Public Health Consequences of E-Cigarettes (2018) / Chapter Skim
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17 Smoking Cessation Among Adults
17 Smoking Cessation Among Adults
Pages 541-588
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From page 541... ...
Additional benefit would be expected if e-cigarette users subsequently stopped using both e-cigarettes and combustible tobacco products. This section addresses the question: Do e-cigarettes help smokers quit smoking combustible tobacco cigarettes?
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or use both combustible tobacco cigarettes and e-cigarettes, a pattern referred to as dual use (1b in Figure 17-1)
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, producing abstinence from both tobacco smoke and nicotine, as well as any other potentially harmful constituents of e-cigarette aerosol. However, a complete switch from combustible tobacco cigarettes to e-cigarettes, with e-cigarette use persisting indefinitely, is still likely to reduce harm (2b)
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; or stops using both combustible tobacco cigarettes and e-cigarettes (3d)
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An optimal prospective observational study design would identify and follow a large cohort of smokers who want to quit or are making a quit attempt, assess e-cigarette exposure in detail before the smoking cessation outcome is assessed, biochemically confirm self-reported tobacco abstinence, and adjust for multiple potential confounding factors associated with e-cigarette use and with smoking cessation. The limitation inherent in this study design is that smokers choose whether or not to use e-cigarettes.
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. As consumer products already easily accessible to smokers, e-cigarettes therefore have the potential to alter population cessation rates as a function of their efficacy as cessation aids and/or as a consequence of their appeal to smokers.
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No new RCTs were identified. Additional observational and cohort studies were identified, but their results were generally consistent with studies in the systematic reviews.
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548 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-1 Systematic Reviews of E-Cigarettes and Smoking Cessation Identified by Literature Search Systematic Search Studies Reference Review Meta-Analysis Through Included El Dib et al., Yes Yes 12/29/2015 12 (3 RCT, 2017 (updated until 9 cohort)
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. Yes "Given the limited available evidence on the risks and benefits of e-cigarette use, large, randomized, controlled trials are urgently needed to definitively establish their potential for smoking cessation" (Franck et al., 2014, p.
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550 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-1 Continued Systematic Search Studies Reference Review Meta-Analysis Through Included Heydari et al., Yes No 9/2014 69 2017 Ioakeimidis et Yes Yes (report 6/2015 2 RCT al., 2016 result of other meta-analyses) Kalkhoran and Yes Yes 6/17/2015 20 (1 RCT, Glantz, 2016 1 NRCT, 15 cohort, 3 cross sectional)
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. Yes "Further research is needed to examine the longer term safety, potential for long-term use and efficacy as a cessation aid" (Ioakeimidis et al., 2016, p.
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552 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-1 Continued Systematic Search Studies Reference Review Meta-Analysis Through Included Knight-West Yes Yes (report 9/2015 11 (3 RCT, 8 and Bullen, result of other cohort) 2016 meta-analyses)
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More research, specifically well conducted large efficacy trials comparing e-cigarettes with standard smoking cessation management (e.g., nicotine replacement therapy plus behavioral support) and long-term prospective studies for adverse events, is urgently needed to fill critical knowledge gaps on these products" (Knight-West and Bullen, 2016, p.
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554 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-1 Continued Systematic Search Studies Reference Review Meta-Analysis Through Included Orr and Asal, Yes No 3/2014 6 2014 Patnode et al., Yes (of reviews, No (for 3/1/2015 2 2015 not original e-cigarettes) studies)
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Primary outcome cigarettes with nicotine was smoking reduction, but decreases tobacco cessation was a secondary consumption among regular outcome smokers. Further studies are needed to specify electronic cigarettes' safety profile and its ability to cause a reduction in consumption and long term cessation in smokers" (Vanderkam et al., 2016, p.
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556 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-1 Continued Systematic Search Studies Reference Review Meta-Analysis Through Included Waghel et al., Yes No 5/2014 7 2015 Excluded Reviews Heydari et al., Yes, but not No n/a n/a 2014 specific to e-cigarettes MacDonald et Yes Not at present Ongoing 13 (in initial al., 2016 time scoping of the literature in April 2014; ongoing at the time of publication) McRobbie et Yes Yes 7/2014 13 (2 RCT, al., 2014 11 cohort)
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. n/a n/a Systematic review of all cessation methods, little focus on e-cigarettes Yes Ongoing project; no Protocol paper for an ongoing conclusions yet meta-narrative review yes "There is evidence from two Updated as Hartmann-Boyce et trials that e-cigarettes help al., 2016 smokers to stop smoking long-term compared with placebo e-cigarettes.
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EVIDENCE REVIEW: RESULTS Systematic Reviews Overall, the reviews report on a small and overlapping evidence base. They consistently identified the same three RCTs whose characteristics and results are summarized in Table 17-2.
