516 e-Letters

  • Methods questions


    I respectfully request answers to the following questions:

    1. Was public use or restricted PATH data used. This is important, since Table 2 contains a cell, n=7, that is not generally approved by NAHDAP.

    2. Was the PATH cohort drawn from Waves 1 and 4, with follow-ups to age 17 years as needed from the other waves?

    3. There were significant differences in youth smoking-vaping between Wave 1 (2013-14) and Wave 4 (2016-18) that might have affected the results. Was each wave analyzed separately as well as together?

    4. The analysis included a variable relating to “parent(s) smoking of cigarettes, cigars, or pipes.” Did the analysis include other combustible tobacco product consumption by the subjects themselves?

    5. Did the authors account for age at first smoking or vaping (public use, < 12 years and 12-14 years) or which product(s) had been used first?

  • Response -- Rodu inquiry


    Regarding the first two questions, the analyses were based on the public use data from both the PATH Study and the MCS, with links to their archives, and the PATH study sample was drawn from the original cohort, the replenishment cohort, and the shadow cohorts (see 1st and 2nd paragraphs of Methods Section). Regarding the remaining questions, please note that our stated goal was to make the MCS and PATH analytical samples as comparable as possible when testing our hypotheses using both cohorts (3rd paragraph of Methods section). As we note in the limitations section (5th paragraph of Discussion section), the MCS had relatively limited items on e-cigarette use and tobacco smoking compared to PATH. The MCS did not assess other combustible tobacco product consumption in early adolescence, nor did MCS measure the sequencing of early adolescent tobacco and e-cigarette use (noted in the limitation section). Also, MCS youth answered survey questions about ever using e-cigarettes from 2015 to 2016 (3rd paragraph of Methods section), which gave us limited variability to test for a wave x e-cigarette interaction in both datasets.

  • Health effects of heated tobacco products remain unknown.

    We appreciate the interest of the world’s largest transnational tobacco company, PMI,1 in our recent systematic review and would like to follow up on the points raised in Dr Baker’s rapid response.

    Our review did not seek to assess the harms or benefits of HTPs. As public health researchers we are most interested in the quality of studies according to whether they give reliable evidence of the health outcomes and public health impact of HTPs. We sought to critically appraise the quality of clinical trials on HTPs and lay out for Tobacco Control readers all aspects of their design which may have implications for interpretation, especially in regard to the potential impacts of HTPs.

    We decided to explore overall risk of bias when excluding the blinding of participants and personnel domain because we wanted to differentiate between studies. This is a really important domain. We excluded it because so few studies were judged to be at low risk of bias in this domain. Performance bias (which blinding if done well can guard against) remains an important source of bias that can influence study results, and one which was present in all of PMI's studies submitted to the U.S. Food and Drug Administration (FDA).1 As we explain in our risk of bias assessments, the consequences of this bias could have been minimised had the control intervention been active. Likewise, PMI’s withdrawal of its carbon-heated tobacco product from the market, which o...

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  • Comments on paper by Asfar et al. “Risk and safety profile of electronic nicotine delivery systems (ENDS): an umbrella review to inform ENDS health communication strategies”

    The paper by Asfar et al (1) had a noble objective, which was to inform ENDS health risk communications by updating the 2018 evidence review by the US. National Academies of Sciences, Engineering and Medicine (NASEM) (2). The need for improved risk communications about ENDS is reinforced by a recent study which found that only 17.4% of US smokers believe that nicotine vaping is safer than smoking (3). While ENDS use is not safe, the evidence from toxicant exposure studies does show that ENDS use is far safer than smoking cigarettes and may benefit public health by assisting those who smoke to quit smoking (4, 5).
    An important limitation of the umbrella review method utilized by the authors is that it does not directly attempt to systematically characterize new research. This is a concern because the marketplace of ENDS products used by consumers has evolved since the 2018 NASEM report (4, 5). Furthermore, the authors have included some meta-analyses of selected reviews for some domains, but these meta-analyses were not in the Prospero pre-registration (6), nor explained in the paper. It’s thus unclear how or why certain reviews were selected for meta-analysis, and also whether the comparators are the same for these reviews. More importantly, these meta-analyses risk single studies contributing multiple times to the same pooled estimate. The authors noted this as a limitation commenting inaccurately that ‘it was impossible to identify articles that were included in...

