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Journal of Migration and Health logoLink to Journal of Migration and Health
. 2023 Jul 12;8:100197. doi: 10.1016/j.jmh.2023.100197

Are migrants diagnosed with a trauma-related disorder at risk of premature mortality? A register-based cohort study in Denmark

Line Bager a,b,⁎, Esben Agerbo a, Niels Skipper c,d, Janne Tidselbak Larsen a, Thomas Munk Laursen a,c
PMCID: PMC10365948  PMID: 37496744

Highlights

  • •

    Migrants in Denmark are overrepresented among those with a trauma-related disorder.

  • •

    Migrants with PTSD/EPCACE do not have an increased risk of premature mortality.

  • •

    Among migrants a psychotic disorder was associated with increased mortality.

Keywords: Mortality, Migrants, Refugees, Traumatic stress disorders, Psychosis

Abstract

Background

Mental illness is common among refugees displaced by conflict and war. While evidence points to the relatively good health in terms of longevity of migrants resettled in the destination country, less is known about the mortality of the most vulnerable migrants with a trauma-related diagnosis alone and those with an additional comorbid psychotic disorder. This study aimed to provide an overview of the number and mortality of foreign-born individuals diagnosed with Post-Traumatic Stress Disorder or Enduring Personality Change after a Catastrophic Event (PTSD/EPCACE), a psychotic disorder or both.

Methods

A nationwide register-based cohort study, including residents in Denmark, followed from 1 January 1995 to 31 December 2016. The exposure was PTSD/EPCACE and psychotic disorders as well as region of origin. Relative all-cause mortality was estimated using Cox proportional hazards regression models and calculated for migrants with one or both groups of disorders compared to those from the same region without the disorder.

Results

During the study period, 6,580,000 individuals (50.4% women) were included in the cohort. Of these 1,249,654 (50.5% women) died during follow-up. For men and women from the former Yugoslavia, the Middle East and Northern Africa, a PTSD/EPCACE diagnosis alone or with comorbid psychotic disorder was not associated with increased mortality after adjusting for region of origin. A psychotic disorder alone, however, was associated with an increased mortality rate.

Conclusion

Despite the severity of many refugees’ traumatic experiences, a diagnosis of a trauma-related psychiatric disorder did not appear to increase the mortality rates.

1. Introduction

Migrants constitute a significant and increasing part of European societies. Recent war and unrest have increased the number of asylum seekers, and residence permits granted (UNHCR 2017). As of early 2022, 11% or 640,922individuals in the Danish population were migrants (Danmarks Statistik 2022). By 2060, the number of non-western immigrants will likely have increased by 7% compared to the 2022 level (Danmarks Statistik 2022) and similar trends are observed across western Europe (International Organization for Migration (IOM) 2017). War, torture and stressors related to the migration process are factors that contribute to migrants’ physical and psychological vulnerability (Steel et al., 2009). Mental illness is prevalent among displaced and war-exposed populations. The most frequently reported mental disorders are Post-Traumatic Stress Disorder (PTSD), depression, anxiety disorders, and psychosis (Steel et al., 2009; Brandt et al., 2019). In a systematic review, the strongest risk factor for developing PTSD was torture and the cumulative exposure to traumatic events (Steel et al., 2009). It has been suggested that as much as 30% of asylum seekers resettled in Western countries have been exposed to torture (Kalt et al., 2013).

PTSD as a diagnosis differs from most other disorders in that in addition to specific symptoms, it requires a traumatic event to have triggered the disorder and that this event is of an exceptionally threatening or catastrophic nature (Maercker et al., 2013). However, concerns have long been raised that the PTSD diagnosis does not capture the more complex mental health trajectories following repeated or prolonged interpersonal trauma (Palic et al., 2016). In addition to re-experiencing, avoidance and hyperarousal, some individuals may also be affected by problems in sustaining relationships, affect regulation, a negative self-image (Palic et al., 2016), or experience persisting mistrust and hostility towards the world (Beltran et al., 2008). With the newest revision of the International Classification of Diseases(11th Revision, ICD-11), some of these difficulties related to self-regulation might be captured in the diagnosis of complex PTSD (Maercker et al., 2013). Thus far, the disorder of Enduring Personality Change after Catastrophic Event (EPCACE; F62.0) in the ICD-10 has in effect been used to describe patients with complex traumatisation, such as torture survivors (Palic et al., 2016). This disorder is in the ICD-10 noted to potentially follow after PTSD and explicitly excludes single-event trauma while listing torture and prolonged captivity as predisposing factors (Maercker et al., 2013; Beltran et al., 2008).

