Summary
Background
Children in families who are refugees might experience more adversities than their peers. Adverse childhood experiences (ACEs) are well known risk factors for poorer adulthood health and adjustment. The risk of ACEs for children with a parent who is a refugee affected by trauma is unknown. We aimed to estimate the hazard of individual and cumulative ACEs using a unique sample of children with parents who are refugees affected by and seeking treatment for trauma and population level data.
Methods
This was a register-based cohort study carried out in Denmark. All children aged 0–15 years, residing in Denmark between Jan 1, 1990, and Dec 31, 2016, were followed up from birth or migration into the country to their 15th birthday. We linked data from the Danish Civil Registration System, the Danish National Patient Register, the Danish Psychiatric Central Research Register, the Employment Classification Module, the Register of Causes of Death, and the Income Statistics Register to investigate ten ACE categories (parental: natural and unnatural death, serious mental illness, substance use disorder, somatic illness, and disability; child: residential instability, family disruption, poverty, and stressors) and the cumulative number of ACE categories for children with a parent from a refugee-sending country and children with a parent who is a refugee in treatment for trauma. The main outcome was the hazard ratio (HR) of the individual and cumulative ACEs among children with a parent from a refugee-sending country and children with a parent who is a refugee affected by trauma, compared with the general population of children in Denmark, both adjusted and unadjusted for parental country of origin.
Findings
2 688 794 children were included in the study, 252 310 of whom had parents from refugee-sending countries. 11 603 children had parents affected by trauma and seeking treatment, of whom 1163 (10%) migrated to Denmark before their second birthday and 10 440 (90%) were born in Denmark. Compared with the general population of children in Denmark, the hazard for most ACEs was significantly higher for both children with parents from a refugee-sending country and children with parents who are refugees affected by trauma. For children with a parent from a refugee-sending country, the highest HR was related to the child living in relative poverty for 3 years (3·62 [95% CI 3·52–3·73]). After adjusting for parental country of origin, the hazards for five ACEs were significantly greater for children of parents who are refugees affected by trauma compared with the remaining children of parents from the same countries. The highest HR for this child group was for parental serious mental illness (1·98 [1·85–2·12]). The hazard for experiencing multiple ACEs was significantly higher for both child groups compared with the general population.
Interpretation
Our findings suggest that children with parents from refugee-sending countries have a higher rate of several ACEs compared with the general population. Furthermore, having a parent who is a refugee affected by trauma and seeking treatment seems to be an independent risk factor for poorer health and adjustment in adulthood. This study informs decision makers and caregivers that there might be much added value in addressing needs within the whole family, as opposed to only attending to the parent who is seeking treatment.
Funding
The Lundbeck Foundation.
Introduction
For children growing up in families who are refugees, the burden of adversity and stress might be profound. Many families who have fled war and persecution manage to create safe environments for their children. However, for the most vulnerable families with parents who are refugees affected by trauma, the cohesion and wellbeing of the family can be severely challenged.
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Unfortunately, traumatic experiences have ramifications across generations.
The vulnerability experienced by parents who are refugees affected by trauma could increase their children’s risk of distressing experiences, and have long-lasting implications into adulthood.
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Early detection and interventions targeting childhood adversities have great potential to improve the health and wellbeing of children in general.
Understanding what vulnerabilities children of parents who are refugees affected by trauma are exposed to could help direct preventive efforts to break the cycle of transmission.
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Evidence before this study
We searched PubMed, Cinahl, Embase, and psychInfo for original research articles and systematic reviews published in English from inception until Feb 2, 2022, using variations and combinations of the terms [“refugee offspring” OR “children of refugees” OR “refugee children”] AND [“adverse childhood experiences” OR “adversity” OR “stressor” OR “resettlement” OR “early life adversity”]. Most of the screened material pertaining to adverse childhood experiences were original research articles or systematic reviews of adversity in the general population. Studies investigating outcomes in children with a refugee background typically focused on a single domain outcome, such as psychological morbidity. Evidence suggests that parental trauma history and post-traumatic stress disorder in the refugee population is associated with adverse behavioural and emotional outcomes, and poorer school outcomes in children. Questionnaire data were a frequent source of information on traumatic or stressful events before, during, and after the migration journey in the reviewed articles. Here, the reviewed articles showed that families who are refugees, including children, are exposed to a range of stressors, spanning individual, family, and community stressors.
