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| Systematic Reviews rank highly on the hierarchy of evidence |
This post provides an update on research related to the potential benefits of allowing the sale of flavoured vaping products. The larger question of whether this belief is supported by evidence is discussed in a separate post.
Policy makers in Canada have faced claims that flavour bans will cause many vapers to return to smoking and fewer smokers to switch to vaping. These claims are often from companies which make vaping products, but are sometimes also from scientists who believe that governments should actively encourage smokers to switch to vaping products.
Until recently, policy makers had access to several competing studies addressing this question, but did not have any published structured reviews to assist them in assessing the overall state of evidence. To address this gap, U.S. researchers have recently published two reviews - a systematic review of research on whether smokers who use flavoured e-cigarettes are more likely to quit than are those who use tobacco- or unflavoured e-cigarettes, and a review of studies on what has happened or what might happen in communities where e-liquid flavours are restricted.
The results of these two papers are presented below. Importantly, they do not cover all of the evidence (they are restricted to English-language published studies, and exclude the extensive reports by governments, including by Health Canada. Notably, enthusiastic supporters of tobacco harm reduction and proponents of flavourings participated in the reviews.
On the basis of these reviews, governments should not accept that "flavours help smokers quit" or that "flavour bans will increase smoking." The reviews instead conclude that:
- "[T]here is presently not enough evidence to determine whether flavored ENDS are superior to tobacco-flavored ENDS for smoking cessation" (Liber et al, 2023)
- "[T]he overall findings on the potential impact of a federal flavoured ENDS restriction are mixed and inconclusive." (Cadhem et al, 2023)
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| Fact sheet: Restrictions on e-cigarette flavours |
The Canadian context: a change of heart and a pivot in approach
The claims that flavour restrictions will cause harm to smokers have particular relevance to Canada federal policy. Despite prodding by some reporters and parliamentarians in the Senate and House of Commons, Health Canada continues to decline all opportunities to reaffirm its previous intention to ban flavourings in vaping liquids.
The official reason given for the delay is that departmental officials continues to review "feedback from the more than 25,000 submissions it received through its consultations" Given that all but 1,000 of those submissions were filed by Rights4Vapers, a group linked to the tobacco and vaping industry, this acknowledges that an industry front group succeeded in stalling regulations by the simple tactic of overwhelming the capacity of the consultation process.
An alternative explanation for the apparent change of direction may be found in a recent pivot in Health Canada's approach to designing policies and programs related to tobacco use. The department's 2023-2024 workplan made public in February flagged a new approach to tobacco - described as a "person-centered approach to smoking cessation" based on "lived experience". This shift was foreshadowed soon after Ministers Duclos and Bennett were appointed as ministers in November 2021. (The flavour restrictions had been announced by the previous Health Minister, Patty Hajdu, in June 2021).
It is in this new context that vapers have been invited to meet with federal-policy makers, although the impact of those meetings on policy decisions has not been made public.
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| 2023–24 Departmental Plan: Health Canada |
Health Canada also announced a change to its approach to youth vaping. The department's "new" focus attributes mental health as the driver of youth vaping: "The department is considering youth vaping within a broader multi-drug use landscape and its connection to mental health."
The impact of this shift in focus can be seen in the revisions to the department's work-plan, from which regulations on flavourings or other marketing have now disappeared. Whereas two years ago the department said it would "take further action to reduce the appeal of and access to vaping products among young Canadians - including new regulatory proposals," such plans have been dropped for the coming year.
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RECENT REVIEWS OF EVIDENCE ON THE IMPACT OF FLAVOUR RESTRICTIONS
1. The role of flavored electronic nicotine delivery systems in smoking cessation: A systematic review.
Liber AC, Knoll M, Cadham CJ, Issabakhsh M, Oh H, Cook S, Warner KE, Mistry R, Levy DT.
Drug Alcohol Depend Rep. 2023 Mar 16;7:100143. doi: 10.1016/j.dadr.2023.100143. PMID: 37012981; PMCID: PMC10066538.
This is the first systematic review of evidence on the impact of flavoured e-cigarette use on quit success. It provides policy-makers with a higher-certainty knowledge that there is insufficient evidence to suggest that flavourings in vaping liquids increase the likelihood that a smoker can use e-cigarettes to quit.
Using PRISMA guidelines, this team located 29 studies published before May 15, 2022 that looked at the impact of flavoured e-cigarettes on encouraging smokers to switch to vaping and on assisting them in stopping smoking. (These studies included some conducted on Canadian smokers by Canadian researchers).
Among the 22 publications that reported on differences in quitting success, only 9 found a statistically significant improvement in quit success among those who chose to use flavours in comparison with those who did not. Of these, at least two were conducted by tobacco industry consultants.
Using the GRADE criteria for quality of evidence, these reviewers assessed the quality of these studies as "low" or "very low". They noted that these studies relied on self-reported outcomes, mostly did nto randomize the assignment of flavours and could not be adequately assessed for risk of bias.
As the reviewers put it: "there is presently not enough evidence to determine whether flavored ENDS are superior to tobacco-flavored ENDS for smoking cessation". Perhaps disappointed by this finding, they noted that this "could change in the future."
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2) The actual and anticipated effects of restrictions on flavoured electronic nicotine delivery systems: a scoping review.
Cadham CJ, Liber AC, Sánchez-Romero LM, Issabakhsh M, Warner KE, Meza R, Levy DT.
TBMC Public Health. 2022 Nov 19;22(1):2128. doi: 10.1186/s12889-022-14440-x. PMID: 36402989; PMCID: PMC9675183.
This review of studies measuring the impact of flavour restrictions ours had been restricted and also experimental studies with smokers that predicted what these outcomes would be.
This review also used PRISMA guidelines and GRADE scores to select and assess studies published up until May 3, 2022 which helped answer the questions of whether flavour restrictions did or would be likely to decrease e-cigarette use or increase tobacco smoking. Of the 30 identified studies, 26 were conducted exclusively in the United States; 21 looked at what happened after restrictions were actually implemented and 9 explored what might happen using psychological experiments or survey questions. Five studies used product sales to measure impact, 17 used reports on behaviour.
This paper provides policy makers with a useful literature search, but does not give much guidance on what will happen if flavours are banned. The reviewers found that the 5 studies comparing the volume cigarette sales in U.S. cities and states which banned flavours produced inconsistent results (two found an increase, two found a decrease and one found no change). The ability of vapers to import products from neighbouring jurisdictions contributed to such evidence being assessed as low quality.
This review could not conclude that flavouring restrictions increased cigarette use. "The overall findings on the potential impact of a federal flavoured ENDS restriction are mixed and inconclusive." |
Click on image to enlarge or see results here |
