Lung function and respiratory symptoms in a randomized smoking cessation trial of electronic cigarettes

A Global Health Survey of People Who Vape but Never Smoked: Protocol for the VERITAS (Vaping Effects: Real-World International Surveillance) Study

BACKGROUND

There is only limited information about the health effects of regular vaping. Research on the health status of people who used to smoke faces the challenge that previous smoking may have caused unknown health effects. Only studies of people who vape but have never smoked combustible cigarettes can enable the detection of harms attributable to vaping. Large prospective studies of well-characterized electronic cigarette users with and without a history of combustible cigarette smoking are warranted to establish the long-term effects of regular vaping on respiratory health.

OBJECTIVE

We will conduct a global cross-sectional survey of individuals from 6 world regions. Respiratory symptoms will be assessed using a validated questionnaire-the Respiratory Symptom Experience Scale (RSES). Current vapers who are nonusers of other tobacco or nicotine products will be compared with matched controls who are nonusers of vapes and other tobacco or nicotine products.

METHODS

This will be a multicountry, cross-sectional internet-based survey of 750 adults aged ≥18 years who satisfy the criteria for inclusion in either a cohort of people who exclusively vape and who are nonusers of other tobacco or nicotine products ("vapers cohort"; target N=500) or a cohort of nonvapers who are also nonusers of other tobacco or nicotine products ("controls cohort"; target N=250). The primary end point of the study is the RSES score. RSES scores of people in the "vapers cohort" will be compared with those of people in the "controls cohort." Additionally, the study will collect data to characterize patterns of vaping product use among the vapers cohort. Data collection will include information about the age initiation of using vape products, reasons for starting and continuing the use of vape products, specific types of products used, flavors and nicotine strengths of recently used products, as well as the frequency and intensity of product use in the past 30 days.

RESULTS

Participant recruitment started in April 2023, and enrollment was completed by November 2023 with 748 participants. Results will be reported in 2024.

CONCLUSIONS

This will be the first study providing key insights into respiratory health effects associated with using electronic cigarettes in people who vape with no established use of combustible cigarettes or other tobacco or nicotine products.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/54236.

Electronic cigarettes for smoking cessation

BACKGROUND

Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol by heating an e-liquid. People who smoke, healthcare providers and regulators want to know if ECs can help people quit smoking, and if they are safe to use for this purpose. This is a review update conducted as part of a living systematic review.

OBJECTIVES

To examine the safety, tolerability and effectiveness of using electronic cigarettes (ECs) to help people who smoke tobacco achieve long-term smoking abstinence, in comparison to non-nicotine EC, other smoking cessation treatments and no treatment.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register to 1 February 2023, and Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 July 2023, and reference-checked and contacted study authors.

SELECTION CRITERIA

We included trials in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention as these studies have the potential to provide further information on harms and longer-term use. Studies had to report an eligible outcome.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods for screening and data extraction. Critical outcomes were abstinence from smoking after at least six months, adverse events (AEs), and serious adverse events (SAEs). We used a fixed-effect Mantel-Haenszel model to calculate risk ratios (RRs) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data in pairwise and network meta-analyses (NMA).

MAIN RESULTS

We included 88 completed studies (10 new to this update), representing 27,235 participants, of which 47 were randomized controlled trials (RCTs). Of the included studies, we rated ten (all but one contributing to our main comparisons) at low risk of bias overall, 58 at high risk overall (including all non-randomized studies), and the remainder at unclear risk. There is high certainty that nicotine EC increases quit rates compared to nicotine replacement therapy (NRT) (RR 1.59, 95% CI 1.29 to 1.93; I2 = 0%; 7 studies, 2544 participants). In absolute terms, this might translate to an additional four quitters per 100 (95% CI 2 to 6 more). There is moderate-certainty evidence (limited by imprecision) that the rate of occurrence of AEs is similar between groups (RR 1.03, 95% CI 0.91 to 1.17; I2 = 0%; 5 studies, 2052 participants). SAEs were rare, and there is insufficient evidence to determine whether rates differ between groups due to very serious imprecision (RR 1.20, 95% CI 0.90 to 1.60; I2 = 32%; 6 studies, 2761 participants; low-certainty evidence). There is moderate-certainty evidence, limited by imprecision, that nicotine EC increases quit rates compared to non-nicotine EC (RR 1.46, 95% CI 1.09 to 1.96; I2 = 4%; 6 studies, 1613 participants). In absolute terms, this might lead to an additional three quitters per 100 (95% CI 1 to 7 more). There is moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 5 studies, 1840 participants). There is insufficient evidence to determine whether rates of SAEs differ between groups, due to very serious imprecision (RR 1.00, 95% CI 0.56 to 1.79; I2 = 0%; 9 studies, 1412 participants; low-certainty evidence). Due to issues with risk of bias, there is low-certainty evidence that, compared to behavioural support only/no support, quit rates may be higher for participants randomized to nicotine EC (RR 1.88, 95% CI 1.56 to 2.25; I2 = 0%; 9 studies, 5024 participants). In absolute terms, this represents an additional four quitters per 100 (95% CI 2 to 5 more). There was some evidence that (non-serious) AEs may be more common in people randomized to nicotine EC (RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low-certainty evidence; 4 studies, 765 participants) and, again, insufficient evidence to determine whether rates of SAEs differed between groups (RR 0.89, 95% CI 0.59 to 1.34; I2 = 23%; 10 studies, 3263 participants; very low-certainty evidence). Results from the NMA were consistent with those from pairwise meta-analyses for all critical outcomes, and there was no indication of inconsistency within the networks. Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued EC use. Very few studies reported data on other outcomes or comparisons, hence, evidence for these is limited, with CIs often encompassing both clinically significant harm and benefit.

AUTHORS' CONCLUSIONS

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

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.

Beyond the label: current evidence and future directions for the interrelationship between electronic cigarettes and mental health

Electronic cigarette use has dramatically increased over the last decade. With this recent technological development and wide range of constituents in various products, putative adverse effects on the brain and body have been largely unexplored. Here, we review current evidence linking electronic nicotine cigarette use with potential health consequences and provide evidence supporting an association between drug use and depression in humans. We also examine the biological effects of individual constituents in electronic cigarette aerosols, which include labeled ingredients, such as propylene glycol, vegetable glycerin, nicotine, and flavorants, as well as unlabeled ingredients found in the aerosols, such as carbonyls and heavy metals. Lastly, we examine the effects of electronic cigarette use on endogenous metabolism via changes in cytochrome P450 enzymes, which can thereby impact therapeutic outcomes. While the current evidence offers insight into the potential effects of electronic cigarette use on biological processes, further studies are necessary to determine the long-term clinical relevance of aerosol inhalation.

Cardiovascular research at the Heart of Clinical Science

Clinical Science was originally established as the journal Heart in 1909 by Sir Thomas Lewis and Sir James Mackenzie. Heart was an influential journal publishing cardiovascular research and was renamed Clinical Science in 1933 to attract broader research interests. Nevertheless, cardiovascular research contributions remain a foundational part of the journal to this day. This editorial provides historical perspective on the journal's cardiovascular origins and includes data related to cardiovascular publications from the past decade. Clinical Science is committed to publishing leading cardiovascular research from the field and looks forward to receiving your submission.

Electronic cigarettes and health outcomes: umbrella and systematic review of the global evidence

OBJECTIVE

To review and synthesise the global evidence regarding the health effects of electronic cigarettes (e-cigarettes, vapes).

STUDY DESIGN

Umbrella review (based on major independent reviews, including the 2018 United States National Academies of Sciences, Engineering, and Medicine [NASEM] report) and top-up systematic review of published, peer-reviewed studies in humans examining the relationship of e-cigarette use to health outcomes published since the NASEM report.

DATA SOURCES

Umbrella review: eight major independent reviews published 2017-2021. Systematic review: PubMed, MEDLINE, Scopus, Web of Science, the Cochrane Library, and PsycINFO (articles published July 2017 - July 2020 and not included in NASEM review).

DATA SYNTHESIS

Four hundred eligible publications were included in our synthesis: 112 from the NASEM review, 189 from our top-up review search, and 99 further publications cited by other reviews. There is conclusive evidence linking e-cigarette use with poisoning, immediate inhalation toxicity (including seizures), and e-cigarette or vaping product use-associated lung injury (EVALI; largely but not exclusively for e-liquids containing tetrahydrocannabinol and vitamin E acetate), as well as for malfunctioning devices causing injuries and burns. Environmental effects include waste, fires, and generation of indoor airborne particulate matter (substantial to conclusive evidence). There is substantial evidence that nicotine e-cigarettes can cause dependence or addiction in non-smokers, and strong evidence that young non-smokers who use e-cigarettes are more likely than non-users to initiate smoking and to become regular smokers. There is limited evidence that freebase nicotine e-cigarettes used with clinical support are efficacious aids for smoking cessation. Evidence regarding effects on other clinical outcomes, including cardiovascular disease, cancer, development, and mental and reproductive health, is insufficient or unavailable.

