Effect of an electronic nicotine delivery device (e cigarette) on desire to smoke and withdrawal, user preferences and nicotine delivery: randomised cross-over trial

Longitudinal transitions of cigarettes and electronic nicotine delivery systems among adolescents: Construction of a retrospective cohort using recall data from a cross-sectional sample

INTRODUCTION

A major concern regarding non-cigarette tobacco or nicotine products (NCTNPs) is whether they facilitate or mitigate overall tobacco or nicotine use. We examined longitudinal transitions of cigarettes and electronic nicotine delivery systems (ENDS) by constructing a retrospective cohort based on the recall data of a cross-sectional sample.

METHODS

Using the Korea Youth Risk Behavior Survey, we constructed crosssectional data of 59576 adolescents into retrospective cohort data. Participants were categorized into 4 mutually exclusive tobacco or nicotine use states. We used a multistate Markov model to identify transitions between the states to calculate transition intensity ratios (TIRs), and examined the current use of tobacco or nicotine products to assess both gateway effects to cigarettes, and whether ENDS use helps adolescents quit cigarette smoking.

RESULTS

Compared with never use, use of ENDS was associated with an increased risk of initiation of cigarette use (TIR=6.8; 95% CI: 4.5-10.2). The risk of transitioning from cigarette ever use to ENDS, compared with never use to ENDS, was even more pronounced (TIR=44.1; 95% CI: 34.1-56.9). The prevalence of current cigarette smoking was higher among those who started ENDS then cigarettes, compared to those who began cigarette use without experimenting with ENDS (43.1% vs 35.8%). Moreover, 27.8% (95% CI: 23.6-32.0%) of adolescents who experimented first with cigarettes then moved to ENDS were current users of cigarettes, and 46.4% (95% CI: 42.1-51.1%) of these adolescents were current users of both cigarettes and ENDS.

CONCLUSIONS

Based on the recall data of a cross-sectional sample, we demonstrate that ENDS experimentation increases the likelihood of cigarette smoking initiation. A significant proportion of these adolescents continue to use cigarettes. Moreover, those who experimented with cigarettes then ENDS also continue smoking cigarettes or both cigarettes and ENDS. We suggest comprehensive tobacco control policies for all tobacco/nicotine products and monitoring the timing of NCTNP initiation in cross-sectional surveys.

E-cigarette Dependence Measures in Dual Users: Reliability and Relations With Dependence Criteria and E-cigarette Cessation

BACKGROUND

Electronic cigarettes (e-cigarettes) have drastically changed the nicotine and tobacco product landscape. However, their potential public health impact is still unclear. A reliable and valid measure of e-cigarette dependence would likely advance assessment and prognostication of the public health impact of e-cigarettes. The aim of this research was to examine the internal consistency, structure, and validity of three e-cigarette dependence scales.

METHODS

Adult dual users (smokers who also vape, N = 256) enrolled in an observational cohort study (45.1% women, 70.7% white). At baseline, participants completed the e-cigarette Fagerström Test of Cigarette Dependence (e-FTCD), the e-cigarette Wisconsin Inventory of Smoking Dependence Motives (e-WISDM), and the Penn State Electronic Cigarette Dependence Index (PS-ECDI). All participants provided a urine sample for cotinine analysis and reported e-cigarette use at 1 year.

RESULTS

The e-WISDM subscales had the highest internal consistency (α = .81-.96), then the PS-ECDI (α = .74) and e-FTCD (α = .51). A single-factor structure for the e-FTCD and an 11-factor structure for the e-WISDM were supported, but the PS-ECDI did not have a single-factor structure. All three e-cigarette dependence scales were highly correlated with validation criteria including continued e-cigarette use at 1 year, but not with e-liquid nicotine concentration or cotinine.

CONCLUSIONS

The e-WISDM and PS-ECDI had stronger internal consistency than did the e-FTCD, despite the e-FTCD's single-factor structure, but all 3 measures appear to be valid measures of e-cigarette dependence as suggested by their significant relations with self-perceived addiction, heavy use, early use after overnight deprivation, and continued use over time.

IMPLICATIONS

This research provides empirical support for three e-cigarette dependence measures: the e-FTCD, the PS-ECDI, and the e-WISDM among dual users of e-cigarettes and combustible cigarettes. The PS-ECDI and e-WISDM are more reliable, but all three measures were strongly correlated with key dependence constructs such as heavy use and continued use over time.

Electronic cigarette dependence and demand among pod mod users as a function of smoking status

Electronic cigarette (e-cigarette) use continues to proliferate with fast-paced product evolution. Pod mod e-cigarettes emerged in the market in 2015 and have changed the tobacco landscape again. However, little is known regarding their addiction potential among users. The current study describes e-cigarette dependence and demand among pod mod users as a function of smoking status (current smokers/dual users, former smokers, and never smokers). Participants were 593 young adult (Mage = 25.9 years) JUUL users recruited via Amazon's Mechanical Turk. Respondents were specifically recruited based on current use of pod mods (but may also be using other e-cigarette devices) and smoking status (never, former, and current/dual users). Participants completed online measures assessing e-cigarette dependence and demand. Dual users of pod mods and cigarettes displayed greater e-cigarette dependence compared to current pod mod users with no history of cigarette smoking (p = .033). Similarly, dual users showed the greatest levels of e-cigarette demand compared to both former smokers and those without a history of smoking (ps < .05). Dual users displayed the greatest e-cigarette dependence and demand. Future research should directly assess potential mechanisms for this effect and continue to monitor e-cigarette dependence as the tobacco landscape changes with the emergence of new e-cigarette products and innovations. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Sensory experiences and cues among E-cigarette users

BACKGROUND AND AIMS

We characterized the extent and quality of respiratory sensations and sensory-related smoking cues associated with e-cigarette use among those who failed to quit combustible tobacco cigarette (CTC) use with traditional FDA approved medications but succeeded in doing so with e-cigarettes. Further, we sought to understand former smokers' perceptions about the influence of sensory experience with e-cigarette use on CTC cessation outcomes.

METHODS

A nonrandom purposive sample of 156 participants recruited in the USA through the Consumer Advocates for Smoke Free Alternatives Association Facebook page completed an online cross-sectional survey to assess sensory experiences and smoking cues associated with e-cigarette use. Descriptive statistics were calculated, and the ANOVA/Kruskal-Wallis test with post hoc testing and the two-sample t test/Wilcoxon rank-sum test, as appropriate based on distribution, were used to assess the association between sample characteristics and sensory experiences and cues using investigator constructed questions, the Modified Cigarette Evaluation Questionnaire (mCEQ) and the Smoking Cue Appeal Survey (SCAS).

RESULTS

With e-cigarette use, participants reported feeling the vapor in their throats, windpipes, noses, lungs, and on their tongues; reductions in nicotine craving; and enjoyment of their e-cigarette, including tasting, smelling, and seeing the vapor and touching the device. Women had greater craving reduction than men (p = 0.023). Those who began smoking at 13 years of age or younger had more satisfaction and had greater sensory enjoyment than those who began smoking at 16-17 years of age (p = 0.015 and p = 0.026, respectively), as well as greater sensory enjoyment than those who began smoking at 14-15 years of age (p = 0.047). There was a significant overall association between the number of years a respondent smoked and e-cigarette sensory enjoyment (p = 0.038). Participants 18-34 years old rated e-cigarettes as being more pleasant compared to 45 + years olds, (p = 0.012). Eighty-four percent of participants reported the sensation of the vapor as important in quitting CTCs, and 91% believed the sensations accompanying e-cigarette use contributed to their smoking cessation success.

CONCLUSIONS

For those who failed to quit previously using approved cessation medications to stop smoking cigarettes, sensory experiences associated with e-cigarette use may help smokers quit smoking.

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.

Injuries associated with electronic nicotine delivery systems: A systematic review

BACKGROUND

Since its introduction on the market in 2007, the number of reports on injuries caused by the overheating, ignition, or explosion of electronic nicotine delivery systems (ENDSs) has increased significantly. These injuries appear to have different causes, the most important one being lithium-ion battery overheating to the point of ignition or explosion.

METHODS

A literature search for all relevant studies concerning ENDS-related traumatic injuries of all kinds was conducted, according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses protocol. The search started with the first introduction of ENDSs in 2007 and ended February 2020. Articles included were reports on patients who sustained flame, chemical, or traumatic injuries of the skin, soft tissue, and/or bone, related to the use of ENDSs.

