Healthy Migrant Hypothesis Research Articles

Impact of migration status on incidence of depression in the middle-aged and elderly population in China: Exploring healthy migrant and salmon bias hypotheses from a mental health perspective

BackgroundThe healthy migrant and salmon bias hypotheses stipulate that those who are healthier are more likely to migrate (a selection effect) and unhealthy migrants have a greater tendency to return to their origin communities than healthier migrants. It remains unclear whether the hypotheses are relevant for mental health, although they have robust evidence for physical health. The current study expands the theoretical foundation underlying these hypotheses by exploring the impact of migration status on depression among the middle-aged and older population in China. MethodLongitudinal data from the China Health and Retirement Longitudinal Study (CHARLS) in 2011, 2013, 2015 and 2018 were used. Participants were divided into three groups, non-migrants, permanent migrants, and return-migrants according to their migration status. The Chinese version of 10-item Center for Epidemiologic Studies Depression Scale was used to assess clinically relevant depressive symptoms. Incidence were estimated by each migration status and compared across strata using log-rank tests. Cox regression models were fit to assess the relationship between migration status and depression incidence. ResultsA total of 9264 middle-aged and elderly participants were included, of whom 7047 (76.1 %) were non-migrants, 1065 (11.5 %) were permanent migrants, and 1152 (12.4 %) were return-migrants, respectively. Incidence rates of depression by different migration statuses were 76.6/103 person-years (73.7/103–79.7/103) in non-migrants, 62.9/103 person-years (55.9/103–70.6/103) in permanent migrants, and 67.3/103 person-years (60.7/103–74.5/103) in return-migrants. After controlling for covariates, only permanent migrants had significantly lower incidence of depression than non-migrants (HR: 0.85 (0.75, 0.96)). After stratifying by current place of residence, urban-permanent-migrants had a lower risk of depression than both rural and urban non-migrants, and the HRs and 95%CIs were 0.62 (0.52–0.74) and 0.81 (0.68–0.97). LimitationsMigration statuses of participants may have changed over time, but due to the lack of raw data on migration status in 2013 and 2015, we used migration status at baseline. We were also not able to contextualize the migration experiences among those who migrated, and these trajectories may be heterogeneous. ConclusionUsing depression as an indicator of mental health, the healthy migrant hypothesis was supported among middle-aged and elderly permanent migrants living in urban areas while the salmon bias hypothesis was not. Significant urban-rural inequities in mental health existed among different types of migrants. Especially among permanent migrants who have migrated and converted Hukou from their original registration place to their current residence.

Pre- and post-COVID-19 all-cause mortality of Japanese citizens versus foreign residents living in Japan, 2015–2021

Immigrants in Japan face multiple health care challenges. There is limited research addressing how all-cause mortality differs between foreign residents and Japanese citizens, including the impact of the COVID-19 pandemic. We assessed whether all-cause mortality rates between Japanese citizens and foreign residents living in Japan differ, and whether these differentials changed after the start of the COVID-19 pandemic. We conducted a cross-sectional analysis using vital statistical data of all deaths among citizens and foreign residents that occurred within Japanese borders aggregated every 6 months between January 1, 2015 and June 30, 2021. Data were used to calculate sex-, region-, and 20-year age group-specific standardized mortality rates using the direct method based on the population distribution of Japanese citizens in 2021 by sex, region, and 20-year age groups. Chi-squared tests and linear regression were used to assess whether the pandemic was associated with changes in mortality rates among groups and changes in the mortality differentials between citizens and non-citizens, respectively. All-cause mortality increased monotonically with age for men and women. Men had higher mortality than women, regardless of age or nationality. All-cause mortality is lower among immigrants than Japanese citizens between the ages of 20–59, but higher under the age of 20 and over the age of 59. The pandemic was associated with significant changes in mortality in most groups, but no statistically significant changes in the mortality differentials between immigrants and Japanese citizens were detected. Young immigrants are generally healthier than their Japanese counterparts, in line with the healthy migrant hypothesis. Younger migrants are at higher risk of mortality, possibly due to increased vulnerability to psychologic stress. Older migrant mortality converged with citizen mortality, consistent with acculturation that occurs with longer duration of residence. The pandemic did not exacerbate health inequities for foreign residents with respect to mortality.