CONCLUSION

E-cigarettes can be harmful to health, particularly for non-smokers and children, adolescents, and young adults. Their effects on many important health outcomes are uncertain. E-cigarettes may be beneficial for smokers who use them to completely and promptly quit smoking, but they are not currently approved smoking cessation aids. Better quality evidence is needed regarding the health impact of e-cigarette use, their safety and efficacy for smoking cessation, and effective regulation.

REGISTRATION

Systematic review: PROSPERO, CRD42020200673 (prospective).

A critique of the Australian National Health and Medical Research Council CEO statement on electronic cigarettes

This paper critically analyses a statement by Australia's National Health and Medical Research Council (NHMRC) on e-cigarettes in May 2022 that will be used to guide national policy. We reviewed the evidence and the conclusions drawn in the NHMRC Statement. In our view, the Statement is not a balanced reflection of the benefits and risks of vaping because it exaggerates the risks of vaping and fails to compare them to the far greater risks of smoking; it uncritically accepts evidence of harms from e-cigarettes while adopting a highly sceptical attitude towards evidence of their benefits; it incorrectly claims that the association between adolescent vaping and subsequent smoking is causal; and it understates the evidence of the benefits of e-cigarettes in assisting smokers to quit. The Statement dismisses the evidence that vaping is probably already having a positive net public health effect and misapplies the precautionary principle. Several sources of evidence supporting our assessment were published after the NHMRC Statement's publication and are also referenced. The NHMRC Statement on e-cigarettes does not present a balanced assessment of the available scientific literature and fails to meet the standard expected of a leading national scientific body.

Effects of chronic electronic cigarettes exposure in inducing respiratory function decline and pulmonary tissue injury - A direct comparison to combustible cigarettes

BACKGROUND

Electronic cigarette (e-cig) use is increasing worldwide, especially among young individuals. Spirometry measures airflow obstruction and is the primary tool for diagnosing/monitoring respiratory diseases in clinical settings. This study aims to assess the effects of chronic e-cig exposure on spirometric traits, and directly compare to conventional combustible-cigarette (c-cig).

METHODS

We employed an e- and c-cig aerosol generation system that resembled human smoking/vaping scenario. Fifty 6-week old C57BL/6 mice were equally divided into five groups and exposed to clean air (control), e-cig aerosol (low- and high-dose), and c-cig aerosol (low- and high-dose), respectively, for 10 weeks. Afterwards, growth trajectory, spirometry and pulmonary pathology were analyzed.

RESULTS

Both e- and c-cig exposure slowed down growth and weight gain. Low dose e-cig exposure (1 h exposure per day) resulted in minimal respiratory function damage. At high dose (2 h exposure per day), e-cig exposure deteriorated 7 spirometry traits but by a smaller magnitude than c-cig exposure. For example, comparing to clean air controls, high dose e- and c-cig exposure increased inspiratory resistance by 24.3% (p = 0.026) and 66.7% (p = 2.6e-5), respectively. Low-dose e-cig exposure increased alveolar macrophage count but did not lead to airway remodeling. In contrast, even low-dose c-cig caused alveoli break down and thickening of the small airway, hallmarks of airway obstructive disease.

CONCLUSIONS

We conducted well-controlled animal exposure experiments assessing chronic e-cig exposure's effects on spirometry traits. Further, mechanistic study characterized airway remodeling, alveolar tissue lesion and inflammation induced by e- and c-cig exposure. Our findings provided scientific and public health insights on e-cig's health consequences, especially in adolescent users.

Electronic cigarettes for smoking cessation

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Electronic Cigarette Use, Misuse, and Harm

Electronic cigarettes (e-cigarettes) are battery-powered devices that use heat to aerosolize a liquid containing a variety of substances (usually nicotine and/or cannabinoids, flavorings, and glycerol or propylene glycol base) that is then inhaled. E-cigarettes are rapidly evolving over time, so the true health effects of e-cigarettes are difficult to study and remain largely unknown. We review the effects of e-cigarettes on nicotine addiction and on pulmonary disease including the effects of dual use and switching from combustible cigarettes to e-cigarettes. Studies show that e-cigarette use can increase the risk to nicotine dependence and combustible tobacco use. Studies show an association between e-cigarette use and pulmonary disease. Some studies suggest reduced harm from e-cigarette use compared with smoking, but this requires further study. Most adults who use e-cigarettes also smoke cigarettes; epidemiologic studies suggest that the combination of e-cigarettes and cigarettes is more harmful than using either product alone.

A Close Look at Vaping in Adolescents and Young Adults in the United States

Vaping by adolescents and young adults is a legitimate concern as there is a risk that some may start smoking and that electronic cigarette (EC) use may have adverse effects in the developing lungs of adolescents. This commentary provides updated information on vaping patterns among adolescents and young adults in the United States, as well as the impact of EC usage on respiratory health. EC use has surged greatly among high school students and young adults over the last decade but fortunately has declined significantly since its peak in 2019. During the same time period, smoking rates have constantly fallen to new low record levels. These trends argue against EC use as a gateway to smoking. Most EC usage is infrequent and unlikely to increase a person's risk of negative health consequences. Furthermore, the majority of EC usage has happened among those who have previously smoked. There is a dearth of data on the long-term health implications of EC usage in adolescents and young adults. We do not know whether short-term or intermittent use of EC in youth can lead to negative health outcomes in adulthood, and long-term high-quality studies in well-defined groups are needed. Although vaping has been linked to respiratory symptoms, they tend to be transient and of uncertain significance. This commentary provides up-to-date information so health care providers can give objective and responsible medical advice on EC usage.

Tobacco Use and Respiratory Symptoms Among Adults: Findings From the Longitudinal Population Assessment of Tobacco and Health (PATH) Study 2014-2016

INTRODUCTION

We examined the relationship between current tobacco use and functionally important respiratory symptoms.

METHODS

Longitudinal cohort study of 16 295 US adults without COPD in Waves 2-3 (W2-3, 2014-2016) of the Population Assessment of Tobacco and Health Study. Exposure-Ten mutually exclusive categories of tobacco use including single product, multiple product, former, and never use (reference). Outcome-Seven questions assessing wheezing/cough were summed to create a respiratory symptom index; cutoffs of ≥2 and ≥3 were associated with functional limitations and poorer health. Multivariable regressions examined both cutoffs cross-sectionally and change over approximately 12 months, adjusting for confounders.

RESULTS

All tobacco use categories featuring cigarettes (>2/3's of users) were associated with higher risk (vs. never users) for functionally important respiratory symptoms at W2, for example, at symptom severity ≥ 3, risk ratio for exclusive cigarette use was 2.34 [95% CI, 1.92, 2.85] and for worsening symptoms at W3 was 2.80 [2.08, 3.76]. There was largely no increased symptom risk for exclusive use of cigars, smokeless tobacco, hookah, or e-cigarettes (adjustment for pack-years and marijuana attenuated the cross-sectional e-cigarette association from 1.53(95% CI 0.98, 2.40) to 1.05 (0.67, 1.63); RRs for these products were also significantly lower compared to exclusive use of cigarettes. The longitudinal e-cigarette-respiratory symptom association was sensitive to the respiratory index cutoff level; exclusive e-cigarette use was associated with worsening symptoms at an index cutoff ≥ 2 (RR = 1.63 [1.02, 2.59]) and with symptom improvement at an index cutoff of ≥ 3 (RR = 1.64 [1.04, 2.58]).

CONCLUSIONS

Past and current cigarette smoking drove functionally important respiratory symptoms, while exclusive use of other tobacco products was largely not associated. However, the relationship between e-cigarette use and symptoms was sensitive to adjustment for pack-years and symptom severity.

IMPLICATIONS

How noncigarette tobacco products affect respiratory symptoms is not clear; some studies implicate e-cigarettes. We examined functionally important respiratory symptoms (wheezing/nighttime cough) among US adults without COPD. The majority of adult tobacco users smoke cigarettes and have higher risk of respiratory symptoms and worsening of symptoms, regardless of other products used with them. Exclusive use of other tobacco products (e-cigarettes, cigars, smokeless, hookah) was largely not associated with functionally important respiratory symptoms and risks associated with their use was significantly lower than for cigarettes. The association for e-cigarettes was greatly attenuated by adjustment for cigarette pack-years and sensitive to how symptoms were defined.