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Both included RCTs and prospective cohort tudies s that enrolled current combustible tobacco cigarette mokers regardless s of intention to quit. They compared nicotine-containing e-cigarettes with non-nicotine e-cigarettes, other smoking cessation aids, or no aid.
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NOTE: ASCEND = A Study of Cessation Using Electronic Nicotine Devices; CO = carbon monoxide; CTL = control; ECLAT = EffiCiency and Safety of an eLectronic CigAreTte; INT = intervention; RR = relative risk.
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SMOKING CESSATION AMONG ADULTS 561 Outcome Assessment Data Pooled Behavioral Abstinence for MetaSupport Follow-Up Measure Rate Difference Analysis? a,b Offered 6 months CO-validated (1)
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Study designs included RCTs and prospective RCTs and prospective cohort studies cohort studies Participants Current smokers Current cigarette smokers Motivated or Motivated or unmotivated unmotivated to quit to quit Interventions E-cigarettes E-cigarettes (with or without nicotine) Comparison conditions Placebo e-cigarettes, Placebo e-cigarettes, other other smoking cessation smoking cessation aid, or no aid, or no cessation aid cessation aid Search strategy: Updated results of Included results of 2014 databases used 2014 Cochrane review Cochrane review, searched using Cochrane Tobacco MEDLINE, CINHAL, Addiction Group EMBASE, CENTRAL, Specialized Register, PsycINFO, Web of Science, Cochrane Central ClinicalTrials.gov, PubMed Register of Controlled Trials, MEDLINE, EMBASE, PsycINFO Search strategy: terms e-cig$ OR elect$ cigar$ MeSH subject headings: used OR electronic nicotine electronic nicotine, OR vape OR vaper OR smoking-cessation, tobacco vapers OR vaping use-disorder, tobacco smoking, quit Literature search ended January 2016 December 29, 2015 (updated until submission, May 2016)
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number of studies) Prospective Cohort Studies Identified meeting 21 9 (13,115 participants)
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Conclusions "There is evidence "Results from 2 RCTs from two trials that suggest a possible increase e-cigarettes help smokers in smoking cessation with to stop smoking in the ENDS in comparison with long term compared ENNDS...."f with placebo e-cigarettes. "There is very limited However, the small evidence regarding the number of trials, low impact of ENDS or ENNDS event rates and wide on tobacco smoking confidence intervals cessation, reduction or around the estimates adverse effects: data from mean that our confidence RCTs are of low certainty in the result is rated low and observational studies of by GRADE standards.
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Additionally, missing outcome data and an imprecise assessment of prognostic factors and outcomes were judged to have produced a risk of bias. Consequently, the evidence provided by the cohort studies was judged to be very low certainty "from which no credible inferences can be drawn" (El Dib et al., 2017, p.
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. Specifically, the authors noted that smokers who have already succeeded in quitting with e-cigarettes would not be eligible for non-randomized observational studies, which recruit only current smokers.
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judged the low confidence in the evidence base and the opposite result of the cohort studies to be sufficient to preclude any conclusion about effectiveness of e-cigarettes at this time. Other Systematic Reviews Table 17-4 describes four of the five other systematic reviews that were published during 2016–2017 (Kalkhoran and Glantz, 2016; Khoudigian et al., 2016; Malas et al., 2016; Vanderkam et al., 2016)
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Comparison conditions Placebo e-cigarettes or Not specified NRT Search strategy: MEDLINE, Embase, PubMed, MEDLINE, databases used PsycINFO, Cochrane PsycINFO, CINAHL, Central Registry of ERIC, ROVER, Scopus, ISI Controlled Trials; also Web of Science, Cochrane found gray literature Library, Ontario Tobacco through searching Research Unit library websites of health catalogue; gray literature technology assessment identified using Grey and related agencies, in Matters, OAIster, OpenGrey, addition to reports of NYAM website, Legacy major smoking cessation Library, BIOSIS Previews, conference proceedings; Conference Papers Index, also used Google ISI Proceedings, Dissertation for more Web-based Abstracts International, materials CIHI, GreyNet International Search strategy: terms Searched controlled Electronic nicotine delivery used vocabularies (MeSH system, ENDS, electronic and EMTREE) and cigarette, e-cigarette, e-cig, keywords on concept of e-juice, e-liquid, e-hookah, "electronic cigarette" or cartomizer, alternative "e-nicotine": tobacco product, tobacco use cessation product, 1.
