Full length articleDependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes
Introduction
Electronic cigarettes (e-cigarettes) are increasingly popular (Hajek et al., 2014). E-cigarettes do not contain tobacco, but a liquid made of propylene glycol, glycerol, flavours, and most of the time nicotine. The liquid is heated electrically to produce a vapour for inhalation.
While there is considerable variability across products and individuals, some users are able to obtain substantial amounts of nicotine from e-cigarettes (Etter and Bullen, 2011a, Etter and Bullen, 2011b; Vansickel and Eissenberg, 2013, Dawkins and Corcoran, 2014, Etter, 2014, Nides et al., 2014). In many cases, plasma nicotine concentration after e-cigarette use is similar or higher than the concentration seen in users of nicotine replacement medications and, in some cases, it approaches that seen after tobacco cigarette smoking (Etter and Bullen, 2011a, Etter and Bullen, 2011b, Vansickel and Eissenberg, 2013, Dawkins and Corcoran, 2014, Etter, 2014, Nides et al., 2014, Spindle et al., 2014). The speed of nicotine delivery to the blood may be slower for e-cigarettes than for tobacco cigarettes, but is certainly similar to or faster than for nicotine medications (Choi et al., 2003, Bullen et al., 2010, Dawkins and Corcoran, 2014, Nides et al., 2014, Spindle et al., 2014), including the nicotine gum (Henningfield, 1995). Because the addictiveness of a drug-delivery device is in part determined by the speed of drug delivery to the brain (Le Houezec, 2003), the differences across devices suggest the hypothesis that some e-cigarettes may be less addictive than tobacco cigarettes, but as or more addictive than nicotine medications, which themselves are not at all (patch), or not very addictive (gum, lozenge; Hughes, 1989, Shiffman et al., 2003). This hypothesis is partially supported by data showing that the abuse liability of e-cigarettes is less than that of tobacco cigarettes, at least for smokers trying an e-cigarette for the first time (Vansickel et al., 2012). Also, in experienced e-cigarette users (called “vapers” because they inhale a vapour), the number of minutes between waking up and first use (a good indicator of dependence) is longer for e-cigarettes than for tobacco cigarettes (Farsalinos et al., 2013a, Farsalinos et al., 2013b, Goniewicz et al., 2013), and vapers report that e-cigarettes are less addictive than tobacco cigarettes (Farsalinos et al., 2013a, Farsalinos et al., 2013b, Goniewicz et al., 2013, Foulds et al., 2014). Long-term e-cigarette users may be more addicted than short-term users, and new e-cigarette models may be more addictive than older models (Foulds et al., 2014). Otherwise, there is little published information on the addictiveness of e-cigarettes. Nevertheless, there is concern that some users may be addicted to nicotine when it is delivered via e-cigarettes.
Consequently, the aims of this study were to describe levels of dependence in users of e-cigarettes (current and former smokers), and to compare them with dependence levels in former smokers who used the nicotine gum and in cigarette smokers.
Section snippets
Materials and methods
We used comparisons to interpret dependence ratings. First, daily vapers who were former smokers compared their current level of dependence on e-cigarettes with their former level of dependence on tobacco cigarettes. Second, we compared dependence ratings in users of e-cigarettes with vs. without nicotine, hypothesizing that dependence would be present in the former only. Third, in former smokers, we compared dependence to the e-cigarette in daily vapers with dependence to the nicotine gum in
Participation in the e-cigarette survey
We obtained 1640 responses but retained only the 1284 daily vapers, including 125 daily smokers (dual users: daily e-cigarettes and daily tobacco cigarettes), 1033 former smokers (911 exclusive e-cigarette users who had not smoked any tobacco in the past 7 days, plus 122 recent quitters who had smoked in the past 7 days), 111 occasional smokers (dual users: daily e-cigarettes and occasionally tobacco cigarettes), and 15 of undeclared smoking status.
Participants lived in France (36%), the USA
Discussion
We used several methods to assess dependence on e-cigarettes: we used adapted versions of widely used dependence scales, we asked vapers to compare their dependence on e-cigarettes with their current or past dependence on tobacco cigarettes, and we compared dependence ratings in vapers, nicotine gum users and tobacco smokers. Overall, our results were convergent across measures and comparisons, and suggested that e-cigarettes are less addictive than tobacco cigarettes, a result congruent with
Role of funding source
This study was partly funded by the Swiss Tobacco Prevention Fund (Swiss Federal Office of Public Health), grant 12.000189 to JFE. The Swiss Tobacco Prevention Fund had no role in the design or conduct of the study, interpretation of the data or decision to submit the paper for publication.
Contributors
Both authors contributed to the design of the study, writing of the manuscript and interpretation of the data. JFE lead the data collection and data analysis. Both authors have approved the final article.
Conflict of interest
JFE was reimbursed by Dekang, a manufacturer of e-cigarettes and e-liquids for traveling to London and to China, to visit e-cigarette factories, but he received no honoraria for these meetings.
JFE's salary is paid by the University of Geneva.
TE: No competing interests.
Acknowledgments
TE is supported by the National Institute on Drug Abuse of the U.S. National Institutes of Health under Award Number P50DA036105 and the Center for Tobacco Products of the U.S. Food and Drug Administration. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Food and Drug Administration.
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