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Rapid growth in disposable e‐cigarette vaping among young adults in Great Britain from 2021 to 2022: a repeat cross‐sectional survey

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Abstract

Aims: To estimate recent trends in the prevalence of disposable e-cigarette vaping in Great Britain, overall and across ages, and to measure these trends in the context of changes in smoking and vaping prevalence. Design: The Smoking Toolkit Study, a monthly representative cross-sectional survey. Setting: Great Britain. Participants: A total of 36 876 adults (≥ 18 years) completed telephone interviews between January 2021 and April 2022. Measurements: Current e-cigarette vapers were asked which type of device they mainly use. We estimated age-specific monthly time trends in the prevalence of current disposable e-cigarette use among vapers and inhaled nicotine use (vaping/smoking), smoking and vaping among adults. Findings: From January 2021 to April 2022, there was an 18-fold increase in the percentage of vapers who used disposables, rising from 1.2 to 22.2% [prevalence ratio (PR) = 18.0; 95% compatibility interval (CI) = 9.18-49.0]. Growth in disposable e-cigarette vaping was most pronounced in younger adults (interaction P-value = 0.013): for example, the percentage of 18-year-old vapers using disposables rose from 0.4 to 54.8% (PR = 129; 95% CI = 28.5-4520), while it rose from 2.1 to 10.0% (PR = 4.73; 95% CI = 2.06-23.6) among 45-year-old vapers. However, the overall percentage of people currently using any inhaled nicotine remained stable over time both among all adults (20.0 versus 21.2%; PR = 1.06; 95% CI = 0.92-1.22) and among 18-year-olds (30.2 versus 29.7%; PR = 0.99; 95% CI = 0.80-1.22). In 18-year-olds, vaping prevalence grew (11.3 versus 17.7%; PR = 1.57; 95% CI = 1.12-2.29), and there was imprecise evidence for a decline in smoking (24.5 versus 19.5%; PR = 0.80; 95% CI = 0.63-1.04). In 45-year-olds, there was relatively little change in vaping (PR = 1.08; 95% CI = 0.88-1.33) or smoking prevalence (PR = 1.01; 95% CI = 0.88-1.16). Conclusions: Use of disposable e-cigarettes in Great Britain grew rapidly between 2021 and 2022, especially among younger adults, but the overall prevalence of inhaled nicotine use was stable over time. Most young adult vapers in Great Britain now use disposable products.
DATA INSIGHT
Rapid growth in disposable e-cigarette vaping among young
adults in Great Britain from 2021 to 2022: a repeat
cross-sectional survey
Harry Tattan-Birch
1,2
| Sarah E. Jackson
1,2
| Loren Kock
1,2
|
Martin Dockrell
3
| Jamie Brown
1,2
1
Department of Behavioural Science and
Health, University College London, London,
UK
2
SPECTRUM Consortium, London, UK
3
Addictions and Inclusion, Office for Health
Improvement and Disparities, London, UK
Correspondence
Harry Tattan-Birch, Institute of Epidemiology
and Health Care, 119 Torrington Place,
Fitzrovia, London WC1E 7HB, UK.
Email: h.tattan-birch@ucl.ac.uk
Funding information
Cancer Research UK, Grant/Award Number:
PRCRPG-Nov21\100002; The Office for
Health Improvement and Disparities,
Grant/Award Number: 558585/180737; The
UK Research Prevention Partnership,
Grant/Award Number: MR/S037519/1
Abstract
Aims: To estimate recent trends in the prevalence of disposable e-cigarette vaping in
Great Britain, overall and across ages, and to measure these trends in the context of
changes in smoking and vaping prevalence.
Design: The Smoking Toolkit Study, a monthly representative cross-sectional survey.
Setting: Great Britain.
Participants: A total of 36 876 adults (18 years) completed telephone interviews
between January 2021 and April 2022.
Measurements: Current e-cigarette vapers were asked which type of device they mainly
use. We estimated age-specific monthly time trends in the prevalence of current dispos-
able e-cigarette use among vapers and inhaled nicotine use (vaping/smoking), smoking
and vaping among adults.
