18B.7Potential positive impacts

Last updated: April 2020 

Suggested citation: Greenhalgh, EM, & Scollo, MM. 18B.7 Potential positive effects. InDepth 18B: Electronic cigarettes (e-cigarettes). In Greenhalgh, EM, Scollo, MM and Winstanley, MH [editors]. Tobacco in Australia: Facts and issues. Melbourne: Cancer Council Victoria; 2020. Available from:  http://www.tobaccoinaustralia.org.au/chapter-18-harm-reduction/indepth-18b-e-cigarettes

 

Consumers of e-cigarettes report mixed reasons for their use. Dual users of tobacco and e-cigarettes commonly report vaping as a substitute for smoking, either in an attempt to reduce consumption of cigarettes, or to enable nicotine use in situations where use of traditional cigarettes would not be allowed or acceptable (see Section 18B.11). As indicated in Section 18B.5, health risks associated with smoking are unlikely to be reduced by e-cigarettes if users continue to smoke. Crucial to assessing the potential public health benefits of increasing use of e-cigarettes, then, is whether such use will increase or decrease the likelihood of a smoker eventually quitting tobacco.1 That is, whether use of e-cigarettes increases or decreases

  • the likelihood of smokers making quit attempts
  • the likelihood of a given quit attempt being successful
  • the likelihood of reducing use of cigarettes eventually leading to quitting.

18B.7.1 Increasing quit attempts?

Many smokers report using e-cigarettes as a cessation aid.2, 3 A large study in England found no clear association between e-cigarette use and prevalence of quit attempts; it also found that such use was associated with a decrease in the use of prescription NRT.4 A subsequent English study found that dual use of e-cigarettes was associated with a slightly higher quit attempt rate than exclusive smoking, but lower than dual use of NRT.5 A number of other studies have found smokers who use e-cigarettes are more likely to attempt to quit conventional cigarettes.6-13 However, this may be due to greater motivation (i.e. smokers who use e-cigarettes are already interested in quitting smoking).14 Some studies showed that such attempts did not appear to translate to increased long-term quitting success,6, 7, 11 while others found an increased rate of sustained cessation among e-cigarette users.9, 12, 13

18B.7.2 Increasing success in quitting

Several major reviews of the effectiveness of e-cigarettes as a cessation aid were published in 2018. Overall, these concluded that there is limited evidence that e-cigarettes may be effective cessation aids in the short-term, particularly when the products contain nicotine; however, it is unclear whether use of e-cigarettes leads to long-term cessation, or whether they are as effective as other forms of cessation support (such as NRT).14-16 Along with using e-cigarettes that contain nicotine,17 sustained9 and frequent18-25 e-cigarette users appear to be more likely to successfully quit than those who use the products short-term or intermittently. Infrequent e-cigarette users—who comprise the majority of users—may be less likely to quit, with research showing an association between non-daily use and both lower motivation to quit18 and lower rates of successful cessation.21

A number of population-based studies published in 2019 and early 2020 found an association between e-cigarette use and quit rates.25-29 For example, research in England found that the increase in prevalence of e‐cigarette use between 2007 and 2017 was associated with increased success rates of quit attempts and overall quit rates.28 However, these studies cannot establish that such relationships are causal. In its latest evaluation, Public Health England reported that using an e-cigarette as part of quit attempt may help support quitting for people attending stop smoking services; however, the proportion of quit attempts using an e-cigarette remained very small.30

Each of the reviews to date note the limited/low quality nature of the evidence,17, 31-43 and call for long-term randomised controlled trials. One randomised trial published in 2019 comparing e-cigarettes with nicotine replacement therapy (NRT) found e-cigarettes to be more effective for smoking cessation than NRT, when both were accompanied by behavioural support. After one year, 18% in the e-cigarette group were abstinent, compared with 10% in the NRT group. However, 80% of the e-cigarette group were still using the products at one year, compared with 9% in the NRT group.44 Another randomised controlled trial found no differences between e-cigarettes and nicotine gum in promoting cessation over the course of 24 weeks.45 New Zealand researchers found that combining nicotine patches with a nicotine e-cigarette led to a modest improvement in smoking cessation at six months among dependent smokers motivated to quit, compared with using patches plus a nicotine free e-cigarette, or patches alone.46

The ITC Four Country (US, Canada, Australia, England) study found that while ex-smokers who vaped daily were more likely to perceive that they were still very addicted to smoking, compared with ex-smokers who were not vaping, vapers also reported greater confidence in remaining a non-smoker, which the authors suggest may help to reduce relapse.47 However, longitudinal research in France found that e-cigarette use was associated with an increase in the rate of smoking relapse among ex-smokers, although the authors note that relapse was not higher among ex-smokers who had quit in recent years.27

18B.7.3 Cutting down as a step towards quitting

Large declines in daily consumption of conventional cigarettes in users of e-cigarettes have been noted in several studies,48-50 and reviews;34, 35 however, this may not lead to meaningful changes in consumption at a population level.51 One study found that although dual use reduced cigarette consumption, total nicotine use and dependence increased, which could hinder the ability to quit either or both products.50 Further, evidence suggests that the health benefits of reducing consumption of conventional tobacco products are limited. Although smokers who substantially reduce the number of cigarettes smoked per day reduce their exposure to some harmful and potentially harmful constituents, these decreases are limited and much smaller in magnitude than reductions following complete cessation.52 Several large cohort studies have found that smokers who reduce their consumption do not significantly reduce their risk of premature death.53, 54 Smoking just 1–4 cigarettes per day significantly increases a person’s risk of dying from smoking-related disease.55 This modesty of the health benefit from smoking reduction  is often attributed to compensatory smoking: those who cut down tend to inhale each cigarette more deeply, and smoke more of it.52, 56 (See Section 18.3 for further detail).

