1. E-cigarettes for tobacco harm reduction
School of Public Health and Community Medicine The University of New South Wales, Sydney
Associate Professor Colin Mendelsohn
E-cigarettes for tobacco harm reduction
ACRA 2018 ASM
Wednesday 1 August

2. What is the evidence?
Is vaping an effective quitting aid and how does it compare to conventional therapies?
Does switching to an e-cigarette reduce harm?
What are the cardiovascular effects of vaping?
Are e-cigarettes a gateway to smoking tobacco?

3. Effectiveness Population studies
Best evidence is in real-world settings
E-cig users have much higher quit rates than non-users
Any use almost doubled quit rates 4.8% vs 8.2% 1
US Current Population Survey-Tobacco Use Supplement, , n=24,684
Daily use increased quit rates 3-8x 2,3
PATH, 2013/4-2014/5, n=32,320 NHIS, , n=15,532
Does the technology work in a real world environment: experiment with range of devices, strengths, flavours
Zhu. Over a 12m period, smokers who used ecigs had twice quit rates for >3m
Nationally representative population studies
1. Zhu S. BMJ Berry K. Tob Control Giovenco D. Addict Behav 2017

4. Effectiveness National surveys
Millions of smokers have quit smoking by vaping
Quit smoking by vaping
Data Source
7.5 million
Eurobarometer #
National Health Interview Survey 2016, CDC
2.62 million
Some are vaping, some are not. But all have quit smoking
Office of National Statistics 2017
2 million
Most popular quitting aid in EU, US, UK

5. Effectiveness Clinical trials
‘The three higher quality reviews all reached similar conclusions… consistent with an approximate doubling of the likelihood of quitting smoking’ 1
Modern devices more effective 2,3
Clinical trials of approved therapies increase % 4
21 reviews of clinical trials of mixed methodological quality
High quality: Cochrane, Malas, El Dib
The remainder were rated as low or critically low quality
RCTs are often not suited to public health research on complex consumer behaviors and are often misleading. Process of finding the right combination is not linear and not easily randomizable. Trials are limited duration.
1. Royal College of Physicians. June Hitchman SC. Nicotine Tob Res O’Leary R. Canadian Institute for Substance Use Research Cahill K. Cochrane review 2013

6. Harm reduction Far less harmful than smoking
Not risk-free
‘the hazard to health arising from long-term vapour inhalation from the e-cigarettes available today is unlikely to exceed 5% of the harm from smoking tobacco’ 1,2
‘no identified health risks of passive vaping to bystanders’ 1,2,3
The Glasser review: exposure to nicotine vapour but the level of exposure was low, and exposure to other compounds were also very low, or at trace or non-detectable levels when compared with second-hand smoke
No sidestream vapour
1. Royal College of Physicians Public Health England British Heart Foundation. Position Statement 2017

7. The dose determines whether a substance is a poison 2
Harm reduction Why?
‘the constituents of cigarette smoke that harm health – including carcinogens – are either absent in e-cigarette vapour or, if present, they are mostly at levels much below 5% of smoking doses (mostly below 1% and far below safety limits for occupational exposure)’ 1
Philippus Theophrastus Aureolus Bombastus von Hohenheim,
All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy.
The dose determines whether a substance is a poison 2
1. Royal College of Physicians Paracelsus. Father of modern toxicology

8. Harm reduction Supporting evidence
Biomarkers: toxins dramatically reduced 1
Clinical improvements
Asthma2, COPD3, BP4, lung function5, pneumonia risk6
Nicotine has only relatively minor health effects
Not a carcinogen7,8; does not cause lung disease7; only a small role in CVD9
Cancer risk <0.5% smoking10; Lung cancer 100,000x less11
No serious adverse events after 10 years
1. Public Health England Polosa R. BMC Med Polosa R. Resp Res Farsalinos K. Int Emerg Med Cibella F. Clin Sci Capagna D. Pneumonia The health consequences of smoking. US Surgeon General IARC Benowitz NL. Nature Rev Cardiology Stevens S. Tob Control Scungio M. J Aerosol Sci 2017

9. Cardiovascular effects Cause of CV effects
Most CV effects of e-cigs are from nicotine 1
Low levels of toxic constituents 1
Benowitz NL. Nature Rev Cardiology 2017

10. Cardiovascular effects Evidence reviews
‘People with established CVD might incur some increased risk from e-cigarette use, the risk is certainly much less than that of smoking’ 1
‘Risks of cardiovascular disease… are likely to be substantially below the risks of smoking’ 2
‘Current research shows that e-cigarettes are significantly less harmful than tobacco products’ 3
1. Benowitz NL. Trends Cardiovasc Med Public Health England. Evidence Review British Heart Foundation. Evidence to UK Parliamentary Inquiry 2018

11. Gateway What is the gateway hypothesis?
try vaping and…
Young people who would not otherwise have smoked
…as a result, become long- term smokers

12. Gateway Association or causation?
Many studies show that young people who try vaping are more likely to also try smoking later 1
Cross sectional studies are unable to show causation 2
“Common liability” more plausible 3
Young people who are impulsive, rebellious and sensation-seeking are more likely to try both behaviours
Smoking usually precedes vaping 2
This association does not mean that vaping causes the behaviour
1. Soneji SS. Pediatrics Etter JF. Addiction Vanyukov MM. Drug Alcohol Depend 2012

13. Gateway Regular use by non-smokers is rareUK US
Bauld L. IJERPH 2017 n=60,000, 15-17yo
National Youth Tobacco Survey 2015 (CDC) n=17,717, 11-18yo
Never-smokers
Regular use rare: 0.6% (≥ 10d per month) 1
Most don’t use nicotine 2
Most use is by smokers
Kids experiment
Never smokers ≥ weekly use rare %
Most past 30-day users were experimenters and had very low prevalence of frequent use
US Almost half 30d ever users used on 1-2d only
39%: past 30-day use
Currently, fewer than 25% of youth ever cigarette users progress to daily cigarette use, indicating that a large proportion of tobacco product use that occurs in adolescence is experimental and does not lead to long-term regular use in adulthood
0.23% used 10 or more days in month
NYTS: Never smokers: Last 30d use 5.4%
1. Farsalinos K. Am J Prev Med 2018
2. Miech R. Tob Control. 2017

14. Gateway Population effects
Youth smoking rates are falling where vaping is available
In US, decline accelerated after (peak vaping year) 1
Vaping is replacing—rather than encouraging—smoking 2
If there is a gateway IN, it is very small and is swamped by the gateway OUT
Levy D. 6 national data sets
1. Levy D. Submitted for publication 2. Canadian Institute for Substance Use Research 2017