Prevalence and incidence rates of atrial fibrillation in Denmark 2004–2018

Abstract

Abstract Background Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with substantial morbidity and mortality. Its prevalence is currently rising partly due to population ageing. However, reported trends in incidence rates are conflicting, and the comparability of existing reports is limited due to methodological inconsistencies across studies. Purpose The main purpose of the current study was to investigate the prevalence of AF in the Danish adult population and time trends in incidence rates from 2004 through 2018. As a secondary purpose, the prevalence and incidence were compared to corresponding Norwegian estimates from 2004 through 2014 derived using the same methodology. Methods A register-based study was conducted including all individuals aged ≥18 years in Denmark from 2004–2018. AF cases were identified in the National Patient Register and the Cause of Death Register, which comprise information on all hospital contacts and deaths in Denmark, respectively. The prevalence of AF was calculated as the number of individuals alive at the end of the study period with at least one registered diagnosis from 1994 through 2018 divided by the number of Danish residents aged ≥18 years. Incidence rates were calculated as the number of annual AF cases with no previous diagnosis noted in the past 10 years divided by the person-time contributed by the population free of AF on 1 January in the same calendar year. All incidence rates were standardized according to a Nordic standard population. The comparison of the Danish and Norwegian incidence estimates focused solely on AF hospitalizations and deaths from 2004 through 2014. Results The cumulative prevalence of AF was 3.0% in the Danish adult population. The incidence increased from 391 per 100,000 person-years in 2004 to 481 per 100,000 person-years in 2015, after which it declined to 367 per 100,000 person-years in 2018 (Figure 1). On average, the incidence increased by 1.7% annually until 2015 (IRR: 1.017 (95% CI: 1.016–1.018); p<0.001) and then declined by 8.5% (IRR: 0.915 (95% CI: 0.909–0.921); p<0.001). Although the incidence rates generally were higher among men and older individuals, a similar time trend was observed in both men and women irrespective of age. Focusing solely on AF hospitalizations and deaths did not change the interpretation of the results. The comparable Norwegian estimates will be presented at the conference. Conclusions The prevalence of AF is currently around 3.0% in the Danish adult population, but the incidence rate has declined steeply since 2015. The observed decline in new cases is promising from a public health perspective and its underlying causes warrant further investigation. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation Figure 1