Recent eLetters

Displaying 1-10 letters out of 395 published

  1. Re:Bauld et al omit evidence on passive exposure to e-cigarette aerosol

    NOT PEER REVIEWED David Bareham cites 'Rip Tripper' as evidence that e-cigarette users report experiences of allergies being exacerbated in non users by vapour and describes Mr Tripper's subsequent rather mangled argument that the devices should not be used in enclosed public spaces as "eloquent".

    Perhaps Mr Bareham is unaware that Mr Tripper has also claimed that vaping causes limb cramps and dry knuckles which was a surprise to most vapers, until they spotted the affiliate link to where they could purchase electrolytes and a lotion to 'cure' them (1).

    (1) 'Rip Trippers exposed as a sellout' Jh Reviews (contains profanity)

    Conflict of Interest:

    I am a trustee of NNA(UK) which is a consumer driven charity which aims to improve health by increasing awareness and understanding of reduced risk alternatives to smoked tobacco.

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  2. Methodological pitfalls in the measurement and decomposition of socioeconomic inequality of smoke exposure

    NOT PEER REVIEWED I would like to point out a few disturbing inaccuracies in the methodology and interpretation. Since the health variable is binary, the authors apply "Wagstaff's correction" to the Concentration Index. This is a perfectly legitimate decision, but the authors mistakenly suggest that this correction can be applied to both the relative and the absolute version of the index, yielding two normalized indices. In fact, there is only one Wagstaff index, which can be expressed as W = RC/(1-m) = AC/[m(1-m)], with m = prevalence. All the results which are presented under the heading "Absolute concentration index" in Table 2 and as "AC" in Table 3 are therefore irrelevant. These results refer to the index mW which nobody has ever used in the literature. It follows that the decomposition formula (6) of the paper is redundant. Similar remarks hold for the application of the alternative "Erreygers correction". The correction leads to one index, not two as suggested by the authors. The index can be written as E = 4mRC = 4AC. As a consequence, the results presented under the heading "Absolute concentration index" in Table A.1 of the supplementary online material are irrelevant. They refer to the index mE, which is not the one defined by Erreygers. After a brief comparison of the Wagstaff and Erreygers indices the authors conclude that "the calculated RC and AC informed qualitatively similar inference" (p. 9). Since E = 4m(1-m)W, the values of E and W clearly will be positively correlated, and the more strongly so if the variation in prevalence is limited. For the whole population, the (unweighted) average of m is 0.28, and the standard deviation 0.19. As expected, the correlation of E and W is high, but not perfect: the coefficient of correlation is 0.8815, and the rank correlation coefficient 0.8726. Nevertheless, countries such as Liberia, Bangladesh and Benin, make large jumps in the rankings if inequality is measured by one index rather than the other. At least for these countries, it may be doubted whether the results are "qualitatively similar". When it comes to the calculation of the between-group and within-group shares, it makes no difference whether the Wagstaff or Erreygers index is used. The main problem here is that any rank-dependent index is not subgroup decomposable. There is always a residual term, which may be quite large. Because of this, the decomposition results presented in the paper are unreliable.

    Conflict of Interest:

    None declared

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  3. Flavor Profiles

    NOT PEER REVIEWED When it comes to vaping my knowledge is somewhat advanced, in the hardware aspect I am in the forefront of technology, I test prototypes and beta models for manufacturers all around the globe, I also have acquired quite a bit of knowledge when it comes to the creation of flavors.

    There's a big difference between something you like and what is referred to an "All Day Vape" or ADV and the impact that has on quitting successfully is quite dramatic.

    I have this one flavor I make that I absolutely love, it's Caramel Apple Crumble with a bit of Creamy Custard, but like many other vapes it's just too decadent for anyone to vape all day much like chocolate flavors generally are. Just because you enjoy it doesn't mean you can tolerate it all day and that can determine your chances at a successful quit attempt.

    The flavors used in the study appear to be much generic to yield results that would reflect the current market as most of it is filled with much more complex mixes and many variations of each flavor..

    There are many variations of flavors that taste like different brands of cigarettes or candy and fruits, if a smoker were to try a tobacco blend that tasted like their brand of cigarette their chances at a successful quit attempt would be much higher than if they tried another variation.

    Flavor is by far the most important aspect of a successful quit attempt when it comes to vaping, once a person finds 1 or 2 flavors they can enjoy all day they then need to find a device with the vapor production they are looking for and the appropriate nicotine level to suit it.