Findings: From January 2021 to April 2022, there was an 18-fold increase in the percent-
age of vapers who used disposables, rising from 1.2 to 22.2% [prevalence ratio (PR)
= 18.0; 95% compatibility interval (CI) = 9.1849.0]. Growth in disposable e-cigarette
vaping was most pronounced in younger adults (interaction P-value = 0.013): for exam-
ple, the percentage of 18-year-old vapers using disposables rose from 0.4 to 54.8%
(PR = 129; 95% CI = 28.54520), while it rose from 2.1 to 10.0% (PR = 4.73; 95%
CI = 2.0623.6) among 45-year-old vapers. However, the overall percentage of people
currently using any inhaled nicotine remained stable over time both among all adults
(20.0 versus 21.2%; PR = 1.06; 95% CI = 0.921.22) and among 18-year-olds (30.2 ver-
sus 29.7%; PR = 0.99; 95% CI = 0.801.22). In 18-year-olds, vaping prevalence grew
(11.3 versus 17.7%; PR = 1.57; 95% CI = 1.122.29), and there was imprecise evidence
for a decline in smoking (24.5 versus 19.5%; PR = 0.80; 95% CI = 0.631.04). In 45-year-
olds, there was relatively little change in vaping (PR = 1.08; 95% CI = 0.881.33) or
smoking prevalence (PR = 1.01; 95% CI = 0.881.16).
Conclusions: Use of disposable e-cigarettes in Great Britain grew rapidly between 2021
and 2022, especially among younger adults, but the overall prevalence of inhaled
Received: 6 May 2022 Accepted: 24 August 2022
DOI: 10.1111/add.16044
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
provided the original work is properly cited.
© 2022 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.
Addiction. 2022;15. wileyonlinelibrary.com/journal/add 1
nicotine use was stable over time. Most young adult vapers in Great Britain now use dis-
posable products.
KEYWORDS
Disposable e-cigarettes, electronic nicotine delivery systems, Elf Bar, ENDS, England, Puff Bar,
Scotland, vaping, Wales, young adults
INTRODUCTION
Early electronic cigarettes (e-cigarettes) were disposable products
that were poor at delivering nicotine. Over time, new e-cigarette
types were developed to deliver nicotine contained in e-liquid more
effectively through rechargeable devices with refillable tanks or
replaceable pods (e.g. Juul) [1]. These devices came to dominate the
global e-cigarette market and, by 2019, fewer than one in 10 vapers
used disposables in England or the United States [13]. Recently, a
new form of disposable e-cigarette has started being sold under brand
names such as Puff bar,Elf baror Geek bar[4]. Unlike earlier dis-
posables, these products deliver nicotine effectively using a similar
technology to pod devices, including high-strength (20 mg/ml in
UK/EU) nicotine salts e-liquid [5]. They retail for approximately £57
(US$79) in the United Kingdomabout half the price of a pack of
20 cigarettes. US data show that, in 2021, disposables surpassed pods
as the most commonly used type of e-cigarette among adolescents
[2]. Little is known about the popularity of disposables in other coun-
tries and older age groups. It is also unclear whether these products
attract people who would otherwise smoke cigarettes, vape other
types of e-cigarettes or who would remain abstinent from nicotine
entirely. This study aims to estimate recent trends in the prevalence
of disposable e-cigarette vaping in Great Britain, overall and across
ages, and to explore these trends in the context of other changes in
smoking and vaping prevalence.
METHODS
Design
The Smoking Toolkit Study (STS) is a monthly cross-sectional survey
that recruits a nationally representative sample of adults (18 years)
in Great Britain. It uses a hybrid of population and quota sampling.
Great Britain is divided into areas of approximately 300 households,
which are stratified by region and demographic profile before being
selected at random to be included on the interview list. In selected
areas, interviews are performed with one individual per household
until age, employment status and gender quotas are met. Raking is
used to construct survey weights, adjusting data so that the demo-
graphic profile of the weighted sample matches that of Great Britain.
