Racial/ethnic differences in the prevalence of atrial fibrillation among older adults--a cross-sectional study.

Background: Atrial fibrillation affects 4% to 8% of individuals over 60 years of age based on studies of predominantly white populations, whether this is true among nonwhite individuals is not clear. This study was undertaken to define racial/ethnic differences in atrial fibrillation prevalence among a large community cohort.
Methods: This is a cross-sectional study. In 2008, there were 430,317 members aged 60 years or older in a large California health maintenance organization. By searching International Classification of Diseases, Ninth Revision codes and electronic electrocardiographic archives, we identified all members in this age group with primary, nonvalvular atrial fibrillation. Race/ethnicity data were assigned using health plan enrollment, service utilization, Asian/Hispanic surname and geocoding methods, and was available for 80.5% of members (79.8% of non-atrial fibrillation and 92% of atrial fibrillation), 99% of which were white, black, Asian, or Hispanic. We assessed the age- and gender-specific atrial fibrillation prevalence rates for each racial/ethnic group. The effect of race/ethnicity on atrial fibrillation was analyzed with logistic regression methods adjusting for potential confounders.
Results: The overall atrial fibrillation prevalence was 5.3%. Among members with assigned race/ethnicity data, the prevalence among whites, blacks, Asians, and Hispanics was 8.0%, 3.8%, 3.9%, and 3.6%, respectively. The adjusted odds ratios (95% confidence intervals) of atrial fibrillation among blacks, Asians, and Hispanics with whites as referent were 0.49 (0.47-0.52), 0.68 (0.64-0.72), and 0.58 (0.55-0.61), respectively.
Conclusions: Atrial fibrillation is less prevalent in older nonwhite individuals than whites. White race/ethnicity is associated with significantly greater odds for atrial fibrillation compared to blacks, Asians, and Hispanics, after adjusting for comorbidities associated with the development of atrial fibrillation.