Repeat immigration: A previously unobserved source of heterogeneity?

AIMS: Register data allow for nuanced analyses of heterogeneities between sub-groups which are not observable in other data sources. One heterogeneity for which register data is particularly useful is in identifying unique migration histories of immigrant populations, a group of interest across disciplines. Years since migration is a commonly used measure of integration in studies seeking to understand the outcomes of immigrants. This study constructs detailed migration histories to test whether misclassified migrations may mask important heterogeneities. In doing so, we identify a previously understudied group of migrants called repeat immigrants, and show that they differ systematically from permanent immigrants. In addition, we quantify the degree to which migration information is misreported in the registers. METHOD: The analysis is carried out in two steps. First, we estimate income trajectories for repeat immigrants and permanent immigrants to understand the degree to which they differ. Second, we test data validity by cross-referencing migration information with changes in income to determine whether there are inconsistencies indicating misreporting. RESULTS: From the first part of the analysis, the results indicate that repeat immigrants systematically differ from permanent immigrants in terms of income trajectories. Furthermore, income trajectories differ based on the way in which years since migration is calculated. The second part of the analysis suggests that misreported migration events, while present, are negligible. CONCLUSIONS: Repeat immigrants differ in terms of income trajectories, and may differ in terms of other outcomes as well. Furthermore, this study underlines that Swedish registers provide a reliable data source to analyze groups which are unidentifiable in other data sources.

A Life-Course Study of Cognitive Reserve in Dementia--From Childhood to Old Age.

OBJECTIVE: To test a life-course model of cognitive reserve in dementia and examine if school grades around age 10 years, formal educational attainment, and lifetime occupational complexity affect the risk of dementia in old age. METHODS: 7,574 men and women from the Uppsala Birth Cohort Multigenerational Study were followed for 21 years. Information on school performance, formal education, and occupational attainment was collected prospectively from elementary school archives and population censuses. Dementia diagnosis was extracted from the two Swedish registers. Discrete-time Cox proportional hazard models were estimated. RESULTS: Dementia was diagnosed in 950 individuals (12.5%). Dementia risk was lower among individuals with higher childhood school grades (hazard ratio [HR]: 0.79; 95% confidence interval [CI]: 0.68 to 0.93) and was lower among individuals in data-complex occupations (HR: 0.77; 95% CI: 0.64 to 0.92). Professional/university education predicted lower risk of dementia in minimally adjusted models (HR: 0.74; 95% CI: 0.60 to 0.91), although the effect faded with adjustment for occupational complexity. Lowest risk was found in the group with both higher childhood school performance and high occupational complexity with data (HR: 0.61; 95% CI: 0.50 to 0.75). Importantly, high occupational complexity could not compensate for the effect of low childhood grades. In contrast, dementia risk was reduced in those with higher school grades, irrespective of occupational complexity. CONCLUSION: Higher childhood school performance is protective of dementia risk, particularly when preserved through complex work environments in adulthood, although it will remain protective even in the absence of later-life educational or occupational stimulation.

Workplace sex composition and ischaemic heart disease: A longitudinal analysis using Swedish register data.

AIMS: The aim of this study is to follow-up on previous research indicating that the sex composition of workplaces is related to a number of health outcomes, including sickness absenteeism and mortality. We test two hypotheses. The first is Kanter's theory of tokenism, which suggests that minority group members suffer from an increased risk of stress. Secondly, we test the hypothesis that workplaces with a higher proportion of men will have a higher incidence rate of ischaemic heart disease (IHD), as men are more likely to engage in negative health behaviours, and through peer effects this will result in a workplace culture that is detrimental to health over the long term. METHODS: Large-scale, longitudinal Swedish administrative register data are used to study the risk of overnight hospitalization for IHD amongst 67,763 men over the period 1990 to 2001. Discrete-time survival analyses were estimated in the form of logistic regression models. RESULTS: Men have an elevated risk of suffering from IHD in non-gender-balanced workplaces, but this association was only statistically significant in workplaces with 61-80% and 81-100% males. However, after adjusting for occupation no clear pattern of association could be discerned. No pattern of association was observed for women. CONCLUSIONS: This study suggests that the gender composition of workplaces is not strongly associated with the risk of suffering from IHD.

Naturalization in a Context of Free Mobility: Evidence from Cross-National Data on Finnish Immigrants in Sweden.

Using unique longitudinal microdata linking administrative records from Sweden and Finland, we study how immigrant naturalization relates to cultural proximity. We analyze how Swedish citizenship acquisition depends on mother tongue by comparing Swedish-speaking and Finnish-speaking immigrants from Finland, who arrived in Sweden in 1988-2004, and contrast with other Nordic-born immigrants. We treat return migration and naturalization as two elements in the decision process of immigrants, being the first to estimate competing risks models for naturalization and return migration for the same study group of persons. The setting of free mobility in the Nordic countries, together with economic, political and social similarities, implies that the direct benefits of naturalization are modest and the same for all Nordic-born immigrants in Sweden. Thus, we assess naturalization in an analytical framework where many confounding factors are circumvented and in which the study groups have grown up in the similar institutional setting. Swedish-speaking Finns are found to have an approximately 30 percent higher standardized risk of naturalization than Finnish-speaking Finns, and a 2.5 times higher risk as compared to people from the other Nordic countries. We argue that these differentials reflect the degree to which the groups broadly differ in affinity with Sweden.

