Professor Chapman’s criticism of Cochrane review findings is deeply flawed

Posted on December 12, 2022 By Colin

COCHRANE REVIEWS ARE THE GOLD STANDARD for determining if a treatment is effective in randomised controlled trials (RCTs). [1] The recent Cochrane review on e-cigarettes found high certainty evidence that vaping help peoples quit smoking better than traditional nicotine replacement therapies (NRTs). [2]

This my response published today in Australian Doctor here.

In his recent interview with Australian Doctor (‘Why Cochrane got it badly wrong: Aussie expert unpicks ‘pro-vaping’ review‘), Professor Chapman dismissed the Cochrane review for not reflecting real world behaviour.

This misunderstands the role of RCTs, which is to find if a treatment works in motivated smokers in a controlled environment

Abundant evidence now also exists showing that vaping works in the real world setting, from UK Stop Smoking Services [3], observational studies [4-6], population studies [7, 8] and declines in national smoking rates [9-11]. While these studies cannot prove causality, their results are consistent with the Cochrane findings.

Longitudinal studies

Professor Chapman refers to longitudinal studies from the US PATH cohort showing very little benefit from vaping. However, these studies typically include vapers not wanting to quit and those vaping occasionally.

Motivated quitters who vape daily have substantially increased quit rates. One PATH study of over 32,000 subjects found that daily vaping increased quit rates by 8 times compared to using other quit methods. [12]

Many other longitudinal studies have found that vaping is effective and that daily vaping increases quit rates by 2-8 times. [12-14]

Population studies in the UK, US and New Zealand have found that smoking rates have declined faster since vaping became widely available. [8, 11, 15] The recent report from the Office of National Statistics in the UK concluded that “Vaping devices such as e-cigarettes have played a major role in the decrease in smoking prevalence in the UK”. [10]

Long-term safety

Professor Chapman is concerned about the lack of evidence for long-term safety. However, leading health and government organisations, such as the Royal College of Physicians [16]  and the New Zealand Ministry of Health [15], have concluded that,

while the long-term harm of using e-cigarettes will not be fully known for many decades, it is highly likely to be far less than smoking, which prematurely kills up to 2 in 3 continuing smokers. [17]

This is to be expected. A dose-response relationship exists between exposure to toxicants from smoking and disease risk and the same is likely for vaping. [18] There are substantially fewer toxicants in vapour than in smoke and those present are in much lower doses. [19-21]  There are also a dramatic reduction of biomarkers of harm in the blood and urine of vapers after switching [17].

Clinical trials have shown improvements in asthma [22], COPD [23], blood pressure [24, 25], muco-ciliary clearance [26], respiratory infections [27], lung function [28], respiratory symptoms [29, 30], cardiovascular markers [31, 32] and gum disease.[33] These changes are in the direction of less impairment and are likely to persist over the longer term.

In the absence of long-term data, modelling studies are a well-accepted way of estimating the population impact of an intervention. Numerous modelling studies suggest that nicotine e-cigarettes are likely to have a net positive public health benefit under all plausible scenarios. [34-36]

Australia’s prescription-only model

Professor Chapman claims that every public health agency wants to continue with the prescription model. This is true in Australia. However, every other western country has rejected this approach and all follow the consumer model.

Australia’s prescription-only model has been a resounding failure. The regulations were intended to prevent youth vaping and to allow access for adult smokers as a smoking cessation aid.

Predictably, it has had the opposite effect. It has been rejected by GPs, vapers and pharmacists

Only 373 doctors are listed publicly as nicotine prescribers [37] and less than 10% of Australia’s 1.1 million vapers have a prescription. [38] Only a handful of pharmacies dispense nicotine liquid.

The prescription model has also created a thriving black market selling illegal, unregulated vaping products from tobacconists, convenience stores, online and on social media. These devices are freely sold to young people and have created legitimate concerns about youth vaping.

The only way to eliminate an illicit market is to replace it with a legal and regulated one. Nicotine liquid should be an adult consumer product, sold from licensed retail outlets such as vape shops, convenience stores, tobacconists and general stores where tobacco is sold.

There should be strict age-verification and severe penalties and loss of licence for under-age sales, with strict enforcement.

After 18 months, Australia’s experiment has failed. We need to bring vaping policy into line with all other western countries. Without a workable regulatory pathway enabling access by the adult smokers who need vapes, whilst restricting access by young people, more smokers will die unnecessarily leading to disastrous public health outcomes in the coming years.

Dr Mendelsohn is the founding chairman of the Australian Tobacco Harm Reduction Association, which promotes vaping as an alternative to those unable or unwilling to quit smoking.


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21. Nicol J, Fraser R, Walker L, Liu C, Murphy J, Proctor CJ. Comprehensive Chemical Characterization of the Aerosol Emissions of a Vaping Product Based on a New Technology. Chem Res Toxicol. 2020;33(3):789-99.

22. Polosa R, Morjaria JB, Caponnetto P, Caruso M, Campagna D, Amaradio MD, et al. Persisting long term benefits of smoking abstinence and reduction in asthmatic smokers who have switched to electronic cigarettes. Discov Med. 2016;21(114):99-108.

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