0.05).

CONCLUSION

The present study suggests that EC use may ameliorate objective and subjective COPD outcomes, and that the benefits gained appear to persist long term. EC use for abstinence and smoking reduction may ameliorate some of the harm resulting from tobacco smoking in COPD patients.

People smoke for nicotine, but lose sexual and reproductive health for tar: a narrative review on the effect of cigarette smoking on male sexuality and reproduction

PURPOSE

To systematically review the impact of smoking habits on cardiovascular (CV) as well as on male sexual and reproductive function and to provide updated evidence on the role of electronic cigarettes (e-Cig) on the same topics.

METHODS

A comprehensive Medline, Embase, and Cochrane search was performed including the following words: smoking, CV system, CV risk, erectile dysfunction (ED), and male fertility. Publications from January 1, 1969 up to February 29, 2020 were included.

RESULTS

Smoking has a tremendous negative impact on CV mortality and morbidity. Current smoking behavior is also negatively associated with erectile dysfunction (ED) and impaired sperm parameters. E-Cig can release significantly lower concentrations of harmful substances when compared to regular combustible cigarettes. Whether or not the latter can result in positive CV, sexual, and fertility outcomes is still under study. Preliminary studies showed that exposure to e-Cig leads to lower vascular damage when compared to the traditional cigarette use. However, data on the long-term effects of e-Cig are lacking. Similarly, preliminary data, obtained in animal models, have suggested a milder effect of e-Cig on erectile function and sperm parameters.

CONCLUSION

Available evidence showed that e-Cig are much less dangerous when compared to the traditional tobacco use. However, it should be recognized that the risk related to e-Cig is still higher when compared to that observed in non-smoking patients. Hence, e-Cig should be considered as a potential tool, in the logic of harm reduction, to reduce the CV, sexual and fertility risk in patients refractory to the fundamental, healthy choice to definitively quit smoking.

Use of E-Cigarettes and Self-Reported Lung Disease Among US Adults

OBJECTIVES

Initially marketed for smoking cessation, electronic cigarettes (e-cigarettes) are commonly regarded as safer than combustible cigarettes because they usually contain less nicotine and do not use combustion. However, few studies have examined the health effects of e-cigarettes. The objective of this study was to examine whether e-cigarette use had a differential effect on the prevalence of lung disease among current, former, and never tobacco users.

METHODS

We analyzed data from respondents aged ≥18 (n = 45 908) who responded to questions about e-cigarette use and lung disease in the 2016 Behavioral Risk Factor Surveillance System (BRFSS) survey. We calculated crude odd ratios (ORs) and ORs adjusted by 15 sociodemographic and health behavior factors: age, sex, race/ethnicity, annual household income, health insurance, personal physician, health status, body mass index, education, marital status, exercise, alcohol use, tobacco smoking, tobacco chewing, and metropolitan status.

RESULTS

We found a significant association between e-cigarette use and lung disease, which was significantly modified by tobacco use. Among never tobacco users, the adjusted odds of reporting lung disease were 4.36 (95% CI, 1.76-10.77) times higher among everyday e-cigarette users than among never e-cigarette users. Among current tobacco users, the adjusted odds of reporting lung disease were 1.47 (95% CI, 1.13-1.92) times higher among everyday e-cigarette users than among never e-cigarette users.

CONCLUSIONS

People who have never smoked combustible cigarettes should refrain from starting e-cigarettes, because e-cigarettes carry a significant risk of lung disease independent of tobacco smoking. Additional prospective research into the harmful effects of e-cigarettes would help to further elucidate this link.

A Qualitative Exploration of Consumers' Perceived Impacts, Behavioural Reactions, and Future Reflections of the EU Tobacco Products Directive (2017) as Applied to Electronic Cigarettes

BACKGROUND

Electronic cigarette regulations included in the Tobacco Products Directive (TPD), Article 20, implemented in Europe by May 2017, aimed to improve safety for e-cigarette consumers, and prevent uptake among non-smokers, particularly young people. Before implementation, there were significant concerns from consumers, industry, and some in the scientific community about the potential negative impact of the TPD on people using e-cigarettes to remain abstinent from smoking. To date, there is limited evidence on how the TPD has affected consumers. This study aimed to add insight into how consumers perceived and experienced the regulations.

