Temporal trends in the incidence of atrial fibrillation‐related strokes in Sweden, 2001‐2020

Abstract Background Atrial fibrillation (AF) increases the risk of stroke, which in turn elevates the risk of dementia in old age. Thus, changes in the incidence of stroke over time could greatly affect population brain health. The prevalence of AF is increasing worldwide, but how this impacts the incidence of stroke is unclear. We aimed to provide an up‐to‐date estimate on the temporal trends in the incidence of AF‐related stroke in Sweden during the period 2001‐2020. Method Data from the total Swedish population aged ≥60 years during the period 2001‐2020 were used. First‐ever stroke and AF diagnoses were identified through hospital admissions and deaths in the national health registers. AF‐related stroke is defined as stroke event with documented AF diagnosis within 5 years before the event, at the time of event, or within 2 months after the event. Result The annual incidence rate of overall stroke declined substantially in both men and women during 2001‐2020 (incidence rate [IR] 2001 vs. 2020 = 153.0 vs. 87.7 for men; 134.7 vs. 72.1 for women). There was only a slight decline in the incidence rate of AF‐related stroke (IR 2001 vs. 2020 = 32.0 vs. 28.3 for men; 30.6 vs. 21.9 for women). The strength of the association between AF and incident stroke also decreased over time. In men, AF was associated with a hazard ratio (HR) of 1.56 (confidence interval [CI]: 1.50‐1.62) for incident stroke in 2006‐2008 as compared to a HR of 1.46 (CI: 4.41‐1.52) in 2015‐2017. In women, the HR for incident stroke associated with AF is 2.15 (CI: 2.08‐2.22) in 2006‐2008 and 1.76 (CI: 1.69‐1.82) in 2015‐2017. On the other hand, the percentage of AF‐related strokes out of all strokes increased during 2001‐2020, from 21.8% to 33.6% for men and from 23.5% to 31.6% for women. Conclusion The incidence of AF‐related strokes among people 60 years and over declined in Sweden during 2001‐2020, and so did the strength of the association between AF and risk of stroke. On the other hand, the percentage of AF‐related strokes out of all strokes increased over time, and one‐third of strokes were AF‐related by the end of 2020.