This demographic profile is ascertained monthly using data from three
sources: the 2011 UK Census, the Office for National Statistics mid-
year estimates and the annual National Readership Survey. Methods
are described in detail elsewhere [6].
Participants
Participants (n= 36 876) completed telephone interviews between
January 2021 and April 2022, inclusive. University College London
Ethics Committee provided approval for the study (0498/001), and
participants gave oral informed consent. All methods were carried out
in accordance with relevant regulations.
Measures
All measures used were routinely collected in the STS. Smoking status
was ascertained by asking participants which of the following applies
to them: (i) I smoke cigarettes (including hand-rolled) every day, (ii) I
smoke cigarettes (including hand-rolled), but not every day, (iii) Ido
not smoke cigarettes at all, but I do smoke tobacco of some kind
(e.g. pipe, cigar or shisha), (iv) I have stopped smoking completely in
the last year, (v) I stopped smoking completely more than a year ago
and (vi) I have never been a smoker (i.e. smoked for a year or more).
Participants were told that this question referred to cigarettes and
other kinds of tobacco, not e-cigarettes or heat-not-burn products.
Participants selecting (i) to (iii) were classified current smokers, (iv) and
(v) former smokers and (vi) never smokers.
Vaping status was assessed by asking participants whether they
were currently using e-cigarettes to cut down on the amount they
smoke, in situations when they are not allowed to smoke, to help
them stop smoking or for any other reason. Those who responded
positively to any of these questions were considered current
vapers.
Current vapers were asked which type of device they mainly use.
Those who responded, a disposable e-cigarette or vaping device
(non-rechargeable)were considered disposable e-cigarette vapers.
They could only choose one device type (the one they mainlyuse).
Participants were asked to provide their exact age in years. Those
who refused to give their exact age were asked to select their age
group from a list. For participants who only responded to the latter
question (2% of respondents), exact age was imputed as the mean age
within the age group they selected. Participants were also asked for
their gender.
Analysis
Weighted logistic regression was used to estimate monthly time
trends in the proportion of (i) adults and (ii) current vapers who use
2TATTAN-BIRCH ET AL.
disposable e-cigarettes, overall and for specific ages (using survey
weights described earlier). For the overall analysis, models only
included predictors for time. For the age-specific analysis, models
included time, age and their interaction as predictorsthus allowing
for time trends to differ across ages. Both age and time were mod-
elled continuously using restricted cubic splines with three knots
(placed at earliest, middle and latest month for time and 5, 50 and
95% quantiles for age among vapers). This allowed the relationship of
prevalence with age and time to be flexible and non-linear, while
avoiding categorization [7]. Age was modelled continuously, so we
displayed estimates for four specific ages (18-, 25-, 35- and 45-year-
olds) to illustrate how trends differed across ages. Note that the
model used to derive these estimates included data from participants
of all ages, not only those who were aged exactly 18, 25, 35 or
45 years.
Prevalence ratios (PR) for the change in prevalence across the
whole time-series (April 2022 versus January 2021) were presented,
alongside 95% compatibility intervals (95% CIs) calculated using
bootstrapping [811]. We ran analogous analyses to estimate time
trends in the proportion of adults who currently (i) vape, (ii) smoke
or (iii) use any form of inhaled nicotinewhether smoked or vaped.
Note that prevalence of disposable e-cigarette use was very low in
older age groups, which meant that we were unable to estimate
time trends in these groups. Finally, we reported the percentage of
disposable e-cigarette vapers who reported being current, former or
never smokers. Participants with missing data for their smoking or
vaping status (< 1%) were excluded from analyses that required this
information. R version 4.1.0 was used for analyses (code: https://
osf.io/km3x6/).
RESULTS
Of the 36 876 eligible adults interviewed, 51.1% were women and
the average age was 51.5 years [standard deviation (SD) = 18.6].