RESULTS

This systematic review includes 180 patients from 41 case series and reports, published between 2016 and 2020. The mean age was 30.8 years (range, 17-59 years) with an overall male predominance (168 of 180 patients, 93%). In most injuries, multiple anatomical sites were affected, with the thigh/lower limb being the most commonly injured area (77%) followed by the upper limb/hand (43%). Eighty-two patients (51%) required a surgical treatment, 70 patients (43%) were managed conservatively with dressings or ointments, and 9 patients (6%) underwent enzymatic debridement. Thirty-five percent of all patients underwent skin grafting.

CONCLUSION

Injuries from overheating, ignition, or explosion of ENDSs are an emerging, underreported, and underresearched issue. There is a need for increased regulation of ENDSs and improved surveillance of related injuries. Both health care providers and consumers should be made aware of the risks and be advised about how to safely handle these devices. In contrast to other articles, this systematic review includes all types of injuries related to ENDS overheating, ignition, and explosion. To our knowledge, this is the most extensive systematic review performed to date.

LEVEL OF EVIDENCE

Review article, level III.

E-Cigarette Use and Transition in Adult Smoking Frequency: A Longitudinal Study

INTRODUCTION

The relationship between e-cigarette use and cigarette smoking is the subject of ongoing debate. There is limited research on e-cigarette use and changes in the frequency of cigarette smoking. This study examines whether the frequency of e-cigarette use is associated with changes in cigarette smoking behavior among U.S. adults.

METHODS

The study used data (n=20,558) from Waves 1 (2013-2014) and 2 (2014-2015) of the Population Assessment of Tobacco and Health, analyzed in 2019. Multivariable multinomial logistic regression assessed the association between e-cigarette use at Wave 1 and change in cigarette smoking frequency between Waves 1 and 2.

RESULTS

Every day cigarette smokers who used e-cigarettes some days (OR=1.95, 95% CI=1.27, 2.98) and every day (OR=3.37, 95% CI=1.78, 6.36) in Wave 1 had significantly higher odds of switching to some days cigarette smoking in Wave 2. Every day smokers who used e-cigarettes every day in Wave 1 had higher odds of becoming former cigarette smokers in Wave 2. Likewise, e-cigarette use at baseline among former cigarette smokers was associated with higher odds of switching to some days cigarette smoking (experimental e-cigarette use: OR=5.43, 95% CI=2.13, 10.72; some days e-cigarette use: OR=4.78, 95% CI=2.13, 10.72). In addition, experimental smokers who were also some days e-cigarettes users in Wave 1 had significantly lower odds of switching to experimental former smokers.

CONCLUSIONS

Although e-cigarette use may reduce cigarette smoking frequency among continuing smokers, findings suggest that e-cigarette use may be associated with cigarette smoking relapse among former smokers.

E-cigarettes: A new hazard for children and adolescents

Objectives

Electronic cigarettes and fluid (e-cigarettes, e-fluid) are hazardous materials that when inhaled or ingested may pose significant health risks to children and adolescents. The objective of this work was to explore the spectrum of injury related to e-cigarette exposure among Canadian children and adolescents.

Methods

A one-time survey was sent to all paediatricians in Canada. Information was collected on children and adolescents who presented with e-cigarette exposure (inhalation and ingestion cases) in the previous 12 months. Questions included the number of injuries and symptoms, in addition to age, sex, treatment setting, intentional e-cigarette use, and how the products were accessed.

Results

A total of 520 surveys were completed and returned, identifying 35 cases. Symptoms related to inhalation were present in 30 cases and in 5 ingestion cases (5 unintentional, 0 intentional). For inhalation cases, most were male, ages 15 to 19 years, who sought treatment for nausea/vomiting, cough, throat irritation, or acute nicotine toxicity in an outpatient clinic/office. Most inhalation cases reported e-cigarette use 2 to 3 days/week, and e-cigarettes purchases from a mall kiosk/store. For ingestion cases, most were male, ages 1 to 4 years presenting to an emergency department with nausea/vomiting, cough, or respiratory irritation. Younger cases accessed e-fluid at home, older cases purchased in a mall kiosk/store. E-fluid flavours reported consumed were fruit, candy, and tobacco.

Conclusions

E-cigarettes, recently introduced into the North American market are hazardous to children and adolescents. Given the low response rate to the survey, further investigation into the true burden of injury, as well as the risks that e-cigarettes pose, together with ways to reduce exposure, is needed.

Twenty-four-hour subjective and pharmacological effects of ad-libitum electronic and combustible cigarette use among dual users

BACKGROUND AND AIMS

Relative pharmacological effects of e-cigarettes and cigarettes during 24 hours of ad-libitum use have not been described. In this study, 24-hour blood plasma nicotine concentrations and 48-hour subjective effects with use of cigarettes and e-cigarettes were measured among dual users.

DESIGN

Two-arm within-subject cross-over design with preferred e-cigarette or cigarette ad-libitum use over 48 hours.

SETTING

Hospital research ward in San Francisco, California, USA.

PARTICIPANTS

Thirty-six healthy dual users of e-cigarettes and cigarettes (n = 8, 25% females).

MEASUREMENTS

Twenty-four-hour blood plasma nicotine and cotinine concentrations and 48-hour self-reported nicotine withdrawal symptoms and rewarding effects.

FINDINGS

Analyses used analysis of variance (ANOVA)-based mixed models with order of product (e-cigarette or cigarette) and product type (combustible cigarette or type of e-cigarette) as fixed effects, and subject as a repeated effect. During a 24-hour period, e-cigarettes produced lower nicotine exposure than cigarettes for the majority of users, although 25% received more nicotine from e-cigarettes, which was predicted by more frequent e-cigarette use or greater dependence. Compared to cigarette smoking, nicotine exposure for variable-power tank users was similar, while cig-a-like (t₍₃₀₎  = 2.71, P = 0.011, d = 0.745) and fixed-power tank users (t₍₃₀₎  = 3.37, P = 0.002, d = 0.993) were exposed to less nicotine. Cigarettes were rated higher than e-cigarettes on some desirable subjective effects (e.g. psychological reward, t₍₃₂₂₎  = 7.24 P < 0.001, d = 0.432), but withdrawal symptom reduction was comparable. No differences were found between e-cigarette types, but Bayes factors indicate that these measures were insensitive.

CONCLUSIONS

During a 24-hour period in a hospital setting in the United States, nicotine exposure for dual users of e-cigarettes and cigarettes was similar when using cigarettes or variable-power tank devices only but was lower for those using cig-a-like or fixed-power devices only. Despite lower nicotine levels, all types of e-cigarette were effective in preventing withdrawal symptoms. E-cigarettes were rated less rewarding than cigarettes.

Comparison of Tobacco and Electronic Cigarette Reward Value Measured During a Cue-Reactivity Task: An Extension of the Choice Behavior Under Cued Conditions Procedure

INTRODUCTION

Up to 24% of electronic cigarette (e-cigarette) users are concurrent users of both tobacco and e-cigarettes (dual users). Dual users provide an opportunity to assess key motivational processes supporting e-cigarette use, such as the reward value of e-cigarettes. This study used the Choice Behavior Under Cued Conditions procedure to examine cue-specific reactions to tobacco and e-cigarettes with a primary focus on evaluating the relative reward value of both forms of cigarettes.

METHODS

Fifty-four dual users were exposed to a lit tobacco cigarette, their own e-cigarette, or a cup of water across multiple trials. On each trial, participants rated their craving for both tobacco and e-cigarettes and indicated the amount of money they would spend to access the cue. Key measures included craving, amount of money spent to access the cue, latency to access the cue, spending choice time, and consumption.

RESULTS

Participants reported significantly higher craving and spent significantly more money on tobacco and e-cigarette trials than on water trials. The magnitude of cue-specific craving was comparable across tobacco and e-cigarettes, but participants spent significantly more to access tobacco cigarettes than e-cigarettes.

CONCLUSIONS

This is the first study to demonstrate cue-specific reactivity to e-cigarettes utilizing a neutral comparison condition and to examine the reward value of e-cigarettes relative to tobacco cigarettes. Overall, the data suggest that e-cigarette puffs are less valued and generate less craving than tobacco cigarette puffs for dual users. The data provide clear support for the utility of Choice Behavior Under Cued Conditions for examining a range of motivational processes supporting e-cigarette use.

IMPLICATIONS

The test procedure used in this research generates multiple indices of nicotine and tobacco motivation and allows for an explicit comparison of those variables in people who use both e-cigarettes and tobacco cigarettes.

