Scientific articles supporting tobacco harm reduction more likely to be industry funded and lack empirical data

Yogi Hendlin, Pam Ling, and their colleagues here at UCSF just published “Financial Conflicts of Interest and Stance on Tobacco Harm Reduction: A Systematic Review” in American Journal of Public Health.  The collected everything published between 1992 and 2016 that talked about tobacco harm reduction in English in peer reviewed journals.

They found 826 articles.  While 49% endorsed tobacco harm reduction, most of these did not actually report original data, but rather were letters, commentaries, and reviews.  These articles are general not subject to the same level of rigorous review as publications reporting original data. 

Citations to these papers can be misleading, because the citations look the same as empirical studies published in the same journal.  Tobacco companies (and other corporations) take advantage of this fact when citing these publications in regulatory, political, and legal filings.

Industry support was strongly predictive of a pro-harm reduction position.

Leaving out the publications that were not obviously industry funded, 49% opposed tobacco harm reduction compared to 41% supporting. 

One limitation of this paper is that the authors relied on disclosed funding or conflicts of interest and people with industry links sometimes leave this information out and some journals do not require vigorous disclosure of funding and conflicts in non-original research.

There was also a big difference between publications from the US and UK, with much stronger support for tobacco harm reduction in the UK.

The authors conclude: “Industry funding strongly influenced the acceptance of THR as product substitution. The THR scientific literature was dominated by nonempirical articles, which were much more likely to support THR if they received industry funding. Industry funding of scien-tific research has likely influenced perceptions of consensus on THR as endorsing productsubstitution as a viable health intervention, when in fact the non–industry-funded scientific literature remained divided on this issue.”

Here is the abstract:

Background. Tobacco companies have actively promoted the substitution of cigarettes with purportedly safer tobacco products (e.g., smokeless tobacco, e-cigarettes) as tobacco harm reduction (THR). Given the tobacco, e-cigarette, and pharmaceutical industries’ substantial financial interests, we quantified industry influence on support for THR.

Objectives. To analyze a comprehensive set of articles published in peer-reviewed journals assessing funding sources and support for or opposition to substitution of tobacco or nicotine products as harm reduction.

Search Methods. We searched PubMed, Embase, Web of Science, and PsycINFO with a comprehensive search string including all articles, comments, and editorials published between January 1, 1992 and July 26, 2016.

Selection Criteria. We included English-language publications published in peer-reviewed journals addressing THR in humans and excluded studies on modified cigarettes, on South Asian smokeless tobacco variants, on pregnant women, on animals, not mentioning a tobacco or nicotine product, on US Food and Drug Administration–approved nicotine replacement therapies, and on nicotine vaccines.

Data Collection and Analysis. We double-coded all articles for article type; primary product type (e.g., snus, e-cigarettes); themes for and against THR; stance on THR; THR concepts; funding or affiliation with tobacco, e-cigarette, pharmaceutical industry, or multiple industries; and each author’s country. We fit exact logistic regression models with stance on THR as the outcome (pro- vs anti-THR) and source of funding or industry affiliation as the predictor taking into account sparse data. Additional models included article type as the outcome (nonempirical or empirical) and industry funding or affiliation as predictor, and stratified analyses for empirical and nonempirical studies with stance on THR as outcome and funding source as predictor.

Main Results. Searches retrieved 826 articles, including nonempirical articles (21%), letters or commentaries (34%), editorials (5%), cross-sectional studies (15%), systematic reviews and meta-analyses (3%), and randomized controlled trials (2%). Overall, 23.9% disclosed support by industry; 49% of articles endorsed THR, 42% opposed it, and 9% took neutral or mixed positions. Support from the e-cigarette industry (odds ratio [OR] = 20.9; 95% confidence interval [CI] = 5.3, 180.7), tobacco industry (OR = 59.4; 95% CI = 10.1, +infinity), or pharmaceutical industry (OR = 2.18; 95% CI = 1.3, 3.7) was significantly associated with supportive stance on THR in analyses accounting for sparse data.

Authors’ Conclusions. Non–industry-funded articles were evenly divided in stance, while industry-funded articles favored THR. Because of their quantity, letters and comments may influence perceptions of THR when empirical studies lack consensus.

Public Health Implications. Public health practitioners and researchers need to account for industry funding when interpreting the evidence in THR debates. (Am J Public Health. Published online ahead of print May 16, 2019: e1–e8. doi:10.2105/AJPH.2019.305106)

The full citation is: Yogi H. Hendlin, Manali Vora, Jesse Elias, and Pamela M. Ling: Financial Conflicts of Interest and Stance on Tobacco Harm Reduction: A Systematic Review. American Journal of Public Health 0, e1_e8, https://doi.org/10.2105/AJPH.2019.305106.  It is available here.