title: Dependence levels in users of electronic cigarettes, nicotine gums and tobacco cigarettes.
abstract: OBJECTIVE
  To assess dependence levels in users of e-cigarettes, and compare them with dependence levels in users of nicotine gums and tobacco cigarettes.
  
  
  METHODS
  Self-reports from cross-sectional Internet and mail surveys. Comparisons of: (a) 766 daily users of nicotine-containing e-cigarettes with 30 daily users of nicotine-free e-cigarettes; (b) 911 former smokers who used the e-cigarette daily with 451 former smokers who used the nicotine gum daily (but no e-cigarette); (c) 125 daily e-cigarette users who smoked daily (dual users) with two samples of daily smokers who did not use e-cigarettes (2206 enrolled on the Internet and 292 enrolled by mail from the general population of Geneva). We used the Fagerström test for nicotine dependence, the nicotine dependence syndrome scale, the cigarette dependence scale and versions of these scales adapted for e-cigarettes and nicotine gums.
  
  
  RESULTS
  Dependence ratings were slightly higher in users of nicotine-containing e-cigarettes than in users of nicotine-free e-cigarettes. In former smokers, long-term (>3 months) users of e-cigarettes were less dependent on e-cigarettes than long-term users of the nicotine gum were dependent on the gum. There were few differences in dependence ratings between short-term (≤3 months) users of gums or e-cigarettes. Dependence on e-cigarettes was generally lower in dual users than dependence on tobacco cigarettes in the two other samples of daily smokers.
  
  
  CONCLUSIONS
  Some e-cigarette users were dependent on nicotine-containing e-cigarettes, but these products were less addictive than tobacco cigarettes. E-cigarettes may be as or less addictive than nicotine gums, which themselves are not very addictive.
authors.affiliation: Institute of Global Health, Faculty of Medicine, University of Geneva, Geneva, Switzerland. Electronic address: Jean-Francois.Etter@unige.ch.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Etter
authors.affiliation: Center for the Study of Tobacco Products, Dept. of Psychology, Virginia Commonwealth University, Richmond, VA, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Eissenberg
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000008:administration & dosage*; D057566:Self Report; D012907:Smoking / Q000453:epidemiology / Q000523:psychology*; D062789:Tobacco Products; D061485:Tobacco Use Cessation Devices; D014029:Tobacco Use Disorder / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*
chemical_list: D009538:Nicotine
keywords: Addiction; Dependence; Electronic cigarette; Electronic nicotine delivery devices (ENDS); Nicotine; Smoking