Added value of this study
By using the population registers, we created a comprehensive overview of adversities faced by children of parents from refugee-sending countries and parents who are refugees affected by trauma and seeking treatment. This study captures more of the burden of the collective stressors in childhood and adolescence, without having to rely on self-reported data. Moreover, the combination of register data and clinical information on a group of parents who are refugees affected by trauma enabled us to follow up the population of interest over a longer time span than most studies investigating outcomes in this group. To our knowledge, this is the first study to give an overview of several types of stressors during childhood and adolescence for this group of children with parents who are refugees affected by trauma.
Implications of all the available evidence
Studies focusing on childhood and adolescence are important as they indicate circumstances important to later life wellbeing that might be modifiable in the earlier stages of life, and thus point to possible future interventions. The results of this study suggest that there might be an unmet need among children of refugees affected by trauma, and thus a potential for improving their health over the life-course through early interventions. The study might inform decision makers and caregivers providing treatment for this group of parents who are refugees affected by trauma that there might be much added value in identifying and addressing needs within the whole family, rather than attending only to the parent seeking treatment. Combining the results of studies using self-reported questionnaire data together with register-based indicators of adverse childhood experiences provides not only persuasive evidence of the effects of trauma in families who are refugees but also points to clearly identifiable and therefore actionable risk factors for caregivers and decision makers.
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Around 40–50% of the general population encounter at least one ACE during childhood.
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Although the amount of distress this causes depends on the context, the widespread nature makes the burden of ACEs a public health concern because ACEs have been shown to negatively affect later life.
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Several studies have documented that adversities such as household substance misuse, household mental illness, family members with convictions, child abuse, financial issues, parental disability, parental death, parental separation, and parental divorce, among others, have a clear link to child distress
and a child’s risk of unipolar depression,
anxiety, psychotic disorders, attention deficit hyperactivity disorder,
and suicide.
In addition to the possible mental health consequences of ACEs, studies have found an association between early adversities and physical inactivity, diabetes, smoking, poor self-rated health, cancer, heart disease, respiratory disease, drug and alcohol misuse, and violence, among other outcomes.
ACEs are also associated with poorer socioeconomic outcomes, such as higher probability of dropping out of school, lower income,
being unemployed, or living in relative poverty in adulthood.
The accumulation of adversities is particularly concerning because individuals who experience four or more ACEs seem to be at higher risk of negative outcomes than those who experience no ACEs.
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Parental trauma has been linked to harsh parenting style as well as being a risk factor for family-related violence and child abuse.
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In addition to the mental health burden of trauma-affected refugee populations, postmigratory stressors
can also be a driver of ACEs in their children.
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Increased focus is directed towards the negative effect of postmigration living difficulties, such as economic hardship, in sustaining refugee trauma over time.
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Such stressors might be part of the underlying mechanisms driving transmission of trauma across generations, possibly intensifying when parents are affected by trauma.
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The aim of this study was to ascertain whether children of migrants from refugee-sending countries (specific countries are listed in the Exposures section of the Methods; information on the legal status of this group is not available and individuals might have refugee status or a different legal status) and children of parents who are refugees affected by trauma and seeking treatment had an increased rate of individual and cumulative ACEs, and whether this increased rate persisted after adjusting for maternal and paternal country or region of origin. Because both groups typically migrate from low-resource settings, and many will have a refugee background, we hypothesised that both children of parents from refugee-sending countries and children of parents who are refugees affected by trauma would experience more adversity compared with the general population.
Methods
Study design and participants
This register-based cohort study used Danish population register data, for which the central pillar is the Civil Registration System (CRS). The CRS contains a unique personal identifier for each individual residing in Denmark after April 2, 1968. This identifier was used to link different databases as well as linking parents and children, and provided information on the study participants’ sex, date and place of birth, vital status, and dates of migration to and from Denmark. All children aged 0–15 years, residing in Denmark between Jan 1, 1990, and Dec 31, 2016, and with a personal identifier, were included in the study. We excluded children who migrated into Denmark after their second birthday and children with no maternal identifier to ensure sufficient information on the children in the study.