112. Age of Immigration and Depressive Symptoms among Latinx Young Adults who Arrived in the US as Children: A Test of Mediational Models

Immigration to the US at younger age is associated with a higher risk of developing depression. Several theories provide possible explanations for this relationship, but none of have been empirically tested. Cultural Stress Theory suggests that individuals who immigrate at an earlier age will undergo more cumulative stress as they acculturate to the US, eventually leading to depression. The Healthy Migrant Hypothesis posits that only those individuals who are mentally and physically well will make the decision to immigrate; however, many children cannot make this decision for themselves, leading to increased migration of younger individuals who may be predisposed to depression.

Has Rural-Urban Migration Promoted the Health of Chinese Migrant Workers？.

The relationship between health and migration has always been an important theme in immigration research. This research develops a new approach to test the healthy migrant hypothesis and the salmon bias hypothesis in China by examining an interaction term combining agricultural hukou and migrant status, non-agricultural employment history, and subsequent area of residence. Based on two Chinese micro-databases, CGSS 2015 and Harmonized CHARLS, we conducted an empirical test on the relationship between migration and health. Our empirical evidence suggests that the initial health advantage among Chinese rural migrant workers was largely due to self-selection rather than migration effects. After controlling for demographic and socioeconomic characteristics, this advantage disappeared. After their health deteriorated, migrant workers returned to their original location. This could exacerbate the contradiction between the allocation of medical resources and the demand in rural and urban China, further intensifying the already widening health status gap between rural and urban residents.

Health Selectivity and Rural-Urban Migration in China: A Nationwide Multiple Cross-Sectional Study in 2012, 2014, 2016.

Background: China is undergoing an unprecedented rural-urban migration, which may deeply influence the health of internal migrants. Previous studies suggested that migrants are a selectively healthier population. This paper examines the evidence for and the changes of health selectivity among Chinese internal migrants. Methods: We use data from the China Labor-force Dynamics Survey (CLDS), a nationally representative survey conducted in 2012, 2014, and 2016, respectively. The health statuses of four groups of research subjects (out-migrants, returned migrants, rural residents, and urban residents) are measured by general health, physical health, and emotional health. Results: By comparing the health status of migrants with that of rural residents, we find supportive evidence for the Healthy Migrant Hypothesis that migrants exhibit better health than rural residents in their hometown. We also add strength to the Salmon Bias Hypothesis that migrants returning to their hometowns are less healthy than those still being outside. However, migrants present worse emotional health in both comparisons. The general and physical health gaps between migrants, rural residents, and returnees widened in all three rounds of the survey, which implies a possibly increasing trend of health selectivity. This study also suggests that bringing family to the destination requires better general and physical health, but not emotional health. Conclusions: Migrants are positively selected on general and physical health. The health selectivity in 2012–2016 is highly likely to increase, which means that there are increasing number of obstacles for migrants to overcome. Family migration’s high requirement for health might also contribute to it. It is urgent to establish and improve primary health care service systems in rural areas in current circumstances.

Do migrants have a mortality advantage?

Do migrants have a mortality advantage?

Immigrants and mental disorders in the united states: New evidence on the healthy migrant hypothesis

ObjectivesDespite experiencing migration-related stress and social adversity, immigrants are less likely to experience an array of adverse behavioral and health outcomes. Guided by the healthy migrant hypothesis, which proposes that this paradox can be explained in part by selection effects, we examine the prevalence and comorbidity of mental disorders among immigrants to the United States (US). MethodsFindings are based on the National Epidemiologic Survey on Alcohol and Related Conditions (2012–2013), a nationally representative survey of 36,309 adults in the US. ResultsImmigrants were significantly less likely than US-born individuals to meet criteria for a lifetime disorder (AOR = 0.63, 95% CI = 0.57–0.71) or to report parental history of psychiatric problems. Compared to US-born individuals, the prevalence of mental disorders was not significantly different among individuals who immigrated as children; however, differences were observed for immigrants who arrived as adolescents (ages 12–17) or as adults (age 18+). DiscussionConsistent with the healthy migrant hypothesis, immigrants are less likely to come from families with psychiatric problems, and those who migrate after childhood—when selection effects are most likely to be observed—have the lowest levels of psychiatric morbidity.