Health effects and known pathology associated with the use of E-cigarettes

In recent years, new nicotine delivery methods have emerged, and many users are choosing electronic cigarettes (e-cigarettes) over traditional tobacco cigarettes. E-cigarette use is very popular among adolescents, with more than 3.5 million currently using these products in the US. Despite the increased prevalence of e-cigarette use, there is limited knowledge regarding the health impact of e-cigarettes on the general population. Based on published findings by others, E-cigarette is associated with lung injury outbreak, which increased health and safety concerns related to consuming this product. Different components of e-cigarettes, including food-safe liquid solvents and flavorings, can cause health issues related to pneumonia, pulmonary injury, and bronchiolitis. In addition, e-cigarettes contain alarmingly high levels of carcinogens and toxicants that may have long-lasting effects on other organ systems, including the development of neurological manifestations, lung cancer, cardiovascular disorders, and tooth decay. Despite the well- documented potential for harm, e-cigarettes do not appear to increase susceptibility to SARS-CoV- 2 infection. Furthermore, some studies have found that e-cigarette users experience improvements in lung health and minimal adverse effects. Therefore, more studies are needed to provide a definitive conclusion on the long-term safety of e-cigarettes. The purpose of this review is to inform the readers about the possible health-risks associated with the use of e-cigarettes, especially among the group of young and young-adults, from a molecular biology point of view.

Biomarkers of Exposure and Biomarkers of Potential Harm in Adult Smokers Who Switch to e-Vapor Products Relative to Cigarette Smoking in a 24-week, Randomized, Clinical Trial

INTRODUCTION

Long-term health effects of e-vapor products (EVPs) are not well-established. We compared biomarkers of exposure (BoE) to select harmful and potentially harmful constituents and biomarkers of potential harm (BoPH) in adult smokers who switched to EVPs versus continued smoking for 24 weeks.

METHODS

Adult smokers (n = 450, >10 cigarettes per day for ≥10 years) were randomly assigned to continue smoking (control) or switch to one of two cartridge-based EVPs (test 1: classic; test 2: menthol, 4% nicotine). BoE and BoPH were measured at baseline and 12 weeks. The results presented here are from a subset of 150 control and EVP subjects (switchers with exhaled carbon monoxide <8 ppm and <10% baseline cigarettes per day) followed for 24 total weeks.

RESULTS

Total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and carboxyhemoglobin were significantly reduced (p < .0001) in tests 1 and 2 at 24 weeks. Urinary nicotine equivalents were not statistically significantly different between the control and EVP groups. At week 24, statistically significant reductions (p < .05) were observed for white blood cell counts, 11-dehydrothromboxane β2, and sICAM in both test groups, and there were several significant changes in measures of pulmonary function. High-density lipoprotein cholesterol and 8-epi-prostaglandin-F2α were directionally favorable in both EVP groups versus control.

CONCLUSIONS

We demonstrate that significant reductions of selected harmful and potentially harmful constituents in EVP aerosol results in significant reductions in BoEs and favorable changes in BoPHs after switching to EVPs for 24 weeks. These changes approached those reported for smoking cessation, suggesting that switching to exclusive use of the EVPs may be less harmful than continuing smoking.

IMPLICATIONS

Cigarette smoking causes serious diseases. Switching from cigarettes to a noncombustible product is a potential harm reduction pathway for adult smokers unable or unwilling to quit. Long-term health effects of e-vapor products (EVPs) compared with continued smoking have not been extensively studied. We present biomarker of exposure evidence on select harmful and potentially harmful constituents and biomarkers of potential harm related to inflammation and oxidative stress in adult smokers switching to two EVPs. This study demonstrates significant reductions in biomarkers of exposure (except for nicotine) accompanied with favorable changes in various biomarkers of potential harm, including pulmonary function. The totality of evidence suggests that exclusive EVP use may present lower health risks compared with smoking cigarettes.

E-Cigarettes and Cardiopulmonary Health: Review for Clinicians

Electronic cigarettes (e-cigarettes) are battery powered electronic nicotine delivery systems that use a propylene glycol/vegetable glycerin base to deliver vaporized nicotine and flavorings to the body. E-cigarettes became commercially available without evidence regarding their risks, long-term safety, or utility in smoking cessation. Recent clinical trials suggest that e-cigarette use with counseling may be effective in reducing cigarette use but not nicotine dependence. However, meta-analyses of observational studies demonstrate that e-cigarette use is not associated with smoking cessation. Cardiovascular studies reported sympathetic activation, vascular stiffening, and endothelial dysfunction, which are associated with adverse cardiovascular events. The majority of pulmonary clinical trials in e-cigarette users included standard spirometry as the primary outcome measure, reporting no change in lung function. However, studies reported increased biomarkers of pulmonary disease in e-cigarette users. These studies were conducted in adults, but >30% of high school-age adolescents reported e-cigarette use. The effects of e-cigarette use on cardiopulmonary endpoints in adolescents and young adults remain unstudied. Because of adverse clinical findings and associations between e-cigarette use and increased incidence of respiratory diseases in people who have never smoked, large longitudinal studies are needed to understand the risk profile of e-cigarettes. Consistent with the Centers for Disease Control and Prevention recommendations, clinicians should monitor the health risks of e-cigarette use, discourage nonsmokers and adolescents from using e-cigarettes, and discourage smokers from engaging in dual use without cigarette reduction or cessation.

Efficacy and safety of electronic cigarettes as a smoking cessation intervention: A systematic review and network meta-analysis

INTRODUCTION

This systematic review of randomized controlled trials (RCTs) evaluated the efficacy and safety of electronic cigarettes (e-cigarettes, ENDS) in helping people who smoke to achieve abstinence compared with electronic non-nicotine delivery systems (ENNDS, no nicotine) or any smoking cessation comparator treatment or combination of treatments at 24–26 weeks and at 52 weeks.

METHODS

Systematic review techniques involved searches of three databases in February 2020 with update searches run on 14 May 2021, two-person independent screening, two-person independent assessment of bias, formal extraction of data with verification by a second person, a feasibility assessment to decide if meta-analysis was appropriate, and network meta-analysis (NMA) of data at 24–26 weeks. Data at 52 weeks were narratively summarized.

RESULTS

Ten RCTs met the inclusion criteria, eight for efficacy and ten for safety. Eight of the nine RCTs were assessed as at high risk of bias. The sample sizes of the RCTs were 30–2012. Using nicotine replacement therapy (NRT) as the reference treatment, the incidences of smoking cessation at 24–26 weeks were comparable between ENDS and NRT groups (RR=1.17; 95% CrI: 0.66–1.86). Three sensitivity analyses were carried out indicating the main findings for 24–26 weeks were robust to assumptions. The findings at 52 weeks were inconclusive.

CONCLUSIONS

This systematic review and NMA indicates that there is no clear evidence of a difference in effect between nicotine containing e-cigarettes and NRT on incidences of smoking cessation at 24–26 weeks, and substantial uncertainty remains.

Electronic cigarettes for smoking cessation

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 May 2021, and reference-checked and contacted study authors. We screened abstracts from the Society for Research on Nicotine and Tobacco (SRNT) 2021 Annual Meeting.   SELECTION CRITERIA: We included randomized controlled trials (RCTs) and randomized cross-over trials, in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. Studies had to report abstinence from cigarettes at six months or longer or data on safety markers at one week or longer, or both.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

We included 61 completed studies, representing 16,759 participants, of which 34 were RCTs. Five of the 61 included studies were new to this review update. Of the included studies, we rated seven (all contributing to our main comparisons) at low risk of bias overall, 42 at high risk overall (including all non-randomized studies), and the remainder at unclear risk. There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (risk ratio (RR) 1.53, 95% confidence interval (CI) 1.21 to 1.93; I2 = 0%; 4 studies, 1924 participants). In absolute terms, this might translate to an additional three quitters per 100 (95% CI 1 to 6). There was low-certainty evidence (limited by very serious imprecision) that the rate of occurrence of AEs was similar (RR 0.98, 95% CI 0.80 to 1.19; I2 = 0%; 2 studies, 485 participants). SAEs were rare, but there was insufficient evidence to determine whether rates differed between groups due to very serious imprecision (RR 1.30, 95% CI 0.89 to 1.90: I2 = 0; 4 studies, 1424 participants). There was moderate-certainty evidence, again limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.94, 95% CI 1.21 to 3.13; I2 = 0%; 5 studies, 1447 participants). In absolute terms, this might lead to an additional seven quitters per 100 (95% CI 2 to 16). There was moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 3 studies, 601 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 1.06, 95% CI 0.47 to 2.38; I2 = 0; 5 studies, 792 participants). Compared to behavioural support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.61, 95% CI 1.44 to 4.74; I2 = 0%; 6 studies, 2886 participants). In absolute terms this represents an additional six quitters per 100 (95% CI 2 to 15). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was some evidence that non-serious AEs were more common in people randomized to nicotine EC (RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low certainty; 4 studies, 765 participants), and again, insufficient evidence to determine whether rates of SAEs differed between groups (RR 1.51, 95% CI 0.70 to 3.24; I2 = 0%; 7 studies, 1303 participants).  Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued use. Very few studies reported data on other outcomes or comparisons, hence evidence for these is limited, with CIs often encompassing clinically significant harm and benefit.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that ECs with nicotine increase quit rates compared to NRT and compared to ECs without nicotine. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the effect size. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, with no difference in AEs between nicotine and non-nicotine ECs. Overall incidence of SAEs was low across all study arms. We did not detect  evidence of harm from nicotine EC, but longest follow-up was two years and the  number of studies was small. The main limitation of the evidence base remains imprecision due to the small number of RCTs, often with low event rates, but further RCTs are underway. To ensure the review continues to provide up-to-date information to decision-makers, this review is now a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.

