Efficacy of Electronic Cigarettes in Smoking Cessation for Adult SmokersSusan Alaei, M.D. Candidate; Brittany Bartolome, M.D. Candidate; Colin Freedman, M.D. Candidate1
1University of Nevada School of Medicine, Reno
IntroductionWhile the complete cessation of smoking is the best form of treatment for smokers, the presence of nicotine in tobacco smoke makes overcoming the addictive properties of nicotine very difficult for those looking to quit smoking. Electronic cigarettes (“e-cigarettes”, EC) are a battery powered delivery system of nicotine that does not require combustion or smoke. Since being marketed in 2006, there has been a steady growth in EC sales, as they are advertised as containing fewer carcinogens compared to traditional cigarettes. Smokers have reported using ECs as a means of reducing smoking, thus contributing to its public attention as a safer smoking alternative or as an aid to help people in their efforts to quit. However, healthcare providers remain hesitant to encourage smokers to switch to ECs, as the efficacy and health risks of such a claim remain uncertain due to the lack sufficient evidence. This has ultimately prompted research on the short and long-term health consequences of frequent electronic cigarette use and whether ECs have, in fact, been effective at achieving smoking abstinence or reducing cigarette consumption, and if it exacerbates nicotine addiction. This information will undoubtedly prove useful as it will determine whether such devices can reduce the harms associated with smoking and be considered as an alternative therapy offered by physicians to smokers looking to quit smoking or inquiring about ECs.
QuestionAre electronic cigarettes more effective at helping adults smokers quit smoking compared to alternative smoking cessation aids?
P = Adult cigarette smokers (>18 years old)I = Electronic cigarettes (ECs)C = Alternative smoking cessation aids, including no interventionO = Smoking cessation
MethodologyA systematic review of articles was conducted using the PubMed database. Terms used for search included “electronic cigarette,” “e-cigarette,” “safety,” “smoking cessation,” and “tobacco use reduction.” Convenience was also considered in our literature search, as only papers that were free of cost or available through the Savitt Medical Library were accessed for the purposes of this review.
Criteria for considering studies for this reviewLiterature search was limited to human studies of adult (>18 years old) patient studies published within the last 5 years (2010 through 2015). We selected and evaluated articles based on subject design, which included selecting first for randomized control trials, where smokers were randomized to electronic cigarettes (ECs) or to a control condition and the measure of abstinence rates or changes in cigarette consumption were taken at a minimum of six months or longer to determine efficacy of ECs in aiding smoking cessation and reduction. Our search results offered few RCTs and thus our search was expanded to prospective and longitudinal based studies that exceeded at least a six month follow up period. We accepted studies regardless of their publication status.
Types of Outcomes MeasuredPrimary outcomes included cessation at the longest follow up point (at least six months) from start of intervention, measured using the strictest definition of abstinence, validated by biochemical results (carbon monoxide, thiocyanate, and other markers of tobacco use). Secondary outcomes included reduction in cigarette use at longest follow up point (at least six months) from start of intervention.
DiscussionOur review of studies found that ECs containing nicotine can aid in smoking cessation, while those without nicotine were not as effective. Regardless of nicotine enrichment, ECs have been effective in reducing tobacco cigarette consumption. It was found that compared to the nicotine transdermal patch, EC cessation rates were similar. However, in absence of cessation, ECs were far more effective in reducing the number of cigarettes used compared with the patch. Furthermore, the correlation between EC use and the reduction in the number of tobacco cigarettes suggests that the device does not contribute to increased nicotine addiction as previously questioned. Only one study found no correlation between EC use and either abstinence or reduction in cigarette consumption. However, this study did not have a clear definition of abstinence and the statistical power was lowered due to low reporting of EC use among participants.
ConclusionIn the population of people who have a long history of smoking, we would recommend EC use as an alternative to other smoking cessation aids that they may not feel are as helpful. We conclude that ECs are more effective in reducing cigarette consumption compared to the transdermal patch and ECs containing nicotine were more effective than those without. In terms of complete abstinence, ECs have similar efficacies as the transdermal patch. As a device that provides an additional means of smoking cessation in the effort to curb tobacco usage and subsequent tobacco harm, there are profound implications for the benefits of ECs in terms of public health. We would like to note, however, that our review is limited to the short-term efficacy of EC and not its safety. We can therefore make no conclusions on the health consequences of EC use compared to alternative cessation methods.
Further ResearchOur review of these studies has been limited to understanding the short-term effects of continued EC use, thus prompting us to inquire and research further the longer-term use and possible health consequences. These studies have also been limited to the adult smoking population, but does not assess the risk of access to ECs and potential abuse among the adolescent population. While ECs have shown a potential for improving the population health, given its high acceptability in today’s society, we must first address whether accessibility in and of itself can result in future health problems not commonly associated with tobacco use.