However, displaced persons are not only at risk of developing PTSD or EPCACE following exposure to war. Migrant status alone is well documented as an independent risk factor for psychosis (Henssler et al., 2020). More persistent exposures such as poverty, discrimination, psychosocial stress and long-term social defeat may increase the risk of psychosis among migrants (Eaton and Harrison, 2000; Katsounari, 2012). Trauma also figures as a prominent risk factor for psychosis among refugees (Parrett and Mason, 2010) and with interpersonal trauma as a particularly influential risk factor for more severe psychotic disorder trajectories (Gibson et al., 2016). However, diagnostic ambiguity arises as PTSD and psychosis present symptoms that overlap (OConghaile and DeLisi, 2015). Flashbacks may be mistaken for intrusions and hallucinations, while mistrust and hypervigilance may be misinterpreted as paranoia (OConghaile and DeLisi, 2015; Compean and Hamner, 2019). The negative symptoms likewise share similarities in that withdrawal in psychotic patients may resemble emotional numbing in those who have PTSD. Both disorders may also present with sleep disturbances, detachment, estrangement from other, and derealisation (Compean and Hamner, 2019). Further, when diagnosing migrants, there can be additional complexity where language and illness concepts differ. The diagnostic ambiguity has led to discussions of whether PTSD with secondary psychotic features (PTSD-SP) should be a distinct disorder or whether it represents comorbidity with other psychotic disorders, such as psychotic depression (Compean and Hamner, 2019). In clinical samples of trauma-affected refugees, not only was psychotic symptoms observed even after excluding those with a primary psychotic diagnosis (Nygaard et al., 2017), but psychotic symptoms were found to overlap with a diagnosis of EPCACE (Rathke et al., 2020).

Excess mortality among those diagnosed with schizophrenia and schizophrenia spectrum disorder (Hjorthøj et al., 2017) and psychotic disorders at large (Bradford and Cunningham, 2016) is well-documented in the general population. Mortality studies among those diagnosed with PTSD primarily originate from US veteran studies and generally do find an association between PTSD and premature mortality (Lohr et al., 2015). Research on excess mortality in populations exposed to natural disaster, subsequently diagnosed with PTSD is less clear (Edmondson et al., 2013). Moreover, studies of mortality in war-exposed civilian populations are fewer and inconclusive (Mollica et al., 2001). EPCACE is not frequently studied although a shorter life expectancy has also been documented in personality disorders at large (Nordentoft et al., 2013). This is in contrast to the evidence on migrants’ mortality in general. Research indicates that non-refugee migrants have lower mortality than refugees (Hollander et al., 2012) but that both groups generally have lower mortality than the local-born population, (Hajat et al., 2010; Norredam et al., 2012) although considerable variation exists (Ikram et al., 2016; Aldridge et al., 2018).

However, mortality has not been investigated for migrants diagnosed with a trauma-related diagnosis alone or those with a comorbid psychotic disorder. This evidence gap persist despite the overrepresentation of the most vulnerable and trauma-affected migrants among individuals diagnosed with these disorders (Steel et al., 2009; Brandt et al., 2019). Moreover, some studies investigating mortality in trauma-affected populations specifically exclude migrants (Gradus et al., 2015). Therefore, this study aimed to provide an overview of the mortality risk of those diagnosed with either PTSD/EPCACE, psychotic disorders or both.

2. Materials and Methods

2.1. Study design, participants and follow-up

All individuals living in Denmark from 2 April 1968 and onwards have been registered with a personal identifier in the Danish Civil Registration System (CRS). This number is unique and can be used to link information across population registers. The CRS contains information on date of birth, sex, place of birth and vital status. From 1969, the CRS also contains information on emigration and immigration.

Information about diagnoses came from the Danish National Patient Register (DNPR) and the Danish Psychiatric Central Research Register (DPCRR). The DNPR, established in 1977, covers information on the individual patient level for diagnoses, treatments, examinations as well as administrative data. The DPCRR goes back to 1969, registering inpatient contacts. Outpatients, as well as emergency room contacts, are included from 1995 forward. Information on household composition and labour market participation was collected from the Population Statistics Register and the Employment Classification Module. Study participants were identified through the CRS, and the entire population of Denmark was followed from either 1 January 1995, date of 15th birthday or date of immigration, whichever came last. Follow-up was concluded on the date study participants were classified as either having; a) died, b) emigrated, c) were lost to follow-up or d) on 31 December 2016, whichever came first.

2.2. Definition of variables

The outcome was all-cause mortality and information on vital status and date of death came from the CRS. The main exposure of interest was a diagnosis of PTSD/EPCACE or a psychotic disorder together with region of origin. Cases with a diagnosis were identified in the DNPR and DPCRR, coded according to ICD-10 (International Classification of Disease, 10th Edition, [ICD-10]) as the ICD-11 has not yet been implemented in Denmark. The disorders were defined as; i) PTSD/EPCACE (F43.1 and F62.0) and ii) psychotic disorders (F2x, F30.2, F31.2, F31.5, F32.3, and F33.3). Region of origin was divided in the following categories; a) Denmark, b) the Middle East and Northern Africa (MENA) including Afghanistan, the c) former Yugoslavia and d) remaining countries. The former Yugoslavia included Bosnia and Herzegovina, Croatia, Macedonia, Montenegro and Serbia. Sub-Saharan Africa, Asia (excluding Afghanistan), northern and southern Americas, Europe (excluding Denmark) and Greenland were grouped into one.