    Personally when I first decided to give vaping a shot I tried over twenty flavors many of which I thought I would enjoy but didn't, I ended up with two flavors Strawberry Creme and Skittles, SBC all day and Sk when I felt like something a little more sweet...

    The ability to allow people to sample flavors is very much the key to their success, if I were not allowed and went with what I thought sounded good I would still be smoking today.

    Conflict of Interest:

    None declared

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  4. Bauld et al omit evidence on passive exposure to e-cigarette aerosol

    NOT PEER REVIEWED The American Indoor Hygiene Association (AIHA) i.e. Experts in in this particular field on passive exposure, have, previously, concluded conversely to Bauld et al (1). As they state:

    "If the only individual affected by using e-cigarettes were the vaper, the discussion could end here. That is not, however, the case. Similar to secondhand smoke, the ingredients exhaled by the vaper include nicotine, metals, flavorings, and glycol that accumulate in the ambient air. Recipients of secondhand vapor have not chosen to - many, in fact, have explicitly chosen not to - use e-cigarettes. The exposure to secondhand vapor, just like secondhand smoke, raises issues of involuntary exposure and competing rights. This is even more critical for groups that may be, and probably are, more susceptible to adverse effects of secondhand vapor, including children, pregnant women, and people with already compromised health, some of whom may have limited ability to leave the spaces in which vaping occurs or has occurred."

    This scientific postulation of second-hand inhalation of e-cigarette aerosol and subsequent adverse health effects has been further substantiated: via users of e-cigarettes, in their own personal, real- world experiences (2). They subsequently, and eloquently argue, that the devices should not be utilised in enclosed public spaces, due to these events occurring.

    Linda Bauld has previously argued in an extended article that:

    ". . . there is no good evidence that [second hand] exposure is harmful to bystanders . . . To argue otherwise is just factually incorrect." (3)

    However, the phrase "harmful to bystanders" provides a hyperlink to a review paper (4) of the potential for second hand exposures that, incongruently to Professor Bauld's claim, concludes that e-cigarettes:

    ". . . impart a LOWER potential disease burden than conventional TCs" (my emphasis)

    I.E. therefore, NOT zero potential disease burden.

    It is to be commended that Bauld et al wish to enhance the potential for adult smoking cessation maximally, however, in this case, there IS evidence that such a policy of non-restricted use potentially infringes the rights of non-users to avoid passive inhalation and subsequent adverse health effects, as the AIHA postulate, and as users of e-cigarettes have confirmed in real-world conditions.

    1) American Industrial Hygiene Association: affairs/Documents/Electronc%20Cig%20Document_Final.pdf

    2) "Vaping e-cigs in public" Available at:

    3) Linda Bauld (2015). Available at: evidence/2015/feb/23/theres-no-evidence-e-cigarettes-are-as-harmful-as- smoking

    4) Oh, A. & Kacker, A. 2014 Do electronic cigarettes impart a lower potential disease burden than conventional tobacco cigarettes? Review on E-cigarette vapor versus tobacco smoke. Laryngoscope 124(12):2702-6. doi: 10.1002/lary.24750. Epub 2014 Oct 9.

    David Bareham

    "All views are my own and do not necessarily reflect those of my employer"

    Conflict of Interest:

    I have 3 presentations to local clinicians in Lincolnshire within the last 18 months entitled: "E-cigarettes: update on evidence", organised by GlaxoSmithKline. No payment was requested nor provided for this work.

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  5. Indoor vaping and brochodilator use are not analogous

    NOT PEER REVIEWED Bauld et al [1] draw an analogy between indoor vaping and the use of bronchodilators for asthma ("if and when vapour products with a medicinal license become available, it will be important to allow their use indoors, just as asthma inhalers, which dispense a drug and propellants into the atmosphere, can be used indoors.")

    Surely, they cannot be serious here?

    Newman et al showed the amount of dosed drug exhaled by asthmatics ranged from just 0.2%-1.7% across different puffing behaviours [2]. A typical person who uses an asthma puffer would be unwise to use it more than 4-6 times a day [3] whereas vapers can take up to 610 puffs a day, with an average of around 200 [4].

    Conversely, the objective of many ENDS users is the absolute opposite. As this article puts it "At the end of the day, Sub Ohm vaping comes down to three words: big ass clouds" [5] Etter [6] notes that "These newer devices deliver more power, more cloud density, [my emphasis] more intense flavors and a better 'throat hit' than older models."