References1 Bullen et al. (2013) “Electronic Cigarettes for smoking cessation: a randomised controlled trial.” Lancet 382:1629-372 Caponnetto et al. (2013) “Efficiency and Safety of an Electronic Cigarette (ECLAT) as tobacco cigarettes substitute: a prospective 12-month randomized control design study.” PLoS One 8(6):e66317.3 Grana et al. (2014) “A longitudinal analysis of electronic cigarette use and smoking cessation.” JAMA Int Med 174(5):812-3.4 Polosa et al. (2014) “Effectiveness and tolerability of electronic cigarette in real life: a 24-month prospective observational study.” Internal and Emergency Medicine 9(5):537-46.
AcknowledgementsDr. Julie Smith-Gagen and Dr. Mary Schultz for their guidance in our web search and ensuring our preparation for this review.
ResultsAUTHOR METHODS FINDINGS LIMITATIONS
Bullen et al, (2013)1
• 657 par(cipants (New Zealand) selected via exclusion and inclusion criteria from newspaper adver(sement
• 4:4:1 ra(o of randomly assigned groups:
• Group A: nico(ne ECs • Group B: nico(ne patches • Group C: placebo EC (no nico(ne) • Assessed at 1, 3, and 6 months
for abs(nence (measured eCO) and reported smoked cigareJes/day
• Verified abs(nence of 7% with nico(ne ECs vs 5% with nico(ne patches vs 4% with placebo ECs
• Insufficient sta(s(cal power to conclude EC superiority to patches or placebo
• ECs were modestly effec(ve at helping smokers quit, with similar achievement of abs(nence as nico(ne patches
• Effect size and es(mates of abs(nence were markedly op(mis(c, thus reducing sta(s(cal power to detect differences
• Group B had higher loss to follow up and withdrawal rates
• Study was not conducted on second genera(on ECs
• 22% loss to follow up rate reduces sta(s(cal power of study
• Sampling bias as convenience sampling was used in the selec(on of par(cipants
Randomized Control Trial
CaponneDo et al, (2013)2
• 300 smokers with no inten(on to quit (Italy); selected via exclusion and inclusion criteria from EC therapy study adver(sement
• 1:1:1 ra(o of EC containing cartridges given to 3 groups:
• Group A: 7.2mg nico(ne for 12 weeks
• Group B: 6-‐week 7.2 mg nico(ne followed by 6-‐week 5.4mg nico(ne
• Group C: no nico(ne for 12 weeks • 9 conducted visits to measure
cigareJe/day use and eCO levels
• Median number of cigareJes per day and exhaled carbon monoxide levels decreased from baseline in all 3 study groups at each visit
• Overall number of cigareJes per day decreased from 21 to 13.9 (p<0.0001) at end of 52-‐week study
• Complete abs(nence from tobacco smoked was documented 10.7% and 8.7% at weeks 12 and 52 respec(vely
• Repor(ng bias as it was unclear if the original inten(on was to combine the two nico(ne-‐containing EC groups or not
• 25%, 29.7%, and 39% drop out rate at follow up weeks 12, 24, and 52, respec(vely contributes to a reduced sta(s(cal power of the study
• Sampling bias as convenience sampling was used for selec(on of par(cipants
Randomized Control Trial
Grana et al, (2014)3
• 1549 total par(cipants (1189 of which were current smokers) surveyed at baseline and follow up aber one year
• Survey asked (1) history of EC use within 30 days, (2) number of cigareJes/day, (3) (me to first cigareJe (<30 vs ≥ 30 mins), and (4) inten(on to quit (never vs ≥ months vs ≤6 months vs ≤1 month)
• EC use by smokers was not followed by either smoking abs(nence or reduc(on in cigareJe consump(on at 1-‐year follow up
• High risk of selec(on bias as they did not validate self-‐reported abs(nence and provide a clear defini(on of abs(nence
• Only 88 of the 949 smokers reported using EC, thus lowering the sta(s(cal power to detect a rela(onship between EC and smoking cessa(on
Cohort study
Polosa et al, (2014)4
• 40 smokers with no inten(on of quifng within 30 days
• 24-‐weeks of interven(on with EC • Par(cipants allowed maximum of
4 cartridges/day and received supplies of nico(ne cartridges at weeks 4, 8, and 12, for eCO measurements
• Follow up conducted at 18 and 24 months following interven(on to address smoking habits, cigareJes/day, exhaled CO measurements, adverse events and EC use
• 80% reduc(on in median cigareJe usage from 25 to 4 by the end of the study (p<0.001)
• Overall quit rate of 12.5 % • Combined 50% sustained
reduc(on and smoking cessa(on in 40% by study end (p<0.001)
• Typical nico(ne withdrawal symptoms appeared mi(gated by EC usage
• Levels of carbon monoxide detected in par(cipants was significantly decreased by study end
• Selec(on bias and performance bias
• Recall bias of withdrawal symptoms, 42.5% of par(cipants failed to aJend final appointment
Cohort study