Several possible covariates were included in the analysis. Both employment and family status were included as they are known factors intertwined with long-term health and well-being (Machů et al., 2022; Van Der Noordt et al., 2014). Labour market participation was categorised in three levels as either a) in employment or education, b) retired, or c) unemployed. Household composition was recorded as a binary variable indicating a single adult household. Because individuals could change status multiple times over the observation period, the number of categories for the individual variables were limited to a few categories. Somatic comorbidity was defined as a three-level variable indicating the presence of one or two or more of the 19 diseases included in Charlson Comorbidity Index (CCI) (Thygesen et al., 2011). Substance use disorders (SUD; F1x) were included as a binary variable indicating the presence of any SUD diagnosis. Calendar time was categorical (1995-2000; 2001-2005; 2006-2011; 2012-2016). Calendar time, the exposure diagnoses, variables of CCI and SUD as well as labour market participation and household composition were all treated as time-varying covariates during follow-up.

2.3. Statistical analyses

Summary statistics (count and percentages) were calculated for the study population by sex, region of origin, and exposure diagnosis by the end of the follow-up period. The total person-time was calculated as person-years at risk by the different groups included in the analyses. The crude mortality rates were obtained from the number of events divided by the person-years. Mortality was estimated as mortality rate ratios (MRRs) using a Cox proportional hazards regression model. All analyses were stratified by sex, and age was treated as the underlying time. Three models were fitted, all with mortality as the dependent variable and diagnoses and region of origin as the independent variable. The three models included the following variables; the first model (model 1) included region of origin, the diagnoses and adjusted for calendar time. The intermediate model (model 2), in addition to model 1 variables, also adjusted for household composition and labour market participation, while the final model (model 3) further added variables of CCI and SUD. All models included the main effect of region of origin and its interaction with the diagnoses, allowing us to compare the effect of the trauma-diagnoses, adjusting for region of origin. Proportionality of hazards was checked for time-fixed covariates by diagnostic plots and no major violations were detected. All statistical analyses were carried out in Stata, version 15.1 (StataCorp., College Station, Tex.) and estimates are reported with 95% confidence intervals (CI).

2.4. Ethical approval

This study was approved by the Danish Data Protection Agency (7th March 2019) and the Danish Health Data Authority (FSE ID 98). The data analysed in this study were not collected for this specific research project but were based on Danish nationwide registers. Individual-level data in the registers can only be accessed through secure servers and only export of aggregated data, as presented in research articles, is allowed as per Danish law. Permission to access data can be made if specific requirements to safeguard the anonymity of the study participants are fulfilled. For these reasons, data cannot be made generally available.

3. Results

During the study period from 1 January 1995 to 31 December 2016, 6,598,000 persons (50.3% women) were included in the study cohort, amounting to 100,301,545 person-years and a median (interquartile range, IQR) time at risk of 20 (14.2) years at the end of follow-up. Among the diagnosed individuals, 73,176 (50.9%) were women who had a median (IQR) age at first diagnosis of 43 (31.3), which was higher than for men (median (IQR) = 38 (24.5)). Table 1 provides an overview of the number of diagnoses in the cohort by sex and region of origin at the end of the observation period. Most notably, men from the MENA represent 2.0% of all males in the cohort but account for 35.5% of the PTSD/EPCACE diagnoses given. For women from the MENA, the equivalent proportions are 1.5% and 24.1%. There is a similar pattern of overrepresentation among the diagnosed men and women from the former Yugoslavia. Men from the former Yugoslavia make up 0.7% of the entire male cohort compared to 10.6% of those diagnosed with PTSD/EPCACE. For women from the former Yugoslavia, the equivalent numbers are 0.7% and 9.4%.

Table 1.

Diagnoses in the population by sex and region of origin (end of follow-up).

None PTSD/EPCACE Psychosis Both total
n % n % n % n % n %
Women
MENA 44509 1.4% 3612 24.1% 871 1.6% 422 19.8% 49414 1.5%
F. Yugoslavia 19636 0.6% 1414 9.4% 495 0.9% 180 8.4% 21725 0.7%
Denmark 2688112 82.8% 8114 54.1% 49199 87.8% 1196 56.0% 2746621 82.8%
Other 493642 15.2% 1850 12.3% 5485 9.8% 338 15.8% 501315 15.1%
Total 3245899 100% 14990 100% 56050 100% 2136 100% 3319075 100%
Men
MENA 58875 1.8% 4686 35.5% 1762 3.2% 1024 41.0% 66347 2.0%
F. Yugoslavia 20426 0.6% 1394 10.6% 545 1.0% 293 11.7% 22658 0.7%
Denmark 2648605 82.6% 5581 42.3% 47011 85.6% 802 32.1% 2701999 82.4%
Other 480416 15.0% 1535 11.6% 5590 10.2% 380 15.2% 487921 14.9%
Total 3208322 100% 13196 100% 54908 100% 2499 100% 3278925 100%
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MENA, the Middle East and North Africa; F. Yugoslavia, Former Yugoslavia; Other, remaining countries

PTSD, Post-traumatic stress disorder; EPCACE, Enduring personality change after catastrophic event

Table 2 and 3 outline the number of deaths and person-years analysed for men and women, respectively, by diagnosis and region of origin. The lowest unadjusted mortality rates were observed for men and women from the MENA region across the groups of disorders. The psychotic disorders showed the highest mortality rates irrespective of the region of origin and gender. As expected, the covariates unemployment, somatic morbidity and substance abuse showed higher unadjusted mortality rates compared to being in employment, healthy and not diagnosed with a SUD, for both men and women.