From January 2021 to April 2022, there was an 18-fold increase in
the percentage of vapers who used disposables, rising from 1.2 to
22.2% [prevalence ratio (PR) = 18.0; 95% compatibility interval (CI)
= 9.1849.0]. Overall, the prevalence of disposable e-cigarette
use increased from 0.08 to 1.85% (Table 1; PR = 22.3; 95%
CI = 10.848.8).
Growth in disposable e-cigarette vaping was most pronounced in
the youngest participants (Fig. 1; interaction P-value = 0.013). For
instance, prevalence of disposable use among 45-year-old vapers rose
from 2.1 to 10.0% (PR = 4.73; 95% CI = 2.0623.6), whereas among
18-year-old vapers it increased from 0.4 to 54.8% (PR = 129; 95%
CI = 28.54520).
Despite this, the overall percentage of adults currently using any
inhaled nicotine (smoked or vaped) was relatively stable during the
study period (Table 1; 20.0 versus 21.2%; PR = 1.06; 95% CI = 0.92
1.22). Among young adults, where the rise in disposable vaping was
most pronounced, inhaled nicotine use changed little over time, esti-
mated to be 30.2% for 18-year-olds in January 2021 and 29.7% April
2022 (Table 1; PR = 0.99; 95% CI = 0.801.22). However, during the
period vaping prevalence rose from 11.3 to 17.7% among 18-year-
olds (Table 1; PR = 1.57; 95% CI = 1.122.29); there was an uncertain
decline in smoking prevalence from 24.5 to 19.5% (Table 1; PR = 0.80;
95% CI = 0.631.04). Conversely, in ages where vaping prevalence
did not substantially increase, there appeared to be little change in
smoking. For instance, the prevalence of vaping (Table 1; PR = 1.08;
95% CI = 0.881.33) and smoking (Table 1; PR = 1.01; 95%
CI = 0.881.16) among 45-year-olds were relatively stable over time.
More detailed monthly trends in the prevalence of inhaled nicotine
use, vaping and smoking among adults of different ages are shown in
Supporting information, Figs S1S3.
Most disposable e-cigarette vapers were current (71.6%) or for-
mer smokers (18.8%), with few reporting never having smoked regu-
larly (9.6%). The proportion of disposable vapers who also smoked
was similar across ages, but it may have declined slightly over time
(Supporting information, Figs S4 and S5).
TABLE 1 Age-specific trends in current vaping, smoking and
disposable e-cigarette vaping prevalence in Great Britain.
Prevalence
January 21 April 22 Prevalence ratio (95% CI)
Currently using inhaled nicotine (vaped or smoked)
18-year-olds 30.2% 29.7% 0.99 (0.801.22)
25-year-olds 28.7% 30.3% 1.06 (0.941.19)
35-year-olds 25.6% 28.6% 1.12 (1.011.23)
45-year-olds 21.6% 24.1% 1.11 (0.991.24)
All adults 20.0% 21.2% 1.06 (0.921.22)
Currently vaping
18-year-olds 11.3% 17.7% 1.57 (1.122.29)
25-year-olds 10.7% 15.2% 1.42 (1.161.77)
35-year-olds 9.4% 11.6% 1.23 (1.031.47)
45-year-olds 7.6% 8.1% 1.08 (0.881.33)
All adults 7.0% 8.2% 1.17 (1.011.35)
Currently smoking
18-year-olds 24.5% 19.5% 0.80 (0.631.04)
25-year-olds 22.7% 19.9% 0.88 (0.761.02)
35-year-olds 19.7% 19.0% 0.97 (0.851.10)
45-year-olds 16.2% 16.3% 1.01 (0.881.16)
All adults 15.2% 14.5% 0.95 (0.871.05)
Currently vaping disposables
18-year-olds 0.1% 10.7% 214 (56.75590)
25-year-olds 0.1% 4.7% 45.1 (17.1247)
35-year-olds 0.2% 1.8% 9.84 (3.2535.9)
45-year-olds 0.2% 0.9% 5.74 (2.5722.2)
All adults 0.1% 1.9% 22.3 (10.848.8)
Weighted prevalence estimates from logistic regression allowing an
interaction between age and month, modelled non-linearly using restricted
cubic splines (three knots). Data, analysis code and estimates for other
months are available on-line (https://osf.io/km3x6/).