Investigating Health Selection Within Mexico and Across the US Border

Despite acquiring lower levels of attainment and earnings, Mexican immigrants exhibit favorable health outcomes relative to their native-born counterparts. And while scholars attempt to reconcile this so-called paradoxical relationship with a variety of theoretical and empirical approaches, patterns of selective migration continue to receive considerable attention. The present study contributes to the literature on health selection by extending the healthy migrant hypothesis in a number of ways. First, we rely on a unique combination of data sets to assess whether the healthy are disproportionately more likely to migrate. We use the latest wave of the Mexican Family Life Survey and the 2013 Migrante Study, a survey that is representative of Mexican-born persons who are actively migrating through Tijuana. Pooling these data also allow us to differentiate between internal and US-bound migrants to shed light on their respective health profiles. Results provide modest support for the healthy migrant hypothesis. Although those who report better overall health are more likely to migrate, we find that the presence of certain chronic conditions increases migration risk. Our findings also suggest that internal migrants are healthier than those traveling to the US, though this is largely because those moving within Mexico reflect a younger and more educated population. This study takes an important step in uncovering variation across migrant flows and highlights the importance of the timing at which health is measured in the migration process.

Self-rated health and wellbeing among the working-age immigrant population in Western Europe: findings from the European social survey (2014) special module on the social determinants of health.

The aim is to study the difference in self-rated health and wellbeing between native non-migrants and different immigrant groups: new (defined as having lived in the host country for 10 years or less), old (living in the host country for more than 10 years) and second-generation immigrants living in Western European countries. We use the European Social Survey Round 7, collected in 2014/15, to study the working-age population aged 20–64. We separate between first (new and old) and second-generation immigrants. Self-rated health was dichotomised as very good and good versus less than good health. Wellbeing was measured by constructing a continuous scale from eight 4-point Likert scale items (CES-D8). Data for 14 Western European countries were pooled together (N = 18 577). Men and women were analyzed separately using binary logistic and OLS regression. For self-rated health, we found support among both men and women for the healthy migrant hypothesis. Among men only, second-generation immigrants had more deteriorating self-rated health by age, and old immigrants were similar to the natives. The four groups differed in wellbeing only among those with primary education, and more so among men than among women. Second-generation immigrants were worse and new immigrants better than natives and old immigrants. This study supports the healthy migrant hypothesis among both men and women. Among men, old and second-generation immigrants’ predicted health falls more steeply by age. There was some variation between migrant groups in wellbeing among those with low education.

Health status and migration: a propensity score matching with difference-in-difference regression approach

BackgroundBy 2014, about 253 million Chinese migrants had left their rural hometowns and were working in cities. The effect of migration on health is unclear, since it is affected by changes in environments and behaviours over the course of migration. Furthermore, previous studies have not thoroughly considered the “healthy migrant hypothesis” (that is, healthy people are more conducive to migrate). This paper strives to explore the potential mechanisms of migration and health over two successive years to provide a useful reference point for health policy targeted at migrants. MethodsData were collected from 9576 participants aged 15–64 years from the 2012 and 2014 China Labour Force Dynamic Survey (a nationwide cross-sectional survey covering 29 provinces with a multi-stage cluster, stratified, probability sampling strategy). The variables of migration included whether to migrate (the treatment and control groups were migrants and non-migrants, respectively), duration of migration, and migration distance during 2012–14. The variables of health status were changes of self-rated general health, physical health, and emotional health between 2012 and 2014. Controlled variables included medical security, and general and occupational health behaviour during 2012–14. We used propensity score matching (PSM) and difference-in-difference (DID) methods to examine potential mechanisms by controlling for the healthy migrant hypothesis. Ethical approval was obtained from Sun Yat-sen University (Guangdong, China). Informed consent was obtained from all participants. FindingsAfter PSM, health status in 2012 remained the same between the matched treatment and the control groups, suggesting that the healthy migrant hypothesis was successfully controlled (that is, the health difference between the two groups can be controlled). Using DID, we found that working overtime and lacking regular health check-ups were factors that worsened the general health of migrant workers after controlling for variables of age, sex, education, working hours, signing the labour contract and buying insurance (p<0·0001); lack of occupational protection measures and lack of regular health check-ups were factors worsening the physical health of migrant workers (p<0·0001). However, we noted no direct migration effect on health. InterpretationThis study provides convincing evidence that priority should be given to improving occupational safety and medical security for migrants. FundingNone.