Table 2.

Mortality rates for males per 1000 person-years analysed - all-cause mortality.

PTSD/EPCACE Psychotic disorder PTSD/EPCACE and psychotic disorder None Total
Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI)
Region
MENA 71 27747 2.56 (2.02-3.23) 154 18630 8.26 (7.05-9.67) 21 8450 2.49 (1.62-3.81) 2002 712949 2.81 (2.68-2.93) 2248 767777 2.93 (2.81-3.04)
F. Yugoslavia 44 10226 4.29 (3.20-5.78) 56 5664 9.89 (7.61-12.84) 12 2239 5.36 (3.04-9.43) 1898 318356 5.96 (5.70-6.24) 2010 336485 5.96 (5.71-6.24)
Denmark 420 35994 11.66 (10.59-12.83) 14262 456273 31.26 (30.75-31.76) 99 4625 21.41 (17.57-26.07) 572774 43989012 13.01 (12.99-13.05) 587555 44485903 13.21 (13.16-13.24)
Other 59 8505 6.94 (5.37-8.95) 902 51111 17.64 (16.53-18.83) 30 2434 12.33 (8.62-17.62) 25344 3735755 6.78 (6.70-6.87) 26335 3797805 6.92 (6.85-7.01)
Single adult household
No 540 75391 7.16 (6.58-7.79) 14591 497113 29.35 (28.87-29.82) 150 16174 9.26 (7.90-10.88) 560885 44577178 12.58 (12.55-12.61) 576166 45165856 12.75 (12.72-12.78)
Yes 54 7082 7.62 (5.83-9.96) 783 34565 22.64 (21.12-24.30) 12 1573 7.62 (4.33-13.42) 41133 4178893 9.83 (9.75-9.93) 41982 4222113 9.93 (9.84-10.03)
Labour market participation
Employed/ education 102 25200 4.04 (3.33-4.91) 1025 107407 9.54 (8.98-10.15) 28 2144 13.06 (9.01-18.91) 67250 35091997 1.91 (1.89-1.92) 68405 35226748 1.93 (1.92-1.96)
Retired 186 3295 56.45 (48.89-65.17) 7003 55377 126.45 (123.53-129.46) 31 393 78.78 (55.40-112.03) 439310 7213332 60.89 (60.71-61.07) 446530 7272397 61.39 (61.21-61.57)
Unemployed† 306 53978 5.66 (5.07-6.33) 7346 368893 19.91 (19.46-20.37) 103 15209 6.76 (5.58-8.21) 95458 6450744 14.80 (14.69-14.89) 103213 6888824 14.98 (14.89-15.07)
CCI
None 156 61872 2.52 (2.16-2.95) 4841 400690 12.08 (11.75-12.42) 61 13017 4.69 (3.64-6.01) 105806 39997645 2.64 (2.62-2.66) 110864 40473226 2.74 (2.72-2.75)
One 128 14303 8.95 (7.53-10.64) 3798 85755 44.28 (42.89-45.71) 41 3267 12.55 (9.24-17.03) 148841 5962961 24.96 (24.82-25.08) 152808 6066286 25.19 (25.05-25.32)
Two or more 310 6297 49.22 (44.03-55.02) 6735 45233 148.90 (145.37-152.50) 60 1463 41.02 (31.85-52.82) 347371 2795466 124.26 (123.84-124.68) 354476 2848458 124.43 (124.04-124.85)
SUD
No 325 67119 4.83 (4.33-5.40) 9136 329495 27.73 (27.16-28.30) 50 11909 4.20 (3.18-5.54) 541227 47036848 11.50 (11.48-11.53) 550738 47445371 11.60 (11.58-11.64)
Yes 269 15354 17.51 (15.55-19.73) 6238 202183 30.85 (30.10-31.62) 112 5838 19.19 (15.93-23.08) 60791 1719224 35.35 (35.07-35.64) 67410 1942598 34.70 (34.43-34.96)
Total 594 82473 7.20 (6.65-7.80) 15374 531678 28.92 (28.46-29.37) 162 17747 9.13 (7.83-10.65) 602018 48756072 12.34 (12.32-12.38) 618148 49387970 12.51 (12.49-12.55)
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MENA, the Middle East and North Africa; F. Yugoslavia, Former Yugoslavia; Other, remaining countries

CCI, Charlson Comorbidity Index; SUD, Substance Use Disorder

†

Includes missing values

Table 3.

Mortality rates for females per 1000 person-years analysed - all-cause mortality.