Application of High-Resolution Mass Spectrometry and a Theoretical Model to the Quantification of Multifunctional Carbonyls and Organic Acids in e-Cigarette Aerosol

Electronic (e-) cigarette aerosol (particle and gas) is a complex mixture of chemicals, of which the profile is highly dependent on device operating parameters and e-liquid flavor formulation. The thermal degradation of the e-liquid solvents propylene glycol and glycerol often generates multifunctional carbonyls that are challenging to quantify because of unavailability of standards. We developed a theoretical method to calculate the relative electrospray ionization sensitivities of hydrazones of organic acids and carbonyls with 2,4-dinitrophenylhydrazine based on their gas-phase basicities (ΔG_{deprotonation}). This method enabled quantification by high-performance liquid chromatography-high-resolution mass spectrometry HPLC-HRMS in the absence of chemical standards. Accurate mass and tandem multistage MS (MSⁿ) were used for structure identification of vaping products. We quantified five simple carbonyls, six hydroxycarbonyls, four dicarbonyls, three acids, and one phenolic carbonyl in the e-cigarette aerosol with Classic Tobacco flavor. Our results suggest that hydroxycarbonyls, such as hydroxyacetone, lactaldehyde, and dihydroxyacetone can be significant components in e-cigarette aerosols but have received less attention in the literature and have poorly understood health effects. The data support the radical-mediated e-liquid thermal degradation scheme that has been previously proposed and emphasize the need for more research on the chemistry and toxicology of the complex product formation in e-cigarette aerosols.

Differential effects of nicotine delivery rate on subjective drug effects, urges to smoke, heart rate and blood pressure in tobacco smokers

RATIONALE

The nicotine delivery rate is a key feature of tobacco product design, yet there have been limited human studies examining the effects of nicotine as a function of delivery rate.

OBJECTIVE

We developed an intravenous nicotine infusion protocol to evaluate differential effects of nicotine delivery rate on subjective drug effects, smoking urges, abstinence symptoms, heart rate, and blood pressure.

METHODS

Eighteen non-treatment seeking, overnight abstinent male and female smokers (18 to 30 years old), who smoked ≥ 5 cigarettes per day for the past year completed four sessions, in which they were randomly assigned to a saline infusion, or a 1 mg per 70-kg body weight dose of nicotine delivered over 1, 5, or 10 min at rates of 0.24, 0.048, or 0.024 μg/kg/s, respectively.

RESULTS

Smoking urges, as assessed by the Brief Questionnaire of Smoking Urges, were reduced relative to placebo for the 1- and 5-min infusion, but not the 10-min infusion. Although the 1- and 5-min infusions reduced smoking urges to a similar extent, the 1-min infusion induced a greater heart rate and blood pressure increase. Changes to subjective drug effects, heart rate, and blood pressure delineate the differential effects of nicotine delivery rate for these outcomes.

CONCLUSIONS

We have characterized the delivery rate-response curve for a nicotine dose that is roughly the amount of nicotine (~ 1 mg) delivered by smoking a standard tobacco cigarette. Our findings reinforce the importance of nicotine delivery rate when evaluating the potential effects of nicotine from tobacco products.

Regulation of DNA methylation signatures on NF-κB and STAT3 pathway genes and TET activity in cigarette smoke extract-challenged cells/COPD exacerbation model in vitro

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a global health problem. Currently, there is a lack of knowledge about the pathobiology of this disease and available therapies are ineffective. Cigarette smoking is the leading cause of COPD; however, not all smokers develop COPD. Exacerbations of COPD caused by microbes are common and detrimental. Approximately 20-50% of patient exacerbations are caused by bacterial colonization in the lower airways. It is generally accepted that epigenetic mechanisms, especially DNA methylation, play an important role during progression of COPD. Thus, we hypothesized that DNA methylation patterns vary significantly following smoke exposure and during exacerbations caused by bacterial infections. To test our hypothesis, we used an in vitro study model that mimics COPD exacerbations and performed extensive studies to understand the role of CpG promoter methylation of NF-κB and STAT3-mediated pathway genes. Both NF-κB and STAT3 transcription factors play critical roles in orchestrating inflammatory responses during cigarette smoke exposure. In brief, human lung adenocarcinoma cells with type II alveolar epithelium characteristics (A549) were challenged with cigarette smoke extract (CSE) or DMSO (control) followed by a 3-h challenge with bacterial lipopolysaccharide (LPS; from Pseudomonas aeruginosa) prior to the termination of CSE exposure (COPD exacerbation group). The production of cytokines/chemokines, regulation of transcription factors, and DNA methylation of specific genes were then assessed. We also studied changes in the expression and activity of ten-eleven translocases (TETs), the enzymes responsible for DNA demethylation, and assessed their role in regulating DNA methylation in the CSE-challenged group.

RESULTS

There was a significant increase in the release of cytokines/chemokines (IL-8, MCP-1, IL-6 and CCL5) in the COPD exacerbation group as compared to the control group. Hypomethylation of NF-κB-mediated pathway genes correlated with their induction in our COPD exacerbation study model. Further, we observed an important role of TET1/2 in regulating the DNA methylation of NF-κB, STAT3, IKK, and NIK genes and cytokine/chemokine production by A549 cells during CSE challenge.

CONCLUSIONS

Studies to further define the role of TETs in CSE-mediated epigenetic regulation may lead to the development of better and more effective therapeutic intervention strategies for COPD.

An online survey of Malaysian long-term e-cigarette user perceptions

INTRODUCTION

The use of e-cigarettes (EC) has reached alarming proportions among Malaysians. On a national level, little is known about the profile and perceptions of Malaysian EC users. This study aimed to explore the prevalence of long-term EC usage and its associated factors among EC users in Malaysia.

METHODS

This nationwide online questionnaire survey was administered among 694 EC users across 13 states and 1 Federal Territory in Malaysia, between January and April 2018. A survey link was e-mailed to EC users that were recruited from an official national vape entity through their Facebook association page. We obtained information on respondents’ sociodemographic characteristics, smoking habits, long-term e-cigarette usage and perceptions of EC use. We estimated long-term EC user prevalence and fitted multivariate regression models to predict factors associated with long-term EC usage. Statistical significance was set at p<0.05.

RESULTS

Respondents were predominantly Malays (87.6%), aged >30 years (68.1%) and tertiary educated (71%). The majority were employed (93.1%) with a monthly household income of MYR 4000 or less (56.6%). About 84% were former smokers, while 10% were current smokers. The prevalence of long-term EC usage in this study was 82.3%. Most users believed that EC had helped them to cut down tobacco smoking (94.8%), reduced the urge to smoke (88.3%) and ultimately helped them to quit smoking (87.2%). Respondents aged >30 years and those who perceived that EC has helped them stop smoking were significantly more likely to be long-term EC users.

CONCLUSIONS

Most respondents engaged in EC use to quit smoking. They were more likely to be long-term EC users if they were older and perceived that EC has helped them to quit smoking. This information is valuable for targeted prevention, health promotion and policy regulations.

Cardiovascular autonomic effects of electronic cigarette use: a systematic review

Purpose

Electronic cigarettes (ECs) are the fastest growing tobacco product in the USA, and ECs, like tobacco cigarettes (TCs), have effects on the cardiovascular autonomic nervous system, with clinical implications. The purpose of this review was to collect and synthesize available studies that have investigated the autonomic cardiovascular effects of EC use in humans. Special attention is paid to the acute and chronic effects of ECs, the relative contributions of the nicotine versus non-nicotine constituents in EC emissions and the relative effects of ECs compared to TCs.

Methods

Using the methodology described in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement, we conducted a literature search of the Ovid PubMed and Embase databases on 6 December 2019 using keywords in titles and abstracts of published literature. Acute (minutes to hours) and chronic (days or longer) changes in heart rate variability (HRV), heart rate (HR) and blood pressure (BP) were used as estimates of cardiovascular autonomic effects.

Results

Nineteen studies were included in this systematic review, all of which used earlier generation EC devices. Acute EC vaping increased HR and BP less than acute TC smoking. Nicotine but not non-nicotine constituents in EC aerosol were responsible for the sympathoexcitatory effects. The results of chronic EC vaping studies were consistent with a chronic sympathoexcitatory effect as estimated by HRV, but this did not translate into chronic increases in HR or BP.

