Differential Impact of Risk Factors in Blacks and Whites in the Development of Atrial Fibrillation: the Reasons for Geographic And Racial Differences in Stroke (REGARDS) Study

  • Wesley T. O’NealEmail author
  • Suzanne E. Judd
  • Nita A. Limdi
  • William F. McIntyre
  • Dawn O. Kleindorfer
  • Mary Cushman
  • Virginia J. Howard
  • George Howard
  • Elsayed Z. Soliman



Despite a higher prevalence of risk factors, atrial fibrillation (AF) is less prevalent in blacks than whites. To address this paradox, we examined racial differences in the magnitude of AF risk associated with common risk factors.


Participants (13,688; mean age = 63 ± 8.4 years; 56 % female; 37 % black) from the Reasons for Geographic And Racial Differences in Stroke study who were free of baseline AF were included. Incident AF was identified at a follow-up examination by electrocardiogram and self-reported medical history. Poisson regression was used to compute relative risk (RR) and 95 % confidence intervals (CI) for the association between risk factors and incident AF in blacks and whites, separately. Age- and sex-adjusted population attributable fractions (PAFs) of modifiable AF risk factors were computed.


After median follow-up of 9.4 years, 997 (7.3 %) incident AF cases were detected. Black race was associated with a lower risk of AF (RR = 0.46, 95 % CI = 0.39, 0.53). Significant risk factors for AF were age, male sex, hypertension, obesity, and cardiovascular disease. A differential association was detected for smoking by race, with the association being stronger in blacks (RR = 1.41, 95 % CI = 1.07, 1.85) compared with whites (RR = 1.01, 95 % CI = 0.88, 1.16; P interaction = 0.030). The PAFs for hypertension (blacks = 27.4 %, whites = 19.4 %), obesity (blacks = 16.9 %, whites = 11.8 %), and smoking (blacks = 17.9 %, whites = 2.5 %) were higher for blacks than whites.


Modifiable risk factors are important in AF development among blacks despite a lower risk of the arrhythmia. Racial differences in the magnitude of the association of individual AF risk factors do not explain the AF paradox.


Atrial fibrillation Risk factors Race Epidemiology 



The authors thank the other investigators, the staff, and the participants of the REGARDS study for their valuable contributions. A full list of participating REGARDS investigators and institutions can be found at


This research project is supported by a cooperative agreement U01 NS041588 from the National Institute of Neurological Disorders and Stroke, National Institutes of Health, and Department of Health and Human Service. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Neurological Disorders and Stroke or the National Institutes of Health.

Compliance with Ethical Standards

Conflict of Interest

The authors declare no conflicts of interest in the writing of this manuscript.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all participants included in the study.


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Copyright information

© W. Montague Cobb-NMA Health Institute 2016

Authors and Affiliations

  • Wesley T. O’Neal
    • 1
    Email author
  • Suzanne E. Judd
    • 2
  • Nita A. Limdi
    • 3
  • William F. McIntyre
    • 4
  • Dawn O. Kleindorfer
    • 5
  • Mary Cushman
    • 6
  • Virginia J. Howard
    • 7
  • George Howard
    • 2
  • Elsayed Z. Soliman
    • 8
    • 9
  1. 1.Department of Medicine, Division of CardiologyEmory University School of MedicineAtlantaUSA
  2. 2.Department of Biostatistics, School of Public HealthUniversity of Alabama at BirminghamBirminghamUSA
  3. 3.Department of NeurologyUniversity of Alabama at Birmingham School of MedicineBirminghamUSA
  4. 4.Section of Cardiology, Department of Internal MedicineUniversity of ManitobaWinnipegCanada
  5. 5.Department of NeurologyUniversity of CincinnatiCincinnatiUSA
  6. 6.Department of MedicineUniversity of VermontBurlingtonUSA
  7. 7.Department of Epidemiology, School of Public HealthUniversity of Alabama at BirminghamBirminghamUSA
  8. 8.Department of Medicine, Section on CardiologyWake Forest School of MedicineWinston-SalemUSA
  9. 9.Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and PreventionWake Forest School of MedicineWinston-SalemUSA

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