DISPOSABLE VAPING IN GREAT BRITAIN 3
DISCUSSION
Use of disposable e-cigarettes rose sharply between 2021 and 2022
in Great Britainwith the most rapid growth observed among the
youngest adults, mirroring trends observed in US adolescents [2]. At
the start of 2021, fewer than 1% of 18-year-old vapers used dispos-
ables. This increased substantially throughout the past year, such that
currently more than half of 18-year-old vapers report mainly using
disposables. Despite this, the overall percentage of young people
using any form of inhaled nicotine was stable over time, with an
increase in vaping and an uncertain decline in smoking among young
adults. This suggests that, in Great Britain up to 2022, disposable
e-cigarettes have primarily attracted those who would otherwise use
rechargeable devices or cigarettes, rather than those who would oth-
erwise not use any nicotine product. Nonetheless, patterns of nicotine
product use can change rapidly. Early and routine publication of data
such as these are needed to guide policy and research. Study limita-
tions include the wide 95% CIs around PRs due to few participants
reporting disposable e-cigarette use in early months. The measure of
disposable e-cigarette vaping also did not distinguish between modern
barstyle disposables from older cigalikes. Moreover, it asked about
which type of e-cigarette vapers mainlyuse, so vapers who used dis-
posables as a secondary product were not captured; therefore, the
estimated prevalence of disposable vaping actually represents a lower
bound for the true prevalence. Future studies should examine why
disposable e-cigarettes have become the product of choice among
young people in Great Britain and the United States [2] and whether
similar trends have occurred in other countries.
ACKNOWLEDGEMENTS
Cancer Research UK provides funding for the Smoking Toolkit Study
in England and salary support for S.J. (PRCRPG-Nov21/100002). The
UK Prevention Research Partnership (MR/S037519/1) funds the
Smoking Toolkit Study in Scotland and Wales and provides salary sup-
port for L.K. The UK Prevention Research Partnership is funded by
the British Heart Foundation, Cancer Research UK, Chief Scientist
Office of the Scottish Government Health and Social Care Director-
ates, Engineering and Physical Sciences Research Council, Economic
and Social Research Council, Health and Social Care Research and
Development Division (Welsh Government), Medical Research Coun-
cil, National Institute for Health Research, Natural Environment
Research Council, Public Health Agency (Northern Ireland), The
Health Foundation and Wellcome. H.T.B.s studentship is funded by
the Office for Health Improvement and Disparities, previously Public
Health England (558585/180737). The funders of the Smoking
Toolkit Study had no role in the study design or conduct; collection,
management, analysis or interpretation of data; preparation, review or
approval of the manuscript; or the decision to submit the manuscript
for publication. University College London Ethics Committee provided
approval for the study (0498/001), and participants gave oral
informed consent.
DECLARATION OF INTERESTS
H.T.B., L.K., M.D. and S.J. declare no conflicts of interest. J.B. has
received unrestricted research funding to study smoking cessation
from manufacturers of smoking cessation medications (Pfizer and
Johnson & Johnson).
AUTHOR CONTRIBUTIONS
Sarah Jackson: Conceptualization; investigation; methodology; super-
vision. Loren Kock: Conceptualization; data curation; investigation;
methodology. Martin Dockrell: Conceptualization; investigation;
supervision. Jamie Brown: Conceptualization; data curation; investiga-
tion; methodology; supervision.
ORCID
Harry Tattan-Birch https://orcid.org/0000-0001-9410-8343
Sarah E. Jackson https://orcid.org/0000-0001-5658-6168
Loren Kock https://orcid.org/0000-0002-2961-8838
Jamie Brown https://orcid.org/0000-0002-2797-5428
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FIGURE 1 Percentage of current vapers using disposable e-
cigarettes across ages in Great Britain from 2021 to April 2022. A
total of 36 876 eligible adults were surveyed (approximately 2300
each month). Lines represent point estimates from logistic regression
allowing an interaction between age and month, modelled non-
linearly using restricted cubic splines (three knots). Shaded areas
represent standard errors. Data and analysis code are available on-line
(https://osf.io/km3x6/)
4TATTAN-BIRCH ET AL.