First, we investigated ACEs in children in a group of migrants from refugee-sending countries residing in Denmark. Second, we investigated ACEs in a group of children with parents who are refugees affected by trauma and seeking treatment, who constitute a subgroup of the children with parents from refugee-sending countries.
The Danish Patient Safety Authority approved the identification of the group of parents who had been affected by trauma. Statistics Denmark approved and guaranteed secured access to register data. The personal identifiers for the study population were encrypted and only aggregated data were extracted from the secured servers.
Outcomes
These ten ACE categories were parental natural and unnatural death, residential instability, parental serious mental illness and substance use disorder, family disruption, parental somatic illness, parental disability, relative poverty, and childhood stressors.
Parental psychopathology was defined as serious mental illness and substance use disorder and this information came from the Danish National Patient Register (DNPR) and the Danish Psychiatric Central Research Register (DPCRR).
For the three variables (parental death, parental serious mental illness, and parental substance use disorder), the outcome was registered if at least one parent experienced the event in question. The parental serious mental illness diagnosis was included because of research showing a high vulnerability among children whose parents were diagnosed with a serious mental illness
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and was defined as follows; schizophrenia (International Classification of Diseases [ICD]-8: 295 [excluding 295·79]; ICD-10: F20), bipolar disorder (ICD-8: 296·19, 296·39, and 298·19; ICD-10: F30, F31, F34·0, and F38·0), and unipolar depression (ICD-8: 296·09, 296·29, 296·89, 296·99, 298·09, 300·49, and 301·19; ICD-10: F32, F33, F34 [excluding F34·0], F38 [excluding F38·0], and F39). Information on parental somatic illness was obtained from the DNPR and defined according to the Charlson Comorbidity Index as the presence of at least one Charlson disease for both parents. Diagnoses in the DPCRR and DNPR are registered as ICD-10 codes from 1994 and ICD-8 codes before 1994. Parental disability was registered as an outcome if at least one parent received disability pension, registered in the Employment Classification Module.
Two measures of relative poverty were defined as the child having lived either 1 or 3 years in relative poverty. Children were defined as living in relative poverty if the combined parental income, including wealth, was less than 50% of the national median income of the entire Danish population aged 18–55 years in the given year (data taken from the Income Statistics Register
). Parental income was weighted according to family size, with the first adult assigned the value 1, each additional adult assigned the value 0·5, and children assigned the value 0·3.
Finally, a variable on childhood stressors was measured. This variable consisted of multiple factors that could be deemed to be stressful or traumatising. These events included accidents recorded in the DNPR from 1987 onwards, assaults, poisonings, and maltreatment as recorded in the DNPR from 1995. As a reference, we also included child mortality, for which the median follow-up time was calculated.
Exposures
Three separate analyses were carried out. In the first analysis (model 1), the primary exposure was whether the child had at least one parent from a refugee-sending country. Having a parent from a refugee-sending country was defined as a binary variable if at least one parent originated from Iraq, Lebanon, Afghanistan, Iran, any other country in the Middle East, Bosnia and Herzegovina, Croatia, Kosovo, Montenegro, North Macedonia, Serbia, Slovenia, Africa, Asia, South America, or information on their country of origin was missing or unknown. The comparison group consisted of the remaining population residing in Denmark.
In models 2a and 2b, the exposed children were a subgroup of the children with one or both parents from a refugee-sending country where at least one parent was a refugee and was known to have received treatment at one of five specialised treatment centres for refugees affected by trauma. This group represents individuals who have been recognised as refugees with formal residency and have been referred mainly by their general practitioner to an outpatient care facility specialising in refugee trauma. This group was sampled through a non-probability approach, ensuring as many individuals as possible could be included in the study. The personal identification number was obtained from the clinics’ electronic patient file systems and, if possible, from the clinics’ physical archives. The sampling covered treatments provided in the period 1982–2017, with more parents identified after 2000.
