Incidence in atrial fibrillation in Denmark in relation to country of origin: a nationwide register-based study

Abstract

Background: Immigrants' healthcare needs can be a considerable challenge, as their risk profile can differ from the native population, and they may experience barriers to accessing health services in recipient countries. Immigration is projected to increase further due to conflicts and climate changes, and awareness on immigrants' health status is therefore warranted. Atrial fibrillation (AF) is the most common sustained arrhythmia with an estimated prevalence of approximately 2%. However, there is a paucity of data on AF epidemiology among immigrants. Purpose: The aim of this study is to examine incidence of AF hospital diagnoses according to country of origin and to study if there is a difference in risk between immigrants and Danish born individuals. Methods: The study period included 1st of January 1998 to 31st of December 2017 and the population consisted of all Danish citizens aged 45 or older. We included individuals as they turned 45 during the study period. Individuals who had been diagnosed with AF were excluded. Data was obtained from the Danish National Patient Registry and the Civil Registration System. Country of origin was based on the ten most represented counties in the population. Immigrants were defined as people born outside Denmark with none of the parents being both Danish citizens and born in Denmark. AF was defined as a hospital diagnosis according to international Classification of Diseases (ICD) version 8 and 10. Poisson regression were used to compute relative risk (RR) and associated 95% confidence intervals (CI). RRs were adjusted for sex, age, socioeconomic status, visits to general practitioner and comorbidity. Results: The study population consist of 3,596,234 Danish-Born and 215,401 immigrants. A total of 334,636 had an incident AF diagnosis during the study period. Compared to Danish-born individuals, migrants from the Nordic countries had a higher adjusted RR of being diagnosed with AF: Norway 1.21 [95% CI: 1.05; 1.40], Sweden 1.16 [95% CI: 0.99; 1.35] and Germany 1.17 [95% CI: 1.06; 1.28]. In contrast, lower adjusted RRs were observed for individuals from Poland (0.82 [95% CI: 0.67; 1.01]), UK (0.89 [95% CI: 0.73; 1.08]), and the US (0.95 [95% CI: 0.72; 1.25]), respectively, and in particular for individuals from the non-Western countries: Turkey (0.49 [95% CI: 0.40; 0.59], Iran (0.48 [95% CI: 0.36; 0.65]), Iraq (0.32 [95% CI: 0.22; 0.45] and Bosnia-Herzegovina (0.63 [95% CI: 0.49; 0.79]). Conclusion: Substantial variation in the incidence rate of incident AF hospital diagnoses according to country of origin. Further studies are warranted in order to clarify to what extent these differences reflets true differences in AF incidence or ethnic inequalities in the detection of AF in the health care system.