    With this generation of ENDS becoming more popular, we would expect to see clouding increase. As we know [7], many vapers in a room can send particle counts above those recorded in room where smoking is allowed.

    There is simply no comparison between the asthma medication and propellant a few asthmatics might exhale into (for example) a crowded bar over a few hours and what potentially dozens of vapers could generate in the sort of exuberant clouding sessions that vaping in bars can entail. And unlike vapers, asthmatics do not participate in asthma puffer social events.

    This vaper puts things plainly


    1. Bauld L, McNeill A, Hajek P, Britton J, Dockrell M. E-cigarette use in public places: striking the right balance. Tob Control 2016; doi:10.1136/tobaccocontrol-2016-053357

    2. Newman SP, Weisz AWB, Talaee N, Clarke SW. Improvement of drug delivery with a breath actuated pressurised aerosol for patients with poor inhaler technique. Thorax 1991; 46:712-16.

    3. Partners Healthcare. Asthma Center. Chapter 33: How many times a day can I safely use my bronchodilator inhaler?

    4. Martin E, Clapp PW, Rebuli ME et al . E-cigarette use results in suppression of immune and inflammatory-response genes in nasal epithelial cells similar to cigarette smoke. merican Journal of Physiology - Lung Cellular and Molecular Physiology Published 10 June 2016 Vol. no. , DOI: 10.1152/ajplung.00170.2016

    5. Kriegel D. What is sub ohm vaping? Our sub ohm vaping guide & tips ohm-vapes/ 2015;May 26.

    6. Etter J-F. A longitudinal study of cotinine in long-term users of e-cigarettes. Drug and Alcohol Dependence 2016;160:218-221.

    7. Soule EK, Maloney SF, Spindle TR, et al. Electronic cigarette use and indoor air quality in a natural setting. Tob Control 2016;???. doi:10.1136/tobaccocontrol-2015-052772

    Conflict of Interest:

    None declared

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  6. Internet cigarette vendors make tax free claims and selling cigarette cheaper:An alarming isssue

    NOT PEER REVIEWED The Internet is widely used source for purchasing and selling products. However,purchasing tobacco products online is a new trend. The internet vendors are often exempted from taxes leading to lowering the cost of cigarettes in certain countries.This is a really alarming situation as it would lead to increase in sales of tobacco products due to lower prices. Countries need to check this trend otherwise all the gain achieved till now through legislation and commitments to reduce tobacco consumption could be lost.

    Conflict of Interest:

    None declared

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  7. Intent-to-treat analysis of observational studies assessing electronic cigarettes' efficacy as an aid to smoking cessation.

