title: Overview of Electronic Nicotine Delivery Systems: A Systematic Review.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia. Electronic address: aglasser@truthinitiative.org.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Glasser
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia.
authors.forename: Lauren
authors.initials: L
authors.lastname: Collins
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Pearson
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia.
authors.forename: Haneen
authors.initials: H
authors.lastname: Abudayyeh
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia; Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington, District of Columbia.
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Niaura
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia; Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington, District of Columbia.
authors.forename: David B
authors.initials: DB
authors.lastname: Abrams
authors.affiliation: The Schroeder Institute for Tobacco Research and Policy Studies at Truth Initiative, Washington, District of Columbia; Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Villanti
mesh_terms: D015415:Biomarkers / Q000032:analysis; D003071:Cognition / Q000187:drug effects; D003132:Commerce; D066300:Electronic Nicotine Delivery Systems; D006801:Humans; D040541:Marketing; D009538:Nicotine / Q000009:adverse effects*; D016540:Smoking Cessation / Q000191:economics / Q000379:methods*; D000074606:Smoking Prevention / Q000191:economics / Q000331:legislation & jurisprudence / Q000379:methods*; D014029:Tobacco Use Disorder / Q000150:complications / Q000209:etiology / Q000517:prevention & control*; D000072137:Vaping / Q000009:adverse effects / Q000191:economics / Q000295:instrumentation* / Q000331:legislation & jurisprudence
chemical_list: D015415:Biomarkers; D009538:Nicotine