The generational gap: Mental disorder prevalence and disability amongst first and second generation immigrants in Australia

Despite unprecedented numbers of migrants internationally, little is known about the mental health needs of immigrant groups residing in common countries of resettlement. The majority of studies support the ‘healthy migrant hypothesis’, but few studies have examined: 1) shifts in prevalence patterns across generations; 2) how prevalence relates to disability in immigrant groups. Our study examined the prevalence of common mental disorders and disability in first and second generation migrants to Australia. Twelve-month and lifetime prevalence rates of affective, anxiety, and substance use disorders were obtained from the Australian National Survey of Mental Health and Wellbeing (N = 8841). First generation immigrants (born overseas) and second generation immigrants (both parents overseas) from non-English and English speaking backgrounds were compared to an Australian-born cohort. Disability was indexed by days out of role and the WHO Disability Assessment Schedule (WHODAS12). First generation immigrants with non-English speaking (1G-NE) backgrounds evidenced reduced prevalence of common mental disorders relative to the Australian-born population (adjusted odds ratio 0.5 [95% CI 0.38–0.66]). This lower prevalence was not observed in second generation immigrant cohorts. While overall levels of disability were equal between all groups (p > 0.05), mental health-related disability was elevated in the 1G-NE group relative to the Australian-born group (p = 0.012). The findings challenge the overarching notion of the “healthy migrant” and suggest a dissociation between reduced prevalence and elevated mental health-related disability amongst first generation immigrants with non-English speaking backgrounds. These findings highlight the heterogeneous psychiatric needs of first and second generation immigrants.

Healthy or unhealthy migrants? Identifying internal migration effects on mortality in Africa using health and demographic surveillance systems of the INDEPTH network

Migration has been hypothesised to be selective on health but this healthy migrant hypothesis has generally been tested at destinations, and for only one type of flow, from deprived to better-off areas. The circulatory nature of migration is rarely accounted for. This study examines the relationship between different types of internal migration and adult mortality in Health and Demographic Surveillance System (HDSS) populations in West, East, and Southern Africa, and asks how the processes of selection, adaptation and propagation explain the migration-mortality relationship experienced in these contexts. The paper uses longitudinal data representing approximately 900 000 adults living in nine sub-Saharan African HDSS sites of the INDEPTH Network. Event History Analysis techniques are employed to examine the relationship between all-cause mortality and migration status, over periods ranging from 3 to 14 years for a total of nearly 4.5 million person-years. The study confirms the importance of migration in explaining variation in mortality, and the diversity of the migration-mortality relationship over a range of rural and urban local areas in the three African regions. The results confirm that the pattern of migration-mortality relationship is not exclusively explained by selection but also by propagation and adaptation. Consequences for public health policy are drawn.

An investigation of the healthy migrant hypothesis: Pre-emigration characteristics of those in the British 1946 birth cohort study.

The finding that migrants to high-income countries have lower rates of morbidity and mortality than non-migrants, controlling for socioeconomic position, is often attributed to the "healthy migrant" hypothesis, which suggests that only the healthiest individuals choose to migrate. This prospective study investigates the healthy migrant hypothesis in a cohort of British emigrants using pre-migration health indicators. We also investigate how early-life health characteristics relate to age at emigration and whether or not the emigrant returned home. Data are from the Medical Research Council National Survey of Health and Development, a nationally representative cohort study of people born in England, Scotland or Wales in March 1946. Childhood socio-economic position, health and cognitive ability were compared between 4,378 non-emigrants and 984 emigrants. Of the emigrants, 427 emigrated before age 20 and 557 after that age; 602 emigrants remained abroad and 382 returned home. Emigrants had better childhood health (especially greater height), higher childhood socio-economic position and better childhood cognitive ability at age 8 than non-emigrants. Return emigrants were very similar to emigrants who remained abroad. We found support for the healthy migrant hypothesis in a cohort of British emigrants. Our findings improve an understanding of how health is distributed within and across nations.

Rural-to-Urban Migration and Changes in Health Among Young Adults in Thailand.

