title: Migration and smoking: an epidemiological study of Finnish twins in Sweden.
abstract: BACKGROUND
  Male migrants from Finland to Sweden have been found to have a reduced risk of coronary heart disease after several years in Sweden. Changes in smoking habits may contribute to this reduced risk.
  
  
  OBJECTIVE
  A study was undertaken to compare smoking habits in Finnish migrants to Sweden and subjects always living in Finland and to analyse whether the migration may have influenced smoking.
  
  
  METHODS
  The study population consisted of same-sex twin pairs born in Finland younger than 76 years with at least one twin that had migrated to Sweden (n = 1,083 pairs). Smoking habits obtained by mailed questionnaire were compared in migration-discordant twin pairs to take into account early childhood and genetic factors.
  
  
  RESULTS
  Immigrants and returnees with a history of smoking had predominantly started to smoke before the migration. Among women, immigrants to Sweden smoked more than never migrants in Finland, odds ratio (OR) 2.1 for current smokers (95% confidence interval CI 1.4-3.3) but this difference was already present before migration. In men there were essentially no differences in smoking prevalence between immigrants and never migrants but heavy smoking was less common among immigrants than among never migrant smokers, OR 0.5 (95% CI 0.2-0.9) and migration was associated with a greater propensity to cease smoking.
  
  
  CONCLUSIONS
  Migration from Finland to Sweden does not seem to have had a strong influence on smoking among migrants. A favourable trend in smoking habits after migration may in part have contributed to reduced mortality and incidence of coronary heart disease in male Finnish migrants after several years in Sweden.
authors.affiliation: Department of Epidemiology, Stockholm Centre for Public Health, Sweden. lena.jorgensen@sll.se
authors.forename: Lena
authors.initials: L
authors.lastname: Jörgensen
authors.forename: Niklas
authors.initials: N
authors.lastname: Hammar
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
authors.forename: Ake
authors.initials: A
authors.lastname: Svensson
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003327:Coronary Disease / Q000208:ethnology / Q000209:etiology; D004641:Emigration and Immigration; D005260:Female; D005387:Finland / Q000208:ethnology; D006801:Humans; D008297:Male; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology* / Q000208:ethnology; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology / Q000208:ethnology; D014427:Twins