title: Electronic cigarette use and its association with smoking in Hong Kong Chinese adolescents.
abstract: BACKGROUND
  Electronic cigarettes (e-cigarettes) are increasingly used in adolescents with unknown impacts on conventional cigarette smoking. We examined the associations of e-cigarette use with smoking intention, nicotine addiction and smoking cessation in Chinese adolescents.
  
  
  METHODS
  A total of 45,128 students (age 14.6 ± 1.9; boys 51.4%) from 75 randomly selected schools in Hong Kong reported e-cigarette use (in the past 30 days), conventional cigarette use and socio-demographic characteristics in an anonymous questionnaire survey. Adjusted odds ratios (AORs) of intention to smoke, morning smoking urge, intention to quit and quit attempts; and beta-coefficient (β) of cigarette consumption per day were calculated in relation to e-cigarette use.
  
  
  RESULTS
  E-cigarette use was associated with intention to smoke with an AOR (95% CI) of 1.74 (1.30-2.31) in all students, 2.18 (1.12-4.23) in never and 2.79 (2.05-3.79) in ever smokers (non-significant interaction by smoking status). The associations were also significant in experimental and former smokers but not in current smokers. In current smokers, e-cigarette use was significantly associated with heavier smoking (β 2.54, 95% CI 1.28-3.81) and morning smoking urge (AOR 2.54, 95% CI 1.50-3.11), and non-significantly associated with lower quit intention (0.76, 0.52-1.09) and attempts (0.80, 0.56-1.23).
  
  
  CONCLUSIONS
  E-cigarette use was associated with smoking intention in never, experimental and former smokers in Hong Kong Chinese adolescents. In current smokers, e-cigarette use was associated with nicotine addiction but not quit intention and attempts. Prospective studies with detailed measurements on e-cigarette use are warranted for further studies.
authors.affiliation: School of Nursing, University of Hong Kong, Hong Kong, China.
authors.forename: Man Ping
authors.initials: MP
authors.lastname: Wang
authors.affiliation: School of Public Health, University of Hong Kong, Hong Kong, China. Electronic address: syho@hku.hk.
authors.forename: Sai Yin
authors.initials: SY
authors.lastname: Ho
authors.affiliation: School of Public Health, University of Hong Kong, Hong Kong, China.
authors.forename: Lok Tung
authors.initials: LT
authors.lastname: Leung
authors.affiliation: School of Public Health, University of Hong Kong, Hong Kong, China.
authors.forename: Tai Hing
authors.initials: TH
authors.lastname: Lam
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D003430:Cross-Sectional Studies; D066300:Electronic Nicotine Delivery Systems / Q000523:psychology* / Q000706:statistics & numerical data*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D033182:Intention; D008297:Male; D016017:Odds Ratio; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology*; D012959:Socioeconomic Factors
keywords: Adolescents; Chinese; E-cigarettes; Smoking