title: The smoking habit of a close friend or family member--how deep is the impact? A cross-sectional study.
abstract: OBJECTIVE
  To assess the risk of becoming a smoker in adulthood associated with parental smoking as well as the smoking of siblings and close friends.
  
  
  METHODS
  A cross-sectional study.
  
  
  METHODS
  4 oral healthcare centres in Finland and a follow-up.
  
  
  METHODS
  An age cohort born in 1979 (n=2586) and living in four Finnish towns. Of those reached by the 2008 follow-up, 46.9% (n=1020) responded.
  
  
  METHODS
  Smoking behaviour at the age of 29. Smoking behaviour at the age of 13 and smoking behaviour of family members and close friends.
  
  
  RESULTS
  Smoking of a current close friend was strongly associated with participants' own smoking (OR 5.6, 95% CI 3.6 to 8.8). The smoking of a close friend during schooldays was similarly associated (OR 2.9, 95% CI 1.8 to 4.5). Smoking among men was associated with the smoking behaviour of mothers and siblings while that among females was not.
  
  
  CONCLUSIONS
  The impact of a smoker as a close friend is greater than that of a smoking parent or sibling in school age when it comes to smoking behaviour in adulthood. This should be taken into consideration when attempting to prevent smoking initiation or continuation.
  
  
  BACKGROUND
  At clinicaltrials.gov (NCT01348646).
authors.affiliation: Department of General Practice, University of Tampere, Tampere, Finland.
authors.forename: Antti J
authors.initials: AJ
authors.lastname: Saari
authors.forename: Jukka
authors.initials: J
authors.lastname: Kentala
authors.forename: Kari J
authors.initials: KJ
authors.lastname: Mattila
mesh_terms: D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D005190:Family; D005260:Female; D005387:Finland; D033062:Friends; D006801:Humans; D008297:Male; D012307:Risk Factors; D012907:Smoking / Q000523:psychology*; D011795:Surveys and Questionnaires
keywords: Preventive Medicine; Public Health