The Impact of Forced Migration on Mortality: A Cohort Study of 242,075 Finns from 1939-2010

Understanding the Intergenerational Impact of Migration: An Adult Mortality Advantage for the Children of Forced Migrants?

BACKGROUND

Children of immigrants often have excess mortality rates, in contrast to the low mortality typically exhibited by their parents' generation. However, prior research has studied children of immigrants who were selected for migration, thereby rendering it difficult to isolate the intergenerational impact of migration on adult mortality.

METHODS

We use semiparametric survival analysis to carry out a total population cohort study estimating all-cause and cause-specific mortality among all adult men and women from age of 17 years among all men and women born in 1953-1972 and resident in Finland in 1970-2020. We compare children of forced migrants from ceded Karelia, an area of Finland that was ceded to Russia during the Second World War, with the children of parents born in present-day Finland.

RESULTS

Children with two parents who were forced migrants have higher mortality than children with two parents born in Northern, Southern, and Western Finland, but similar or lower mortality than the subpopulation of children whose parents were born in the more comparable areas of Eastern Finland. For women and men, a mortality advantage is largest for external causes and persists after controlling for socioeconomic factors.

CONCLUSION

Our findings suggest that forced migration can have a beneficial impact on the mortality of later generations, at least in the case where forced migrants are able to move to contextually similar locations that offer opportunities for rapid integration and social mobility. The findings also highlight the importance of making appropriate comparisons when evaluating the impact of forced migration.

What is the impact of forced displacement on health? A scoping review

While there is a broad literature analysing the effects of migration on health, important knowledge gaps persist particularly on the causal effects of forced displacement on health outcomes. We undertake a scoping review of applied epidemiological, statistical and econometric studies examining causal health impacts of forced displacement, which initially identified 1454 studies from the health and social sciences disciplines published up to May 2021. Our study makes two key contributions. First, we offer a comprehensive overview of the evidence generated, methodologies adopted and analytical challenges faced by current research examining the causal relationship between forced displacement and health. Second, we present concrete examples of how key challenges around study design and estimation approaches influence the strength of the evidence-base on the topic, using as a case study the broad domain of reproductive health. We find that, beyond the increased mortality risk that can be attributed to forced displacement, most of the available empirical evidence for a wide range of health outcomes is prone to substantial bias, making it difficult to draw firm conclusions. Our synthesis of credible studies conducted in different settings indicates that current research practice in the field could be strengthened through selection of valid control groups and application of more appropriate causal inference methods. Our findings are useful to promote the generation of further evidence on the topic that can reliably inform the design of policies to protect the health of displaced populations.

Forced Migration and the Childbearing of Women and Men: A Disruption of the Tempo and Quantum of Fertility?

It is well known that migrant fertility is associated with age at migration, but little is known about this relationship for forced migrants. We study an example of displacement in which the entire population of Finnish Karelia was forced to move elsewhere in Finland in the 1940s. This displacement was unique because of its size and scale, because we have data on almost the whole population of both men and women who moved, and because of the similarity between origin and destination. These aspects enable us to investigate the disruptive impact of forced migration, net of other factors such as adaptation and selection. For all ages at migration from one to 20, female forced migrants had lower levels of completed fertility than similar women born in present-day Finland, which suggests a permanent impact of migration. However, women born in the same year as the initial forced migration showed no difference, which may indicate the presence of a counterbalancing fertility-increasing effect, as observed elsewhere for people born during a humanitarian crisis. There is less evidence of an impact for men, which suggests a gendered impact of forced migration-and its timing-on fertility. Results are similar after controlling for social and spatial mobility, indicating that there may be no major trade-off between reproduction and these forms of mobility.

Prevalence of Suicide in Immigrants/Refugees: A Systematic Review and Meta-Analysis

OBJECTIVE

In recent years, there has been an increase in immigrant populations worldwide. This study aims to present the global prevalence of suicide between immigrants and refugees as well as to report the prevalence of suicide ideation, suicide mortality, suicide attempts, and plan of suicide.

METHOD

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA's) rules were used as a guide in the current research path. PubMed and EMBASE were targeted for the study until December 2019. After collecting the data, the number of events and sample size extracted for each study and also pooled odds ratio and confidence interval (CI) were used to investigate the suicide ratio among immigrants and refugees compared to the native population.