The chemistry and toxicology of vaping

Vaping is the process of inhaling and exhaling an aerosol produced by an e-cigarette, vape pen, or personal aerosolizer. When the device contains nicotine, the Food and Drug Administration (FDA) lists the product as an electronic nicotine delivery system or ENDS device. Similar electronic devices can be used to vape cannabis extracts. Over the past decade, the vaping market has increased exponentially, raising health concerns over the number of people exposed and a nationwide outbreak of cases of severe, sometimes fatal, lung dysfunction that arose suddenly in otherwise healthy individuals. In this review, we discuss the various vaping technologies, which are remarkably diverse, and summarize the use prevalence in the U.S. over time by youths and adults. We examine the complex chemistry of vape carrier solvents, flavoring chemicals, and transformation products. We review the health effects from epidemiological and laboratory studies and, finally, discuss the proposed mechanisms underlying some of these health effects. We conclude that since much of the research in this area is recent and vaping technologies are dynamic, our understanding of the health effects is insufficient. With the rapid growth of ENDS use, consumers and regulatory bodies need a better understanding of constituent-dependent toxicity to guide product use and regulatory decisions.

Effectiveness and Safety Profile of Alternative Tobacco and Nicotine Products for Smoking Reduction and Cessation: A Systematic Review

BACKGROUND

Alternative tobacco and nicotine products such as electronic cigarettes (EC), smokeless tobacco, and nicotine replacement therapy (NRT) are currently being assessed as options in tobacco harm reduction due to their potential role in smoking reduction and smoking cessation.

OBJECTIVE

To provide the current evidence on the effectiveness and safety of various alternative tobacco and nicotine products for smoking reduction and cessation.

METHODS

A systematic review using databases from MEDLINE (PubMed), EMBASE, and The Cochrane Library was conducted up to December 2020 to identify eligible experimental and observational studies assessing the use of alternative tobacco and nicotine products on smoking reduction and smoking cessation and the safety of these products. The Cochrane Risk of Bias 2 (RoB 2) and ROBINS-I tools were used to assess the risk of bias of the included studies. Results were described through a narrative synthesis of the evidence.

RESULTS

From 1955 retrieved references, 44 studies (31 randomized controlled trials/RCTs and 13 prospective cohort studies) met the inclusion criteria and were included in the review. Twenty-nine studies were assessing EC, one study evaluated heat-not-burn (HNB) product, five studies were focused on snus, and nine studies assessed NRT in the form of nicotine patch, gum, etc. The overall results suggested that alternative tobacco and nicotine products in the form of EC, snus, and NRT can moderately reduce daily cigarette consumption and has potential to assist smoking cessation attempts, with fewer adverse events.

CONCLUSION

The findings suggested that alternative tobacco and nicotine products have a potential role in assisting smoking reduction and cessation, highlighting their role in the tobacco harm reduction approach. Further studies should focus on investigating long-term outcomes, safety, and effectiveness of alternative tobacco and nicotine products to better inform smoking reduction/cessation policy.

PROSPERO REGISTRATION NUMBER

CRD42020205830.

Electronic cigarettes for smoking cessation

BACKGROUND

Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol formed by heating an e-liquid. Some people who smoke use ECs to stop or reduce smoking, but some organizations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit and if they are safe to use for this purpose. This is an update of a review first published in 2014.

OBJECTIVES

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

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 February 2021, together with reference-checking and contact with study authors.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and randomized cross-over trials in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. To be included, studies had to report abstinence from cigarettes at six months or longer and/or data on adverse events (AEs) or other markers of safety at one week or longer.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months follow-up, adverse events (AEs), and serious adverse events (SAEs). Secondary outcomes included changes in carbon monoxide, blood pressure, heart rate, blood oxygen saturation, lung function, and levels of known carcinogens/toxicants. We used a fixed-effect Mantel-Haenszel model to calculate the risk ratio (RR) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data from these studies in meta-analyses.

MAIN RESULTS

We included 56 completed studies, representing 12,804 participants, of which 29 were RCTs. Six of the 56 included studies were new to this review update. Of the included studies, we rated five (all contributing to our main comparisons) at low risk of bias overall, 41 at high risk overall (including the 25 non-randomized studies), and the remainder at unclear risk. There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (risk ratio (RR) 1.69, 95% confidence interval (CI) 1.25 to 2.27; I2 = 0%; 3 studies, 1498 participants). In absolute terms, this might translate to an additional four successful quitters per 100 (95% CI 2 to 8). There was low-certainty evidence (limited by very serious imprecision) that the rate of occurrence of AEs was similar) (RR 0.98, 95% CI 0.80 to 1.19; I2 = 0%; 2 studies, 485 participants). SAEs occurred rarely, with no evidence that their frequency differed between nicotine EC and NRT, but very serious imprecision led to low certainty in this finding (RR 1.37, 95% CI 0.77 to 2.41: I2 = n/a; 2 studies, 727 participants). There was moderate-certainty evidence, again limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.70, 95% CI 1.03 to 2.81; I2 = 0%; 4 studies, 1057 participants). In absolute terms, this might again lead to an additional four successful quitters per 100 (95% CI 0 to 11). These trials mainly used older EC with relatively low nicotine delivery. There was moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 3 studies, 601 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 0.60, 95% CI 0.15 to 2.44; I2 = n/a; 4 studies, 494 participants). Compared to behavioral support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.70, 95% CI 1.39 to 5.26; I2 = 0%; 5 studies, 2561 participants). In absolute terms this represents an increase of seven per 100 (95% CI 2 to 17). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was no evidence that the rate of SAEs differed, but some evidence that non-serious AEs were more common in people randomized to nicotine EC (AEs: RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low certainty; 4 studies, 765 participants; SAEs: RR 1.17, 95% CI 0.33 to 4.09; I2 = 5%; 6 studies, 1011 participants, very low certainty). Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued use. Very few studies reported data on other outcomes or comparisons and hence evidence for these is limited, with confidence intervals often encompassing clinically significant harm and benefit.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that ECs with nicotine increase quit rates compared to ECs without nicotine and compared to NRT. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the size of effect, particularly when using modern EC products. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, though evidence indicated no difference in AEs between nicotine and non-nicotine ECs. Overall incidence of SAEs was low across all study arms. We did not detect any clear evidence of harm from nicotine EC, but longest follow-up was two years and the overall number of studies was small. The evidence is limited mainly by imprecision due to the small number of RCTs, often with low event rates. Further RCTs are underway. To ensure the review continues to provide up-to-date information, this review is now a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.

Two Weeks of Smoking Cessation Reverse Cigarette Smoke-Induced Skeletal Muscle Atrophy and Mitochondrial Dysfunction in Mice

INTRODUCTION

Apart from its adverse effects on the respiratory system, cigarette smoking also induces skeletal muscle atrophy and dysfunction. Whether short-term smoking cessation can restore muscle mass and function is unknown. We, therefore, studied the impact of 1- and 2-week smoking cessation on skeletal muscles in a mouse model.

METHODS

Male mice were divided into four groups: Air-exposed (14 weeks); cigarette smoke (CS)-exposed (14 weeks); CS-exposed (13 weeks) followed by 1-week cessation; CS-exposed (12 weeks) followed by 2 weeks cessation to examine exercise capacity, physical activity levels, body composition, muscle function, capillarization, mitochondrial function and protein expression in the soleus, plantaris, and diaphragm muscles.

