Smoking remains the leading preventable cause of illness and premature death, responsible for more than eight million deaths a year globally.
Some parts of the world are witnessing dramatic reductions in smoking prevalence rates in parallel with the uptake of tobacco harm reduction (THR) products, with notable examples of Sweden and Norway where cigarette smoking has almost been eliminated as a result of snus use.
Together these afford a timely opportunity to drive down smoking-related mortality and morbidity to such as extent that it would constitute one of the greatest achievements in the history of public health. A major obstacle to this is the perceived safety profile of THR products, which has resulted in restrictions and bans of their sale and use, and a misinformed public leading to hesitation of their uptake.
Previous estimates reported ecigarettes to be 25 x less harmful than cigarettes which was incorporated into UK tobacco harm reduction policy. Direct human data have been limited due to the limitations of conducting conventional high-level evidence such as trial data in real world settings.
We set out to provide a comprehensive and definitive summary of the health risks from use of THR products by conducting systematic reviews of studies investigating health outcomes in human subjects from the use of electronic nicotine delivery systems (ENDS) such as e-cigarettes and vapes. We applied stringent criteria for inclusion, in line with PRISMA protocols, and rated studies for quality and strength of evidence against standardised frameworks.
Of 37 studies eligible for inclusion in our review, the majority were low levels of evidence and over a half were rated as ‘poor’. Nevertheless, ENDS use was not shown to causative of harmful CVD or respiratory outcomes and switching from cigarettes to e-cigarettes was associated with improved hypertensive control and reduced exacerbations of COPD, with no evidence of increased risk of asthma or long-term respiratory harm. Mental health was not studied sufficiently to form a conclusion due to the complex relationship with addiction and nicotine use, however no negative health outcomes were confirmed. Cancer and mortality outcomes have not been adequately studied to form a consensus.
This week the Medicine and Healthcare Products Regulatory Agency (MHRA) in the UK published its plans to enable high-quality and effective e-cigarette products to be licensed as medicines, and therefore enable clinicians to prescribe them to patients wishing to quit smoking.
Our review provides important information on health risks and the findings should urgently inform policy globally in order to facilitate the safe transition away from harmful tobacco products such as cigarettes towards safer forms of THR products.
Recommendations for THR policy endeavours are that nicotine delivery products deemed to be at very low risk due to the absence of tobacco eg ENDS, nicotine pouches, snus, should not be considered as tobacco products for the sake of policy and regulation, and instead be regarded as valuable aids for smokers wishing to quit. Furthermore, future research in the THR space should meet some basic methodological standards, such as the use of standard definitions for THR product exposures and comparison groups.
In summary, the findings of our review are that risks from use of ENDS range from minimal to zero and support the consensus by a growing number of organisations that use of these products is safer than the risks posed from smoking cigarettes. A clear distinction needs to be made between harmful tobacco products such as cigarettes and some forms of chewing tobacco, and nicotine delivery systems that can aid the fight against tobacco use.
Policies intended to protect the public from harm due to ENDS and SLT products must be updated to factor in the broader harms and benefits to society, such as dependence, and weigh up any product-specific harms against the alternative scenario, which in most cases is the continuation of cigarette smoking.
The broader individual, household and societal impacts from use of tobacco and THR products fell out of scope for our analysis but are important considerations and we hope will be taken up by future researchers to further inform policy.
Cother Hajat – LinkedIn – 2022-11-01.
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