Conclusions

Electronic cigarettes are sympathoexcitatory. Cardiac sympathoexcitatory effects are less when vaping using the earlier generation ECs than when smoking TCs. Additional studies of the latest pod-like EC devices, which deliver nicotine similarly to a TC, are necessary.

Electronic supplementary material

The online version of this article (10.1007/s10286-020-00683-4) contains supplementary material, which is available to authorized users.

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.

The oral health impact of electronic cigarette use: a systematic review

Introduction: Electronic cigarette (e-cigarette) use is becoming more prevalent and is particularly popular among adolescents and conventional smokers. While the oral health sequelae of conventional smoking are well-established, the impact of e-cigarettes on oral health is still unknown. This study aims to systematically review the available research evidence on the oral health impact of e-cigarette use.Methods: This systematic review was conducted according to PRISMA guidelines and used the Effective Public Health Practice Project Quality Assessment Tool to evaluate the evidence. Three electronic databases (PubMed, Web of Science, and Embase) were systematically searched for studies including case reports. Two independent reviewers extracted data and synthesized the findings.Results: Ninety-nine articles were included in this systematic review. Analyses of the articles yielded seven categories based on symptom similarity and/or focus: mouth effects, throat effects, periodontal effects, dental effects, cytotoxic/genotoxic/oncologic effects, oral microbiome effects, and traumatic/accidental injury. The majority of mouth and throat symptoms experienced by e-cigarette users were relatively minor and temporary, with some evidence that conventional smokers who switched to e-cigarettes experienced mitigation of these symptoms. E-cigarette exposure increased the risk for deteriorating periodontal, dental and gingival health as well as changes to the oral microbiome. Extensive dental damage as a result of e-cigarette explosions were described in case reports. Components of e-cigarette vapor have known cytotoxic, genotoxic, and carcinogenic properties.Conclusions: Although switching to e-cigarettes may mitigate oral symptomatology for conventional smokers, findings from this review suggest that a wide range of oral health sequelae may be associated with e-cigarette use. Well-designed studies to investigate oral health outcomes of e-cigarette use are needed.

Perceived safety and effectiveness of electronic cigarettes among Malaysian adults and public support for regulations

Context:

Electronic cigarettes have been used as a harm reduction method toward tobacco cessation. Malaysian government has enforced a strict policy to regulate the sale of electronic cigarette products because its liquid contains nicotine.

Aims:

This study aimed to explore the general public’s perception toward electronic cigarette use. Public support toward electronic cigarette regulation was also examined.

Settings and Design:

This was a Malaysian population-based survey.

Materials and Methods:

Data were obtained from the National E-Cigarette Survey (NECS) 2016, which used a multistage stratified cluster sampling household survey representing all Malaysian adults aged 18 years old. A cross-sectional survey was conducted among a total of 4288 adults.

Statistical Analysis Used:

Descriptive and logistic regression analysis.

Results:

Majority were aged 25–44 years old (44%), completed at least secondary education (69%), of Malay ethnicity (73%), and married (68%). Majority (88.1%) have never used electronic cigarette. A quarter (25.5%) perceived electronic cigarette helps people quit cigarette smoking, whereas 20.3% perceived electronic cigarette helps people to maintain cigarette abstinence. Approximately 85% believed that electronic cigarette use does not help in improving breathing and coughing. Majority (91.8%) disagreed that electronic cigarettes should be allowed in places where tobacco smoking is banned. Thus, 63.4% agreed that electronic cigarette should be banned completely rather than regulated.

Conclusion:

Majority of general public had negative perception about electronic cigarette use.

A pilot study to examine the acceptability and health effects of electronic cigarettes in HIV-positive smokers

INTRODUCTION

Some HIV-positive smokers report ambivalence about quitting. Switching to electronic cigarettes (ECs) may be a viable option to reduce the negative health effects for smokers who are unable or unwilling to quit smoking combustible cigarettes (CCs). This study examined the acceptability and health-related effects of ECs in HIV-positive smokers who were not seeking smoking cessation treatment.

METHODS

HIV-positive smokers (N = 19) were enrolled and followed for 12 weeks. Cartridge-based ECs were provided at baseline, and E-liquid was provided weekly for 8 weeks. At baseline, weeks 1-8, and week 12, EC and CC use, cardiopulmonary function, respiratory symptoms, and carbon monoxide (CO) levels were measured.

RESULTS

At week 8, cigarettes per day (CPD) were reduced by more than 80%, with reduction maintained at week 12 (p's < .001). Cigarette dependence scores were 40% lower at week 8 than at baseline (p <  .001). Seven (36.8%) participants reported transitioning completely from CCs to ECs. Mean CO decreased significantly from BL to week 8 (p < .05) and remained significantly lower at week 12 (p <  .001). Intention to quit increased significantly over time.

CONCLUSIONS

Switching from CCs to ECs in HIV-positive smokers who are not ready to quit smoking in the next 30 days appears to be feasible. Beneficial effects were seen, such as reduced CPD, reduced CO and CC dependence, and increased motivation to quit. ECs may be promising as a harm reduction approach among HIV-positive smokers who are unable or unwilling to quit smoking.

Electronic Cigarettes and Cardiovascular Risk: Caution Waiting for Evidence

Electronic cigarettes use is a growing trend in contemporary societies, with the propensity to compete with traditional tobacco smoking. Some preclinical studies demonstrated the toxic and detrimental effects of electronic cigarettes liquid components. Its impact on human health remains unknown and insufficiently studied. While some studies suggest that electronic cigarettes use might be associated with endothelial dysfunction, impaired platelet function and increased risk of adverse clinical events, other studies did not confirm these findings and epidemiological data mostly suggest that the use of electronic cigarettes appears to be safer than that of traditional tobacco cigarettes. This article provides an up-to-date overview of the current state of knowledge regarding electronic cigarettes and their impact on human health, with special emphasis on their effect on cardiovascular diseases.

A Conceptual Framework for Understanding Multiple Tobacco Product Use and the Impact of Regulatory Action

INTRODUCTION

Over 35% of the adult tobacco-using population regularly use more than one tobacco product. Although rates of tobacco use in the United States have declined over the last decade, rates of multiple tobacco product (MTP) have either remained stable (among adults) or increased (among youth).

METHODS

In this paper, we review the literature and propose a framework for understanding both MTP use and how regulatory actions on any single tobacco product (STP) may influence the use of other tobacco products.

RESULTS AND CONCLUSIONS

Within the framework, Product, Person, and Context/Situational factors (and their interactions) influence product cross-substitution and thus patterns of use of MTPs. In addition, we propose that Context/Situation effects specifically increase the complexity of MTP-use patterns resulting in "dynamic complementarity" in addition to substitution-like relationships between tobacco products. Experimentation with, and use of, various tobacco products results in reinforcement histories that affect which products are used, in what contexts, and by whom, which in turn has downstream impacts on toxicant exposure and health. We conclude our analysis with an examination of how regulation of STPs can have impacts on the use of other STP and MTP use and provide research questions for further examining MTP use.

IMPLICATIONS

Though rates of tobacco use have declined in the United States, over 35% of the adult tobacco-using population regularly uses more than one tobacco product. This paper provides a framework for understanding MTP use and how regulatory actions on any STP may influence the use of other tobacco products. We conclude our analysis by providing research questions for further examining MTP use.

Impact of Nicotine Replacement and Electronic Nicotine Delivery Systems on Fetal Brain Development

Maternal tobacco smoking during pregnancy remains a major public health issue. The neurotoxic properties of nicotine are associated with fetal neurodevelopmental disorders and perinatal morbimortality. Recent research has demonstrated the effects of nicotine toxicity on genetic and epigenetic alterations. Smoking cessation strategies including nicotine replacement therapy (NRT) and electronic nicotine delivery systems (ENDS) show lack of clear evidence of effectiveness and safety in pregnant women. Limited trials using randomized controls concluded that the intermittent use formulation of NRT (gum, sprays, inhaler) in pregnant women is safe because the total dose of nicotine delivered to the fetus is less than continuous-use formulations (transdermal patch). Electronic nicotine delivery systems (ENDS) were hyped as a safer alternative during pregnancy. However, refill liquids of ENDS are suspected to be cytotoxic for the fetus. Animal studies revealed the impact of ENDS on neural stem cells, showing a similar risk of pre- and postnatal neurobiological and neurobehavioral disorders to that associated with the exposure to traditional tobacco smoking during early life. There is currently no clear evidence of impact on fetal brain development, but recent research suggests that the current guidelines should be reconsidered. The safety of NRT and ENDS is increasingly being called into question. In this review, we discuss the special features (pharmacodynamics, pharmacokinetics, and metabolism) of nicotine, NRT, and ENDS during pregnancy and postnatal environmental exposure. Further, we assess their impact on pre- and postnatal neurodevelopment.