RESULTS

CS-induced loss of body and muscle mass was significantly improved within 1 week of cessation due to increased lean and fat mass. Mitochondrial respiration and protein levels of the respiratory complexes in the soleus were lower in CS-exposed mice, but similar to control values after 2 weeks of cessation. Exposing isolated soleus muscles to CS extracts reduced mitochondrial respiration that was reversed after removing the extract. While physical activity was reduced in all groups, exercise capacity, limb muscle force, fatigue resistance, fiber size and capillarization, and diaphragm cytoplasmic HIF-1α were unaltered by CS-exposure. However, CS-induced diaphragm atrophy and increased capillary density were not seen after 2 weeks of smoking cessation.

CONCLUSION

In male mice, 2 weeks of smoking cessation reversed smoking-induced mitochondrial dysfunction, limb muscle mass loss, and diaphragm muscle atrophy, highlighting immediate benefits of cessation on skeletal muscles.

IMPLICATIONS

Our study demonstrates that CS-induced skeletal muscle mitochondrial dysfunction and atrophy are significantly improved by 2 weeks of cessation in male mice. We show for the first time that smoking cessation as short as 1 to 2 weeks is associated with immediate beneficial effects on skeletal muscle structure and function with the diaphragm being particularly sensitive to CS-exposure and cessation. This could help motivate smokers to quit smoking as early as possible. The knowledge that smoking cessation has potential positive extrapulmonary effects is particularly relevant for patients referred to rehabilitation programs and those admitted to hospitals suffering from acute or chronic muscle deterioration yet struggling with smoking cessation.

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.

Personal PM2.5 exposure and lung function: Potential mediating role of systematic inflammation and oxidative damage in urban adults from the general population

BACKGROUND

Short-term effects of fine particulate matter (PM_2.5) exposure on lung function have been reported. However, few studies have assessed PM_2.5 exposure on the personal level, and the mechanism underlying the effects of PM_2.5 exposure on lung function remains less clear.

OBJECTIVES

To evaluate the association between personal PM_2.5 exposure and lung function alteration in general population and to explore the roles of systematic inflammation and oxidative damage in this association.

METHODS

A total of 7685 lung function tests were completed among 4697 urban adults in Wuhan, China. Plasma C-reactive protein (CRP), urinary 8-iso-prostaglandin-F_2α (8-iso-PGF_2α) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels were measured. Personal PM_2.5 exposure levels were estimated using an estimation model from the actual measurements of individual PM_2.5 levels in 191 participants. Mixed linear models were used to evaluate the association between personal PM_2.5 exposure and lung function. Mediation analyses were conducted to investigate the roles of CRP, 8-iso-PGF_2α and 8-OHdG in above associations.

RESULTS

After adjusting for confounders, each 10 μg/m³ increase in the previous-day personal PM_2.5 exposure was associated with 2.94 mL, 2.02 mL and 16.14 mL/s decreases in forced vital capacity (FVC), forced expiration volume in 1 s (FEV₁) and peak expiratory flow, respectively. The associations were more obvious among never smokers compared with current smokers. Cumulative 7-day exposure to PM_2.5 led to the strongest adverse effects on lung function. Among never smokers with high PM_2.5 exposure levels, a positive relationship was observed between personal PM_2.5 level and urinary 8-iso-PGF_2α, and 8-iso-PGF_2α meditated 4.69% and 12.30% of the association between the 7-day moving PM_2.5 concentration and FVC and FEV₁, respectively. We did not observe a significant positive association between PM_2.5 exposure and plasma CRP or urinary 8-OHdG.

CONCLUSION

Short-term personal exposure to PM_2.5 is associated with reduced pulmonary ventilation function. Urinary 8-iso-PGF_2α partly mediates these associations.

E-Cigarettes and Cardiopulmonary Health

E-cigarettes have surged in popularity over the last few years, particularly among youth and young adults. These battery-powered devices aerosolize e-liquids, comprised of propylene glycol and vegetable glycerin, typically with nicotine, flavors, and stabilizers/humectants. Although the use of combustible cigarettes is associated with several adverse health effects including multiple pulmonary and cardiovascular diseases, the effects of e-cigarettes on both short- and long-term health have only begun to be investigated. Given the recent increase in the popularity of e-cigarettes, there is an urgent need for studies to address their potential adverse health effects, particularly as many researchers have suggested that e-cigarettes may pose less of a health risk than traditional combustible cigarettes and should be used as nicotine replacements. This report is prepared for clinicians, researchers, and other health care providers to provide the current state of knowledge on how e-cigarette use might affect cardiopulmonary health, along with research gaps to be addressed in future studies.

Reduction of bronchial response to mannitol after partial switch from conventional tobacco to electronic cigarette consumption

BACKGROUND

Regarding the multiple health effects of e-cigarettes, there are insufficient data on potential effects on bronchial reactivity (BHR). In the present study, we assessed the impact of a switch from conventional to e-cigarettes on BHR under realistic conditions over a period of 3 months.

METHODS

Sixty subjects who declared to reduce or stop their tobacco consumption by inhalation of nicotine-containing liquids via e-cigarette, and 20 volunteers participating in a stop-smoking program were included. Data was analysed using parametric and non-parametric statistical procedures. Spirometry, determinations of exhaled carbon monoxide (eCO) and nitric oxide (FeNO), provocation testing with mannitol as an indirect bronchial stimulus, and cotinine measurements were used to investigate BHR and nicotine abstinence.

RESULTS

BHR to mannitol significantly decreased in the group using e-cigarettes and nicotine-containing liquids over a period of three months in this real-life setting. Participants reduced their tobacco consumption to about 25% or lower, confirmed by a reduction in eCO. Changes in lung function and FeNO were small and not statistically significant, and changes in the stop-smoking group were similar to those in the e-cigarette group.

CONCLUSION

The reduction in BHR that can be expected after a reduction of cigarette consumption was not abolished by the concomitant use of e-cigarettes. Whether the decrease in BHR observed after 3 months is maintained when using e-cigarettes over longer time periods or has an individual prognostic value, must be clarified in long-term studies.

Differences in Levels of Biomarkers of Potential Harm Among Users of a Heat-Not-Burn Tobacco Product, Cigarette Smokers, and Never-Smokers in Japan: A Post-Marketing Observational Study

Introduction

Cigarette smoking is associated with the risk of certain diseases, but non-combustible products may lower these risks. The potential long-term health effects of the next-generation non-combustible products (heat-not-burn tobacco products (HNBP) or electronic vapor products) have not been thoroughly studied. The present study aimed to investigate the impact of biomarkers of potential harm (BoPH) of one of HNBP (a novel vapor product: NTV (novel tobacco vapor)), under the conditions of actual use.

Aims and Methods

This study was an observational, cross-sectional, three-group, multi-center study. Exclusive NTV users (NTV, n = 259), conventional cigarette smokers (CC, n = 100) and never-smokers (NS, n = 100) were enrolled. Biomarkers of tobacco smoke exposure (cotinine and total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL)) and BoPH including parameters of physical pulmonary functions relevant to smoking-related diseases were examined, and subjects answered a questionnaire on cough-related symptoms (J-LCQ) and health-related quality of life (SF-36v2®).

Results

Levels of cotinine, total NNAL and BoPH (high-density lipoprotein (HDL)-cholesterol, triglyceride, sICAM-1, WBC count, 11-DHTXB2, 2,3-d-TXB2, 8-epi-PGF2α, forced expiratory volume in 1 second (FEV1), % predicted value of FEV1 (%FEV1) and maximum midexpiratory flow (FEF_25-75)) were significantly different in the NTV group as compared to levels in CC group (p < .05). Significantly higher levels of cotinine, total NNAL, and 2,3-d-TXB2, and lower levels of FEV1 and %FEV1, were observed among NTV users compared to the NS group.

Conclusion

In a post-marketing study under actual use conditions, BoPH associated with smoking-related disease examined in exclusive NTV users were found to be favorably different from those of CC smokers, a finding attributable to a reduction in exposure to harmful substances of tobacco smoke.

Implications

Cigarette smoking is associated with an increased risk of pulmonary diseases like COPD, cardiovascular diseases, and certain cancers. There is a growing body of evidence that HNBP reduces the exposure associated with smoking and that there is a favorable change in BoPH. However, long-term effects regarding the relative health risks to HNBP users compared to CC smokers have not been examined. This study provides post-marketing data under actual use conditions of the effects on biomarkers of potential harm in NTV, one of HNBP, exclusive users compared to CC smokers and never-smokers. The evidence suggests that exclusive NTV users have favorable levels of BoPH compared to CC smokers, and that is result from a sustained reduction in exposure to harmful substances of tobacco smoke.