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  • Authors make broad-reaching conclusions that are not supported by the facts

    The objective of the systematic review by Braznell et al. was “𝘵𝘰 𝘤𝘳𝘪𝘵𝘪𝘤𝘢𝘭𝘭𝘺 𝘢𝘴𝘴𝘦𝘴𝘴 𝘵𝘩𝘦 𝘮𝘦𝘵𝘩𝘰𝘥𝘰𝘭𝘰𝘨𝘪𝘤𝘢𝘭 𝘤𝘩𝘢𝘳𝘢𝘤𝘵𝘦𝘳𝘪𝘴𝘵𝘪𝘤𝘴 𝘢𝘯𝘥 𝘲𝘶𝘢𝘭𝘪𝘵𝘺 𝘰𝘧 𝘪𝘯𝘵𝘦𝘳𝘷𝘦𝘯𝘵𝘪𝘰𝘯𝘢𝘭 𝘤𝘭𝘪𝘯𝘪𝘤𝘢𝘭 𝘵𝘳𝘪𝘢𝘭𝘴 𝘪𝘯𝘷𝘦𝘴𝘵𝘪𝘨𝘢𝘵𝘪𝘯𝘨 𝘵𝘩𝘦 𝘦𝘧𝘧𝘦𝘤𝘵𝘴 𝘰𝘧 𝘩𝘦𝘢𝘵𝘦𝘥 𝘵𝘰𝘣𝘢𝘤𝘤𝘰 𝘱𝘳𝘰𝘥𝘶𝘤𝘵𝘴 (𝘏𝘛𝘗𝘴).” ¹ The review was intended to examine the quality of HTP clinical trials “𝘣𝘦𝘧𝘰𝘳𝘦 𝘤𝘰𝘯𝘴𝘶𝘮𝘦𝘳𝘴 𝘢𝘯𝘥 𝘳𝘦𝘨𝘶𝘭𝘢𝘵𝘰𝘳𝘴 𝘮𝘢𝘬𝘦 𝘪𝘮𝘱𝘰𝘳𝘵𝘢𝘯𝘵 𝘥𝘦𝘤𝘪𝘴𝘪𝘰𝘯𝘴 𝘣𝘢𝘴𝘦𝘥 𝘰𝘯 𝘵𝘩𝘦 𝘳𝘦𝘴𝘶𝘭𝘵𝘴 𝘰𝘧 𝘵𝘩𝘦𝘴𝘦 𝘴𝘵𝘶𝘥𝘪𝘦𝘴.” We have three important observations in relation to Philip Morris International’s (PMI) clinical program, which impact the interpretation of the authors’ broad-reaching conclusions.

    (𝟭) 𝗥𝗲𝗴𝘂𝗹𝗮𝘁𝗼𝗿𝘆 𝗱𝗲𝗰𝗶𝘀𝗶𝗼𝗻𝘀 𝗵𝗮𝘃𝗲 𝗯𝗲𝗲𝗻 𝗺𝗮𝗱𝗲 𝗯𝗮𝘀𝗲𝗱 𝗼𝗻 𝗣𝗠𝗜’𝘀 𝗰𝗹𝗶𝗻𝗶𝗰𝗮𝗹 𝘀𝘁𝘂𝗱𝗶𝗲𝘀, 𝘄𝗵𝗶𝗰𝗵 𝘄𝗲𝗿𝗲 𝗷𝘂𝗱𝗴𝗲𝗱 𝘁𝗼 𝗯𝗲 𝗮𝘁 𝗹𝗼𝘄 𝗿𝗶𝘀𝗸 𝗼𝗳 𝗯𝗶𝗮𝘀
    Whilst we will only comment on the clinical studies performed by PMI, we were pleased to see the confirmation that the study designs in our clinical assessment program were not significantly associated with a risk of bias. The authors judged that all Tobacco Heating System (marketed as IQOS) clinical studies submitted to the United States Food and Drug Administration (FDA) and other regulators were at low risk of bias when the authors excluded “blinding of participants and personnel” to the product, due to the impracticality of concealing visually distinctive products. The authors also noted that the scoring was slightly improved when compared to a similar exercise performed as part of the recent Cochrane review. ²

    We agree that regulatory decisio...

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  • Response to critiques on Asfar et al. in Tobacco Control: “Risk and safety profile of electronic nicotine delivery systems (ENDS): an umbrella review to inform ENDS health communication strategies.”

    We thank Cummings and colleagues for their interest in and comments on our umbrella review published recently in Tobacco Control.[1] The authors criticize us for not including the latest studies. Yet, for an umbrella review, those studies need to be in a published review to be included, as we indicated in our methods and limitations. Generally, given the lengthy review and publication processes, any review will not be inclusive of all studies in a field that has as high a publication breadth and intensity as tobacco regulatory science. In addition, the authors mentioned that our meta-analysis was not available in PROSPERO pre-registration. This is because the review registration was completed in the very early stages of the review. We have updated this information in PROSPERO now to include the meta-analysis. The issue of overlap was addressed in our limitations, as we had to screen over 3,000 studies included in our selected reviews. However, given the importance of this issue for the meta-analysis, we performed a new meta-analysis that included the individual studies in each domain instead of using the odds ratio reported by the review to eliminate the effect of including the same study more than one time on our results. We confirm that the results of the new meta-analysis, which includes each study only once, are similar to the original meta-analysis (Supplement A: https://www.publichealth.me...

