Socioeconomic status and the incidence of atrial fibrillation in whites and blacks: the Atherosclerosis Risk in Communities (ARIC) study.

BACKGROUND: No previous studies have examined the interplay among socioeconomic status, sex, and race with the risk of atrial fibrillation (AF).

METHODS AND RESULTS: We prospectively followed 14 352 persons (25% black, 75% white, 55% women, mean age 54 years) who were free of AF and participating in the Atherosclerosis Risk in Communities (ARIC) study. Socioeconomic status was assessed at baseline (1987-1989) through educational level and total family income. Incident AF through 2009 was ascertained from electrocardiograms, hospitalizations, and death certificates. Cox regression was used to estimate hazard ratios and 95% CIs of AF for education and family income. Interactions were tested between socioeconomic status and age, race, or sex. Over a median follow-up of 20.6 years, 1794 AF cases occurred. Lower family income was associated with higher AF risk (hazard ratio 1.45, 95% CI 1.27 to 1.67 in those with income less than $25 000 per year compared with those with $50 000 or more per year). The association between education and AF risk varied by sex (P=0.01), with the lowest education group associated with higher AF risk in women (hazard ratio 1.88, 95% CI 1.55 to 2.28) but not in men (hazard ratio 1.15, 95% CI 0.97 to 1.36) compared with the highest education group. Adjustment for cardiovascular risk factors attenuated the associations. There were no interactions with race or age. Blacks had lower AF risk than whites in all income and education groups.

CONCLUSIONS: Lower family income was associated with a higher AF risk overall, whereas the impact of education on AF risk was present only in women. Differences in socioeconomic status do not explain the lower risk of AF in blacks compared with whites.