Objectives: To define the incidence and cumulative risk of atrial fibrillation (AF) in a population-based cohort of whites and African Americans. Background: African-Americans reportedly have a lower risk of AF than whites despite their higher exposure to AF risk factors. However, precise estimates of AF incidence in African Americans have not been previously published. Methods: We studied the incidence of AF in the Atherosclerosis Risk in Communities (ARIC) study, which has followed up 15,792 men and women 45 to 65 years of age at baseline from 4 communities in the United States since 1987. Atrial fibrillation cases were identified from electrocardiograms conducted at baseline and 3 follow-up visits, and from hospitalizations and death certificates through the end of 2004. During follow-up, 1,085 new cases of AF were identified (196 in African Americans, 889 in whites). Results: Crude incidence rates of AF were 6.7, 4.0, 3.9, and 3.0 per 1,000 persons per year in white men, white women, African-American men, and African-American women, respectively. Increasing age was exponentially associated with an elevated risk of AF. Compared to whites, African-Americans had a 41% (95% CI: 8%-62%) lower age- and sex-adjusted risk of being diagnosed with AF. The cumulative risk of AF at 80 years of age was 21% in white men, 17% in white women, and 11% in African-American men and women. Conclusion: In this population-based cohort, African Americans presented a lower risk of AF than whites. Still, the burden of AF among the former is substantial, with 1 in 9 receiving a diagnosis of AF before 80 years of age.
Bibliographical noteFunding Information:
This research was sponsored by National Heart, Lung, and Blood Institute contracts N01-HC-55015, 55016, 55018, 55019, 55020, 55021, and 55022. Alanna M. Chamberlain was supported by National Heart, Lung, and Blood Institute grant T32-HL-007779. The authors are solely responsible for the design and conduct of this study, all study analyses, the drafting and editing of the article, and its final contents.