METHODS

Qualitative data, collected between March 2018 and March 2019, relating to participant views of the TPD were extracted from 160 interviews/extended surveys of e-cigarette consumers as part of a wider study into e-cigarette use trajectories (ECtra study). Data were thematically analysed.

RESULTS

Awareness of the TPD among consumers was not universal. Participants' smoking behaviour did not appear to be influenced by the legislation. Participants were reassured by manufacturing regulations and requirements for ingredients labels. Participants responded negatively to changes perceived to cause inconvenience and extra plastic waste. The product restrictions prompted some participants to purchase non-compliant products illegally, potentially putting their safety at risk.

CONCLUSIONS

E-cigarette regulation should focus on ensuring product safety. Raising awareness of the TPD among consumers and smokers could be beneficial.

Inhalation Toxicology of Vaping Products and Implications for Pulmonary Health

E-cigarettes have a liquid that may contain flavors, solvents, and nicotine. Heating this liquid generates an aerosol that is inhaled into the lungs in a process commonly referred to as vaping. E-cigarette devices can also contain cannabis-based products including tetrahydrocannabinol (THC), the psychoactive component of cannabis (marijuana). E-cigarette use has rapidly increased among current and former smokers as well as youth who have never smoked. The long-term health effects are unknown, and emerging preclinical and clinical studies suggest that e-cigarettes may not be harmless and can cause cellular alterations analogous to traditional tobacco smoke. Here, we review the historical context and the components of e-cigarettes and discuss toxicological similarities and differences between cigarette smoke and e-cigarette aerosol, with specific reference to adverse respiratory outcomes. Finally, we outline possible clinical disorders associated with vaping on pulmonary health and the recent escalation of acute lung injuries, which led to the declaration of the vaping product use-associated lung injury (EVALI) outbreak. It is clear there is much about vaping that is not understood. Consequently, until more is known about the health effects of vaping, individual factors that need to be taken into consideration include age, current and prior use of combustible tobacco products, and whether the user has preexisting lung conditions such as asthma and chronic obstructive pulmonary disease (COPD).

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects"

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

A Summary of In Vitro and In Vivo Studies Evaluating the Impact of E-Cigarette Exposure on Living Organisms and the Environment

Worldwide use of electronic cigarettes has been rapidly expanding over recent years, but the long-term effect of e-cigarette vapor exposure on human health and environment is not well established; however, its mechanism of action entails the production of reactive oxygen species and trace metals, and the exacerbation of inflammation, which are associated with potential cytotoxicity and genotoxicity. The present study examines the effects of selected liquid chemicals used in e-cigarettes, such as propylene glycol/vegetable glycerin, nicotine and flavorings, on living organisms; the data collected indicates that exposure to e-cigarette liquid has potentially detrimental effects on cells in vitro, and on animals and humans in vivo. While e-liquid exposure can adversely influence the physiology of living organisms, vaping is recommended as an alternative for tobacco smoking. The study also compares the impact of e-cigarette liquid exposure and traditional cigarette smoke on organisms and the environmental impact. The environmental influence of e-cigarette use is closely connected with the emission of airborne particulate matter, suggesting the possibility of passive smoking. The obtained data provides an insight into the impact of nicotine delivery systems on living organisms and the environment.

E-cigarette Retail Licensing Policy and E-cigarette Use Among Adolescents

PURPOSE

The present study evaluated whether Pennsylvania's 2016 law requiring a retail license for the sale of e-cigarettes was associated with adolescent e-cigarette use.

METHODS

Data were drawn from the 2015-2017 Youth Risk Behavior Surveillance System. We examined the prepolicy and postpolicy change in e-cigarette use for the state with the retail licensing requirement (Pennsylvania) compared with control states (New York and Virginia).