A content analysis of the promotional strategies employed by e-cigarette brands on Twitter

Cigarette smoking in the U.S. is declining, but e-cigarette (e-cig) use is rapidly expanding. E-cig brands utilize social media for promotion and have the autonomy to disseminate messages that encourage the use of their products. The current study categorized the most frequent strategies among popular e-cig brands on Twitter. A content analysis of over 1800 tweets was performed based on Philip Morris brand personality characteristics. Most tweets emphasized e-cigs' economic value (24.2%) and normalized their use by portraying e-cigs as "cool" (23.1%). E-cig brands are employing similar strategies as tobacco companies and easily connecting to young adults through social media.

The Effect of E-cigarette Commercials on Youth Smoking: A Prospective Study

Objectives: In this study, we assessed whether commercials for electronic cigarettes (e-cigarettes) influence the use of e-cigarettes, cigarettes, and cigars among high-risk youth in southern California. Methods: We recruited students (N = 1060) from 29 alternative high schools into a prospective cohort study. We used multilevel Poisson regression models to examine whether exposure to e-cigarette commercials and perceptions of their appeal predicted increased use of e-cigarettes, cigarettes, and cigars one year later. We also tested the potential moderating effect of gender and ethnicity. Results: Models with and without covariates suggest that exposure to e-cigarette commercials is a statistically significant predictor of increased use of e-cigarettes. When gender was added to the models as a moderator, the relationships between commercial exposure and future use of e-cigarettes and cigars were found to be stronger among females. Unadjusted and adjusted models also indicated that students with favorable perceptions of e-cigarette commercials reported greater use of e-cigarettes, cigarettes, and cigars one year later. Conclusions: E-cigarette commercials may play an important role in persuading high-risk youth to use nicotine and tobacco products. Extending the Broadcast Advertising Ban of 1971 to include a broader range of products may be critical to preventing future generations from becoming addicted to nicotine.

Predicting Short-Term Uptake of Electronic Cigarettes: Effects of Nicotine, Subjective Effects, and Simulated Demand

Introduction

E-cigarettes have potential to support tobacco cessation or reduction, but how nicotine content affects smokers' subjective perceptions and use of e-cigarettes, rather than tobacco, is unclear.

Method

Thirty-five adult daily smokers who had not previously tried e-cigarettes were recruited from two cities in New Zealand in 2016-2017. Smokers were given four e-cigarette cartridges (0, 6, 12, and 18 mg nicotine) in a randomized, blinded order over four 2-week periods. Daily cigarette smoking and e-cigarette use was monitored using ecological momentary analysis and participants completed the modified Cigarette Evaluation Questionnaire after each 2-week period.

Results

Mean cigarettes per day decreased by 37% (9.69 to 6.09) when e-cigarettes were available relative to baseline (p = .008). Nicotine-containing cartridges (>0 mg) were associated with greater use (p = .023) and craving reduction (p = .026) than 0 mg. Alleviation of withdrawal symptoms (p = .048) and taste and enjoyment factors (p = .039) predicted e-cigarette use.

Conclusion

Availability of e-cigarettes reduced cigarette smoking behavior regardless of nicotine content, and e-cigarette use was greater with nicotine-containing cartridges. First-time users' e-cigarette use can be predicted using subjective ratings and more research is required to clarify the effect of nicotine content on subjective perceptions and use.

Implications

For low-moderate dependence smokers, availability of e-cigarettes may reduce cigarette smoking behavior regardless of nicotine content, but the availability of nicotine-containing cartridges may promote greater e-cigarette use. First response to trialing e-cigarettes is an important factor in determining subsequent experimental and possibly longer-term use.

What is the nicotine delivery profile of electronic cigarettes?

Introduction: Electronic cigarettes (e-cigarettes) are a rapidly evolving class of tobacco products intended to deliver nicotine to users. There are many types of e-cigarettes available and the most popular type today in the United States are 'pod' based devices that use high nicotine concentration liquids. Understanding the nicotine delivery capabilities of e-cigarettes is imperative for understanding their addictive potential and safety profile, informing regulation, and revealing their potential use as smoking cessation aids. Areas covered: This review discusses nicotine content of e-cigarettes, effectiveness of nicotine aerosolization by devices, delivery of nicotine to users, and user and device characteristics that impact each of these. Expert opinion: Modern e-cigarettes have the potential to deliver equal or more nicotine compared to a tobacco cigarette. Future research needs to identify the nicotine delivery profiles likely to benefit public health and the means to regulate them appropriately while also identifying those that are likely to cause harm. Public health benefit accrues if e-cigarettes help smokers quit combustible cigarettes completely. Harm is possible if inadequate nicotine delivery undermines cessation attempts, e-cigarettes facilitate continued combustible cigarette use, long-term e-cigarette use is associated with substantial morbidity/mortality, and/or e-cigarettes increase the initiation of combustible cigarette use among never smokers.

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

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

A randomised, open-label, cross-over clinical study to evaluate the pharmacokinetic profiles of cigarettes and e-cigarettes with nicotine salt formulations in US adult smokers

E-cigarettes containing 'nicotine salts' aim to increase smoker's satisfaction by improving blood nicotine delivery and other sensory properties. Here, we evaluated the pharmacokinetic profiles and subjective effects of nicotine from two e-cigarette device platforms with varying concentrations of nicotine lactate (nicotine salt) e-liquid relative to conventional cigarettes. A randomised, open-label, cross-over clinical study was conducted in 15 healthy US adult smokers. Five different e-cigarette products were evaluated consecutively on different days after use of own brand conventional cigarette. Plasma nicotine pharmacokinetics, subjective effects, and tolerability were assessed following controlled use of the products. The rate of nicotine absorption into the bloodstream was comparable from all e-cigarettes tested and was as rapid as that for conventional cigarette. However, in all cases, nicotine delivery did not exceed that of the conventional cigarette. The pharmacokinetic profiles of nicotine salt emissions were also dependent upon the properties of the e-cigarette device. Subjective scores were numerically highest after smoking a conventional cigarette followed by the myblu 40-mg nicotine salt formulation. The rise in nicotine blood levels following use of all the tested e-cigarettes was quantified as 'a little' to 'modestly' satisfying at relieving the desire to smoke. All products were well tolerated with no notable adverse events reported. These results demonstrate that, while delivering less nicotine than a conventional cigarette, the use of nicotine salts in e-cigarettes enables cigarette-like pulmonary delivery of nicotine that reduces desire to smoke.

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

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

Prevalence and characteristics of e-cigarette users among Malaysian current and ex-smokers

INTRODUCTION

Electronic cigarettes (ECs) are new devices that have been accepted widely by both smokers and non-smokers. However, the evidence on EC used in Malaysia is scarce. The objective of this study was to determine the prevalence of EC use and the socio-demographic and smoking characteristics associated with current EC use among Malaysian current and ex-smokers.

METHODS

This was a sub-analysis of data from a cross-sectional, national-population- based EC study conducted from May to June in 2016 in Malaysia. A detailed description of the sampling methods can be found in the National E-cigarette Survey (NECS) 2016 report. Briefly, data were obtained from 1396 individuals who had ever been smokers, i.e., 957 (68.6%) current smokers and 439 (31.4%) ex-smokers.

RESULTS

Current EC use was found predominantly among current smokers (8.0%) as compared with ex-smokers (4.3%). Among current smokers, the main reasons given for smoking ECs were wanting to try it (44.7%), followed by intention to quit tobacco smoking (15.8%) and to reduce tobacco smoking (10.5%). Using multiple logistic regression analysis, we found that among current smokers, current EC users were more likely to be younger, i.e., 18-44 years (aOR= 4.83, 95% CI= 1.97-11.86, p=0.001), urban residents (aOR= 1.89, 95% CI= 1.15-3.11, p=0.012), single/ divorced/ widowed (aOR= 2.11, 95% CI= 1.24-3.61, p=0.006) and students (aOR= 2.25, 95% CI= 1.01-5.01, p=0.048). Among exsmokers, only younger respondents (18-44 years old) was reported as being more likely to be current EC users (aOR= 3.81, 95% CI= 1.14-12.76, p=0.030).