Well-being and harm reduction, the consolidated reality of electronic cigarettes ten years later from this emerging phenomenon: A narrative review

Tobacco use is the greatest threat to public health worldwide, killing more than seven million people annually. This paper, about 10 years after the first review on electronic cigarettes, analyses the evolution that this tool has had in these years. It concludes with comments on the significance of the research and why it constitutes an original contribution. We searched PubMed (National Library of Medicine), and PsycINFO (Ovid) (2006-2020) for studies on e-cigarettes (harms and benefits, e-cigarette use, craving and smoking cessation) and smoking cessation treatment (smoking cessation treatment or varenicline or tobacco cessation or reduction or bupropion or NRT or behavioral treatment or ecigarette) and evidence suggests that they may effective as smoking cessation tool and may be less harmful alternatives to combustible cigarette smoking. Consequently, e-cigarettes could be considered as an applicable instrument for Tobacco Harm Reduction (THR) and smoking cessation.

Exclusive E-Cigarette Users Report Lower Levels of Respiratory Symptoms Relative to Dual E-Cigarette and Cigarette Users

INTRODUCTION

Exclusive e-cigarette use has been shown to be associated with reduced levels of respiratory symptoms relative to smoking combustible cigarettes; this association has been less frequently studied in smokers using advanced-generation e-cigarette devices. Advanced-generation devices generate denser vapor than either early generation or pod-style devices, and engender longer inhalations; these vaping topography patterns may contribute to respiratory symptoms.

METHODS

In a single-session, cross-sectional study of exclusive e-cigarette users (N = 59) and dual users of e-cigarettes and cigarettes (N = 54), participants completed questionnaires, including the American Thoracic Society Questionnaire (ATSQ) and were videotaped vaping their own device in the lab for 1 hour. Using a hierarchical regression method, we examined whether topography variables, level of nicotine concentration used in their e-cigarette device in the past month, e-cigarette dependence, amount of e-cigarette use in the past month, and smoking status (any smoking in the last month vs. none) predicted ATSQ score severity.

RESULTS

There was a significant mean difference in ATSQ score across smoking status, with greater ATSQ scores for vapers who also smoked cigarettes (19.0, SD = 6.7) than for exclusive vapers (13.4, SD = 5.3). In the final model, of the predictors of interest, only cigarette smoking status predicted significantly greater ATSQ scores (overall F = 2.51, p = .006; R2 = .26; smoking status β = 0.39, p < .0001).

CONCLUSIONS

Findings suggest that differences in respiratory symptoms between dual and exclusive e-cigarette users appear to be attributable to combustible cigarette smoking, rather than more intense or frequent e-cigarette use across groups.

IMPLICATIONS

In this comparison of exclusive advanced-generation vape device users (N = 59) versus dual users of these devices and combustible cigarettes (N = 54), we set out to determine the extent to which smoking status and e-cigarette use variables predicted self-reported respiratory symptom severity. We found that dual users showed greater respiratory symptom severity (ATSQ scores) than exclusive vapers. Despite examining vaping topography and other variables, smoking status and race were the only significant predictor of respiratory symptoms. We conclude that combustible cigarette use, not individual vaping topography, likely accounts for differences in respiratory symptoms between dual users and exclusive vapers.

User-Perceived Negative Respiratory Symptoms Associated with Electronic Cigarette Use

INTRODUCTION

Electronic cigarettes (ECIGs) expose users to an aerosol containing chemicals, which could affect the respiratory system negatively. This study examined negative respiratory symptoms associated with ECIG use.

METHODS

In 2019, adult current ECIG users from 24 US states who reported experiencing negative respiratory symptoms from ECIG use (n = 49; 44.9% women; mean age = 35.2, SD = 11.5) completed an online survey and brainstormed statements that completed the prompt: "A specific negative effect or symptom related to my breathing, nose, mouth, throat, or lungs that I have experienced from vaping/using my e-cigarette is..." Participants sorted the final list of 56 statements into groups of similar content and rated statements on how true they were for them. Multidimensional scaling analysis identified thematic clusters.

RESULTS

Eight ECIG use respiratory symptom clusters identified in analysis included Mucus and Congestion, Fatigue, Throat Symptoms, Breathing Problems, Mouth Symptoms, Chest Symptoms, Illness Symptoms, and Nose and Sinus Symptoms. Highly rated (ie, most common) symptoms included dry throat or mouth, fatigue during physical activity, coughing, shortness of breath, excessive phlegm, and bad taste in mouth. Mean cluster ratings did not differ based on lifetime cigarette smoking status (100 lifetime cigarettes smoked), but current cigarette smokers (ie, dual users) rated the Fatigue, Breathing Problems, Mucus and Congestion, and Nose and Sinus Symptoms clusters higher than noncurrent cigarette smokers.

CONCLUSIONS

Participant-identified respiratory symptoms perceived to be ECIG related, many similar to cigarette smoking symptoms. Future research should assess if these symptoms are associated with other negative health outcomes.

IMPLICATIONS

ECIG use exposes users to chemicals that may have negative health impacts on the respiratory system. Limited research has examined the broad range of negative respiratory symptoms associated with e-cigarette use. This study identified that ECIG-cigarette users perceive their ECIG use to be associated with negative respiratory symptoms. Many e-cigarette user-reported negative respiratory symptoms are similar to those associated with cigarette smoking, though some appear unique to e-cigarette use. Future research should continue to monitor respiratory symptoms reported by ECIG users and whether these are associated with health outcomes over time.

Acute e-cig inhalation impacts vascular health: a study in smoking naïve subjects

This study was designed to investigate the acute effects of nonnicotinized e-cigarette (e-cig) aerosol inhalation in nonsmokers both in terms of blood-based markers of inflammation and oxidative stress and evaluate their association with hemodynamic-metabolic MRI parameters quantifying peripheral vascular reactivity, cerebrovascular reactivity, and aortic stiffness. Thirty-one healthy nonsmokers were subjected to two blood draws and two identical MRI protocols, each one before and after a standardized e-cig vaping session. After vaping, the serum levels of C-reactive protein, soluble intercellular adhesion molecule, and the danger signal machinery high-mobility group box 1 (HMGB1) and its downstream effector and the NLR family pyrin domain containing 3 (NLRP3) inflammasome (as monitored by its adaptor protein ASC) increased significantly relative to the respective baseline (prevaping) values. Moreover, nitric oxide metabolites and reactive oxygen species production decreased and increased, respectively. These observations were paralleled by impaired peripheral vascular reactivity (with reduced flow-mediated dilation and attenuated hyperemic response after a cuff-occlusion test) and metabolic alterations expressed by decreased venous oxygen saturation, postvaping. The current results suggest propagation of inflammation signaling via activation of the danger signaling axis (HMGB1-NLRP3). The findings indicate that a single episode of vaping has adverse impacts on vascular inflammation and function.NEW & NOTWORTHY Endothelial cell signaling and blood biomarkers were found to correlate with functional vascular changes in a single episode e-cigarettes inhalation in healthy adults. This is indicative of the potential of e-cigarettes (even when inhaled acutely) to lead of vascular dysfunction.

Effects of e-cigarettes and vaping devices on cardiac and pulmonary physiology

E-cigarette aerosols are exceedingly different from conventional tobacco smoke, containing dozens of chemicals not found in cigarette smoke. It is highly likely that chronic use of e-cigarettes will induce pathological changes in both the heart and lungs. Here we review human and animal studies published to date and summarize the cardiopulmonary physiological changes caused by vaping. In terms of cardiac physiology, acute exposure to e-cigarette aerosols in human subjects led to increased blood pressure and heart rate, similar to traditional cigarettes. Chronic exposure to e-cigarette aerosols using animal models caused increased arterial stiffness, vascular endothelial changes, increased angiogenesis, cardiorenal fibrosis and increased atherosclerotic plaque formation. Pulmonary physiology is also affected by e-cigarette aerosol inhalation, with increased airway reactivity, airway obstruction, inflammation and emphysema. Research thus far demonstrates that the heart and lung undergo numerous changes in response to e-cigarette use, and disease development will depend on how those changes combine with both environmental and genetic factors. E-cigarettes have been advertised as a healthy alternative to cigarette smoking, and users are under the impression that vaping of e-cigarettes is harmless, but these claims that e-cigarettes are safer and healthier are not based on evidence. Data from both humans and animal models are consistent in demonstrating that vaping of e-cigarettes causes health effects both similar to and disparate from those of cigarette smoking. Further work is needed to define the long-term cardiopulmonary effects of e-cigarette use in humans.

Electronic cigarettes for smoking cessation

BACKGROUND

Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol formed by heating an e-liquid. People who smoke report using ECs to stop or reduce smoking, but some organisations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit and if they are safe to use for this purpose. This review is an update of a review first published in 2014.