RESULTS

Fifty-one studies were included in the meta-analysis to investigate suicide prevalence or suicide odds ratio. The prevalence of suicidal ideation was 16% (CI: 0.12-0.20, I² = 99.4%), for attempted suicide was 6% (CI: 0.05-0.08, I² = 98.0%), and for suicide plan prevalence was 4% (CI: 0.00-0.08, I² = 96.8%). The prevalence of suicidal ideation was 10% (CI: 0.04-0.17, I² = 0.0%) in men and 17% (CI: 0.10-0.24, I² = 96.8%) in women. The prevalence of attempted suicide was 1% (CI: 0.01-0.02, I² = 0.0%) in men and 7% (CI: 0.03-0.10, I² = 94.4%) in women. The odds ratio of suicide mortality among immigrants was 0.91 (CI: 0.90-0.93, p < 0.001; I² = 97.6%) and for attempted suicide was 1.15 (CI: 1.10-1.20, p < 0.001; I² = 92.0%). Begg's test (p = 0.933) (Egger test; p = 0.936) rejected publication bias.

CONCLUSION

Given the high prevalence of suicide, especially suicide ideation and suicide attempts in immigrants, increased attention needs to be paid to the mental health of this population.

Mortality and major disease risk among migrants of the 1991-2001 Balkan wars to Sweden: A register-based cohort study

BACKGROUND

In recent decades, millions of refugees and migrants have fled wars and sought asylum in Europe. The aim of this study was to quantify the risk of mortality and major diseases among migrants during the 1991-2001 Balkan wars to Sweden in comparison to other European migrants to Sweden during the same period.

METHODS AND FINDINGS

We conducted a register-based cohort study of 104,770 migrants to Sweden from the former Yugoslavia during the Balkan wars and 147,430 migrants to Sweden from 24 other European countries during the same period (1991-2001). Inpatient and specialized outpatient diagnoses of cardiovascular disease (CVD), cancer, and psychiatric disorders were obtained from the Swedish National Patient Register and the Swedish Cancer Register, and mortality data from the Swedish Cause of Death Register. Adjusting for individual-level data on sociodemographic characteristics and emigration country smoking prevalence, we used Cox regressions to contrast risks of health outcomes for migrants of the Balkan wars and other European migrants. During an average of 12.26 years of follow-up, being a migrant of the Balkan wars was associated with an elevated risk of being diagnosed with CVD (HR 1.39, 95% CI 1.34-1.43, p < 0.001) and dying from CVD (HR 1.45, 95% CI 1.29-1.62, p < 0.001), as well as being diagnosed with cancer (HR 1.16, 95% CI 1.08-1.24, p < 0.001) and dying from cancer (HR 1.27, 95% CI 1.15-1.41, p < 0.001), compared to other European migrants. Being a migrant of the Balkan wars was also associated with a greater overall risk of being diagnosed with a psychiatric disorder (HR 1.19, 95% CI 1.14-1.23, p < 0.001), particularly post-traumatic stress disorder (HR 9.33, 95% CI 7.96-10.94, p < 0.001), while being associated with a reduced risk of suicide (HR 0.68, 95% CI 0.48-0.96, p = 0.030) and suicide attempt (HR 0.57, 95% CI 0.51-0.65, p < 0.001). Later time period of migration and not having any first-degree relatives in Sweden at the time of immigration were associated with greater increases in risk of CVD and psychiatric disorders. Limitations of the study included lack of individual-level information on health status and behaviors of migrants at the time of immigration.

CONCLUSIONS

Our findings indicate that migrants of the Balkan wars faced considerably elevated risks of major diseases and mortality in their first decade in Sweden compared to other European migrants. War migrants without family members in Sweden or with more recent immigration may be particularly vulnerable to adverse health outcomes. Results underscore that persons displaced by war are a vulnerable group in need of long-term health surveillance for psychiatric disorders and somatic disease.

The Impact of Forced Migration on Mortality: Evidence From German Pension Insurance Records

We examine the long-run effects of forced migration for individuals who were displaced from Eastern Europe to Germany in the aftermath of World War II. Evidence suggests that displaced individuals were worse off economically, facing a considerably lower income and a higher unemployment risk than comparable nondisplaced Germans, even 20 years after being expelled. We extend this literature by investigating mortality outcomes. Using social security records that document the exact date of death and a proxy for pre-retirement lifetime earnings, we estimate a significantly and considerably higher mortality risk among forced migrants compared with nondisplaced West Germans. The adverse displacement effect persists throughout the earnings distribution except for the top quintile. Although forced migrants were generally worse off regarding mortality outcomes, those with successful labor market histories seem to have overcome the long-lasting negative consequences of flight and expulsion.