Covariates
The sex and age of the included children were obtained from the CRS. Maternal country or region of origin and paternal country or region of origin were coded in two separate variables as follows; Denmark, Iraq, Lebanon, Afghanistan, Iran, any other country the Middle East, Bosnia and Herzegovina, Croatia, Kosovo, Montenegro, North Macedonia, Serbia, Slovenia, Africa, Asia, South America, any other country, and data missing or unknown. Calendar time was defined as a categorical and time-varying variable (1990–94, 1995–99, 2000–04, 2005–11, and 2012–16).
Statistical analysis
The study population was followed up from birth, migration into Denmark if this occurred before their second birthday, or from Jan 1, 1990, whichever came last. Cohort members were followed up until the event of interest, their 15th birthday, date of migration out of Denmark, death, or to the end of the study period (Dec 31, 2016), whichever came first. The total person-time was calculated as person-years at risk by the different groups included in the analyses. The crude incidence rates were obtained from the number of events divided by the person-years. Quadratic approximation to the Poisson log-likelihood for the log-rate parameter was used to calculate the CIs for the incidence rates. Cox proportional hazards regression was used to estimate the hazard ratio (HR) for the individual ACEs and the cumulative number of different ACE categories, by analysing the HR for the first, second, third, and fourth ACE experienced by the exposed children versus the comparison group.
In the first analysis (model 1), parental migration status into Denmark from a refugee-sending country was the exposure of interest. This model adjusted for calendar time, the child’s sex, and the child’s age as the underlying timescale. These covariates were chosen to consider possible differences between the groups being compared as well as the possible effect of changes in the registers over time.
In the second and third analyses (models 2a and 2b), the main exposure was being a child of a parent who is a refugee affected by, and seeking treatment for, trauma. In model 2a, the estimated HRs for the outcomes were adjusted for child age, sex, and calendar time, effectively comparing this group to all others residing in Denmark. Model 2b was adjusted for maternal and paternal country or region of origin in addition to the basic covariates (age, sex, and calendar year), to allow for a comparison of children of the parents who are refugees affected by trauma with children of parents from the same country of origin with unknown trauma history. Maternal and paternal origin were included in the analysis because country of origin is closely related to refugee status, trauma history, as well as many of the ACE categories, such as parental mental illness.
All models were estimated with 95% CIs and robust SEs were used to account for the correlation between siblings with the same mother. Potential violations of the proportional hazard assumption were visually checked in a log–log plot. To evaluate the robustness of the results to changes in the variables over time, a prespecified sensitivity analysis was also done with follow-up commencing Jan 1, 2000. Statistical analyses were carried out in Stata (version 15.1).
Role of the funding source
The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.
Results
Figure 1Flowchart of the study population
Table 1Crude incidence rates for ACEs per 1000 person-years analysed among children of parents affected by trauma compared with the general population
ACE=adverse children experience.
Table 2Estimated HRs for individual adverse childhood experiences in the three models
Figure 2HRs for individual and cumulative ACEs
(A) HRs for individual ACEs, plus child death, in each of the three models. (B) HRs for cumulative ACEs, in each of the three models. Error bars are 95% CIs. ACE=adverse childhood experience. HR=hazard ratio. Model 1=parent migrated from a refugee-sending country. Model 2a=parent who is a refugee and affected by trauma (unadjusted). Model 2b=parent who is a refugee and affected by trauma (adjusted).
Table 3Crude incidence rates of cumulative ACE categories per 1000 person-years analysed
ACE=adverse childhood experience.
Table 4Estimated HRs for cumulative number of ACE categories in the three models
ACE=adverse childhood experience. HR=hazard ratio.
Discussion
This study aimed to investigate whether children of all migrants from refugee-sending countries, and a subgroup children of parents who are refugees affected by and seeking treatment for trauma, experienced increased individual and cumulative ACEs. We found an increased hazard for a range of childhood adversities among children of parents from refugee-sending countries in general and in those whose parents had been affected by torture and war trauma. For children of parents affected by trauma, after adjusting for parental country of origin, several adversities stood out as being elevated, including parental disability, psychopathology, substance use disorder, and somatic illness. Overall, the results suggest that children of parents who are refugees affected by trauma live with substantial stressors. Knowing how influential early life stress is in terms of long-term health and wellbeing, these findings are concerning.
