title: Social network and inequalities in smoking amongst school-aged adolescents in six European countries.
abstract: OBJECTIVE
  Smoking contributes to socio-economic health inequalities; but it is unclear how smoking inequalities emerge at a young age. So far, little attention has been paid to the role of friendship ties. We hypothesised that the combination of peer exposure and friendship social homophily may contribute to socio-economic inequalities in smoking at school.
  
  
  METHODS
  In 2013, a social network survey was carried out in 50 schools in six medium-size European cities (Namur, Tampere, Hanover, Latina, Amersfoort, and Coimbra). Adolescents in grades corresponding to the 14-to-16 age group were recruited (n = 11.015, participation rate = 79.4 %). We modelled adolescents' smoking behaviour as a function of socio-economic background, and analysed the mediating role of social homophily and peer exposure.
  
  
  RESULTS
  Lower socio-economic groups were more likely to smoke and were more frequently exposed to smoking by their close and distant friends, compared with adolescents of higher SES. The smoking risk of the lowest socio-economic group decreased after controlling for friends smoking and social homophily.
  
  
  CONCLUSIONS
  Smoking socio-economic inequalities amongst adolescents are driven by friendship networks.
authors.affiliation: Institute of Health and Society, Université Catholique de Louvain, Clos chapelle aux champs 30/B1.30.15.05, 1200, Brussels, Belgium. Vincent.lorant@uclouvain.be.
authors.forename: Vincent
authors.initials: V
authors.lastname: Lorant
authors.affiliation: Institute of Health and Society, Université Catholique de Louvain, Clos chapelle aux champs 30/B1.30.15.05, 1200, Brussels, Belgium.
authors.forename: Victoria Soto
authors.initials: VS
authors.lastname: Rojas
authors.affiliation: Institute of Health and Society, Université Catholique de Louvain, Clos chapelle aux champs 30/B1.30.15.05, 1200, Brussels, Belgium.
authors.forename: Pierre-Olivier
authors.initials: PO
authors.lastname: Robert
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Jaana M
authors.initials: JM
authors.lastname: Kinnunen
authors.affiliation: Department of Public Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Mirte A G
authors.initials: MA
authors.lastname: Kuipers
authors.affiliation: Institute of Medical Sociology (IMS), Medical Faculty, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Moor
authors.affiliation: Department of Human Sciences, Society and Health, University of Cassino and Southern Lazio, Cassino, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Roscillo
authors.affiliation: National School of Public Health, University of Lisbon, Lisbon, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Alves
authors.affiliation: School of Health Sciences, University of Tampere, Tampere, Finland.|Department of Adolescent Psychiatry, Pitkäniemi Hospital, Nokia, Tampere University Hospital, Tampere, Finland.
authors.forename: Arja
authors.initials: A
authors.lastname: Rimpelä
authors.affiliation: Department of Human Sciences, Society and Health, University of Cassino and Southern Lazio, Cassino, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Federico
authors.affiliation: Institute of Medical Sociology (IMS), Medical Faculty, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Richter
authors.affiliation: National School of Public Health, University of Lisbon, Lisbon, Portugal.
authors.forename: Julian
authors.initials: J
authors.lastname: Perelman
authors.affiliation: Department of Public Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Anton E
authors.initials: AE
authors.lastname: Kunst
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D010379:Peer Group; D012574:Schools; D012907:Smoking / Q000453:epidemiology*; D012944:Social Support; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires
keywords: Adolescent; Smoking; Social network; Socio-economic inequalities