PTSD/EPCACE Psychotic disorder PTSD/EPCACE and psychotic disorder None Total
Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI) Deaths Person-years Crude MR (95% CI)
Region
MENA 13 17783 0.73 (0.42-1.26) 34 8399 4.04 (2.89-5.66) N/A‡ N/A‡ N/A‡ 950-960‡ >540000‡ 1.76 (1.64-1.87) 1004 571280 1.76 (1.64-1.87)
F. Yugoslavia 27 10231 2.64 (1.81-3.85) 60 5321 11.27 (8.75-14.51) 6 1505 3.99 (1.79-8.88) 1383 311204 4.44 (4.21-4.67) 1476 328260 4.50 (4.26-4.73)
Denmark 411 58088 7.08 (6.41-7.79) 17338 469853 36.89 (36.35-37.45) 92 7359 12.50 (10.18-15.33) 582626 45247573 12.88 (12.83-12.91) 600467 45782873 13.11 (13.08-13.15)
Other 51 10091 5.04 (3.83-6.65) 1085 50305 21.57 (20.32-22.89) 9-14‡ >2000‡ 5.54 (3.14-9.75) 27410-27420‡ >4168000‡ 6.58 (6.50-6.65) 28559 4231162 6.75 (6.66-6.83)
Single adult household
No 473 87946 5.37 (4.91-5.88) 17718 493421 35.90 (35.38-36.43) 102 12553 8.13 (6.69-9.87) 581577 46025668 12.64 (12.59-12.66) 599870 46619589 12.86 (12.83-12.90)
Yes 29 8247 3.52 (2.43-5.05) 799 40456 19.75 (18.42-21.17) 10 1241 8.06 (4.33-14.98) 30798 4244042 7.25 (7.17-7.33) 31636 4293986 7.37 (7.29-7.45)
Labour market participation
Employed/ education 74 32483 2.27 (1.81-2.85) 517 98201 5.25 (4.83-5.74) 5 2372 2.10 (0.88-5.05) 32803 31940180 1.03 (1.02-1.04) 33399 32073236 1.04 (1.03-1.05)
Retired 209 4591 45.52 (39.75-52.13) 13503 124821 108.18 (106.37-110.01) 40 607 65.85 (48.31-89.79) 512697 9963224 51.46 (51.32-51.60) 526449 10093243 52.15 (52.02-52.29)
Unemployed† 219 59119 3.70 (3.24-4.23) 4497 310856 14.47 (14.05-14.90) 67 10814 6.20 (4.87-7.87) 66875 8366307 7.99 (7.93-8.05) 71658 8747096 8.18 (8.13-8.25)
CCI
None 92 72270 1.27 (1.04-1.56) 4353 368742 11.80 (11.46-12.16) 25 9578 2.60 (1.76-3.85) 105031 40816709 2.56 (2.56-2.58) 109501 41267299 2.64 (2.64-2.66)
One 137 17675 7.75 (6.55-9.16) 5312 105521 50.34 (49.00-51.71) 27 3072 8.79 (6.03-12.82) 176765 6752360 26.17 (26.05-26.30) 182241 6878629 26.48 (26.37-26.62)
Two or more 273 6248 43.70 (38.81-49.20) 8852 59615 148.49 (145.43-151.61) 60 1144 52.45 (40.71-67.54) 330579 2700641 122.40 (121.98-122.82) 339764 2767648 122.76 (122.34-123.18)
SUD
No 311 84313 3.68 (3.29-4.12) 15034 426259 35.27 (34.71-35.84) 57 10314 5.53 (4.25-7.16) 584074 49230319 11.85 (11.83-11.89) 599476 49751206 12.05 (12.01-12.08)
Yes 191 11880 16.07 (13.94-18.53) 3483 107618 32.35 (31.30-33.46) 55 3480 15.81 (12.13-20.58) 28301 1039391 27.23 (26.91-27.55) 32030 1162369 27.55 (27.26-27.85)
Total 502 96193 5.21 (4.78-5.70) 18517 533878 34.67 (34.18-35.18) 112 13794 8.12 (6.75-9.76) 612375 50269710 12.17 (12.15-12.21) 631506 50913575 12.40 (12.36-12.42)
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PTSD, Post-traumatic stress disorder; EPCACE, Enduring personality change after catastrophic event

MENA, the Middle East and North Africa; F. Yugoslavia, Former Yugoslavia; Other, remaining countries

CCI, Charlson Comorbidity Index; SUD, Substance Use Disorder

†

Includes missing values

‡

Obscured because of low numbers

Table 4 and 5 report the estimates from the stratified regressions, models 1 to 3. The tables show the main effect of region of origin as well as the effect of the exposure diagnoses, adjusted for region. The main effect of region of origin in the first model (model 1) indicates that men (MRR=0.68 [95% CI: 0.65,0.71]) and women (MRR=0.66 [95% CI: 0.62,0.70]) from the MENA region without the exposure disorders had significantly lower MRRs as compared to the Danish-born references. For those from the former Yugoslavia, the estimated mortality was marginally higher compared to the Danish-born reference in model 1 for men (MRR=1.06 [95% CI: 1.01,1.10]) and women (MRR=1.06 [95% CI: 1.01,1.12]).

Table 4.

Mortality rate ratios (MRR) for males per 1000 person-years analysed - all-cause mortality.

