Risk of long COVID and associated symptoms after acute SARS-COV-2 infection in ethnic minorities: A nationwide register-linked cohort study in Denmark

BACKGROUND

Ethnic minorities living in high-income countries have been disproportionately affected by Coronavirus Disease 2019 (COVID-19) in terms of infection rates, hospitalisations, and deaths; however, less is known about long COVID in these populations. Our aim was to examine the risk of long COVID and associated symptoms among ethnic minorities.

METHODS AND FINDINGS

We used nationwide register-based cohort data on individuals diagnosed with COVID-19 aged ≥18 years (n = 2,287,175) between January 2020 and August 2022 in Denmark. We calculated the risk of long COVID diagnosis and long COVID symptoms among ethnic minorities compared with native Danes using multivariable Cox proportional hazard regression and logistic regression, respectively. Among individuals who were first time diagnosed with COVID-19 during the study period, 39,876 (1.7%) were hospitalised and 2,247,299 (98.3%) were nonhospitalised individuals. Of the diagnosed COVID-19 cases, 1,952,021 (85.3%) were native Danes and 335,154 (14.7%) were ethnic minorities. After adjustment for age, sex, civil status, education, family income, and Charlson comorbidity index, ethnic minorities from North Africa (adjusted hazard ratio [aHR] 1.41, 95% confidence interval [CI] [1.12,1.79], p = 0.003), Middle East (aHR 1.38, 95% CI [1.24,1.55], p < 0.001), Eastern Europe (aHR 1.35, 95% CI [1.22,1.49], p < 0.001), and Asia (aHR 1.23, 95% CI [1.09,1.40], p = 0.001) had significantly greater risk of long COVID diagnosis than native Danes. In the analysis by largest countries of origin, the greater risks of long COVID diagnosis were found in people of Iraqi origin (aHR 1.56, 95% CI [1.30,1.88], p < 0.001), people of Turkish origin (aHR 1.42, 95% CI [1.24,1.63], p < 0.001), and people of Somali origin (aHR 1.42, 95% CI [1.07,1.91], p = 0.016). A significant factor associated with an increased risk of long COVID diagnosis was COVID-19 hospitalisation. The risk of long COVID diagnosis among ethnic minorities was more pronounced between January 2020 and June 2021. Furthermore, the odds of reporting cardiopulmonary symptoms (including dyspnoea, cough, and chest pain) and any long COVID symptoms were higher among people of North African, Middle Eastern, Eastern European, and Asian origins than among native Danes in both unadjusted and adjusted models. Despite including the nationwide sample of individuals diagnosed with COVID-19, the precision of our estimates on long COVID was limited to the sample of patients with symptoms who had contacted the hospital.

CONCLUSIONS

Belonging to an ethnic minority group was significantly associated with an increased risk of long COVID, indicating the need to better understand long COVID drivers and address care and treatment strategies in these populations.

Incidence of stroke, transient ischaemic attack and determinants of poststroke mortality among immigrants in Denmark, 2004‒2018: a population-based cohort study

OBJECTIVE

Using recent registry data, we aimed to quantify the incidence of stroke and transient ischaemic attack (TIA) and to examine factors influencing the risk of poststroke mortality among immigrants compared with Danish-born individuals.

DESIGN

Population-based cohort study between 2004 and 2018. We estimated age-standardised incidence rate ratios (IRR) of stroke, stroke types and TIA for each ethnic group using Danish-born individuals as the reference by direct method of standardisation. We calculated the risk of poststroke mortality using Cox proportional hazard regression.

SETTING

The study was conducted using Danish nationwide registers.

PARTICIPANTS

All cases of first-ever stroke and TIA by country of origin (n=132 936) were included.

RESULTS

Overall, Western immigrants (IRR=2.25; 95% CI 2.20 to 2.31) and non-Western immigrants (IRR=1.37; 95% CI 1.30 to 1.44) had a higher risk of stroke than Danish-born individuals. The risk of TIA was higher in Western immigrants (IRR=2.08; 95% CI 1.93 to 2.23) followed by non-Western immigrants (IRR=1.45; 95% CI 1.27 to 1.63) than in Danish-born individuals. All-cause 1-year mortality hazard was higher but not significantly different in non-Western men (adjusted HR=1.38; 95% CI 0.92 to 2.08) compared with Danish-born men and additional adjustment for comorbidities reduced the HR to 0.85 (0.51 to 1.40) among ischaemic stroke cases. Among intracerebral haemorrhage cases, the adjusted mortality hazard was decreased in Western men (from HR of 1.76; 95% CI 1.09 to 2.85 to HR of 1.30; 95% CI 0.80 to 2.11) compared with Danish-born men after adjustment for stroke severity. Immigrants with ≤15 years of residence had a lower poststroke mortality hazard than Danish-born individuals after additional adjustment for sociodemographic factors (HR=0.36; 95% CI 0.14 to 0.91).

CONCLUSIONS

The age-standardised risk of stroke and TIA was significantly higher among the majority of immigrants than Danish-born individuals. Interventions that reduce the burden of comorbidities, improve acute stroke care and target sociodemographic factors may address the higher risk of poststroke mortality among immigrants.

Ethnic differences in incidence and mortality of stroke in Denmark

Background

Stroke is a leading cause of disability and mortality worldwide. However, studies on incidence and mortality of stroke hereof among ethnic minorities compared with local born are still limited.

Methods

We conducted a Danish nationwide register-based cohort study between 2004 and 2018. All cases of first ever stroke aged 18-95 years were included. Country of birth was used to construct ethnic groups. Age standardized incidence rate ratio (IRR) of stroke stratified by country of birth and sex were estimated with the Danish born as a reference group. Ethnic minorities were grouped as Western and Non-western for mortality hazard ratio (HR) estimates.

Results

In overall, ethnic minorities had a higher risk of stroke compared with Danish born. Particularly, the IRR of all stroke was estimated to be 8.3 times higher among Polish men compared to Danish born men (IRR, 8.32; 95% CI, 6.89-10.05). Compared with Danish born women, Pakistan women had the highest risk of all stroke (IRR, 2.89; 95% CI, 2.46-3.39). By contrast, Swedish women had reduced risk of hemorrhagic stroke (IRR, 0.40; 95% CI, 0.18-0.89) and Norwegian women had reduced risk of ischemic stroke (IRR, 0.87; 95% CI, 0.72-1.06). Compared with Danish born men, all-cause 1-year mortality hazard for Non-western men was (HR, 1.61; 95% CI, 1.13-2.29) while for Western men was (HR, 1.07; 95% CI, 0.90-1.29) among ischemic stroke patients. Among hemorrhagic stroke patients, 1-year mortality hazard for Non-western men was (HR, 0.75; 95% CI, 0.39-1.47) whereas Western men had (HR, 1.48; 95% CI, 1.04-2.10). Among women, we observed reduced all cause 1-year mortality hazard in Non-western (HR, 0.32; 95% CI, 0.13-0.80) for hemorrhagic stroke whereas no difference in mortality hazard was observed for ischemic stroke.

Conclusions

Incidence and post stroke mortality appear to vary among ethnic minorities in comparison to Danish born. It may depend on the type of stroke and sex.

Key messages

The study contributes knowledge in migration and health. With good quality registers, we are in unique position to establish findings in Denmark, which has a growing migrant population.