CONCLUSION

This study showed that currently using and ever having used ECs were more prevalent among current smokers. The reasons given for initiating EC use among current smokers were mainly wanting to try it, followed by intention to quit and to reduce tobacco smoking. Current EC use appears to be common among current smokers who are younger, urban residents, single/divorced/widowed and students. Therefore, EC cessation intervention strategies and policies should target these high-prevalence groups.

Nicotine and Carbonyl Emissions From Popular Electronic Cigarette Products: Correlation to Liquid Composition and Design Characteristics

Introduction

Available in hundreds of device designs and thousands of flavors, electronic cigarette (ECIG) may have differing toxicant emission characteristics. This study assesses nicotine and carbonyl yields in the most popular brands in the U.S. market. These products included disposable, prefilled cartridge, and tank-based ECIGs.

Methods

Twenty-seven ECIG products of 10 brands were procured and their power outputs were measured. The e-liquids were characterized for pH, nicotine concentration, propylene glycol/vegetable glycerin (PG/VG) ratio, and water content. Aerosols were generated using a puffing machine and nicotine and carbonyls were, respectively, quantified using gas chromatograph and high-performance liquid chromatography. A multiregression model was used to interpret the data.

Results

Nicotine yields varied from 0.27 to 2.91 mg/15 puffs, a range corresponding to the nicotine yield of less than 1 to more than 3 combustible cigarettes. Nicotine yield was highly correlated with ECIG type and brand, liquid nicotine concentration, and PG/VG ratio, and to a lower significance with electrical power, but not with pH and water content. Carbonyls, including the carcinogen formaldehyde, were detected in all ECIG aerosols, with total carbonyl concentrations ranging from 3.72 to 48.85 µg/15 puffs. Unlike nicotine, carbonyl concentrations were mainly correlated with power.

Conclusion

In 15 puffs, some ECIG devices emit nicotine quantities that exceed those of tobacco cigarettes. Nicotine emissions vary widely across products but carbonyl emissions showed little variations. In spite of that ECIG users are exposed to toxicologically significant levels of carbonyl compounds, especially formaldehyde. Regression analysis showed the importance of design and e-liquid characteristics as determinants of nicotine and carbonyl emissions.

Implications

Periodic surveying of characteristics of ECIG products available in the marketplace is valuable for understanding population-wide changes in ECIG use patterns over time.

Smoke screen: The teen vaping epidemic uncovers a new concerning addiction

The use of nicotine products among adolescents is now designated as a national epidemic by the United States Surgeon General. The largest one-year increase ever recorded for substance use in the adolescent population should sound the alarm for Nurse Practitioners (NPs) practicing in family health and pediatrics. Vaping, or the use of e-cigarettes or electronic nicotine delivery systems (ENDS), has been purported by the vaping industry as a less harmful alternative for tobacco users in their attempt to quit smoking. In adolescents, vaping represents a dangerous and highly addictive health behavior. Initiatives on both the state and federal levels have begun to address marketing and access to young users. However, the active involvement of NPs on the front line of primary care will be necessary to combat this imposing threat. The protection of our young patients from nicotine addiction and the education of patients and families about the potential dangers of e-cigarettes are imperative to prevent harm. This article addresses concerns related to e-cigarette use in the adolescent population and the important role NPs can play in promoting their health and well-being.

Adolescent Dual Use Classification and Its Association With Nicotine Dependence and Quit Intentions

PURPOSE

Electronic cigarettes (e-cigarette) use is rapidly increasing in the U.S., especially among adolescents. A significant number of adolescents use both cigarettes and e-cigarettes, often referred to as dual use. We used a new classification of dual use, taking into account the frequency of use of both products. In addition, we examined the association between dual use with time to first cigarette after waking (a nicotine dependence measure) and quit intention.

METHODS

Data were drawn from the 2015-2018 National Youth Tobacco Survey. We grouped participants by dual use frequency. Multivariable logistic regression was used to examine the association of dual use frequency with nicotine dependence and quit intention.

RESULTS

Different categories of dual users varied in demographic characteristics and beliefs on the harms of cigarette smoking and e-cigarette use. Compared with cigarette-only smokers, significantly higher odds of nicotine dependence were found for high-frequency e-cigarette dual users (within 5 minutes of awakening, odds ratio [OR]: 1.67, 95% confidence interval [CI], 1.07-2.62; within 30 minutes, OR: 1.61, 95% CI, 1.15-2.27), high-frequency cigarette dual users (5 minutes, OR: 2.85, 95% CI, 1.76-4.63; within 30 minutes, OR: 4.14, 95% CI, 2.96-5.80), and high-frequency dual users (5 minutes, OR: 4.46, 95% CI, 2.88-6.91; 30 minutes, OR: 3.94, 95% CI, 2.43-6.42). In addition, high-frequency e-cigarette dual users had significantly lower quit intention compared with both cigarette-only smokers and low-frequency dual users.

CONCLUSIONS

Findings highlight the need for a standard, granulated classification of dual user, as important characteristics may vary between different categories. Future studies on dual use should consider categorizing dual use into the four classifications described in this study.

Nicotine absorption during electronic cigarette use among regular users

BACKGROUND

The capability of electronic cigarette devices (e-cigs) to deliver nicotine is key to their potential to replace combustible cigarettes. We compared nicotine delivery and subjective effects associated with the use of two classes of e-cigarettes and cigarettes.

METHODS

14 e-cigarette users were instructed to vape their own e-cigarette device every 20 seconds for 10 minutes while blood was drawn at 1, 2, 4, 6, 8, 10,12, and 15 minutes after initiating vaping. Users rated withdrawal symptoms and side effects before and after vaping. E-cigarette devices were classified as first-generation (same size as cigarette, no activation button) or advanced (larger than cigarette with an activation button). Separately, 10 cigarette smokers completed a similar protocol. Fisher's Exact Test and two-sided t-tests were used as appropriate to determine differences in outcomes between first-generation e-cigarette users, advanced e-cigarette users, and smokers.

RESULTS

Compared to first-generation devices, advanced devices were associated with greater serum nicotine Cmax (ng/ml) (11.5 v. 2.8, p = 0.0231) and greater nicotine boost (ng/ml) (10.8 v. 1.8, p = 0.0177). Overall, e-cigarettes users experienced a significant reduction in withdrawal and craving, although there were no significant differences between users of first-generation and advanced devices. Comparing e-cigarettes overall to cigarettes, cigarettes were associated with greater Cmax (25.9 v. 9.0, p = 0.0043) and greater nicotine boost (21.0 v. 8.2, p = 0.0128).

CONCLUSIONS

Advanced e-cigarettes delivered significantly more nicotine than first-generation devices but less than combustible cigarettes. Overall, e-cigarette use was associated with a reduction in withdrawal and craving with no reported side effects. The wide variation in nicotine absorption from different e-cigarette devices should be considered in studies of e-cigarettes for smoking cessation.

Randomised, placebo-controlled, double-blind, double-dummy, multicentre trial comparing electronic cigarettes with nicotine to varenicline and to electronic cigarettes without nicotine: the ECSMOKE trial protocol

INTRODUCTION

Electronic cigarettes (EC) mainly with nicotine content are widely used worldwide. Although the number of publications about its use is increasing exponentially, evidence-based, unbiased, conclusive, head-to-head comparisons about its efficacy and safety as an aid for smoking cessation are lacking. METHODS AND ANALYSIS: Design: randomised, placebo and reference treatment-controlled, multicentre, double-blind, double-dummy, parallel-group trial. Participants: smokers smoking at least 10 cigarettes/day in the past year and motivated to quit, aged 18-70 years. Interventions: (A) EC without nicotine (ECwoN) plus placebo tablets of varenicline administered by oral route: placebo condition, (B) EC with nicotine (ECwN) plus placebo tablets of varenicline: ECwN condition. Voltage regulated EC will be used with liquid containing 12 mg/mL of nicotine for ad libitum use. Flavour: blond tobacco. (C) Reference: ECwoN plus 0.5 mg varenicline tablets: varenicline condition. Varenicline administered according to the marketing authorisationauthorisation. Treatment duration: 1 week+3 months. Primary outcome: continuous smoking abstinence rate (CAR) (abstinence from conventional/combustible cigarettes) during the last 4 weeks (weeks 9-12) of the treatment period defined as self-report of no smoking during the previous 2 weeks and expired air carbon monoxide ≤8 at visit 4 at week 10 after target quit date (TQD), that is, 11 weeks after treatment initiation AND at visit 5, week 12 after TQD, that is, 13 weeks after treatment initiation. Secondary outcomes: safety profile; point prevalence abstinence rate; CAR confirmed by urinary anabasine concentration; changes in cigarettes/day consumption; craving for tobacco and withdrawal symptoms with respect of baseline.