RESULTS

Results showed that e-cigarette licensing policy was significantly associated with e-cigarette use. E-cigarette use among Pennsylvania adolescents reduced by 5.2 percentage points in 2017 when compared with New York adolescents, and a corresponding 21.6% decrease from its baseline prevalence level in 2015. Similarly, there was a 7.4 percentage point decrease in e-cigarette use in Pennsylvania when compared with Virginia (30.7% relative decrease from the baseline prevalence).

CONCLUSIONS

An e-cigarette retail licensing requirement may be a useful policy tool in reducing e-cigarette use among adolescents.

Adult E-Cigarettes Use Associated with a Self-Reported Diagnosis of COPD

The use of electronic cigarettes (e-cigarettes) has increased in the US, but little is known about the effects of these products on lung health. The main purpose of this study was to examine the association between e-cigarette use and a participant's report of being diagnosed with chronic obstructive pulmonary disease (COPD) in a nationally representative sample of adults. Methods: The first wave of the Population Assessment of Tobacco and Health (PATH) survey adult data was used (N = 32,320). Potential confounders between e-cigarette users and non-users were balanced using propensity score matching. Odds ratios (OR) were calculated to examine the association between e-cigarette use and COPD in the propensity-matched sample, the entire sample, different age groups, and in nonsmokers. Replicate weights and balanced repeated replication methods were utilized to account for the complex survey design. Results: Of the 3642 participants who met the criteria for e-cigarette use, 2727 were propensity matched with 2727 non e-cigarette users. In the propensity-matched sample, e-cigarette users were more likely to report being diagnosed with COPD (OR 1.43, 95% confidence interval [CI] 1.12-1.85) than non-e-cigarette users after adjusting for confounders. The result was similar in the entire sample and in the different age subgroups. Among nonsmokers, the odds of reporting a COPD diagnosis were even greater among e-cigarette users (OR 2.94, 95% CI 1.73-4.99) compared to non-e-cigarette users. Conclusion: Our findings demonstrate that e-cigarette use was associated with a reported diagnosis of COPD among adults in the US. Further research is necessary to characterize the nature of this association and on the long-term effects of using e-cigarettes.

Cigarette smoking, e-cigarette use, and sexual identity among high school students in the USA

Although tobacco use has decreased in the general population in recent years, smoking remains high among subpopulations. This study examined whether sexual identity is associated with cigarette smoking and e-cigarette use among high school students. Data were drawn from the US Youth Risk Behavior Surveillance System (n = 28811). We grouped participants according to sexual identity status. Propensity score matching technique was used to address covariate imbalance among sexual identity groups. Subgroup analyses were performed for male and female students. Of the four sexual identity groups analyzed in this study, bisexual adolescents had significantly higher odds of cigarette smoking (cigarette smoking, OR, 1.61; 95% CI, 1.24-2.08; cigarette smoking for ≥ 10 days, OR, 1.79; 95% CI, 1.28-2.51; cigarette smoking for ≥ 20 days, OR, 2.04; 95% CI, 1.38-3.03). Further, in a sex-based subgroup analysis, results showed significant differences, with bisexual females more likely to smoke cigarettes and use e-cigarettes for ≥ 20 days compared with heterosexual female adolescents.Conclusions: Sexual identity status is strongly associated with cigarette smoking and e-cigarette use. Female bisexual adolescents have an increased risk of cigarette smoking and e-cigarette use for ≥ 20 days. While tobacco control policies have been effective in reducing cigarette use in the general population, targeting policy toward sexual minorities is an important consideration. What is Known: • Sexual minority groups face a disproportionate amount of stress and have a heightened risk of substance use. • Methodological concerns exist in the extant literature, including limited data at the national level. What is New: • Propensity score matching was used to account for imbalances in sexual identity subgroups, and findings show significant heterogeneity in cigarette and e-cigarette use among sexual minority high school students. • Sexual identity status is strongly associated with cigarette smoking and e-cigarette use, especially among bisexual identity female subgroup.