OBJECTIVES

To evaluate the effect and safety of using electronic cigarettes (ECs) to help people who smoke achieve long-term smoking abstinence.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO for relevant records to January 2020, together with reference-checking and contact with study authors.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and randomized cross-over trials in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. To be included, studies had to report abstinence from cigarettes at six months or longer and/or data on adverse events (AEs) or other markers of safety at one week or longer.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months follow-up, AEs, and serious adverse events (SAEs). Secondary outcomes included changes in carbon monoxide, blood pressure, heart rate, blood oxygen saturation, lung function, and levels of known carcinogens/toxicants. We used a fixed-effect Mantel-Haenszel model to calculate the risk ratio (RR) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data from these studies in meta-analyses.

MAIN RESULTS

We include 50 completed studies, representing 12,430 participants, of which 26 are RCTs. Thirty-five of the 50 included studies are new to this review update. Of the included studies, we rated four (all which contribute to our main comparisons) at low risk of bias overall, 37 at high risk overall (including the 24 non-randomized studies), and the remainder at unclear risk. There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (risk ratio (RR) 1.69, 95% confidence interval (CI) 1.25 to 2.27; I2 = 0%; 3 studies, 1498 participants). In absolute terms, this might translate to an additional four successful quitters per 100 (95% CI 2 to 8). There was low-certainty evidence (limited by very serious imprecision) of no difference in the rate of adverse events (AEs) (RR 0.98, 95% CI 0.80 to 1.19; I2 = 0%; 2 studies, 485 participants). SAEs occurred rarely, with no evidence that their frequency differed between nicotine EC and NRT, but very serious imprecision led to low certainty in this finding (RR 1.37, 95% CI 0.77 to 2.41: I2 = n/a; 2 studies, 727 participants). There was moderate-certainty evidence, again limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.71, 95% CI 1.00 to 2.92; I2 = 0%; 3 studies, 802 participants). In absolute terms, this might again lead to an additional four successful quitters per 100 (95% CI 0 to 12). These trials used EC with relatively low nicotine delivery. There was low-certainty evidence, limited by very serious imprecision, that there was no difference in the rate of AEs between these groups (RR 1.00, 95% CI 0.73 to 1.36; I2 = 0%; 2 studies, 346 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 0.25, 95% CI 0.03 to 2.19; I2 = n/a; 4 studies, 494 participants). Compared to behavioural support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.50, 95% CI 1.24 to 5.04; I2 = 0%; 4 studies, 2312 participants). In absolute terms this represents an increase of six per 100 (95% CI 1 to 14). However, this finding was very low-certainty, due to issues with imprecision and risk of bias. There was no evidence that the rate of SAEs varied, but some evidence that non-serious AEs were more common in people randomized to nicotine EC (AEs: RR 1.17, 95% CI 1.04 to 1.31; I2 = 28%; 3 studies, 516 participants; SAEs: RR 1.33, 95% CI 0.25 to 6.96; I2 = 17%; 5 studies, 842 participants). Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate over time with continued use. Very few studies reported data on other outcomes or comparisons and hence evidence for these is limited, with confidence intervals often encompassing clinically significant harm and benefit.

AUTHORS' CONCLUSIONS

There is moderate-certainty evidence that ECs with nicotine increase quit rates compared to ECs without nicotine and compared to NRT. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the degree of effect, particularly when using modern EC products. Confidence intervals were wide for data on AEs, SAEs and other safety markers. Overall incidence of SAEs was low across all study arms. We did not detect any clear evidence of harm from nicotine EC, but longest follow-up was two years and the overall number of studies was small. The main limitation of the evidence base remains imprecision due to the small number of RCTs, often with low event rates. Further RCTs are underway. To ensure the review continues to provide up-to-date information for decision-makers, this review is now a living systematic review. We will run searches monthly from December 2020, with the review updated as relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.

Tobacco smoking, related harm and motivation to quit smoking in people with schizophrenia spectrum disorders

This narrative review focuses on the topic of tobacco smoking amongst people with schizophrenia spectrum disorders. We searched PubMed, PsycInfo and Scopus databases for schizophrenia spectrum disorders and smoking and included articles about the epidemiology of tobacco smoking in people with schizophrenia spectrum disorders, examining the relationship between smoking and mental health. This narrative review describes that a higher prevalence, frequency and impact of both high nicotine dependence and its harmful effects in patients with schizophrenia spectrum disorders compared with those in the general population. Despite several existent theories, the reasons for high smoking rates, the high dependence on nicotine and severity of nicotine withdrawal symptoms are not fully understood. The main aim of this paper is to inform mental health personnel and particularly clinical and health psychologists about the impact and role of tobacco smoking for smokers with schizophrenia spectrum disorders.

Neurotoxicity of e-cigarettes

It appears that electronic cigarettes (EC) are a less harmful alternative to conventional cigarette (CC) smoking, as they generate substantially lower levels of harmful carcinogens and other toxic compounds. Thus, switching from CC to EC may be beneficial for smokers. However, recent accounts of EC- or vaping-associated lung injury (EVALI) has raised concerns regarding their adverse health effects. Additionally, the increasing popularity of EC among vulnerable populations, such as adolescents and pregnant women, calls for further EC safety evaluation. In this state-of-the-art review, we provide an update on recent findings regarding the neurological effects induced by EC exposure. Moreover, we discuss possible neurotoxic effects of nicotine and numerous other chemicals which are inherent both to e-liquids and EC aerosols. We conclude that in recognizing pertinent issues associated with EC usage, both government and scientific researchers must address this public health issue with utmost urgency.

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.

Piloting a clinical laboratory method to evaluate the influence of potential modified risk tobacco products on smokers' quit-related motivation, choice, and behavior

Research methods are needed that can predict whether the availability of potential modified risk tobacco products (MRTPs) may influence smokers' quit-related motivation, choice, and behavior. This pilot study assessed the primary outcomes of feasibility and adherence to address this need using an electronic cigarette (ECIG) as a model MRTP. Cigarette smokers were randomly assigned to use only their own brand of cigarettes (OB-only) or a second-generation ECIG (18 ng/ml nicotine) plus their OB cigarettes (ECIG+OB) ad libitum for four weeks. Participants logged products using a mobile device, collected used cigarette filters, and provided saliva samples every day for analysis of cotinine. They returned to the lab once per week to provide a breath sample and accept or decline a choice to quit all tobacco products (i.e., cigarettes and/or ECIGs). They also returned for a one-month follow-up visit. Of those participants randomized (n = 60), 56.7% completed the 4-week intervention and 40.0% completed the follow-up visit. The primary reason for withdrawal was poor adherence with mobile device use. Comparable numbers of participants in each group chose to make a quit attempt, although more OB-only participants chose to quit during the first two weeks and more ECIG+OB participants during the last two weeks. With protocol modifications to reduce participation burden, the current method might ultimately be used by regulators to predict how smokers' quit-related motivation, choice, and behavior are influenced by current and future MRTPs.

What are the respiratory effects of e-cigarettes?

Electronic cigarettes (e-cigarettes) are alternative, non-combustible tobacco products that generate an inhalable aerosol containing nicotine, flavors, propylene glycol, and vegetable glycerin. Vaping is now a multibillion dollar industry that appeals to current smokers, former smokers, and young people who have never smoked. E-cigarettes reached the market without either extensive preclinical toxicology testing or long term safety trials that would be required of conventional therapeutics or medical devices. Their effectiveness as a smoking cessation intervention, their impact at a population level, and whether they are less harmful than combustible tobacco products are highly controversial. Here, we review the evidence on the effects of e-cigarettes on respiratory health. Studies show measurable adverse biologic effects on organ and cellular health in humans, in animals, and in vitro. The effects of e-cigarettes have similarities to and important differences from those of cigarettes. Decades of chronic smoking are needed for development of lung diseases such as lung cancer or chronic obstructive pulmonary disease, so the population effects of e-cigarette use may not be apparent until the middle of this century. We conclude that current knowledge of these effects is insufficient to determine whether the respiratory health effects of e-cigarette are less than those of combustible tobacco products.

Assessing the lung cancer risk reduction potential of candidate modified risk tobacco products

Smoking is the major cause of lung cancer. While the risk of lung cancer increases with the number of cigarettes smoked and the duration of smoking, it also decreases upon smoking cessation. The development of candidate modified risk tobacco products (cMRTP) is aimed at providing smokers who will not quit with alternatives to cigarettes that present less risk of harm and smoking-related disease. It is necessary to assess the risk reduction potential of cMRTPs, including their potential to reduce the risk of lung cancer. Assessing the lung cancer risk reduction potential of cMRTPs is hampered by (i) the absence of clinical risk markers that are predictive of future lung cancer development, (ii) the latency of lung cancer manifestation (decades of smoking), and (iii) the slow reduction in excess risk upon cessation and a fortiori upon switching to a cMRTP. It is, therefore, likely that only long-term epidemiology will provide definitive answers to this question and allow to first verify that a cMRTP reduces the risk of lung cancer and if it does, to quantify the reduction in excess lung cancer risk associated with a cMRTP. For this to be possible, the cMRTP would need to be available in the market and used exclusively by a large portion of current smokers. Here, we propose that a mechanism-based approach represents a solid alternative to show in a pre-market setting that switching to a cMRTP is likely to significantly reduce the risk of lung cancer. This approach is based on the causal chain of events that leads from smoking to disease and leverages both non-clinical and clinical studies as well as the principles of systems toxicology. We also discuss several important challenges inherent to the assessment of cMRTPs as well as key aspects regarding product use behavior.

