REVIEW ARTICLE
Overview of Electronic Nicotine Delivery Systems: A Systematic Review

https://doi.org/10.1016/j.amepre.2016.10.036Get rights and content

Context

Rapid developments in e-cigarettes, or electronic nicotine delivery systems (ENDS), and the evolution of the overall tobacco product marketplace warrant frequent evaluation of the published literature. The purpose of this article is to report updated findings from a comprehensive review of the published scientific literature on ENDS.

Evidence acquisition

The authors conducted a systematic review of published empirical research literature on ENDS through May 31, 2016, using a detailed search strategy in the PubMed electronic database, expert review, and additional targeted searches. Included studies presented empirical findings and were coded to at least one of nine topics: (1) Product Features; (2) Health Effects; (3) Consumer Perceptions; (4) Patterns of Use; (5) Potential to Induce Dependence; (6) Smoking Cessation; (7) Marketing and Communication; (8) Sales; and (9) Policies; reviews and commentaries were excluded. Data from included studies were extracted by multiple coders (October 2015 to August 2016) into a standardized form and synthesized qualitatively by topic.

Evidence synthesis

There were 687 articles included in this systematic review. The majority of studies assessed patterns of ENDS use and consumer perceptions of ENDS, followed by studies examining health effects of vaping and product features.

Conclusions

Studies indicate that ENDS are increasing in use, particularly among current smokers, pose substantially less harm to smokers than cigarettes, are being used to reduce/quit smoking, and are widely available. More longitudinal studies and controlled trials are needed to evaluate the impact of ENDS on population-level tobacco use and determine the health effects of longer-term vaping.

Section snippets

Context

Electronic nicotine delivery systems (ENDS), or e-cigarettes, produce an inhaled aerosol instead of smoke, providing an alternative mode of nicotine delivery.1, 2, 3, 4, 5, 6 The U.S. Food and Drug Administration’s Center for Tobacco Products finalized a rule to regulate ENDS.7 Thus, there is a pressing need to identify the pathways by which to manage ENDS and how to strike a balance between potential benefits and harms to public health.4, 8, 9

Reviews have been published on ENDS in general10, 11

Evidence Acquisition

A systematic review of empirical articles on ENDS was conducted via a PubMed search through May 31, 2016 (Appendix Table 1 [available online] shows search strategy and eligibility criteria).107 Analyses were conducted from October 2015 to August 2016. Included studies (Figure 1) were catalogued into one or more of the following topics:

  • 1.

    Product Features;

  • 2.

    Health Effects;

  • 3.

    Consumer Perceptions;

  • 4.

    Patterns of Use;

  • 5.

    Potential to Induce Dependence;

  • 6.

    Smoking Cessation;

  • 7.

    Marketing and Communication;

  • 8.

    Sales; and

  • 9.

Evidence Synthesis

Of 1,634 articles identified through PubMed, 675 were included in the review (Figure 1). An additional twelve studies were included through targeted searches or discussion with experts.

Discussion

This review highlights several major findings. First, ENDS are a heterogeneous and evolving product category, with variation in physical factors that can influence vapor production (e.g., tank style, battery power, temperature). E-liquids contain various combinations of nicotine, flavors, and carriers. These factors affect nicotine delivery, appeal, and ease of product use and underscore the degree to which individual preferences may play a role in use patterns. Second, detectable levels of

Conclusions

There are a number of factors to consider when synthesizing the results. First, ENDS products are highly variable. A standardized method is needed to characterize products with respect to nicotine and toxicant delivery and their potential harms, both relative to smoking and relative to no use (absolute harm). Second, the field lacks consistent definitions of types of users and patterns of use, which complicates the interpretation of research findings. Third, many studies have small sample or

Acknowledgments

Financial support for this study was provided by the Schroeder Institute at Truth Initiative, the Robert Wood Johnson Foundation (Grant ID: 72208 and 72390), and a NIH K01 Career Development Award in Tobacco Control Regulatory Research (Principal Investigator, Pearson; 1K01DA037950-01). The funding agreement ensured the authors’ independence in designing the study, interpreting the data, and writing and publishing the report. All authors are employed by Truth Initiative. No financial

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