E-Cigarette and COPD: Unreliable Conclusion About Health Risks
K. Michael Cummings, PhD, MPH
and Riccardo Polosa, MD, PhD
Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, USA;
Department of Clinical and
Experimental Medicine, University of Catania, Catania, Italy;
Institute of Internal and Emergency Medicine, Teaching Hospital BPoliclinico - V.
Emanuele,^ University of Catania, Catania, Italy.
J Gen Intern Med 33(6):784–5
© Society of General Internal Medicine 2018
n their recent paper, Bowler and colleagues
used data from
two large observational studies to investigate the question
of whether use of e-cigarettes (ECs) by patients at risk of, or
with, COPD impacted respiratory health outcomes. The con-
clusion was that the use of ECs was associated with poorer
health outcomes. Unfortunately, the evidence presented in the
paper is inadequate to provide much confidence in this
First, the authors have relied on poorly constructed mea-
sures of EC use, which makes it hard to determine if the
reported association is real or merely the result of misclassifi-
cation error. The authors relied on ever and current use of ECs
to define exposure. While these measures have value for
documenting trends in EC use, they are not as helpful as in
evaluating whether or not ECs contribute to smoking cessation
or health outcomes since it is impossible to differentiate
smokers who may have tried an EC from those who used
them frequently for an extended period. Accounting for the
frequency of EC use is important since previous studies have
shown that daily use of ECs is related to a greater probability
of smoking abstinence, which in turn would be expected to
improve COPD health outcomes.
Another limitation of the study was failure to account for
the type of EC used which is important since the type of EC
used impacts nicotine delivery and the likely success smokers
might have quitting
and likely varied over the six-year period
of the study (2010–2016).
Finally, selection bias is an important potential confounder.
While EC users were found to be more addicted and have a
more prolonged exposure to cigarettes (i.e., pack/years), this
would also be expected to be associated with poorer COPD
outcomes. Controlling for baseline cigarette use attenuated the
negative association with COPD outcomes suggesting that the
patient’s cigarette smoking history, not their use of ECs, could
be the cause of poor COPD outcomes.
It is important to note that findings from this study differ from
those of another study on the same topic.
Moreover, the potential
risks and benefits of switching smokers to an alternative nicotine
product were well articulated in the Lung Health Study.
would strongly caution clinicians, public health experts, and
policy-makers from reaching firm conclusions about the potential
risks or benefits of EC use based on the studies reported to date.
Corresponding Author: Riccardo Polosa, MD, PhD; Institute of
Internal and Emergency Medicine, Teaching Hospital BPoliclinico - V.
Emanuele,^ University of Catania, Catania, Italy
Author Contributions K.M.C. and R.P. drafted, revised, and ap-
proved the final version of the manuscript.
Compliance with Ethical Standards:
Conflict of Interest: K. Michael Cummings is a Professor in the De-
partment of Psychiatry and Behavioral Sciences and a member of the
Hollings Cancer Center Cancer Control Program where he co-leads the
tobacco control research program for the Medical University of South
Carolina, Charleston, SC, USA. His current research which is focused
on electronic cigarettes is funded by the National Institute of Health. Dr.
Cummings has never received funding from a business or trade group
involved the sale of electronic cigarettes. Dr. Cummings has received
consulting fees and grant support from Pfizer for his work in smoking
cessation. He has also received fees as a paid expert witness in litiga-
tion filed against cigarette manufacturers.
R. Polosa is a full-time employee of the University of Catania, Italy. In
relation to his work in the area of tobacco control, RP has received lecture
fees and research funding from Pfizer and GlaxoSmithKline, manufac-
turers of stop smoking medications. He has also received support from
The Consumer Advocates for Smoke-free Alternatives (CASAA) for publi-
cation and open access costs of one paper. He has also served as a
consultant for Pfizer, Global Health Alliance for treatment of tobacco
dependence, ECITA (Electronic Cigarette Industry Trade Association, in
the UK), Arbi Group Srl., and Health Diplomat (consulting company that
delivers solutions to global health problems with special emphasis on
harm minimization). Lectures’ fees from a number of European electronic
cigarette industry and trade associations (including FIVAPE in France
and FIESEL in Italy) were directly donated to vapers advocacy no-profit
organizations. He is also currently involved in the following pro bono
activities: scientific advisor for LIAF, Lega Italiana Anti Fumo (Italian
acronym for Italian Anti Smoking League) and for the Consumer Advo-
cates for Smoke-free Alternatives (CASAA); Chair of the European Tech-
nical Committee for standardization on BRequirements and test methods
for emissions of electronic cigarettes^ (CEN/TC 437; WG4).
1. Bowler RP, Hansel NN, Jacobson S, et al. Electronic Cigarette Use in US
Adults at Risk for or with COPD: Analysis from Two Observational Cohorts.
J Gen Intern Med. 2017. https://doi.org/10.1007/s11606-017-4150-7.
2. Polosa R, Caponnetto P, Niaura R, Abrams D. Analysis of E-cigarette use in
the 2014 Eurobarometer survey: calling out deficiencies in epidemiology
Published online March 21, 2018