Associations of perinatal characteristics with endometriosis: a nationwide birth cohort study.

BACKGROUND: Perinatal characteristics are associated with subsequent risk of several chronic diseases. Previous studies regarding endometriosis were based on small samples and retrospective data and were limited by unmeasured confounding bias, leading to conflicting and inconclusive findings. We investigated the associations of maternal and birth characteristics with risk of endometriosis among Swedish women of reproductive age. METHODS: This total-population register-based cohort study consisted of 628 312 singleton women born in Sweden between 1973 and 1987, who were followed for diagnosed endometriosis from age 15 years until the end of 2012. Multivariable Cox regression was applied to examine associations with perinatal characteristics. Residual unmeasured confounding was assessed through within-family and E-value analyses. RESULTS: During follow-up, 8262 women received an endometriosis diagnosis. There were clear dose-response/linear associations of endometriosis with lower maternal education, endometriosis in the mother [adjusted hazard ratio (aHR): 2.24, 95% confidence interval (CI): 2.04-2.46], maternal smoking during pregnancy (aHR: 1.18, 95% CI: 1.04-1.33 for moderate smoker and aHR: 1.36, 95% CI: 1.18-1.57 for heavy smoker vs non-smoker), lower birthweight, and lower birthweight-for-gestational age (aHR: 0.93 per standard deviation increase, 95% CI: 0.91-0.95). Within-family and E-value analyses suggested that these perinatal characteristics are robust predictors of the incidence of endometriosis. We also found that an estimated 26% of the association between maternal smoking and early-onset endometriosis could be explained by birthweight-for-gestational age. CONCLUSION: This study finds support for fetal origins of endometriosis, in that exposure to adverse environment or restricted development during the perinatal period may increase the risk. Further research is needed to provide an understanding of the underlying mechanisms.

Time and Generation: Parents' Integration and Children's School Performance in Sweden, 1989-2011.

A central element of assimilation theory is that increasing time and number of previous immigrant generations in a host country leaves immigrants and their children more integrated and capable of navigating the host society. However, the underperformance of some immigrant groups in Sweden calls into question this relationship. Additionally, many studies regard intermarriage as an outcome of immigrant integration and rarely investigate whether integration continues after intermarriage. Using population level data from the Swedish interdisciplinary panel on 22 cohorts of ninth-grade students born between 1973 and 1995, we examine the effect of parents' time in Sweden on their children's grade point average using family fixed effects. Additionally, we investigate whether this relationship differs between "2.0" and "2.5" generation children. We find, generally, that parents' time in Sweden increases their children's educational performance, though some variation by parents' region of origin exists. This supports the idea that integration experiences in immigrant families can be transmitted across generations. Further, this generally holds for both the 2.0 and 2.5 generation children. This relationship among the 2.5 generation is notable as previous studies using a family-based approach looking at the intergenerational transmission of integration have largely focused on the children of two foreign-born parents.

Relative deprivation and sickness absence in Sweden.

BACKGROUND: A high prevalence of sickness absence in many countries, at a substantial societal cost, underlines the importance to understand its determining mechanisms. This study focuses on the link between relative deprivation and the probability of sickness absence. METHODS: 184,000 men and women in Sweden were followed between 1982 and 2001. The sample consists of working individuals between the ages of 19 and 65. The outcome is defined as experiencing more than 14 days of sickness absence during a year. Based on the complete Swedish population, an individual's degree of relative deprivation is measured through income compared to individuals of the same age, sex, educational level and type. In accounting for the possibility that sickness absence and socioeconomic status are determined by common factors, discrete-time duration models were estimated, accounting for unobserved heterogeneity through random effects. RESULTS: The results confirm that the failure to account for the dynamics of the individual's career biases the influence from socioeconomic characteristics. Results consistently suggest a major influence from relative deprivation, with a consistently lower risk of sickness absence among the highly educated. CONCLUSIONS: Altering individual's health behavior through education appears more efficient in reducing the reliance on sickness absence, rather than redistributive policies.

Labour-market status and first-time parenthood: the experience of immigrant women in Sweden, 1981-97.

This paper investigates the impact of labour-market attachment on first births of foreign-born women in Sweden. The study uses a longitudinal, register-based dataset consisting of the entire population of immigrants from ten nations and a 5-per-cent random sample of natives. The effects of earned income are evident, with increased income levels increasing the probability of becoming a mother for all observed nationalities. The effects of various forms of participation and non-participation in the labour force do not vary greatly between immigrants and the Swedish-born. Among all subgroups, we find a higher propensity to begin childbearing among those who are established in the labour market. Contrary to popular belief, receiving welfare benefits clearly reduces first-birth intensity for immigrants but not for natives. The similarity in patterns across widely different national groups supports the notion that various institutional factors affecting all subgroups are crucial in influencing childbearing behaviour.