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SUPPORTING INFORMATION
Additional supporting information can be found online in the Support-
ing Information section at the end of this article.
How to cite this article: Tattan-Birch H, Jackson SE, Kock L,
Dockrell M, Brown J. Rapid growth in disposable e-cigarette
vaping among young adults in Great Britain from 2021 to
2022: a repeat cross-sectional survey. Addiction. 2022.
https://doi.org/10.1111/add.16044
DISPOSABLE VAPING IN GREAT BRITAIN 5
... It is also consistent with the footage material examined in [54]: 80% of users of sub-ohm devices practice DTL and 98% of DTL vapers use sub-ohm devices, while 95% of users of low-powered supra-ohm devices practice MTL. However, the rapidly evolving dynamics of the vaping market might lead to substantial changes in the prevalence of these styles, such as a gradual increase of consumer preference for new low powered pod devices in the US [59], the UK [60] and Germany [61], as well as increasing popularity of low powered disposable devices, specially among young adults and teenagers [60,62,63]. ...
... Balushkin [18] Since the CORESTA protocol used in most of the revised literature was conceived for testing early ciga-like devices, its puffing parameters (airflow 1 L/min, puff volume 50-70 mL) are appropriate for testing the low powered recent device types (cartridge based and refillable pods, disposables) used by substantial numbers of vapers for MTL style, specially young adults [60,62,63]. The CORESTA or CORESTA-like puffing parameters might not be wholly appropriate for testing even those devices that are also meant for MTL vaping, but operate at power levels 10-30 W above recent pods and disposables. ...
... Since, as we argued in Section 3.1, usage of sub-ohm devices involves more expertise and maintenance than low powered devices, so it should occur typically among long time ex-smoking vapers. Since between 40-60% of vapers are now ex-smokers in the US and UK markets [59,60], it is reasonable to assume (as a working hypothesis) that sub-ohm devices are used by a large minority within the 40-60% of ex-smokers, which should roughly translate into 20%-25% of all vapers, with 75-80% using low powered devices (though demographic trends seem to show a steady evolution to low powered devices and even disposables [60,62,63]). ...
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Background: Electronic cigarettes (ECs) are handheld electronic vaping devices which produce an aerosol by heating an e-liquid. Some people who smoke use ECs to stop or reduce smoking, although some organizations, advocacy groups and policymakers have discouraged this, citing lack of evidence of efficacy and safety. People who smoke, healthcare providers and regulators want to know if ECs can help people quit smoking, and if they are safe to use for this purpose. This is a review update conducted as part of a living systematic review. Objectives: To examine the effectiveness, tolerability, and safety of using electronic cigarettes (ECs) to help people who smoke tobacco achieve long-term smoking abstinence. Search methods: We searched the Cochrane Tobacco Addiction Group's Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and PsycINFO to 1 July 2022, and reference-checked and contacted study authors. SELECTION CRITERIA: We included randomized controlled trials (RCTs) and randomized cross-over trials, in which people who smoke were randomized to an EC or control condition. We also included uncontrolled intervention studies in which all participants received an EC intervention. Studies had to report abstinence from cigarettes at six months or longer or data on safety markers at one week or longer, or both. Data collection and analysis: We followed standard Cochrane methods for screening and data extraction. Our primary outcome measures were abstinence from smoking after at least six months follow-up, adverse events (AEs), and serious adverse events (SAEs). Secondary outcomes included the proportion of people still using study product (EC or pharmacotherapy) at six or more months after randomization or starting EC use, changes in carbon monoxide (CO), blood pressure (BP), heart rate, arterial oxygen saturation, lung function, and levels of carcinogens or toxicants, or both. We used a fixed-effect Mantel-Haenszel