A number of studies have shown that dual use of NRT and cigarettes can help alleviate the issue of compensation,57-59 leading some to advocate long-term use of NRT in combination with cutting down as a harm reduction strategy.60, 61 Researchers have suggested that it may be possible that the use of e-cigarettes while smoking could similarly reduce intake of nicotine and toxins from each cigarette. However, data on the long-term safety of e-cigarettes is lacking, and they may be less safe than existing, licenced NRT products.7

The main benefit of cutting down seems to be its role as a step toward quitting.53, 62 A 2015 review exploring the usefulness of cutting down determined that smokers who reduce the number of daily cigarettes smoked are more likely than smokers who do not cut down to attempt to quit and actually achieve smoking cessation. This is particularly the case when the quit attempt is combined with NRT.63 A 2019 Cochrane review concluded that cutting down may result in similar quit rates to going cold turkey, and that reduction‐to‐quit interventions may be more effective when pharmacotherapy is used, particularly fast‐acting NRT or varenicline.64 NRT-assisted reduction appears to be an effective intervention for achieving sustained smoking abstinence, particularly for smokers not currently intending to quit (or quit abruptly),65, 66 and is effective and cost effective compared to no quit attempt.62 E-cigarettes may similarly prove to be a useful form of NRT in combination with smoking reduction as part of ‘cutting down to quit’, but further research is needed on the efficacy of the products in this context.63

18B.7.4 Modelling of net impact of use of e-cigarettes on smoking prevalence and tobacco-related disease

Given the uncertainty of the effects of the rapid increase in e-cigarette use on smoking behaviours and public health, researchers have attempted to model hypothetical scenarios and estimate possible outcomes. Such modelling is limited by a lack of understanding of long-term health effects, effects on smoking uptake, and effectiveness for cessation, and conclusions subsequently vary substantially depending on the assumptions and parameters used by researchers.

One study modelled the potential future effects of e-cigarette use on smoking behaviour and concluded that, based on current usage patterns, smoking prevalence appears to be far more sensitive to e-cigarette effects on smoking cessation than initiation. Results from the model suggested that if e-cigarettes increase both uptake and quitting of conventional cigarettes, the effects on uptake would have to be extremely large (i.e., increase over 200%) to offset even small cessation effects on population smoking prevalence.67

Another study similarly concluded that a substantial gateway effect (of vaping to smoking by never smokers) or an increase in the magnitude of harms from e-cigarettes relative to cigarettes (or both) would be required before the harms to public health outweigh the benefits of e-cigarette uptake. The authors estimate a net public health benefit associated with e-cigarettes resulting in 21% fewer smoking-attributable deaths and a 20% reduction in life years lost.68 A more recent modelling study by some of the same researchers concluded that, under an ‘optimistic scenario’, replacement of cigarette by e-cigarette use over a 10-year period would yield 6.6 million fewer premature deaths with 86.7 million fewer life years lost. Even under pessimistic assumptions regarding cessation, initiation and relative harm, they argue that replacing cigarette smoking with vaping would yield substantial life year gains, particularly among younger cohorts.69 A modelling study of the health and cost impacts of e-cigarettes in New Zealand concluded that a fairly permissive regulatory environment achieves net health gain and cost savings. However, there was a large degree of uncertainty for this finding, given the uncertainty around the impact of vaping on cessation rates and the relative health risk of vaping compared with smoking.70

On the other hand, other researchers have estimated that, based on the most up-to-date evidence, e-cigarette use in 2014 represents a population-level harm in the US of about 1.6 million years of life lost over the lifetime of all adolescent and young adult never-cigarette smokers and adult current cigarette smokers. If e-cigarette use confers long-term health risks, the model estimated even greater population-level harm. They argue that previous models—which reached more favourable conclusions about the public health impact of e-cigarettes—are based on faulty assumptions about uptake and smoking initiation among young people.71

Another study that modelled the potential health effects of increasing e-cigarette use concluded that—in order for there to be any benefits to public health—most e-cigarette users need to be current smokers interested in quitting or people who would have otherwise gone on to be smokers.  Other scenarios, such as e-cigarette use renormalising smoking, dual use, or significant uptake by young people (those young people who would otherwise never have smoked tobacco cigarettes) have the potential to increase population-level harm. The authors suggest that the likelihood of negative scenarios eventuating will ultimately depend on the regulatory environment, with benefits to public health being more probable with strict regulations on the sale, promotion, and use of the products; i.e., regulations that encourage use only by smokers,72  and only without simultaneous use of tobacco products.

Researchers in Singapore modelled the potential impact of different e-cigarette and tobacco cigarette policies over 50 years, combining evidence from Singapore (where e-cigarettes are currently banned) with evidence from Japan, the UK and the US (where e-cigarettes are much more widely accessible). The study concluded that while a less restrictive e-cigarette policy could reduce smoking prevalence in the short term, it is not as effective as other policies in the long term. The most effective single policies were ‘smokefree generation’ and substantial tax increases; the most effective combination of policies was raising the minimum legal age plus moderate tax increases and e-cigarettes on prescription.73

Overall, any population-level effects may include some groups incurring harm (e.g., young people who start smoking), and some incurring benefits (e.g., smokers who quit). Changing cessation rates are seen earlier than the effects of changing initiation rates, due to the health effects of smoking taking many years to manifest. Conclusions of various models will therefore vary based on whether the projections are short- or long-term, with potential harms from increased initiation by youth occurring decades after the benefits of increased cessation are seen.16

 

Relevant news and research

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