    NOT PEER REVIEWED In the last decade, electronic cigarettes (EC) have become increasingly popular in particular among smokers. Most EC users choose to use nicotine containing liquids (electronic nicotine delivery system, ENDS); these ENDS can be considered as similar to nicotine replacement therapies. Among the several questions EC use raises, one is of major importance: Are EC a smoking cessation aid and if yes to what extent compared to existing pharmacotherapies such as nicotine replacement therapies, varenicline or bupropion? Several systematic reviews tried to approach the role of EC as a smoking cessation aid. As of today, only two randomized trials assessed the efficacy of EC with controversial results (1,2). As an editorial (3) and the last systematic review (4) concluded, because of the absence of well- designed and sufficiently powered randomized, controlled, head-to-head therapeutic trials the current accumulation of data originating essentially from observational studies does not allow us to make any conclusion as to EC's therapeutic efficacy in smoking cessation. Manzoli et al. (5, 6) assessed abstinence from tobacco cigarettes or tobacco and electronic cigarettes ('any product') in a prospective cohort study. They included at baseline EC only users, individuals using tobacco cigarettes and EC (dual use) and those using only tobacco cigarettes. They reported the 12-month (5) and 24-month (6) results in two separate papers the latter published online in the June 2016 issue of Tobacco Control. For both papers, the analyses were restricted to individuals whose data were available at 12 or 24 months (completers). This study raises the question whether observational studies assessing efficacy should be analyzed similarly to randomized efficacy trials for which the gold standard approach is the intent-to treat-analysis (ITT) (7) which defines the population submitted to the main data analysis. Table 1. compares Manzoli et al. results for the 12-month and 24-month abstinence outcomes (5,6). For all baseline categories, completers' abstinence rates are higher than abstinence rates of the baseline population that we can call here as the "ITT" population i.e. of all individuals included. Of particular interest is that EC only users had higher tobacco cigarettes but not 'any product' abstinence rates both at 12 and 24 months than the two other groups. The (unadjusted) "ITT" tobacco cigarettes abstinence rates are 42% and 40.8 % versus the completers abstinence rates of 61.9% and 61.1 % at 12 and 24 months, respectively; all higher than among dual users or tobacco cigarette only users suggesting that EC can be an aid to quit smoking. Unfortunately, both papers report only confounder adjusted odds ratios for completers and not for the "ITT" population. Observational studies looking for treatment efficacy could be analyzed like randomized efficacy trials (8,9) to narrow the gap between randomized clinical trials and observational data (8). Non-ITT, usually completer analyses, aim to estimate the effect of treatments received as opposed to treatments assigned under the ITT approach and by this exclude all factors contributing to non-completion of the trial (lost to follow up, adverse events, discontinuation for any reasons). The advantage of the ITT analysis is that it evaluates the true treatment effect which is the sum of the biological effects, positive or negative such as adverse events, and study adherence. The limitation of the ITT analysis of randomized efficacy trials is the underestimation of efficacy because of non- treatment related confounders (e.g. lost to follow-up for moving to another city). On the other hand, completer analysis overestimates efficacy by ignoring e.g. discontinuation because of adverse events and cannot, therefore, help to assess the benefit/risk ratio of a given intervention. Until results of high-quality, large-scale, comparative, randomized trials of EC' efficacy will be available, data of well conducted prospective observational studies as that of Manzoli at al. (5,6) could estimate EC's efficacy by analyzing "ITT" data and not completers' data while adjusting for all available and potential confounders. Thus, in the Manzoli et al. study (5,6) adjusted "ITT" population abstinence rates would have provided more convincing results about EC's efficacy as an aid for smoking cessation than completers' adjusted abstinence rates. REFERENCES 1. Caponnetto P, Campagna D, Cibella F, et al. EffiCiency and Safety of an eLectronic cigAreTte (ECLAT) as tobacco cigarettes substitute: a prospective 12-month randomized control design study. PLoS One. 2013 Jun 24;8(6):e66317. doi: 10.1371/journal.pone.0066317. Print 2013. 2. Bullen C, Howe C, Laugesen M, et al. Electronic cigarettes for smoking cessation: a randomised controlled trial. Lancet. 2013 Nov 16;382(9905):1629-37. doi: 10.1016/S0140-6736(13)61842-5. Epub 2013 Sep 9. 3. Bernstein SL. Electronic cigarettes: more light, less heat needed. Lancet Respir Med. 2016; Feb;4(2):85-7. doi: 10.1016/S2213-2600(16)00010- 2. Epub 2016 Jan 14 4. Malas M, van der Tempel J, Schwartz R, et al. Electronic Cigarettes for Smoking Cessation: A Systematic Review. Nicotine Tob Res. 2016 Apr 25. pii: ntw119. [Epub ahead of print] Review. 5. Manzoli L, Flacco ME, Fiore M, et al. , Electronic cigarettes efficacy and safety at 12 months: Cohort Study. PLoS One. 2015 Jun 10;10(6):e0129443. doi: 10.1371/journal.pone.0129443. eCollection 2015. 6. Manzoli L, Flacco ME, Ferrante M, et al. Cohort study of electronic cigarette use: effectiveness and safety at 24 months. Tob Control. 2016 Jun 6. pii: tobaccocontrol-2015-052822. doi: 10.1136/tobaccocontrol-2015- 052822. [Epub ahead of print] 7. Detry MA, Lewis RJ. The Intention-to Treat principle. How to assess the true effect of choosing a medical treatment. JAMA 2014; 312:85-86. 8.Wilcox A, Wacholder S. Observational data and clinical trials. Narrowing the gap? Editorial. Epidemiology 2008;19: 765. 9. Herna?n MA, Alonso A, Logan R, et al. Observational studies analyzed like randomized experiments: an application to postmenopausal hormone therapy and coronary heart disease. Epidemiology. 2008;19:766-779.