ETHICS AND DISSEMINATION

The ethics committee approval was obtained on 17 April 2018. All data collected about the study participants will be anonymised. Investigators will communicate trial results to participants, health authorities, healthcare professionals, the public and other relevant groups without any publication restrictions.

TRIAL REGISTRATION NUMBER

NCT03630614; Pre-results.

A Pilot Study of E-Cigarette Naïve Cigarette Smokers and the Effects on Craving After Acute Exposure to E-Cigarettes in the Laboratory

BACKGROUND AND OBJECTIVES

Recent surveys confirm continued increases in the use of electronic-cigarettes (e-cigarettes) in adolescents and adults. Users often state that e-cigarettes reduce tobacco craving and withdrawal symptoms in addition to their smoking. Data from laboratory studies and clinical trials have confirmed these statements, though there are inconsistencies in the outcomes. In this pilot study, we set out to evaluate the effects of e-cigarettes, as compared to the participants' own cigarettes, on baseline craving and smoking severity.

METHODS

Using a within-subjects, placebo-controlled study design, 15 tobacco-dependent, e-cigarette naïve participants sustained abstinence overnight. They completed distinct phases of this protocol during four separate study sessions. Participants were randomized to an e-cigarette device containing one of three doses of nicotine (0, 18, or 36 mg/ml) or their own cigarette. Each study visit was ~3 hours long and separated by at least 7 days. Visits included assessments of craving and smoking severity.

RESULTS

The data showed that after 10 puffs in both the Own cigarette and e-cigarette conditions, breath carbon monoxide levels increased significantly in the former but not the latter. Questionnaire of Smoking Urges and Choices to Smoke scores were not statistically different across groups after two distinct bouts of 10 puffs each. Additionally, E-cigarette Perceptions Questionnaire responses were not significantly different according to dose.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

This experiment provides data demonstrating that e-cigarettes did not reduce craving or smoking severity in e-cigarette naïve users. However, since this was a pilot study, the conclusions that can be drawn are limited. (Am J Addict 2019;28:361-366).

e-Cigarettes for smoking cessation: Do they deliver?

WHAT IS KNOWN AND OBJECTIVE

Electronic nicotine delivery systems (ENDS) are battery-powered devices that allow nicotine and/or other substances to be inhaled in aerosolized form. e-Cigarettes (electronic cigarettes), the most commonly used ENDS, have been proposed to be smoking cessation aids. However, despite the rapid surge in their popularity, little is known about long-term health consequences of e-cigarette usage. We assess published data to see if they deliver what they promise.

COMMENT

e-Cigarettes may contain uncertain quantities of various ingredients, and evidence of adulteration has been identified. Flavouring agents can alter the pharmacokinetics of nicotine and have uncertain impact on the nature of e-cigarette use (eg ab initio use vs smoking cessation).

WHAT IS NEW AND CONCLUSION

Although e-cigarettes have been proposed to be a safe approach to encouraging smoking cessation, there are inconsistencies in available data. And further data are needed regarding long-term implications of primary and secondary exposure to e-cigarette products.

A pre-post pilot study of electronic cigarettes to reduce smoking in people with severe mental illness

BACKGROUND

Smoking is the largest single contributor to poor physical health and increased mortality in people with serious mental illnesses. The aim of the study was to investigate the utility of electronic cigarettes (e-cigarettes) as a harm reduction intervention in this population.

METHOD

Fifty tobacco smokers with a psychotic disorder were enrolled onto a 24-week pilot study (ClinicalTrials.gov: NCT02212041) investigating the efficacy of a 6-week free e-cigarette intervention to reduce smoking. Cigarette and e-cigarette use was self-reported at weekly visits, and verified using carbon monoxide tests. Psychopathology, e-cigarette acceptability and adverse effects were assessed using standardised scales.

RESULTS

There was a significant (⩾50%) reduction in cigarettes consumed per day between baseline and week 6 [F(2.596,116.800) = 25.878, p &lt; 0.001], and e-cigarette use was stable during this period [F(2.932,46.504) = 2.023, p = 0.115]. These changes were verified by significant carbon monoxide reductions between these time points [F(3.335,126.633) = 5.063, p = 0.002].

CONCLUSIONS

The provision of e-cigarettes is a potentially useful harm reduction intervention in smokers with a psychotic disorder.

Psychological distress and responses to comparative risk messages about electronic and combusted cigarettes

BACKGROUND

People with mental illness suffer disproportionately high health burdens of smoking. Communicating to these smokers that electronic cigarettes (e-cigarettes) are a less harmful alternative to combusted cigarettes might help them reduce their health risks by encouraging complete switching to e-cigarettes. However, such messages might also cause unintended consequences (e.g., dual use of both combusted and e-cigarettes). Our study examined how smokers with vs. without serious psychological distress (SPD) responded to messages communicating reduced harm of e-cigarettes in relation to cigarettes.

METHOD

In an online experiment, 1400 U.S. adult smokers with and without SPD viewed 1 of 6 messages about reduced harm of e-cigarettes compared to cigarettes or a control message. Then participants reported e-cigarette- and cigarette-related beliefs, and behavioral intentions.

RESULTS

Message type (comparative risk messages vs. control) did not interact with SPD status to produce differential impacts on smokers with and without SPD. Regardless of being exposed to a comparative risk message or a control message, smokers with SPD reported greater perceived absolute risk of e-cigarettes and cigarettes, greater support for tobacco control, greater intentions to switch to e-cigarettes completely and seek help with quitting, and were less likely to report e-cigarettes were less harmful than cigarettes compared to smokers without SPD.

DISCUSSION

Smokers with SPD had greater intentions to switch to e-cigarettes completely and seek help quitting compared to smokers without SPD, which indicates that smokers with SPD may be optimistic about e-cigarettes to help them quit smoking.

Electronic cigarette use after the adoption of a tobacco-free campus policy

Electronic (e)-cigarette use has increased markedly across groups in the past few years. For this reason, risk factors associated with e-cigarette use warrant further research. This study presents secondary data analyses on e-cigarette use from a large cross-sectional database assessing attitudes toward a tobacco-free campus (TFC) policy prior to policy implementation (n = 1188), one-month post policy (n = 1442), and one-year post policy(n = 1125). Students from a U.S. university located on the border with Mexico (M_age = 25.02 years, SD = 7.99; 59.2% female) were recruited via email to complete an online assessment of their tobacco use, attitudes toward TFC policies, perceived problematic tobacco use, and knowledge of tobacco use risk. The prevalence of any past-30-day e-cigarette use significantly increased from 4.4% to 26.6% between baseline and one-month post-policy, and reduced to 17.3% between one-month post-policy and one-year post policy. Weekly alcohol use was associated with e-cigarette use at each assessment point. There was some evidence of higher e-cigarette use among younger students and current smokers. Additional studies are needed to understand the influence of comprehensive TFC policies on both e-cigarette use and polysubstance use (i.e., alcohol and combustible cigarettes).

Effectiveness and safety of nicotine patches combined with e-cigarettes (with and without nicotine) for smoking cessation: study protocol for a randomised controlled trial

INTRODUCTION

Evidence indicates e-cigarettes can help people quit smoking; however, more confirmatory trials are needed. To date, no trials have evaluated the effectiveness and safety of combining nicotine patches with e-cigarettes (with and without nicotine) for smoking cessation.

METHODS AND ANALYSIS

This study is a pragmatic, three-arm, community-based, single-blind, randomised trial undertaken in New Zealand. Eligible participants are daily/non-daily smokers, aged ≥18 years, naive e-cigarette users and motivated to quit smoking in the next 2 weeks. Participants (n=1809), recruited using multi-media advertising, are randomised to 14 weeks of (1) 21 mg nicotine patches (n=201); (2) 21 mg nicotine patches+18 mg/mL nicotine e-cigarette (n=804); or (3) 21 mg nicotine patches+nicotine free e-cigarette (n=804). Participants receive weekly withdrawal-oriented behavioural support calls for 6 weeks post-randomisation. The primary outcome is self-reported biochemically verified continuous abstinence (CA) at 6 months post quit-date. The primary comparison is nicotine patch + nicotine e-cigarette versus nicotine patch + nicotine free e-cigarette, and the secondary comparison is nicotine patch versus nicotine patch +nicotine e-cigarette (90% power, p=0.05, to detect an absolute difference in 6 month CA rates of 8% and 15% respectively). Secondary outcomes, collected by phone interview at quit date, then 1, 3, 6 and 12 months post-quit date, include self-reported CA, 7 day point prevalence abstinence, cigarettes per day (if smoking, or when smoking for non-daily smokers), time to relapse (if returned to smoking), belief in ability to quit, use of other cessation support, side effects/serious adverse events, treatment compliance, seeking additional support around e-cigarette use, daily use of both e-cigarettes and cigarettes, use of treatment past 14 weeks, views on treatment and recommendation to others, weight and cost-per-quitter.

