Ethnic differences in incidence and mortality of stroke in Denmark

Abstract

Abstract 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.