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Electronic cigarettes for smoking cessationResults from the most recent Cochrane updateJamie Hartmann-Boyce*, Hayden McRobbie, Chris Bullen, Rachna Begh, Lindsay F Stead, Peter Hajek
*Cochrane Tobacco Addiction Group, Nuffied Department of Primary Care Health Sciences, University of Oxford. [email protected]
7 September 2016
Acknowledgements
I am funded by the NIHR and have no conflicts of interest to declare
Objective of this review
Evaluate the safety and effect of using EC to help people who smoke achieve
long-term smoking abstinence
Inclusion criteria: quitting studies
• Smokers randomized to EC or control
• Quit rates at six months or longer
Randomized controlled trials
• All people in the study offered EC• Quit rates at six months or longer
Uncontrolled intervention
studies
• No intervention provided• Survey existing smokers, ask about
EC use, report quit rates at 6m+
Longitudinal surveys
Won’t be included in next update due to nature of their design and risk of confounding
Inclusion criteria: participantsPeople defined as current smokers at enrollment into study, motivated or unmotivated to quit
Searches• 7 electronic databases
searched to Jan 2016• Researchers contacted• Trial registries &
conference abstracts for ongoing studies
Screening and data extraction• Followed standard Cochrane
methods• Done in duplicate by two
independent reviewers• Risk of bias assessed using
Cochrane Risk of Bias Tool
Abstinence• Six months or longer• Intention to treat• Strictest definition available• Biochemically verified where
available(as per standard Cochrane methods)
Numerical analyses• Pooled data where appropriate following
standard Cochrane methods• Meta-analyses using fixed-effect Mantel-
Haenszel model to calculate risk ratio (RR) with 95% confidence interval for each study
Included studies Ongoing studies Excluded studies0
5
10
15
20
25
30
35
40
45
136
39 2014
Search results
Included studies Ongoing studies Excluded studies05
101520253035404550
136
3911 21
7
20162014
• 4 uncontrolled intervention
• 5 non intervention
• 2 AEs only
Primary outcome: Quitting at 6-12 months, EC versus placebo
GRADE quality of evidence: LOW (small number of studies, Bullen poor nicotine delivery)
Primary outcome: Quitting at 6 months, EC versus NRT
GRADE quality of evidence: VERY LOW (only one study, issue with nicotine delivery)
Polosa 2011 (6m)
Polosa 2014b (6m)
Ely 2013 (6
m)
Polosa 2015 (6m)
Adriaens 2
014 (8m)
Pacifici
2015 (1 ye
ar)
Caponetto 2013b (1 ye
ar)
Polosa 2015 (1 ye
ar)
Polosa 2011 (2 ye
ars)0
10
20
30
40
50
60
Uncontrolled intervention studiesPe
rcen
tage
abs
tinen
t
Study ID
= new to this review
• Smoking cessation clinic, Italy
• N = 50, unwilling to quit• Provided with personal
vaporisers (9mg/ml nicotine), instructions for use
• 30 day PP, CO verified
• Vape shops, Italy• N = 71, first purchase at
participating shop• Instructed how to fill,
activate and use EC in anticipation of reducing cpd
• 30 day PP, self-report
• RCT but all participants provided EC at week 8
• N = 50, unmotivated to quit• Provided 2nd generation EC (18mg/ml
nicotine) and instructions on use (control group didn’t receive instructions)
• CO validated cessation, not defined
• Smoking cessation clinic, Italy• N = 34, unwilling to quit• Provided with EC, nicotine
content tailored to match individual daily intake
• Training programme and encouraged to quit
• Cessation not defined
Non-intervention studies
Etter 2
014
Grana 2014b
Choi 2014
Al-Delaim
y 2015*
Borderu
d 2014*
Brose 2015
Manzo
li 2015
Proch
aska 201405
101520253035404550
Percentage abstinent, ECPercentage abstinent, non ECPe
rcen
tage
abs
tinen
t
Study ID
new studies
Ongoing studiesOf the 27 ongoing studies, 14 may contribute to future cessation meta-analyses (RCTs, measure cessation, 6m+ FU)
NRT; 6
Placebo EC; 7
Usual care; 3
Be-havioural interven-
tion only; 2
Different gener-ations; 1
Control/comparison groups in ongoing cessation RCTs
Comparison with other reviews• 11 other systematic reviews look at efficacy of EC for
quitting smoking (8 of which published 2015-2016)• All agree more evidence is needed; most are cautiously
optimistic re: efficacy• 3 (all 2015-2016) conduct meta-analyses for quitting; 2
have results consistent with ours (Khoudigan and Rahman)
• The 3rd (Kalkhoran) finds the opposite – that ECs hinder quitting – includes longitudinal cohorts
Why do the RCTs provide different answers than the observational studies?