A lower impact of an acute exposure to electronic cigarette aerosols than to cigarette smoke in human organotypic buccal and small airway cultures was demonstrated using systems toxicology assessment

In the context of tobacco harm-reduction strategy, the potential reduced impact of electronic cigarette (EC) exposure should be evaluated relative to the impact of cigarette smoke exposure. We conducted a series of in vitro studies to compare the biological impact of an acute exposure to aerosols of "test mix" (flavors, nicotine, and humectants), "base" (nicotine and humectants), and "carrier" (humectants) formulations using MarkTen® EC devices with the impact of exposure to smoke of 3R4F reference cigarettes, at a matching puff number, using human organotypic air-liquid interface buccal and small airway cultures. We measured the concentrations of nicotine and carbonyls deposited in the exposure chamber after each exposure experiment. The deposited carbonyl concentrations were used as representative measures to assess the reduced exposure to potentially toxic volatile substances. We followed a systems toxicology approach whereby functional biological endpoints, such as histopathology and ciliary beating frequency, were complemented by multiplex and omics assays to measure secreted inflammatory proteins and whole-genome transcriptomes, respectively. Among the endpoints analyzed, the only parameters that showed a significant response to EC exposure were secretion of proteins and whole-genome transcriptomes. Based on the multiplex and omics analyzes, the cellular responses to EC aerosol exposure were tissue type-specific; however, those alterations were much smaller than those following cigarette smoke exposure, even when the EC aerosol exposure under the testing conditions resulted in a deposited nicotine concentration approximately 200 times that in saliva of EC users.

Frequency of E-cigarette use and cigarette smoking among Canadian students

The emergence of electronic nicotine delivery systems (commonly referred to as e-cigarettes) has created an ongoing public health debate and concerns, especially in regards to adolescents. The present study examined associations between the frequency of e-cigarette use and cigarette smoking among school students. Data on students (grades 7-12) was obtained from the 2016-2017 Canadian Student Tobacco, Alcohol and Drugs Survey (n = 51,661). Multivariable logistic regression analyses were conducted to examine associations between the frequency of e-cigarette use and smoking. Subgroup analyses were performed for male and female students. Among those who reported any cigarette smoking in the past 30 days, 55% reported e-cigarette use at least once in the last 30 days. Additionally, 17% reported e-cigarette use for 21-30 days among those who smoked cigarettes for at least 21 days. Multivariable logistic regression analysis showed e-cigarette use was associated with higher odds of cigarette smoking, especially among more frequent e-cigarette users. Those who used an e-cigarette 21-30 days had higher odds of cigarette smoking (smoked cigarette at least once AOR = 4.83, CI = 3.33-7.01; at least 11 days AOR = 3.73, CI = 2.40-5.80; at least 21 days AOR = 3.39, CI = 2.16-5.34). Findings suggest that those who smoked cigarettes at least once in the past 30 days had a higher frequency of e-cigarette use.

The effect of e-cigarette aerosol emissions on respiratory health: a narrative review

Introduction: Due to the uptake in the use of e-cigarettes (ECs), evidence on their health effects is needed to inform health care and policy. Some regulators and health professionals have raised concerns that the respirable aerosols generated by ECs contain several constituents of potential toxicological and biological relevance to respiratory health. Areas covered: We critically assess published research on the respiratory system investigating the effects of ECs in preclinical models, clinical studies of people who switched to ECs from tobacco cigarettes, and population surveys. We assess the studies for the quality of their methodology and accuracy of their interpretation. To adequately assess the impact of EC use on human health, addressing common mistakes and developing robust and realistic methodological recommendations is an urgent priority. The findings of this review indicate that ECs under normal conditions of use demonstrate far fewer respiratory risks than combustible tobacco cigarettes. EC users and smokers considering ECs have the right to be informed about the relative risks of EC use, and to be made aware that findings of studies published by the media are not always reliable. Expert opinion: Growing evidence supports the relative safety of EC emission aerosols for the respiratory tract compared to tobacco smoke.