Model 1 Model 2 Model 3
Exposure MRR (95% CI) p MRR (95% CI) p MRR (95% CI) p
Main effect of region MENA 0.68 (0.65,0.71) <0.001 0.47 (0.45,0.49) <0.001 0.55 (0.53,0.58) <0.001
F. Yugoslavia 1.06 (1.01,1.10) 0.019 0.78 (0.74,0.82) <0.001 0.94 (0.90,0.98) 0.006
Denmark 1.00 (ref) 1.00 (ref) 1.00 (ref)
Other 1.13 (1.12,1.15) <0.001 0.95 (0.94,0.96) <0.001 1.00 (0.98,1.01) 0.845
Interaction
PTSD/EPCACE MENA 1.06 (0.84,1.35) 0.605 0.65 (0.51,0.82) <0.001 0.65 (0.52,0.83) <0.001
F. Yugoslavia 0.92 (0.68,1.24) 0.578 0.58 (0.43,0.78) <0.001 0.64 (0.47,0.86) 0.003
Denmark 2.05 (1.86,2.26) <0.001 1.45 (1.32,1.60) <0.001 0.96 (0.87,1.06) 0.438
Other 1.48 (1.15,1.92) 0.002 0.91 (0.70,1.17) 0.446 0.80 (0.62,1.04) 0.091
Psychotic disorder MENA 3.79 (3.21,4.46) <0.001 2.32 (1.97,2.74) <0.001 1.88 (1.59,2.21) <0.001
F. Yugoslavia 1.88 (1.44,2.45) <0.001 1.35 (1.03,1.76) 0.028 1.09 (0.83,1.42) 0.533
Denmark 3.35 (3.29,3.41) <0.001 2.35 (2.31,2.39) <0.001 1.80 (1.77,1.83) <0.001
Other 3.30 (3.09,3.53) <0.001 2.22 (2.07,2.38) <0.001 1.61 (1.51,1.73) <0.001
PTSD/EPCACE and psychotic disorder MENA 1.18 (0.76,1.81) 0.461 0.64 (0.42,0.98) 0.042 0.51 (0.33,0.79) 0.002
F. Yugoslavia 1.34 (0.76,2.37) 0.311 0.80 (0.45,1.41) 0.445 0.84 (0.48,1.48) 0.546
Denmark 4.60 (3.78,5.61) <0.001 2.62 (2.15,3.19) <0.001 1.53 (1.26,1.86) <0.001
Other 2.77 (1.94,3.96) <0.001 1.63 (1.14,2.33) 0.008 0.99 (0.69,1.42) 0.952
None MENA 1.00 (ref) 1.00 (ref) 1.00 (ref)
F. Yugoslavia 1.00 (ref) 1.00 (ref) 1.00 (ref)
Denmark 1.00 (ref) 1.00 (ref) 1.00 (ref)
Other 1.00 (ref) 1.00 (ref) 1.00 (ref)
Covariates
Single adult household No 1.00 (ref) 1.00 (ref)
Yes 1.17 (1.16,1.18) <0.001 1.17 (1.16,1.18) <0.001
Labour market participation Employed/education 1.00 (ref) 1.00 (ref)
Retired 3.69 (3.62,3.76) <0.001 2.29 (2.25,2.33) <0.001
Unemployed 4.47 (4.42,4.52) <0.001 2.38 (2.35,2.40) <0.001
CCI None 1.00 (ref)
One 3.87 (3.84,3.90) <0.001
Two or more 11.77 (11.68,11.87) <0.001
SUD No 1.00 (ref)
Yes 2.32 (2.30,2.34) <0.001
Open in a new tab

PTSD, Post-traumatic stress disorder; EPCACE, Enduring personality change after catastrophic event

MENA, the Middle East and North Africa; F. Yugoslavia, Former Yugoslavia; Other, remaining countries

CCI, Charlson Comorbidity Index; SUD, Substance Use Disorder

Table 5.

Mortality rate ratios (MRR) for females per 1000 person-years analysed - all-cause mortality.