Many different reasons, including:• variations in the effectiveness of ECs depending on the level of support provided• issues around definitions of baseline EC usage• unexplored confounders (not specific to EC – same has been found for NRT when we
don’t control for confounders)• studies which analyse results in smokers based on EC use at baseline have by the nature
of their design already excluded people who have successfully quit using EC, and therefore only retain participants who, at entrance to the study, would be classed as 'treatment failures' or are in the midst of a cessation attempt involving cutting down to quit.
>>Following the standard methods of the Cochrane Tobacco Addiction Group and the protocol for this review, we focused on evidence from RCTs for cessation outcomes
Implications for practice (efficacy)
Certainty about the effects is low and more data are needed to strengthen confidence in the estimates.
Evidence from the pooled results of two trials that EC with nicotine, compared with placebo ECs, helped smokers to stop smoking long-term. Corresponds to findings from placebo-controlled trials of NRT.
Evidence from one trial that ECs may lead to six-month quit rates similar to those achieved with NRT, but the confidence interval is wide. The effects of newer devices with better nicotine delivery are unknown.
Implications for research (efficacy)
Future studies should: focus on comparing ECs with ‘usual care’ or minimal treatment, and with
alternative pharmacological and behavioural treatments measure the proportions of smokers who successfully quit smoking with
the help of ECs and who continue to use ECs long-term, and the proportion who eventually become nicotine-free
select ECs with good nicotine delivery that are representative of the best current standard in terms of reliability and user satisfaction.
be adequately powered consider providing ECs in a way that would be used in real-world settings
(e.g. taking into account individual preferences for strengths and flavours of e-liquids and even EC devices).
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Thank you
Included studies: RCTs
Caponetto 2013
• 300 smokers not intending to quit
• EC with and without nicotine
• 12 month follow-up
Bullen 2013
• 657 smokers wanting to quit
• EC with nicotine, EC without nicotine, NRT (patches)
• 6 month follow-up
Included studies: observational data
Intervention cohort (quit data)
• 7 studies (4 new)• Provided participants
with EC and/or instructions on how to use EC to cut down or quit smoking
Longitudinal surveys (quit data)
• 8 studies (5 new)• Included smokers
who had tried or used EC in past 6m
• Will be excluded in next update
New non-intervention studies• Al-Delaimy 2015 - longitudinal telephone-based survey, California residents who had
smoked at least 100 cigarettes in their lifetime and smoked cigarettes 'at least some days' at baseline. Self-reported prolonged abstinence for one month or longer, quit attempts, and reduction were assessed at 12 months.
• Brose 2015 - web-based survey, recruited 4064 UK residents who had smoked in the past year, with 1769 followed up at 12 months. 23% EC users at baseline, the majority of whom indicated they were using first-generation ECs. At 12m, asked if identified as ex smoker.
• Borderud 2014 recruited 1074 patients presenting with cancer at a large US cancer centre, referred to and completed intake assessment for the centre's tobacco cessation programme. All offered multicomponent, evidence-based behavioural and pharmacological treatment for tobacco dependence. Follow up 6-12m, 7d PP abstinence collected.
• Manzoli 2015 - community settings, Italy. 491 tobacco smokers and 232 dual EC and tobacco smokers were followed up at 12 months, with further follow-ups planned at 24, 36 and 60 months. Follow-up measures included 30-day sustained abstinence with CO verified in a subsample, and 30-day abstinence from tobacco and EC.
• Prochaska 2014 reports a secondary analysis of data from RCT in inpatient psychiatric hospital in California. 956 smokers of at least 5cpd recruited and randomized to different levels of behavioural support. At baseline, 11% of participants used an EC. This paper reports cessation measures (not defined) in EC and non-EC users at the longest available follow-up (not defined, but study length was 18 months).
Risk of bias
Generations of EC
• 1st generation
• ‘cig-a-like’• Cartridge,
atomizer and battery
• 2nd generation
• Tank and battery
• Refillable
• 3rd generation
• Mechanical ‘mods’
• Variable power options