ETHICS AND DISSEMINATION

The Northern A Health and Disability Ethics Committee approved the trial. Findings will be disseminated through publication, conference/meeting presentations, and media.

TRIAL REGISTRATION NUMBER

NCT02521662; Pre-results.

A Randomized Trial of E-Cigarettes versus Nicotine-Replacement Therapy

BACKGROUND

E-cigarettes are commonly used in attempts to stop smoking, but evidence is limited regarding their effectiveness as compared with that of nicotine products approved as smoking-cessation treatments.

METHODS

We randomly assigned adults attending U.K. National Health Service stop-smoking services to either nicotine-replacement products of their choice, including product combinations, provided for up to 3 months, or an e-cigarette starter pack (a second-generation refillable e-cigarette with one bottle of nicotine e-liquid [18 mg per milliliter]), with a recommendation to purchase further e-liquids of the flavor and strength of their choice. Treatment included weekly behavioral support for at least 4 weeks. The primary outcome was sustained abstinence for 1 year, which was validated biochemically at the final visit. Participants who were lost to follow-up or did not provide biochemical validation were considered to not be abstinent. Secondary outcomes included participant-reported treatment usage and respiratory symptoms.

RESULTS

A total of 886 participants underwent randomization. The 1-year abstinence rate was 18.0% in the e-cigarette group, as compared with 9.9% in the nicotine-replacement group (relative risk, 1.83; 95% confidence interval [CI], 1.30 to 2.58; P<0.001). Among participants with 1-year abstinence, those in the e-cigarette group were more likely than those in the nicotine-replacement group to use their assigned product at 52 weeks (80% [63 of 79 participants] vs. 9% [4 of 44 participants]). Overall, throat or mouth irritation was reported more frequently in the e-cigarette group (65.3%, vs. 51.2% in the nicotine-replacement group) and nausea more frequently in the nicotine-replacement group (37.9%, vs. 31.3% in the e-cigarette group). The e-cigarette group reported greater declines in the incidence of cough and phlegm production from baseline to 52 weeks than did the nicotine-replacement group (relative risk for cough, 0.8; 95% CI, 0.6 to 0.9; relative risk for phlegm, 0.7; 95% CI, 0.6 to 0.9). There were no significant between-group differences in the incidence of wheezing or shortness of breath.

CONCLUSIONS

E-cigarettes were more effective for smoking cessation than nicotine-replacement therapy, when both products were accompanied by behavioral support. (Funded by the National Institute for Health Research and Cancer Research UK; Current Controlled Trials number, ISRCTN60477608 .).

The Messages Presented in Electronic Cigarette-Related Social Media Promotions and Discussion: Scoping Review

BACKGROUND

There has been a rapid rise in the popularity of electronic cigarettes (e-cigarettes) over the last decade, with growth predicted to continue. The uptake of these devices has escalated despite inconclusive evidence of their efficacy as a smoking cessation device and unknown long-term health consequences. As smoking rates continue to drop or plateau in many well-developed countries, transnational tobacco companies have transitioned into the vaping industry and are now using social media to promote their products. Evidence indicates e-cigarettes are being marketed on social media as a harm reduction alternative, with retailers and manufacturers utilizing marketing techniques historically used by the tobacco industry.

OBJECTIVE

This study aimed to identify and describe the messages presented in e-cigarette-related social media (Twitter, YouTube, Instagram, and Pinterest) promotions and discussions and identify future directions for research, surveillance, and regulation.

METHODS

Data sources included MEDLINE, Scopus, ProQuest, Informit, the Journal of Medical Internet Research, and Google Scholar. Included studies were published in English between 2007 and 2017, analyzed content captured from e-cigarette-related social media promotions or discussions, and reported results for e-cigarettes separately from other forms of tobacco and nicotine delivery. Database search ceased in October 2017. Initial searches identified 536 studies. Two reviewers screened studies by title and abstract. One reviewer examined 71 full-text articles to determine eligibility and identified 25 studies for inclusion. This process was undertaken with the assistance of the Web-based screening and data extraction tool-Covidence. The review was registered with the Joanna Briggs Institute (JBI) Systematic Reviews database and followed the methodology for JBI Scoping Reviews.

RESULTS

Several key messages are being used to promote e-cigarettes including as a safer alternative to cigarettes, efficacy as a smoking cessation aid, and for use where smoking is prohibited. Other major marketing efforts aimed at capturing a larger market involve promotion of innovative flavoring and highlighting the public performance of vaping. Discussion and promotion of these devices appear to be predominantly occurring among the general public and those with vested interests such as retailers and manufacturers. There is a noticeable silence from the public health and government sector in these discussions on social media.

CONCLUSIONS

The social media landscape is dominated by pro-vaping messages disseminated by the vaping industry and vaping proponents. The uncertainty surrounding e-cigarette regulation expressed within the public health field appears not to be reflected in ongoing social media dialogues and highlights the need for public health professionals to interact with the public to actively influence social media conversations and create a more balanced discussion. With the vaping industry changing so rapidly, real-time monitoring and surveillance of how these devices are discussed, promoted, and used on social media is necessary in conjunction with evidence published in academic journals.

Bibliometric Analysis of Electronic Cigarette Publications: 2003⁻2018

Electronic cigarettes are at the center of a public health policy debate which leverages scientific publications. This study characterizes e-cigarette publication trends over the past 15 years via a bibliometric analysis. Scopus was searched for “electronic cigarette”, “e-cig”, “e-cigarette”, “vape”, “vaping”, “juul”, or “electronic nicotine delivery system” between 2003–2018. Data included Hirsch index, document type and frequency, and publications by institution, journal, and country. VOSviewer was used to visualize authorship network maps. A total of 4490 e-cigarette publications were identified, most (62.8%) being articles. After 2009, the annual growth rate for e-cigarette publications was the largest in 2014. The annual growth rate was nearly flat in 2017 but increased in 2018. The U.S. produced 51.6% of publications. Annual National Institutes of Health NIH funding for tobacco research mapped closely with the annual volume of e-cigarette publications. Author network analyses illustrated investigator collaborative patterns. The frequency of e-cigarette publications increased significantly in the past decade. A strong relationship of NIH funding for tobacco research and e-cigarette publications demonstrates the importance of e-cigarettes in tobacco research.

Mining e-cigarette adverse events in social media using Bi-LSTM recurrent neural network with word embedding representation

Objective

Recent years have seen increased worldwide popularity of e-cigarette use. However, the risks of e-cigarettes are underexamined. Most e-cigarette adverse event studies have achieved low detection rates due to limited subject sample sizes in the experiments and surveys. Social media provides a large data repository of consumers' e-cigarette feedback and experiences, which are useful for e-cigarette safety surveillance. However, it is difficult to automatically interpret the informal and nontechnical consumer vocabulary about e-cigarettes in social media. This issue hinders the use of social media content for e-cigarette safety surveillance. Recent developments in deep neural network methods have shown promise for named entity extraction from noisy text. Motivated by these observations, we aimed to design a deep neural network approach to extract e-cigarette safety information in social media.

Methods

Our deep neural language model utilizes word embedding as the representation of text input and recognizes named entity types with the state-of-the-art Bidirectional Long Short-Term Memory (Bi-LSTM) Recurrent Neural Network.

Results

Our Bi-LSTM model achieved the best performance compared to 3 baseline models, with a precision of 94.10%, a recall of 91.80%, and an F-measure of 92.94%. We identified 1591 unique adverse events and 9930 unique e-cigarette components (ie, chemicals, flavors, and devices) from our research testbed.

Conclusion

Although the conditional random field baseline model had slightly better precision than our approach, our Bi-LSTM model achieved much higher recall, resulting in the best F-measure. Our method can be generalized to extract medical concepts from social media for other medical applications.