title: Reasons for smoking among male teenagers in tehran, iran: two case-control studies using snowball sampling.
abstract: OBJECTIVE
  Identifying the underlying factors contributing to smoking among teenagers is important in establishing smoking control programs. The present study was designed to identify and compare factors revealed in a preceding qualitative study conducted on 13-15 year-old boys living in two different socio-economic districts in the Northern and Southern parts of Tehran.
  
  
  METHODS
  Two completely similar case-control studies, each with 200 subjects, were conducted using a snowball sampling. The case and control subjects were matched based on the intimacy relations, i.e. six smokers were recruited in each of the Northern and Southern districts; they were then asked to introduce one of their smoker friends as a case and a non-smoker one as a control.
  
  
  RESULTS
  Multi-variable conditional logistic regression revealed that having a smoker father is the single effective factor in the two districts. As for boys living in the Northern (wealthier) part of the city, social capital (OR: 0.59, 95% CI: 0.43-0.81) played a protective role against smoking, whereas quitting home after a quarrel (OR: 15.07, 95% CI: 1.54-147.25), monthly allowance (OR: 2.22, 95% CI: 1.29-3.82) and hyperactivity (OR: 1.69, 95% CI: 2.64-240.45) were associated with a higher risk of becoming a smoker.
  
  
  CONCLUSIONS
  The studied variables can be classified as personal, familial, and school-level factors. Familial intervention is effective for all the factors which revealed to be influential on the risk of becoming a smoker. It could be concluded that interventions on the family level should be used to prevent the cigarette use in Tehran.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran and Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Rezaei
authors.forename: Saharnaz
authors.initials: S
authors.lastname: Nedjat
authors.forename: Banafsheh
authors.initials: B
authors.lastname: Golestan
authors.forename: Reza
authors.initials: R
authors.lastname: Majdzadeh