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Not using e-cigarettes Placebo e-cigarette Placebo e-cigarette or other PubMed, Web of Science MEDLINE, Cochrane PubMed, Web of Core Collection Knowledge, Scopus Electronic cigarette, Electronic cigarette, "electronic cigarettes OR e-cigarette, electronic nicotine e-cigarettes" AND "smoking electronic nicotine delivery device, cessation OR quit smoking" delivery, electronic nicotine 1 or 2 or 3, delivery system, vaping, stop, e-cigarette quit, cessation, abstain, abstinence, 5 or 6 or 7 or 8 or 9, 4 and 10 June 17, 2015 June 14, 2015 May 2014 continued
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570 PUBLIC HEALTH CONSEQUENCES OF E-CIGARETTES TABLE 17-4 Continued Characteristic Khoudigian et al., 2016 Malas et al., 2016 Study selection and data 2 authors 2 authors extraction Risk of bias assessment Yes Yes Cochrane Risk of Bias Modified version of tool (RCTs) ; same QualSysta tool by combining criteria for controlled quantitative and qualitative before–after studies, checklists and revising but "random sequence criteria based on Cochrane generation" and Handbook guidelines "allocation concealment" domains were reported as "high risk of bias" Outcome measures Smoking abstinence for Smoking abstinence for 6 months or more; also 30 days; also reduction, desire to smoke, number withdrawal symptoms, of cigarettes smoked, craving withdrawal symptoms Studies identified 5 (4 RCTs [2 of which 62 used in meta-analysis]
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, Downs and Black Cochrane Risk of Bias instrument (observational tool (clinical trials) studies)
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Eligible study designs included RCTs, experimental studies, prospective observational studies, and cross-sectional studies. The primary outcome was cessation, defined as smoking abstinence or reduction with at least a
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2. NOTE: NRT = nicotine replacement therapy; OR = odds ratio; RCT = randomized controlled trial; RR = relative risk.
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. Unlike other meta-analyses that separated RCTs and observational studies, this meta-analysis combined all study designs (15 cohort studies, 3 cross-sectional studies, and 2 clinical trials [only 1 randomized]
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reviewed controlled trials, prospective cohort studies, and cross-sectional studies of e-cigarette use that were published up to May 2014. The review included studies that compared current smokers (variously defined and irrespective of interest in quitting)
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Although this difference led to slightly different interpretations, all reviews agreed that their confidence in their conclusion was low and that additional evidence might shift their conclusions. In contrast to RCTs, different groups of observational studies, primarily longitudinal cohort studies, were included in the systematic reviews.
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. That study found a higher success rate of quit attempts among smokers who used e-cigarettes during a quit attempt, compared with those who did not use e-cigarettes during a quit attempt.
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. Recall bias of e-cigarette use and quit attempts is a limitation of the Giovenco and Delnevo (2018)
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SYNTHESIS There is general agreement that the number, size, and quality of studies for judging the effectiveness of e-cigarettes as cessation aids in comparison with cessation aids of proven efficacy are limited, and therefore there is insufficient evidence to permit a definitive conclusion at this time. Not only are existing studies limited in number, but the randomized trials provide a limited range of treatment comparisons.
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The committee also considered the substantial body of RCT evidence demonstrating the efficacy of nicotine replacement products compared with placebo products as smoking cessation aids as evidence that provided plausibility for the role of nicotine in enhancing the likelihood of smoking cessation. The combination of RCT evidence and indirect supportive evidence was judged by the committee to provide moderate evidence that e-cigarettes with nicotine are more effective than e-cigarettes without nicotine for smoking cessation.
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The results of cohort studies have produced mixed results, but the associations in cohort studies published prior to 2016 generally indicate that e-cigarette users are less likely than non-users of combustible tobacco cigarettes to quit smoking. The two systematic reviews that included cohort studies published between 2013 and 2015 in meta-analyses each found a negative association between -cigarette use e
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Another important reason for the discrepancy is bias in cohort studies due to self-selection. This would occur if the smokers who choose to use e-cigarettes are less likely to succeed because of stronger nicotine dependence, less access to or interest in using effective smoking cessation medications, having failed to quit after having exhausted all other smoking cessation aids, or other factors that could bias relative risk estimates of associations with e-cigarette use toward less favorable cessation outcomes.
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Furthermore, substantial evidence exists to associate higher cessation rates with better adherence to FDA-approved cessation aids among smokers who are attempting to quit. Based on this biological plausibility and the strong, consistent body of evidence from higher-quality studies published more recently that overcome measurement limitations of studies published in the past, the committee concluded that there was moderate evidence that more frequent use of e-cigarettes is associated with quitting smoking.
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. For both randomized trials and observational studies, critical modifiers of the association of e-cigarette use and smoking cessation may exist, such that certain patterns of use or types of e-cigarettes may be more effective as cessation aids than others.
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2017. Electronic nicotine de livery systems and/or electronic non-nicotine delivery systems for tobacco smoking cessation or reduction: A systematic review and meta-analysis.
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Cochrane Database of Systematic Reviews 9:CD010216. Heydari, G., M
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Cochrane Database of Systematic Reviews 12:CD010216. NASEM (National Academies of Sciences, Engineering, and Medicine)
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2016. Long-term e-cigarette use and smoking cessation: A longitudinal study with U.S.
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