A paper published in the journal Tobacco Control[1] by US academics shows how studies on vaping, funded by the tobacco and nicotine industry, have methodological flaws leading to misleading conclusions supporting the industry’s commercial goals. They point out that studies funded by the tobacco and nicotine industry must be reviewed by experts in the field who have no connection with this industry.
An analysis of studies investigating e-cigarettes and their health effects found that studies whose authors had a financial conflict of interest (i.e. the research was supported by funding from the tobacco, vaping, or pharmaceutical industries) were 91.5 times more likely to report that e-cigarettes were associated with less harmful health effects than studies that did not have a conflict of interest financial interests.
Methodological flaws that lead to misleading conclusions favoring the objectives of the tobacco industry
The authors point out that while some industry-funded studies appear methodologically sound at first glance, closer examination sometimes reveals flaws that result in misleading conclusions, often in favor of an industry objective and in direct contradiction to other other research results not funded by industry. Academics take example from a recent study funded by manufacturer Juul Labs, Inc. (Altria)[2] who concluded that “Controlled use of the Juul e-cigarette containing 50 mg/ml nicotine in adult smokers of combustible cigarettes presents less abuse risk than combustible cigarettes and may provide sufficient nicotine to support substitution of combustible cigarettes (in comparison to certain nicotine substitutes such as chewing gum) ».
However, a closer look at the study protocol reveals that participants were required to take 10 puffs of each product studied (a JUUL e-cig with 50 mg/ml nicotine, a VUSE e-cig with 48 mg/ml nicotine and a combustible cigarette of the usual brand used by the smoker), at intervals of approximately 30 seconds. Each puff had to be 3 seconds long. Data from non-industry-funded studies, meanwhile, shows that 3-second puffs are shorter than typical puffs taken by people who regularly use e-cigarettes (e.g., 5.6 seconds average puff duration) and longer than typical puffs taken by people who smoke cigarettes regularly (e.g.,
The appeal of flavored e-cigarettes among young people is another example of research funded by the tobacco and nicotine industry. The scientific literature agrees that flavor is one of the most attractive characteristics of e-cigarettes for youth and young adults. Numerous studies highlight that these attractive aromas are one of the main reasons for the initiation and use of e-cigarettes. However, a 2014 tobacco industry-funded study on the impact of e-cigarette flavor descriptors on product appeal concluded that “interest in e-cigarette flavors was lower among young people than among adults”. In this study, the authors asked participants to answer the following question: “How interested would you be in using a (flavor) (product)?” », the flavors offered include bubble gum, cotton candy and gummy bear. The products examined included flavored water bottles, ice cream and e-cigarettes, as part of a balanced sampling plan, which the authors said “validates the assessment.”
A closer look at the methods reveals that the authors compared ratings between adults who currently smoke cigarettes and non-smoking adolescents. Additionally, any adolescent who smoked or had ever tried an e-cigarette in the past was excluded from the study. Furthermore, the design of the online survey did not include any visual stimuli such as “mock-ups of real products…in order to focus the evaluation on flavors and not graphics or other characteristics.” This approach risks reducing the appeal of aromas for all the products studied. In the real world, flavored e-cigarettes are marketed with attractive images and descriptors that promote the tastes, sensations and experiences of the product in great detail.
Finally, an analysis by Pinney Associates, a U.S.-based health consulting firm funded exclusively by Juul Inc. Lab since 2019, examined 2010-2019 data from the U.S. National Health Survey Interview Survey). This study, published in the journal BMC Public Health, evaluated the prevalence rates of cigarette and e-cigarette use over time. The authors concluded: “population-level data suggest that smoking prevalence has fallen faster than expected, correlating with increases in e-cigarette use”. The authors of the Tobacco Control paper clarify that population-level data should not be used to draw conclusions at the individual level. A decline in smoking rates that coincides with an increase in e-cigarette use rates does not necessarily indicate that people switched from cigarettes to e-cigarettes and could have been caused by other factors.
A detailed analysis of the methodology shows that the statistical analysis included a linear interpolation from an assumed zero prevalence for e-cigarette use in 2010 to the average for the years 2014-2019. The prevalence data clearly demonstrated that linear interpolation did not match the data based on the figures included in the tobacco industry analysis. Additionally, most results became statistically insignificant when omitting the interpolated data, but these details are in supplemental files that readers cannot view. This study has been retracted[3] by the BMC magazine due to “the hypothesis of a “0” prevalence of e-cigarette use in 2010, which contradicts the available data which led the editors to lose confidence in the results presented in the article”.
Increased vigilance regarding studies funded by the nicotine industry
The authors call on researchers, health professionals, regulators and the public to view studies funded by the tobacco industry, including studies funded by the vaping industry, with a skeptical eye. The authors support the position taken by the BMJ Journal Tobacco Control which: “will not agree to publish articles reporting on work funded, in whole or in part, by a tobacco manufacturer or tobacco industry organization. The journal will also not consider articles from authors who accept funding from the tobacco industry, including funding of research costs, for all or part of an author’s salary, or other forms personal remuneration”.
For the authors, it is essential to explicitly include the vaping industry in this policy, and in particular not to take into account articles written by people receiving funds from this industry. They specify that policy debates must be based on a transparent and solid body of research. For them, because of the methodological flaws present in research funded by the tobacco and vaping industry, any research funded by this industry must be subject to careful and detailed review by completely independent experts in the field.
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[1] Soule EK, Rossheim ME, Livingston MDet al Hidden flaws in e-cigarette industry-funded studies Tobacco Control Published Online First: 11 June 2024. doi: 10.1136/tc-2024-058609
[2] Goldenson NI, Buchhalter AR, Augustson EM, et al. Abuse liability assessment of the JUUL system in four flavors relative to combustible cigarette, nicotine gum and a comparator electronic nicotine delivery system among adult smokers. Drug Alcohol Depend 2020;217:108395. doi:10.1016/j.drugalcdep.2020.108395
[3] Foxon, F., Selya, A., Gitchell, J. et al. Retraction Note: Population-level counterfactual trend modeling to examine the relationship between smoking prevalence and e-cigarette use among US adults. BMC Public Health 23, 1898 (2023). https://doi.org/10.1186/s12889-023-16800-7
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