The stresses and life changes associated with migration may have harmful long-term health effects, especially for mental health. These effects are exceedingly difficult to establish, because migrants are typically a highly selected group.
We examined the impact of migration on health using “naturally occurring” historical events. In this article, we use the forced migration of 11% of the Finnish population after WWII as such a natural experiment. We observed the date and cause of death starting from 1 January 1971 and ending in 31 December 2010 for the cohort of 242,075 people. Data were obtained by linking individual-level data from the 1950 and 1970 population censuses and the register of death certificates from 1971 to 2010 (10% random sample). All-cause and cause-specific mortalities were modeled using Poisson regression.
Models with full adjustment for background variables showed that both all-cause mortality (RR 1.03, 95% CI 1.01, 1.05), and ischemic heart disease mortality (RR 1.11, 95% CI 1.08, 1.15) were higher in the displaced population than in the nondisplaced population. Suicide mortality was lower (RR 0.77, 95% CI 0.64, 0.92) in displaced than in the general population.
In our long-term follow-up study, forced migration was associated with increased risk of death due to ischemic heart diseases. In contrast, lower suicide mortality was observed in association with forced migration 25 years or more.
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From the aClinicum, Department of Public Health, University of Helsinki, Helsinki, Finland; bMental Health Unit, National Institute for Health and Welfare, Helsinki, Finland; cDepartment of Economics, Aalto University School of Business, Helsinki, Finland; dVATT Institute for Economic Research, Helsinki, Finland; ePopulation Research Unit, Department of Social Research, University of Helsinki, Helsinki, Finland; fCentre for Health Equity Studies, Stockholm University and Karolinska Institutet, Stockholm, Sweden; and gMax Planck Institute for Demographic Research, Rostock, Germany.
Submitted 3 May 2016; accepted 28 March 2017.
Financially supported by Yrjö Jansson Foundation (Grant Number 5919).
The authors report no conflicts of interest.
J.H., J.S., M.S., and P.M. designed the study. J.H., M.S., and P.M. collected data, and J.H. analyzed data. J.H. prepared results and wrote the first draft of the report with input from other authors. All authors commented on draft report and approved the final version.
Data are not available in open access. Source code of analyses is available from corresponding author by request.
Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).
Correspondence: Jari Haukka, Clinicum, Department of Public Health, University of Helsinki, Helsinki, Finland. E-mail: email@example.com.