We investigate the impacts of rural-to-urban migration on the health of young adult migrants. A key methodological challenge involves the potentially confounding effects of selection on the relationship between migration and health. Our study addresses this challenge in two ways. To control for potential effects of prior health status on post-migration health outcomes, we employ a longitudinal approach. To control for static unobserved characteristics that can affect migration propensity as well as health outcomes, we use fixed-effects analyses. Data were collected in 2005 and 2007 for a cohort of young adults in rural Kanchanaburi province, western Thailand. The migrant sample includes individuals who subsequently moved to urban destinations where they were reinterviewed in 2007. Return migrants were interviewed in rural Kanchanaburi in both years but moved to an urban area and returned in the meantime. A rural comparison group comprises respondents who remained in the origin villages. An urban comparison sample includes longer-term residents of the urban destination communities. Physical and mental health measures are based on the SF-36 health survey. Findings support the "healthy migrant hypothesis." Migrants are physically healthier than their nonmigrant counterparts both before and after moving to the city. We did not find an effect of migration on physical health. Rural-to-urban migrants who stayed at destination experienced a significant improvement in mental health status. Fixed-effects analyses indicate that rural-to-urban migration positively affects mental health. Return migrants do not fare as well as migrants who stayed at destination on both physical and mental health status--evidence of selective return migration.

Beyond Networks: Health, Crime, and Migration in Mexico

Two rounds of a longitudinal survey from Mexico, representative at the national, urban, rural, and regional level, are used to examine the determinants of local, domestic, and international migration. Aside from the typical covariates in the migration decision, this study considers health conditions, crime, and individual’s perspectives on life as explanatory variables. Coefficient estimates for most health variables do not offer significant support to the healthy migrant hypothesis. In terms of crime, the results suggest that females respond to worsening safety conditions in Mexico by migrating domestically, but not abroad. The decision to migrate domestically or abroad for males is not statistically correlated with increases in crime. Overall, having access to international migration networks continues to play a significant role in the decision to migrate to the US.

Duration of residence and disease occurrence among refugees and family reunited immigrants: test of the ‘healthy migrant effect’ hypothesis

The 'healthy migrant effect' (HME) hypothesis postulates that health selection has a positive effect on migrants' health outcomes, especially in the first years after migration. We examined the potential role of the HME by assessing the association between residence duration and disease occurrence. We performed a historical prospective cohort study. We included migrants who obtained residence permits in Denmark between 1 January 1993 and 31 December 2010 (n = 114,331). Occurrence of severe conditions was identified through linkage to the Danish National Patient Register. Hazard Ratios (HRs) were modelled for disease incidence by residence duration since arrival (0-5 years; 0-10 years; 0-18 years) adjusting for age and sex. Compared with Danish-born individuals, refugees and family reunited immigrants had lower HRs of stroke and breast cancer within 5 years after arrival; however, HRs increased at longer follow-up. For example, HRs of stroke among refugees increased from 0.77 (95% CI: 0.66; 0.91) to 0.96 (95% CI: 0.88; 1.05). For ischaemic heart disease (IHD) and diabetes, refugees and family reunited migrants had higher HRs within 5 years after arrival, and most HRs had increased by end of follow-up. For example, HRs of IHD among family reunited migrants increased from 1.29 (95% CI: 1.17; 1.42) to 1.43 (95% CI: 1.39; 1.52). In contrast, HRs for TB and HIV/AIDS showed a consistent decrease over time. Our analyses of the effect of duration of residence on disease occurrence among migrants imply that, when explaining migrants' advantageous health outcomes, the ruling theory of the HME should be used with caution, and other explanatory models should be included.

The Immigrant and Hispanic Paradoxes: A Systematic Review of Their Predictions and Effects.

A survey of the literature indicates that reported advantages of the Immigrant and Hispanic Paradox are inconsistent and equivocal. The healthy migrant hypothesis also suggests that current research approaches consider only "healthy" groups. Other methodological concerns include the simple underreporting of deaths, and that commonly used databases may not include all significant attributes and characteristics. We conducted a systematic review, synthesizing and identifying themes not explicitly found in the current literature. We also employ a simple quantitative index to assess the scholarly strength of references. Paradox protection appears uneven and is not generalizable across races, ethnicities, age groups and genders. In addition, acculturation, health behaviors and diet, ethnicity, acculturative stress, adolescence, undocumented and uninsured status, age of arrival in the United States and length of exposure, gender and age appear to be significant in predicting any beneficial effects.