model to calculate risk ratios (RRs) with a 95% confidence interval (CI) for dichotomous outcomes. For continuous outcomes, we calculated mean differences. Where appropriate, we pooled data in meta-analyses. Main results: We included 78 completed studies, representing 22,052 participants, of which 40 were RCTs. Seventeen of the 78 included studies were new to this review update. Of the included studies, we rated ten (all but one contributing to our main comparisons) at low risk of bias overall, 50 at high risk overall (including all non-randomized studies), and the remainder at unclear risk. There was high certainty that quit rates were higher in people randomized to nicotine EC than in those randomized to nicotine replacement therapy (NRT) (RR 1.63, 95% CI 1.30 to 2.04; I2 = 10%; 6 studies, 2378 participants). In absolute terms, this might translate to an additional four quitters per 100 (95% CI 2 to 6). There was moderate-certainty evidence (limited by imprecision) that the rate of occurrence of AEs was similar between groups (RR 1.02, 95% CI 0.88 to 1.19; I2 = 0%; 4 studies, 1702 participants). SAEs were rare, but there was insufficient evidence to determine whether rates differed between groups due to very serious imprecision (RR 1.12, 95% CI 0.82 to 1.52; I2 = 34%; 5 studies, 2411 participants). There was moderate-certainty evidence, limited by imprecision, that quit rates were higher in people randomized to nicotine EC than to non-nicotine EC (RR 1.94, 95% CI 1.21 to 3.13; I2 = 0%; 5 studies, 1447 participants). In absolute terms, this might lead to an additional seven quitters per 100 (95% CI 2 to 16). There was moderate-certainty evidence of no difference in the rate of AEs between these groups (RR 1.01, 95% CI 0.91 to 1.11; I2 = 0%; 5 studies, 1840 participants). There was insufficient evidence to determine whether rates of SAEs differed between groups, due to very serious imprecision (RR 1.00, 95% CI 0.56 to 1.79; I2 = 0%; 8 studies, 1272 participants). Compared to behavioural support only/no support, quit rates were higher for participants randomized to nicotine EC (RR 2.66, 95% CI 1.52 to 4.65; I2 = 0%; 7 studies, 3126 participants). In absolute terms, this represents an additional two quitters per 100 (95% CI 1 to 3). However, this finding was of very low certainty, due to issues with imprecision and risk of bias. There was some evidence that (non-serious) AEs were more common in people randomized to nicotine EC (RR 1.22, 95% CI 1.12 to 1.32; I2 = 41%, low certainty; 4 studies, 765 participants) and, again, insufficient evidence to determine whether rates of SAEs differed between groups (RR 1.03, 95% CI 0.54 to 1.97; I2 = 38%; 9 studies, 1993 participants). Data from non-randomized studies were consistent with RCT data. The most commonly reported AEs were throat/mouth irritation, headache, cough, and nausea, which tended to dissipate with continued EC use. Very few studies reported data on other outcomes or comparisons, hence evidence for these is limited, with CIs often encompassing clinically significant harm and benefit. Authors' conclusions: There is high-certainty evidence that ECs with nicotine increase quit rates compared to NRT and moderate-certainty evidence that they increase quit rates compared to ECs without nicotine. Evidence comparing nicotine EC with usual care/no treatment also suggests benefit, but is less certain. More studies are needed to confirm the effect size. Confidence intervals were for the most part wide for data on AEs, SAEs and other safety markers, with no difference in AEs between nicotine and non-nicotine ECs nor between nicotine ECs and NRT. Overall incidence of SAEs was low across all study arms. We did not detect evidence of serious harm from nicotine EC, but longest follow-up was two years and the number of studies was small. The main limitation of the evidence base remains imprecision due to the small number of RCTs, often with low event rates, but further RCTs are underway. To ensure the review continues to provide up-to-date information to decision-makers, this review is a living systematic review. We run searches monthly, with the review updated when relevant new evidence becomes available. Please refer to the Cochrane Database of Systematic Reviews for the review's current status.
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