Does the Type of Temporary Housing Make a Difference in Social Participation and Health for Evacuees of the Great East Japan Earthquake and Tsunami? A Cross-Sectional Study

Background

Although the majority of survivors of the huge Great East Japan Earthquake and Tsunami evacuated to two types of temporary housings, prefabricated housing and rented housing, health effects of these different environments were unclear. We examined whether prevalent social participation in prefabricated housing brought larger health benefits than in rented housing using the largest health survey data of the disaster survivors.

Methods

This cross-sectional study used a 2012 survey by the Miyagi Prefectural Government, in which almost all of evacuees were targeted (response rate: 61.6%). Self-rated health (SRH) and psychological distress measured via K6 score were the dependent variables, and social participation was the independent variable. Odds ratios of the social participation on health variables were estimated using logistic regression models. To assess the contribution of social participation, the population attributable fraction (PAF) was estimated.

Results

The participants lived in prefabricated and rented housing numbered 19,726 and 28,270, respectively. Participants in prefabricated housing had poorer SRH and K6 than those in rented housing. The proportions of participants engaging in social participation of prefabricated and rented housing were 38.2% and 15.4%, respectively. The absence of social participation was significantly associated with poor SRH and K6 among participants in both housing types. The PAFs of social participation with good SRH were 39.5% in prefabricated housing and 14.4% in rented housing. For K6, the PAFs were 47.1% and 19.5% in prefabricated and rented housing, respectively.

Conclusion

Compared to the residents in rented housing, residents in prefabricated housing had more frequent opportunities for social participation, which was associated with larger health benefits.

Calibration adjustments to address bias in mortality analyses due to informative sampling-a census-linked survey analysis in Switzerland

BACKGROUND

Sampling bias, like survey participants' nonresponse, needs to be adequately addressed in the analysis of sampling designs. Often survey weights will be calibrated on specific covariates related to the probability of selection and nonresponse to get representative population estimates. However, such calibrated survey (CS) weights are usually constructed for cross-sectional results, but not for longitudinal analyses. For example, when the outcome of interest is time to death, and sampling selection is related to time to death and censoring, sampling is informative. Then, unweighted or CS weighted inferential statistical analyses may be biased. In 2010, Switzerland changed from a decennial full enumeration census to a yearly registry-based (i.e., data from harmonised community registries) and a survey-based census system. In the present study, we investigated the potential bias due to informative sampling when time to death is the outcome of interest, using data from the new Swiss census system.

METHODS

We analysed more than 6.5 million individuals aged 15 years or older from registry-based census data from years 2010 to 2013, linked with mortality records up to end of 2014. Out of this population, a target sample of 3.5% was sampled from the Swiss Federal Statistical Office (SFSO) in a stratified yearly micro census. The SFSO calculated CS weights to enable representative population estimates from the micro census. We additionally constructed inverse probability (IP) weights, where we used survival information in addition to known sampling covariates. We compared CS and IP weighted mortality rates (MR) and life expectancy (LE) with estimates from the underlying population. Additionally, we performed a simulation study under different sampling and nonresponse scenarios.

RESULTS

We found that individuals who died in 2011, had a 0.67 (95% CI [0.64-0.70]) times lower odds of participating in the 2010 micro census, using a multivariable logistic regression model with covariates age, gender, nationality, civil status, region and survival information. IP weighted MR were comparable to estimates from the total population, whereas CS weighted MR underestimated the population MR in general. The IP weighted LE estimates at age 30 years for men were 50.9 years (95% CI [50.2-51.6] years), whereas the CS weighted overestimated LE by 2.5 years. Our results from the simulation study confirmed that IP weighted models are comparable to population estimates.

CONCLUSION

Mortality analyses based on the new Swiss survey-based census system may be biased, because of informative sampling. We conclude that mortality analyses based on census-linked survey data have to be carefully conducted, and if possible, validated by registry information to allow for unbiased interpretation and generalisation.

Invited commentary: The long term impact of forced migration during childhood on adult health

Saarela and Elo (SSM-Population Health; Volume 2, December 2016, Pages 813–823) provide new evidence of early life forced displacement not being adversely associated with adult health. Their study highlights some of the challenges to identifying a causal effect of childhood exposure on adult health in the context of complex emergencies. Importantly, it opens up for future research that can address commonly recognized sources of bias and identify intervening pathways linking forced migration with adult health outcomes.