title: Development of a questionnaire for assessing dependence on electronic cigarettes among a large sample of ex-smoking E-cigarette users.
abstract: BACKGROUND
  Electronic cigarettes (e-cigs) are becoming increasingly popular, but little is known about their dependence potential. This study aimed to assess ratings of dependence on electronic cigarettes and retrospectively compare them with rated dependence on tobacco cigarettes among a large sample of ex-smokers who switched to e-cigs.
  
  
  METHODS
  A total of 3,609 current users of e-cigs who were ex-cigarette smokers completed a 158-item online survey about their e-cig use, including 10 items designed to assess their previous dependence on cigarettes and 10 almost identical items, worded to assess their current dependence on e-cigs (range 0-20).
  
  
  RESULTS
  Scores on the 10-item Penn State (PS) Cigarette Dependence Index were significantly higher than on the comparable PS Electronic Cigarette Dependence Index (14.5 vs. 8.1, p < .0001). In multivariate analysis, those who had used e-cigs longer had higher e-cig dependence scores, as did those using more advanced e-cigs that were larger than a cigarette and had a manual button. Those using zero nicotine liquid had significantly lower e-cig dependence scores than those using 1-12 mg/ml, who scored significantly lower than those using 13 or greater mg/ml nicotine liquid (p < .003).
  
  
  CONCLUSIONS
  Current e-cigarette users reported being less dependent on e-cigarettes than they retrospectively reported having been dependent on cigarettes prior to switching. E-cig dependence appears to vary by product characteristics and liquid nicotine concentration, and it may increase over time.
authors.affiliation: Department of Public Health Sciences, Tobacco Center of Regulatory Science, College of Medicine, Penn State University, Hershey, PA; jfoulds@psu.edu.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Foulds
authors.affiliation: Department of Public Health Sciences, Tobacco Center of Regulatory Science, College of Medicine, Penn State University, Hershey, PA;
authors.forename: Susan
authors.initials: S
authors.lastname: Veldheer
authors.affiliation: Department of Public Health Sciences, Tobacco Center of Regulatory Science, College of Medicine, Penn State University, Hershey, PA;
authors.forename: Jessica
authors.initials: J
authors.lastname: Yingst
authors.affiliation: Department of Public Health Sciences, Tobacco Center of Regulatory Science, College of Medicine, Penn State University, Hershey, PA;
authors.forename: Shari
authors.initials: S
authors.lastname: Hrabovsky
authors.affiliation: Department of Psychology, Penn State University, State College, PA;
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wilson
authors.affiliation: Department of Psychology, Penn State University, State College, PA;
authors.forename: Travis T
authors.initials: TT
authors.lastname: Nichols
authors.affiliation: Center for the Study of Tobacco Products, Virginia Commonwealth University, Richmond, VA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Eissenberg
mesh_terms: D000328:Adult; D066300:Electronic Nicotine Delivery Systems; D005260:Female; D006801:Humans; D008297:Male; D009538:Nicotine / Q000008:administration & dosage; D012189:Retrospective Studies; D016540:Smoking Cessation; D000074606:Smoking Prevention; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D009538:Nicotine