Model 1 Model 2 Model 3
Exposure MRR (95% CI) p MRR (95% CI) p MRR (95% CI) p
Main effect of region MENA 0.66 (0.62,0.70) <0.001 0.49 (0.46,0.53) <0.001 0.54 (0.50,0.57) <0.001
F. Yugoslavia 1.06 (1.01,1.12) 0.030 0.85 (0.81,0.90) <0.001 0.95 (0.90,1.00) 0.059
Denmark 1.00 (ref) 1.00 (ref) 1.00 (ref)
Other 1.07 (1.06,1.09) <0.001 0.97 (0.95,0.98) <0.001 0.98 (0.97,0.99) 0.004
Interaction
PTSD/EPCACE MENA 0.57 (0.33,0.98) 0.043 0.35 (0.20,0.61) <0.001 0.40 (0.23,0.69) 0.001
F. Yugoslavia 0.91 (0.62,1.33) 0.620 0.59 (0.40,0.86) 0.006 0.65 (0.44,0.95) 0.025
Denmark 1.70 (1.54,1.87) <0.001 1.35 (1.23,1.49) <0.001 0.98 (0.89,1.08) 0.669
Other 1.63 (1.24,2.15) <0.001 1.15 (0.87,1.51) 0.317 0.91 (0.69,1.19) 0.488
Psychotic disorder MENA 2.93 (2.08,4.13) <0.001 2.07 (1.47,2.91) <0.001 1.79 (1.27,2.53) 0.001
F. Yugoslavia 2.12 (1.63,2.74) <0.001 1.77 (1.37,2.30) <0.001 1.45 (1.12,1.87) 0.005
Denmark 2.40 (2.36,2.43) <0.001 2.15 (2.11,2.18) <0.001 1.71 (1.68,1.73) <0.001
Other 2.55 (2.40,2.71) <0.001 2.26 (2.13,2.41) <0.001 1.68 (1.58,1.79) <0.001
PTSD/EPCACE and psychotic disorder MENA N/A† N/A† N/A†
F. Yugoslavia 1.59 (0.71,3.54) 0.257 0.96 (0.43,2.15) 0.925 0.90 (0.41,2.02) 0.806
Denmark 3.22 (2.62,3.95) <0.001 2.28 (1.86,2.80) <0.001 1.31 (1.06,1.60) 0.010
Other 1.85 (1.05,3.26) 0.033 1.12 (0.62,2.02) 0.712 0.77 (0.43,1.40) 0.396
None MENA 1.00 (ref) 1.00 (ref) 1.00 (ref)
F. Yugoslavia 1.00 (ref) 1.00 (ref) 1.00 (ref)
Denmark 1.00 (ref) 1.00 (ref) 1.00 (ref)
Other 1.00 (ref) 1.00 (ref) 1.00 (ref)
Covariates
Single adult household No 1.00 (ref) 1.00 (ref)
Yes 0.85 (0.84,0.86) <0.001 0.93 (0.92,0.94) <0.001
Labour market participation Employed/education 1.00 (ref) 1.00 (ref)
Retired 3.51 (3.41,3.60) <0.001 2.31 (2.25,2.37) <0.001
Unemployed 4.16 (4.11,4.23) <0.001 2.52 (2.48,2.56) <0.001
CCI None 1.00 (ref)
One 4.02 (3.98,4.05) <0.001
Two or more 11.49 (11.40,11.57) <0.001
SUD No 1.00 (ref)
Yes 2.09 (2.07,2.12) <0.001
Open in a new tab

PTSD, Post-traumatic stress disorder; EPCACE, Enduring personality change after catastrophic event

MENA, the Middle East and North Africa; F. Yugoslavia, Former Yugoslavia; Other, remaining countries

CCI, Charlson Comorbidity Index; SUD, Substance Use Disorder

†

Because of low numbers

Among the diagnosed, no detectable differences were observed for migrant men with and without a PTSD diagnosis (Table 4), after adjusting for the main effect of region. In contrast, highly elevated MRRs were observed for men for all regions of origin among those diagnosed with psychotic disorders, adjusted for region. For migrant men diagnosed with both groups of disorders, the evidence was mixed with no detectable differences observed between those from the MENA region and former Yugoslavia and individuals from the same region without one of the disorders. A similar pattern was observed among women with the disorders in question, although a deviation from the pattern observed for women was seen in model 1; Women from the MENA region diagnosed with PTSD/EPCACE had a lower MRR (0.57 (95% CI: 0.33,0.98)) than undiagnosed women from the MENA (Table 5). Including the covariates of civil status and labour market participation (model 2) and CCI and SUD (model 3) strengthened the association of PTSD/EPCACE with mortality while it for psychotic disorders attenuated across the regions of origin.

4. Discussion

The trauma-related diagnoses of PTSD and EPCACE are overrepresented among those emigrating from the MENA region and former Yugoslavia. While the results from the regression analyses confirm previous research demonstrating a lower MRR of migrants from the MENA region compared to those born in Denmark, no increase in mortality was observed among those with a PTSD/EPCACE diagnosis when taking region of origin into account. Similarly, the highly elevated MRRs for psychotic disorders have been demonstrated in various populations. We did not, however, find a dose-response relationship in terms of further elevated MRRs of those with comorbid PTSD/EPCACE and psychotic disorders, except for Danish-born men and women (model 1).

It is counterintuitive that a diagnosis of PTSD/EPCACE for men and women from the MENA and former Yugoslavia is associated with a lower mortality rate compared to the undiagnosed from the same region (Model 2 and 3 and model 1 for women from the MENA). The relative long-term health advantage of refugees and migrants with a PTSD diagnosis has been observed elsewhere. A population-based study from Sweden indicated that refugees with PTSD had a significantly lower mortality rate compared to Swedish born individuals with the same disorder (Helgesson et al., 2022). Yet the magnitude of the effect in this study comparing the diagnosed individuals to those from the same region of origin could suggest that the results are skewed by other factors such as a strong selection of those receiving a PTSD/EPCACE diagnosis or in the estimation of mortality in this group. Migrant groups use health care services differently according to country of origin and compared to the background population (Nielsen et al., May 2012). The differential contact to the health care system could be one mechanism influencing the observed results.