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.

Immunological and pathological effects of electronic cigarettes

Electronic cigarettes (E-cigarettes) are considered a preferable alternative to conventional cigarettes due to the lack of combustion and the absence of tobacco-specific toxicants. E-cigarettes have rapidly gained in popularity in recent years amongst both existing smokers and previous non-smokers. However, a growing literature demonstrates that E-cigarettes are not as safe as generally believed. Here, we discuss the immunological, and other, deleterious effects of E-cigarettes on a variety of cell types and host defence mechanisms in humans and in murine models. We review not only the effects of complete E-cigarette liquids, but also each of the main components-nicotine, humectants and flavourings. This MiniReview thus highlights the possible role of E-cigarettes in the pathogenesis of disease and raises awareness of the potential harm that E-cigarettes may cause.

Acute exposure to e-cigarettes causes inflammation and pulmonary endothelial oxidative stress in nonsmoking, healthy young subjects

The effects of e-cigarette (e-cig) aerosol inhalation by nonsmokers have not been examined to date. The present study was designed to evaluate the acute response to aerosol inhalation of non-nicotinized e-cigarettes in terms of oxidative stress and indices of endothelial activation in human pulmonary microvascular endothelial cells (HPMVEC). Ten smoking-naïve healthy subjects (mean age ± SD = 28.7 ± 5.5 yr) were subjected to an e-cig challenge, following which their serum was monitored for markers of inflammation [C-reactive protein (CRP) and soluble intercellular adhesion molecule (sICAM)] and nitric oxide metabolites (NOx). The oxidative stress and inflammation burden of the circulating serum on the vascular network was also assessed by measuring reactive oxygen species (ROS) production and induction of ICAM-1 expression on HPMVEC. Our results show that serum indices of oxidative stress and inflammation increased significantly (P < 0.05 as compared with baseline), reaching a peak at approximately 1-2 h post-e-cig aerosol inhalation and returning to baseline levels at 6 h. The circulatory burden of the serum (ICAM-1 and ROS) increased significantly at 2 h and returned to baseline values 6 h post-e-cig challenge. ROS production by HPMVEC was found to occur via activation of the NADPH oxidase 2 (NOX2) pathways. These findings suggest that even in the absence of nicotine, acute e-cig aerosol inhalation leads to a transient increase in oxidative stress and inflammation. This can adversely affect the vascular endothelial network by promoting oxidative stress and immune cell adhesion. Thus e-cig inhalation has the potential to drive the onset of vascular pathologies.

Pulmonary and other health effects of electronic cigarette use among adult smokers participating in a randomized controlled smoking reduction trial

BACKGROUND

There is limited evidence about the effects of dual electronic cigarette (e-cig) and combustible cigarette use on lung health or other health outcomes. Studies that have evaluated these outcomes have not included estimates of e-cig or cigarette exposure in the analyses.

MATERIALS AND METHODS

Data analyzed were from 263 smokers participating in a randomized controlled trial designed to encourage participants to reduce their combustible cigarette use by substituting with an e-cig or a non-electronic cigarette substitute (cig-sub). t-tests were used to evaluate changes from baseline at 1 month and 3 months in lung function, blood pressure, pulse, exhaled carbon monoxide, and weight. Linear mixed effects models were used to test associations between health outcomes and study product group, including exposure to the study products (e-cig and cig-sub times used and days used in the past 7 days) and cigarettes per day (CPD).

RESULTS

There were few significant differences between the groups for lung function indices at any time point in the unadjusted analyses. There were significant reductions in diastolic blood pressure and pulse at 1 month in the unadjusted analyses for those in the e-cig group compared to the cig-sub group. CPD decreased significantly more for the e-cig group than for the cig-sub group at both time points. There were no significant associations between any measured health outcomes and group in the linear mixed effects models.

CONCLUSION

E-cig use did not contribute to significant changes in health outcome markers as compared with use of a non-electronic cig-sub.

Perceived health effects of vaping among Hungarian adult e-cigarette-only and dual users: a cross-sectional internet survey

BACKGROUND

Knowledge about the health effects of e-cigarette use (or vaping) among past and current combustible cigarette users is limited. Several studies have assessed vaping-related adverse events (AEs) and beneficial health effects, however, most studies focused on AEs in general and examined only a few physiological changes that vapers experience. This study aims to explore self-reported AEs and perceived health changes due to e-cigarette use among Hungarian adult e-cigarette-only users (former smokers who switched completely to e-cigarette use) and dual users (smokers who use e-cigarettes and combustible tobacco cigarettes concomitantly).

METHODS

A cross-sectional, web-based survey of 1042 adult Hungarian e-cigarette users was conducted in 2015. Participants reported AEs and changes in physiological functions since they switched from smoking to e-cigarette use or while dually using e-cigarettes and combustible cigarettes. Confirmatory factor analysis with covariates was applied to explain perceived health changes due to e-cigarette-only use and dual use.

RESULTS

Dual users (17.6%) were significantly more likely to report AEs of vaping than e-cigarette-only users (26.2% vs. 11.8%, p < 0.001). Experiencing health improvements were significantly more likely among e-cigarette-only users than for dual users for all surveyed physiological functions. E-cigarette-only users reported larger effects of vaping on sensory, physical functioning, and mental health factors compared to dual users. Self-reported changes in sensory and physical functioning were significantly higher among individuals using e-cigarettes more than a year and people who were past heavy smokers (smoked ≥20 cigarettes per day). Gender was related to sensory improvement only; males reported greater improvement than females.

CONCLUSIONS

The majority of e-cigarette-only users reported more perceived beneficial changes in physiological functions and fewer AEs than dual users. Perceived short-term benefits of e-cigarette use may reinforce users despite the uncertainty of long-term health consequences. Health professionals should provide balanced information regarding the possible short- and long-term positive and negative health effects of e-cigarette use during consultations with patients.

Electronic cigarettes: a task force report from the European Respiratory Society

There is a marked increase in the development and use of electronic nicotine delivery systems or electronic cigarettes (ECIGs). This statement covers electronic cigarettes (ECIGs), defined as "electrical devices that generate an aerosol from a liquid" and thus excludes devices that contain tobacco. Database searches identified published articles that were used to summarise the current knowledge on the epidemiology of ECIG use; their ingredients and accompanied health effects; second-hand exposure; use of ECIGs for smoking cessation; behavioural aspects of ECIGs and social impact; in vitro and animal studies; and user perspectives.ECIG aerosol contains potentially toxic chemicals. As compared to conventional cigarettes, these are fewer and generally in lower concentrations. Second-hand exposures to ECIG chemicals may represent a potential risk, especially to vulnerable populations. There is not enough scientific evidence to support ECIGs as an aid to smoking cessation due to a lack of controlled trials, including those that compare ECIGs with licenced stop-smoking treatments. So far, there are conflicting data that use of ECIGs results in a renormalisation of smoking behaviour or for the gateway hypothesis. Experiments in cell cultures and animal studies show that ECIGs can have multiple negative effects. The long-term effects of ECIG use are unknown, and there is therefore no evidence that ECIGs are safer than tobacco in the long term. Based on current knowledge, negative health effects cannot be ruled out.

Existing and emerging smoking cessation options for people with schizophrenia spectrum disorders

Tobacco cigarette addiction is a deeply entrenched behavior among people with Schizophrenia Spectrum Disorders, and consequently these individuals die an average of 25 years earlier than the general population. The aim of this review was to evaluate the state-of-the-science focused on cessation and reduction interventions for people with SSD. We searched peer-reviewed articles from medline, psycinfo, web of science, scopus, and cochrane library, about cessation interventions for people with SSD. The search was carried out by combining an exhaustive list of terms denoting schizophrenic disorder and smoking cessation treatment. The review search period was limited from January 2000-November 2018, 260 studies were identified and a total of 24 of studies were included in the final review. This review demonstrates the vulnerability of smokers with SSD and underscores the need for research in these areas with large enough sample sizes to detect treatment effects: 1) outcomes using and comparing standard treatments 2) long-term cessation/reduction outcomes 3) flexible treatment options 4) more research to develop the evidence-base for e-cigarettes intervention.