HEALTH SELECTION EFFECTS IN CHINA'S INTERNAL MIGRATION

Drawing data from the 2008 survey of Internal Migration and Health in China, we compare various health indicators among current rural-to-urban migrants, rural residents who never migrated, return migrants, and urban citizens. Two health-selective mechanisms, the healthy migrant hypothesis and the salmon bias hypothesis, are empirically tested. Results provide empirical support to both these hypotheses. After controlling for individual's age, sex, socioeconomic status and major health-related behaviours, current rural-to-urban migrants are still better off than rural residents who never migrated regarding their self-rated general health, chronic diseases, self-perceived physical discomfort and lung capacity. Current rural-to-urban migrants are also less likely to have chronic diseases or to report physical discomfort than return migrants. Except for self-reported chronic diseases and abnormally high heart rate, there is no significant difference between rural-to-urban migrants and urban residents regarding the health measures used in this study.

Suburban Migration and the Birth Outcome of Chicago-Born White and African–American Women: The Merit of the Healthy Migrant Theory?

The healthy migrant theory posits that women who migrate before pregnancy are intrinsically healthier and therefore have better birth outcomes than those who don't move. Objective. To determine whether migration to the suburbs is associated with lower rates of preterm (<37weeks) birth among Chicago-born White and African-American mothers. We performed stratified and multilevel logistic regression analyses on an Illinois transgenerational dataset of non-Latino White and African-American infants (1989-1991) and their mothers (1956-1976) with appended US census income information. Forty percent of Chicago-born White mothers (N=45,135) migrated to Suburban Cook County and 30% migrated to the more geographically distant collar counties. In contrast, 10% of Chicago-born African-American mothers (N=41,221) migrated to Suburban Cook and only two percent migrated to the collar counties. Chicago-born White and African-American migrant mothers to Suburban Cook County had lower preterm birth rates than their non-migrant counterparts; RR=0.8 (0.8-0.9) and 0.8 (0.7-0.8), respectively. When neighborhood income was singularly taken into account, the protective association of suburban migration and preterm birth disappeared among Chicago-born Whites. In race-specific multilevel multivariate regression models which included neighborhood income, the adjusted odds ratio of preterm birth, low birth weight, and small for gestational-age for Chicago-born White and African-American migrant (compared to non-migrant) mothers approximated unity. Neighborhood income underlies the protective association of suburban migration and birth outcome among Chicago-born White and African-American mothers. These findings do not support the healthy migrant hypothesis of reproductive outcome.

Understanding ethnic and nativity-related differences in low cardiovascular risk status among Mexican-Americans and non-Hispanic Whites

ObjectiveRecent guidelines highlight the importance of improving cardiovascular health in the general population in addition to disease prevention among high risk individuals. We investigated factors associated with ethnic and nativity-related differences in the prevalence of low cardiovascular risk (optimal levels of all major cardiovascular risk factors). MethodsWe used logistic regression to estimate differences in likelihood of being low risk (not currently smoking; no diabetes; untreated total cholesterol <200mg/dL; untreated blood pressure <120/<80; and body mass index <25kg/m2) among 8693 foreign- and U.S.-born Mexican-American and non-Hispanic White 2003–2008 U.S. National Health and Nutrition Examination Survey participants before and after adjustment for socioeconomic, lifestyle, and acculturation-related factors. ResultsForeign-born Mexican-Americans were more likely to be low risk than non-Hispanic Whites after adjustment for all covariates (Odds Ratio [OR]: 1.53; 95% Confidence Interval [CI]: 1.00, 2.34). In contrast, U.S.-born Mexican-Americans were less likely to be low risk compared to Whites (OR: 0.60; 95% CI: 0.43, 0.84). Differences between foreign-born and U.S.-born Mexican-Americans were largely attenuated after adjustment for acculturation indicators. ConclusionsOur findings support the healthy migrant hypothesis and suggest that acculturation-related factors may be important drivers of ethnic and nativity-related differences in low cardiovascular risk.