Moreover, evidence suggests that migrants self-select into their destination countries based on individual migrant characteristics and the reception context at the destination country (Hagen-Zanker and Mallett, 2016). The migration process can be both highly stressful and dangerous and migrants in poor health, and those lacking the necessary resources will be less likely to make the journey. One study also finds that internally displaced population have a higher mortality rate than those fleeing to other countries as refugees (Heudtlass et al., 2016). Therefore these results might indicate that despite their potential traumatic experiences and poor mental health, individuals reaching Europe and who gain residence permit are indicatively a resilient group as shown in several other studies (Helgesson et al., 2022; Aldridge et al., 2018).

The adjustments included in models 2 and 3 indicated that being a single adult household for men was associated with increased mortality, but for women, the opposite was the case. While this variable for men may indicate a degree of social isolation, for women, it likely reflects that women on average live longer and thus are more likely to be widowed at the later stages of their life. Similarly, the variable of labour market participation showed that both unemployment and retirement was associated with increased mortality risk for both men and women. The unemployment category included both disability pension and other social benefits. This category may, therefore, both be associated with poorer health, older age, and indicate a relatively lower socioeconomic status. Non-western migrants in Denmark are overrepresented in the lower-income quintiles, and thus adjusting for job status, consequently, reduces the main effect of region substantially (Lundby Hansen et al., 2019). Retirement, on the other hand, is correlated with higher age and thus naturally associated with mortality (Machů et al., 2022; Van Der Noordt et al., 2014).

Both psychotic disorders and PTSD are frequently co-occurring with substance abuse (Jacobsen et al., 2001; Hunt et al., 2018) which is associated with a shorter lifespan (Nordentoft et al., 2013). Including CCI and SUD does not substantially affect the estimates for those from the MENA or former Yugoslavia, diagnosed with PTSD/EPCACE. While it reduces the estimates for those with psychotic disorders, adjusted for the main effect of region, it increases the estimates for the main effect of region for the MENA and former Yugoslavia for both men and women as compared to the Danish-born reference. Other studies have found lower rates of SUD among non-western migrants (Horyniak et al., 2016). It has been hypothesised that different cultural norms and religious practices act as a protective factor against developing a SUD (Horyniak et al., 2016). Substance abuse and poor health will, to a degree, be on the causal pathway from the exposure to the outcome. Adjusting for SUD and CCI will probably underestimate the mortality of those diagnosed with PTSD/EPCACE and psychotic disorders. This could also be the case for labour market participation and civil status (single adult household). Consequently, model 1 is presented as the primary analysis and the most plausible estimate.

4.1. Strengths and limitations

There has long been a discussion on how to avoid underestimating mortality in migrant populations (Weitoft et al., 1999). The concern is that the observed relatively lower mortality rate does not reflect a real health advantage but rather is a consequence of re-migration not accounted for in the analysis. No convincing evidence has been found to support this notion of the ‘salmon bias’ in which elder or those in poor health return to their country of origin (Norredam et al., 2015). Furthermore, this bias can be minimised as we did here, by adjusting for region of origin (Hollander et al., 2012).

The study estimates the mortality of those migrants with PTSD/EPCACE or a psychotic disorder on the premise that these diagnoses constitute an indicator of vulnerability and traumatic experiences. Yet, as we do not find indication that a PTSD/EPCACE disorder alone or with comorbid psychotic disorder is an increased risk factor for early death, it is also a possibility that a formal diagnosis in the registries is indicative of the individuals’ resources and resilience in general as they have been able to navigate the health care system. We were unfortunately not able to include data on specific traumatic experiences, symptom severity, or refugee status (asylum seeker, family reunification migrant or other migrants) which limits the extent of the conclusions.

Moreover, the group of psychotic disorders included in the analysis, represent a broad spectrum of disorders with various complex causes and does not, like the PTSD/EPCACE diagnosis, necessitate a traumatic event to precede the diagnosis. The highest mortality rates were seen for psychotic disorders alone, perhaps indicating that the psychotic disorders comorbid with PTSD/EPCACE were less severe than those in the psychotic disorder group solely. Finally, it should be noted that many factors throughout the individual's life that affect the risk of excess mortality. A few factors of education, employment, and family structure were included here. These and other potential factors not included here are however complex social phenomena and their relationship with longevity not easily captured in an observational study (Machů et al., 2022; Van Der Noordt et al., 2014).

5. Conclusion

This study provided an overview of the number of migrants and refugees diagnosed with two trauma-related diagnoses, Post-Traumatic Stress Disorder (PTSD) and Enduring Personality Change after Catastrophic Experience (EPCACE), the latter being largely unresearched. The study adds to the literature on mortality of migrants by addressing a gap in research specifically related to the mortality of those with a trauma-related diagnosis and comorbid psychosis. The findings suggest that severe trauma-related diagnoses of PTSD/EPCACE are not associated with excess mortality among those from the Middle East and Northern Africa and former Yugoslavia, even in the face of comorbid psychotic disorders.

Financial support

Drs Agerbo and Laursen were supported by The Lundbeck Foundation Initiative for Integrative Psychiatric Research (LF Grant number: R248-2017-2003)

Role of Funder/Sponsor: The funders did not influence the design and had no role in the conduct of the study.

Declaration of Competing Interest

The authors confirm that they have no conflict of interest to report.

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