Our results also suggest that children of parents who are refugees affected by trauma who also received treatment for their trauma, had an increased likelihood of multiple ACEs during their childhood and adolescence. The HR increased with the number of ACEs, underlining the relative burden of vulnerability placed on children of this parent group.
The association of parental country or region of origin with relative poverty and disability pension is also evident in that the estimates change from model 2a to 2b. For instance, the HR for disability pension is lower in model 2b than in model 2a, suggesting that much of the initial increased risk is associated with parental country or region of origin.
Early detection of these risk factors might occur when children and their families interact with the surrounding communities. Approximately 80% of Danish children attend the public school system for primary and secondary school.
Therefore, public schools are a particularly relevant place to monitor the wellbeing of children, as all children are routinely seen by a school nurse. Moreover, we have previously demonstrated that children of parents who are refugees affected by trauma show early indications of falling behind academically.
Therefore, extra effort might be needed to ensure the social inclusion and skill development of children of parents who are refugees affected by trauma. For instance, to avoid social exclusion driven by economic hardship, children living in low-income households could participate in youth clubs or sports activities with reduced or waived fees. In some cases, parental support through counselling focusing on facilitating healthy parent–child interaction might be needed. As many parents who are refugees seek treatment in the somatic health-care system for the consequences of their trauma, training health professionals to identify and treat refugees who are affected by trauma could increase timely and relevant interventions for the affected individuals and their families.
this study is not subject to issues of recall bias and issues of attrition.
Although our study provides important knowledge about this group of children, several limitations need to be considered. Although the group of migrants from refugee-sending countries included most refugees in Denmark, it was also highly heterogeneous and should be expected to encompass widely different migration experiences. The parents affected by trauma represented a sample of parents who are refugees seeking treatment. We do not know how many refugees in the comparison group were severely affected by trauma, potentially having sought help elsewhere, or not at all, but with similar levels of distress. The substantial difference in some of the estimates after adjusting for parental country of origin probably indicates that children of parents from the same countries as those seeking help for their trauma at the specialised clinics might be experiencing trauma as a consequence of war. However, because several hazard estimates were higher despite adjusting for parental country or region of origin, those receiving specialised care for their traumatic experiences are likely to be a vulnerable subgroup within a minority of people living in Denmark. There is currently no systematic assessment of refugees’ health upon starting their residency in Denmark. Therefore, the process of receiving specialised care is dependent on the refugee’s own health-seeking behaviour and the attentiveness and vigilance of primary health-care providers. For instance, refugees accessing a specialised clinic might also be more likely to be in contact with the general psychiatric care system and have received a serious mental illness diagnosis, which was one of the outcomes investigated. Consequently, whether these results can be replicated in societies with a different health-care system is unknown.
Moreover, the cumulative approach to ACEs implies that each experience has the same effect on later life outcomes. This is a simplification because we do not know how the sequence and combination of specific adversities were subjectively experienced.
Nevertheless, register data enable long-term follow-up with little to no attrition. Therefore, we believe this study adds to the evidence base by investigating multiple ACE categories for children of parents who are refugees affected by trauma.
ACEs are known to be risk factors associated with adverse mental, physical, and socioeconomic outcomes in later life. In this study, we found evidence of increased risk for a range of ACEs as well as the cumulative number of ACEs for children of refugees affected by trauma who had sought treatment at five specialised clinics across Denmark. This increased risk persisted even after taking maternal and paternal country of origin into account. The risk was especially high for parental serious mental illness, parental disability, and parental substance use disorder. However, children of survivors of torture not only experience the ACEs specifically associated with parental torture or war trauma, but they might also have risk factors associated with having a parent who migrated from a refugee-sending country, which we found to be years lived in relative poverty, among others. These estimates point to the burden of adversity children experience, and point to avenues of intervention for breaking the transmission of trauma.
LB and MHT were responsible for the conception of the study. Design and formal analysis were carried out by LB and TML. LB and TML had access to and verified the underlying data. LB wrote the original draft. MHT, TML, SP, and LN reviewed, edited, and approved the final manuscript. LB and TML had access to all the data in the study. All authors were responsible for the decision to submit for publication.
