All-cause mortality by income level in working- age migrants and the majority settled population of Finland: a follow-up from 2001 to 2014
Kouvonen, A., Patel, K., Koskinen, A., Kokkinen, L., Donnelly, M., O'Reilly, D. & Vaananen, A. (2017) UK Administrative Data Research Network Annual Research Conference, Royal College of Surgeons, Edinburgh, UK, 1 - 2 June 2017
In most studies migrants seem to display a survival advantage over the settled population, but the relationship with income is as yet unknown. The aim of this record-linkage study was to explore the relationship between income and the risk of mortality between the settled majority population and different migrant groups.
A random sample of 1,058,381 working age people (age range 18 to 64 years) living in Finland in 2000 were drawn from the Finnish Population Register, and linked to mortality data from 2001 to 2014 obtained from the National Death Register. Records were linked by national, personal ID numbers. We formed five different regions of birth: Finland; Russia or USSR; Eastern Europe and the Balkans; Western Europe and other Western countries; and Africa, Middle East and Asia. We assigned each person to one of two income classes, 'high' or 'low' income, calculated from the median income (from work and benefits) of the entire cohort in 2001. Cox proportional hazard models were used to investigate the association between migrant status and all-cause mortality.
After adjustment for age, sex, marital status, and employment status, the risk of mortality was significantly reduced for low-income migrants when compared to the majority Finnish population (hazard ratio, 0.46 (95% CI 0.42-0.50)). Results comparing high-income groups were not statistically significant. Low-income migrants from Africa, the Middle East and Asia had the lowest mortality risk of any group studied (hazard ratio, 0.32 (95% CI 0.27-0.39)).
Particularly low-income migrants seem to display a survival advantage when compared to the corresponding income group in the settled majority. We suggest that downward social mobility, differences in health-related lifestyles, and healthy migrant effect may explain this phenomenon.