Migration and smoking: an epidemiological study of Finnish twins in Sweden.
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.
Jörgensen
Lena
L
Department of Epidemiology, Stockholm Centre for Public Health, Sweden. lena.jorgensen@sll.se
Hammar
Niklas
N
Kaprio
Jaakko
J
Koskenvuo
Markku
M
Svensson
Ake
A
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