    Conflict of Interest:

    None declared

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  8. Impact of e-cigarette adverts on children's perceptions of smoking

    NOT PEER REVIEWED The study conducted in England by Petrescu and colleagues [1] concludes that there is a "potential for e-cigarette adverts to undermine tobacco control efforts by reducing a potential barrier (i.e. beliefs about harm) to occasional smoking". Clearly it is important to keep monitoring the impact of advertising, particularly on children, and this research paper is a welcome contribution. However, it is important to put this in context.

    The most recent survey of smoking among children in England found the lowest recorded smoking rates among youth aged 11-15 since records began in 1982.[2] It's worth noting that rates have continued to fall since e- cigarette use and marketing of products began to take off in Great Britain after 2010.[3][4] In 2010, 5% of 11-15 year olds were regular smokers falling to 3% in 2014. Also, in 2010 27% had ever tried smoking, falling to 18% in 2014.

    So it doesn't appear that e-cigarette advertising in England has had an impact so far on the number of children trying smoking, or becoming regular smokers. Furthermore from May 2016 all cross border advertising including TV, radio, internet and newspaper advertising has been banned throughout the European Union, thereby limiting advertising to that with local impact.

    It should also be noted that in the UK e-cigarette manufacturers are required to adhere to strict rules on advertising content.[5] These rules specify in particular that advertisers must ensure ads do not target, feature or appeal to children; that they do not confuse e-cigarettes with tobacco products; that they do not mislead with regard to product ingredients.

    In jurisdictions where e-cigarette ads are unregulated and resemble tobacco promotion, it's reasonable to assume that they could affect children's perceptions of both e-cigarettes and smoking. This study underlines the need to monitor e-cigarette marketing but the potential risks that e-cigarette advertisements are undermining tobacco control efforts in England are likely to be over-stated.

    [1] D C Petrescu, M Vasiljevic, J K Pepper, K M Ribisl, T M Marteau. What is the impact of adverts on children's perceptions of tobacco smoking? Tobacco Control published online 6 Sept. 2016. Doi: 10.1136/tobaccocontrol-2016-052940

    [2] Smoking, drinking and drug use among young people in England in 2014. Health & Social Care Information Centre, 2015.

    [3] ASH Fact sheet. Use of electronic cigarettes (vapourisers) among adults in Great Britain. ASH, 2016

    [4] De Andrade M et al. The marketing of e-cigarettes in the UK. Cancer Research UK, 2013.

    [5] Committee on Advertising Practice. Database/Electronic-cigarettes.aspx#.V86Snf_6uvE

    Conflict of Interest:

    None declared

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  9. Indoor air laws and hookah smoking

    The authors rightly point out that loopholes exist in some smoke-free air laws, exempting smoking of "tobacco-free or herbal hookah products" in public places.
    In New York City, where this study took place, the governing laws are: (1) New York State Clean Indoor Air Act, and (2) New York City Smoke Free Air Act.[1] Between 2002-2003, both laws were amended to "prohibit smoking in virtually all indoor places in New York State where people work or socialize."[2] The changes were made "in response to mounting scientific evidence that links exposure to the airborne smoke that is a by-product of smoking . . . to serious health risks to non-smokers."[3] Unfortunately, smoking was narrowly defined as "the burning of a lighted cigar, cigarette, pipe or any other matter or substance which contains tobacco."[4] Thus, giving rise to New York's loophole allowing non-tobacco hookah smoking.
    By comparison, the situation is different in neighboring New Jersey. In 2006, the state legislature enacted the New Jersey Smoke-Free Air Act prohibiting smoking in public places.[5] In the Act, smoking is defined as "the burning of, inhaling from, exhaling the smoke from, or the possession of a lighted cigar, cigarette, pipe or any other matter or substance which contains tobacco or any other matter that can be smoked."[6] New Jersey courts have interpreted the Act to include regulation of hookah bars - even when non-tobacco products are used in these devices. [7] Constitutional challenges to overturn this statute have failed underscoring its strength.
    Weakly worded "smoking" definitions are a chief source of statutory loopholes allowing public use of hookahs, as well as electronic cigarettes. Advocates for stronger clean indoor air laws should consider developing a model rule with commentary containing explanations and examples. This lays a foundation to assist legislators in statutory creation and helps judges with interpretation. Such model rules exist for many other areas of the law. States are free to adopt model rules in whole or in part. Smoking in the "new age" encompasses modalities not in existence when many smoking prohibitions were enacted. Vigilance is needed to ensure anti-smoking laws keep pace with the times.