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  • Strengthening Smoke-Free Laws and Compliance: Insights from Taiwan for Ethiopia and Beyond


    I am writing in response to the article "Smoke-free law compliance and predictive factors in Ethiopia: observational assessment of public places and workplaces" published in Tobacco Control. As a psychiatrist from Taiwan, I would like to commend the authors for shedding light on the low compliance rates of smoke-free laws in public places and workplaces in Ethiopia.

    The study's findings highlight the urgent need to strengthen smoke-free laws and promote compliance to reduce tobacco use and its related health consequences. As a country that has implemented comprehensive smoke-free laws for over a decade, Taiwan has faced similar challenges in enforcing the ban in indoor environments. However, our government has taken various measures to address non-compliance, including increasing penalties and expanding the scope of smoke-free areas.

    In addition to government efforts, collaboration between businesses, civil society organizations, and public health advocates is crucial in promoting compliance and a smoke-free culture. The Ethiopian government and civil society can learn from our experiences in Taiwan and other countries that have successfully implemented smoke-free laws.

    The study's findings provide a valuable framework for policymakers and public health advocates to address the challenges of enforcement and promote a smoke-free culture. I urge the Ethiopian government and civil society to work together to im...

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  • Inappropriate study design cannot predict smoking initiation and relapse with e-cigarette and heated tobacco product use

    The study by Gallus et al. [1] sought to establish whether electronic cigarettes (ECs) and heated
    tobacco products (HTPs) reduce or increase the probability of smoking in a cohort of Italian
    participants and concluded that both EC and HTP use predict smoking initiation and relapse
    among respondents. We would like to raise some concerns about the interpretation of the study
    findings. The study suffers from a potentially crucial bias of the outcome being present at baseline, as
    compared non-users with people who were already using products at baseline. Specifically,
    smokers who were using ECs or HTPs at baseline may already represent failed attempts to quit at
    baseline. Additionally, ex-smokers using these products may have already been in a trajectory to
    relapse to smoking at, or even long before, baseline, and may in fact have initiated such product
    use in order to avoid relapse. Still, this group may represent ex-smokers who were at higher risk
    for relapsing at baseline compared to ex-smokers who did not use these products. Similarly,
    never smokers who use novel nicotine products may represent individuals prone to the
    engagement of an inhalational habit. Therefore, they would be more likely to initiate smoking.
    The situation is very similar to assessing if people who drink beer at baseline are more likely to
    drink whiskey at follow up compared to non-drinkers of bee...

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  • No uncertainty exists around the failure of novel products as harm reduction strategies in Italy

    We welcome discussion of our research even when it comes from those whose view on accepting tobacco industry funding is very different from ours. Tomaselli and Caponnetto, from the Center of Excellence for the acceleration of HArm Reduction (CoEHAR),[1] a group funded by the Foundation for a Smoke-Free World (FSFW), an organisation established by Philip Morris International (PMI) with funding of US$1 billion that promotes electronic cigarettes (e-cigarette) and heated tobacco products (HTP),[2] take issue with our finding [3] that these products increase smoking initiation and relapse and reduce quitting. [4]
    First, we are puzzled by their main criticism. Of course we agree that smokers who have failed to quit, ex-smokers prone to relapse, and never smokers prone to engage in addictive behaviours could be overrepresented among the baseline e-cigarette or HTP users in our study.[4] But this does not undermine our main conclusions. Even if we were to assume that either none or all novel product users in our cohort were more prone to addiction, our results would still be incompatible with the argument, which underpins the work of FSFW, that these products can reduce smoking conventional cigarettes when used as consumer products.
    Second, we hope that they agree with us that we should consider the totality of evidence on a topic as it is rare for a single study to provide a definitive answer, and especially given the record of the tobacco ind...

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  • Do high e-cigarette taxes lead to increases in initiation of cigarette smoking?


    In his rapid response to our paper, Dr Pesko expresses concern with the paper’s conclusions. Our study, conducted at the US population level, demonstrated that the prolonged decline in cigarette smoking among young adults was largely unaffected by the introduction of e-cigarettes. Dr Pesko reminds us that this conclusion is contrary to findings from several quasi-experimental designs, which he feels should have primacy over our population-level analysis of time trends. We acknowledge that there are potential threats to the validity and generalizability of the findings of our study, and indeed of every study. Hence, a conclusion of causality requires that an association be robust and replicable across settings and methods. Given the significant public policy implications of any finding that e-cigarette vaping has a role in reducing cigarette smoking prevalence, we feel that presentation of transparent and easily understood population trends have an important role to play in policy discussions. In particular, to support the argument that high e-cigarette taxes cause increased smoking among youth, it would be important to have an exemplar of one or more jurisdictions that imposed a high e-cigarette tax and subsequently experienced an increase in cigarette smoking.

    A substantial portion of Dr Pesko’s critique of our paper is directed towards our commentary on a paper that he co-authored, Abouk et al. (1). This commentary was incorporated at t...

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