    References [1] New York City C.L.A.S.H. v. City of New York, 315 F. Supp. 2d 461, 465 (2004).
    [2] Id. at 466.
    [3] Id. at 466-67.
    [4] N.Y. Pub Health Law 1399n(8) (Consol. 2003) (emphasis added).
    [5] N.J. Stat. 26:3D-55-64.
    [6] N.J.S.A. 26:3D-57
    [7] See State v. Badr, 415 N.J. Super 455 (2009).

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  10. Addiction refuses to allow discussion of industry ties to criticism of our paper

    NOT PEER REVIEWED In June 2015 we published our paper "The smoking population in the USA and EU is softening not hardening" in the journal Tobacco Control. We showed that as smoking prevalence has declined over time, quit attempts increased in the USA and remained stable in Europe, US quit ratios increased (no data for EU), and consumption dropped in the USA and Europe. These results contradict the hardening hypothesis which is often used as part of the tobacco industry's strategy to avoid meaningful regulation and protect its political agenda and markets, claiming that there is a need for harm reduction among those smokers who "cannot or will not quit." Indeed, rather than "hardening" the remaining smoking population is "softening."

    In February 2016 we received an email from Robert West, editor of the journal Addiction, informing us that Addiction was about to publish an article by Plurphanswat and Rodu entitled "A Critique of Kulik and Glantz: Is the smoking population in the US really softening?" whose sole purpose was to critique our Tobacco Control paper, and offered to let us respond to the criticism. (The full collection of emails is available at criticism-our-%E2%80%9Csoftening-paper%E2%80%9D)

    The fact that Plurphanswat and Rodu sent their paper to Addiction was unusual because normal scientific procedure would have had them sending a letter to the editor of the journal that originally published the work (Tobacco Control).

    As detailed below, we did respond, noting that Plurphanswat and Rodu's paper fits into a well-established pattern of tobacco industry- funded researchers trying, without any proper scientific justification, to create controversy about research inconsistent with industry interests, the fact that Rodu had understated his financial ties to the industry, and, of course, showing how their criticism was based on statistical error that they made.

    Addiction rejected our response because we would not delete the first two points and limit our response only to the statistical issue. Here is our full response:


    Consider the Source

    "Harm reduction" is a key part of the tobacco industry's strategy to avoid meaningful regulation and protect its political agenda and markets.[1] This agenda is premised on the existence of "hard core" smokers who "cannot or will not" quit.[2-4] Our paper, "The smoking population in the USA and EU is softening not hardening",[5] undermined this agenda because it showed that, contrary to the hardening hypothesis, as smoking prevalence has declined over time, quit attempts increased in the USA and remained stable in Europe, US quit ratios increased (no data for EU), and consumption dropped in the USA and Europe.

    There is a longstanding pattern of tobacco industry-funded experts writing letters criticizing work that threatens the industry's position, first described in 1993 by then-JAMA Deputy Editor Drummond Rennie.[6] Rodu and various co-authors have written several such letters.[7-10] Another similarity to past efforts is industry-linked experts submitting critiques of a paper published in one journal to another,[11-15] which is also the case here, with this critique of our paper published in Tobacco Control being published in Addiction. One would have expected any criticism to have been published as a letter in Tobacco Control.

    Addiction requires "full disclosure of potential conflicts of interest, including any fees, expenses, funding or other benefits received from any interested party or organisation connected with that party, whether or not connected with the letter or the article that is the subject of discussion." As with another investigator supported by the tobacco industry,[16] the conflict of interest statement Plurphanswat and Rodu provide may not truly reflect the extent of Rodu's involvement with the tobacco industry. For example:

    * Rodu's Endowed Chair in Tobacco Harm Reduction Research at the University of Louisville is funded by the U.S. Smokeless Tobacco Company (US Tobacco) and Swedish Match North America, Inc.[17]

    * Rodu is a Senior Fellow at the Heartland Institute, which has received tobacco industry funding.[18-20]

    * Rodu is a Member and Contributor to the R Street Institute, which has received tobacco industry funding.[19,21]

    * Before moving to Louisville, Dr. Rodu was supported in part by an unrestricted gift from the United States Smokeless Tobacco Company to the Tobacco Research Fund of the University of Alabama at Birmingham.[8]

    * Rodu was a keynote speaker at the 2013 Tobacco Plus Expo International, a tobacco industry trade fair to discuss "How has the tobacco retail business evolved; where was it fifteen years ago, where is it today and where is it going".[22]

    * Rodu has worked with RJ Reynolds executives between at least 2000 and 2009 to help promote industry positions on harm reduction, including specific products.[23-26]

    The substance of Plurphanswat and Rodu's criticism is that the statistically significant negative association between smoking prevalence and quit attempts and the positive association between prevalence and cigarettes smoked per day both become non-significant when more tobacco control variables are included in the model (state fixed effects, cigarette excise taxes, workplace smoking bans and home smoking bans). The problem with including all these variables is that it results in a seriously overspecified model, which splits any actual effects between so many variables that all the results become nonsignificant. The regression diagnostic for this multicollinearity is the Variance Inflation Factor (VIF); values of the VIF above 4 indicate serious multicollinearity. For the United States, adding all the other variables increases the VIF for the effect of changes in smoking prevalence from 1.8 in our model for quit attempts to 16.7, and from 1.8 in our model to 17.9 for cigarettes per day, respectively. Plurphanswat and Rodu's model is a textbook case of why one has to be careful not to put too many variables in a multiple regression.

    The Plurphanswat and Rodu criticism misrepresents our conclusions. We did not argue that drops in prevalence caused increased quit attempts and reduced consumption; we simply present the observation that, as prevalence falls, quit attempts increase or remain constant and consumption falls, which is the exact opposite of what the hardening hypothesis predicts.


    This work was supported by National Cancer Institute Grants CA-61021 and CA-113710. The sponsor played no role in the conduct of the research or preparation of the manuscript.


    1. Peeters S, Gilmore AB (2015) Understanding the emergence of the tobacco industry's use of the term tobacco harm reduction in order to inform public health policy. Tob Control 24: 182-189.

    2. Abrams DB (2014) Promise and peril of e-cigarettes: can disruptive technology make cigarettes obsolete? JAMA 311: 135-136.

    3. Polosa R, Rodu B, Caponnetto P, Maglia M, Raciti C (2013) A fresh look at tobacco harm reduction: the case for the electronic cigarette. Harm Reduct J 10: 19.

    4. Nitzkin JL (2014) The case in favor of E-cigarettes for tobacco harm reduction. Int J Environ Res Public Health 11: 6459-6471.

    5. Kulik MC, Glantz SA (2015) The smoking population in the USA and EU is softening not hardening. Tob Control doi:10.1136/tobaccocontrol-2015 -052329 Published online 24 June 2015.

    6. Rennie D (1993) Smoke and letters. JAMA 270: 1742-1743.

    7. Rodu B, Phillips CV (2015) Letter by Rodu and Phillips regarding article, "Discontinuation of smokeless tobacco and mortality risk after myocardial infarction". Circulation 131: e422.

    8. Rodu B, Cole P (2006) A deficient study of smokeless tobacco use and cancer. Int J Cancer 118: 1585; author reply 1586-1587.

    9. Rodu B, Plurphanswat N, Phillips CV (2015) Discrepant results for smoking and cessation among electronic cigarette users. Cancer. 121(13):2286-7. doi: 10.1002/cncr.29307. Epub 2015 Mar 4.

    10. Rodu B, Heavner KK (2009) Errors and omissions in the study of snuff use and hypertension. J Intern Med 265: 507-508; author reply 509- 510.

    11. Glantz SA, Parmley WW (1992) Passive smoking causes heart disease and lung cancer. J Clin Epidemiol 45: 815-819.

    12. Mantel N (1992) Dubious evidence of heart and cancer deaths due to passive smoking. J Clin Epidemiol 45: 809-813.

    13. Glantz SA, Parmley WW (1991) Passive smoking and heart disease. Epidemiology, physiology, and biochemistry. Circulation 83: 1-12.

    14. Jensen RP, Luo W, Pankow JF, Strongin RM, Peyton DH (2015) Hidden formaldehyde in e-cigarette aerosols. N Engl J Med 372: 392-394.

    15. Bates CD, Farsalinos KE (2015) Research letter on e-cigarette cancer risk was so misleading it should be retracted. Addiction 110: 1686- 1687.

    16. Bero LA, Glantz S, Hong MK (2005) The limits of competing interest disclosures. Tob Control 14: 118-126.

    17. University of Louisville. Available at, accessed February 2016.

    18. The Heartland Institute. Available at, accessed February 2016.

    19. Nitzkin email string "Dialogue with Tobacco Industry re 3d Party Research". Available at s..., accessed February 2016.

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