Racial disparities in stroke risk factors: the impact of socioeconomic status.

BACKGROUND AND PURPOSE

In the US, blacks have a higher incidence of stroke and more severe strokes than whites. Our objective was to determine if differences in income, education, and insurance, as well as differences in the prevalence of stroke risk factors, accounted for the association between ethnicity and stroke.

METHODS

We used data from the Third National Health and Nutrition Survey (NHANES III), a cross-sectional sample of the noninstitutionalized US population (1988-1994), and included blacks and whites aged 40 years or older with a self-reported stroke history. Income was assessed using a ratio of income to US Census Bureau annual poverty threshold.

RESULTS

Among 11 163 participants, 2752 (25%) were black and 619 (6%) had a stroke history (blacks: 160/2752 [6%]; whites: 459/8411 [6%]; P=0.48). Blacks had a higher prevalence of 5 risk factors independently associated with stroke: hypertension, treated diabetes, claudication, higher C-reactive protein, and inactivity; whites had a higher prevalence of 3 risk factors: older age, myocardial infarction, and lower high-density lipoprotein cholesterol. Ethnicity was independently associated with stroke after adjusting for the 8 risk factors (adjusted odds ratio, 1.32; 95% CI, 1.04 to 1.67). Ethnicity was not independently associated with stroke after adjustment for income and income was independently associated with stroke (adjusted odds ratios for: ethnicity, 1.15; 95% CI, 0.88 to 1.49; income, 0.89; 95% CI, 0.82 to 0.95). Adjustment for neither education nor insurance altered the ethnicity-stroke association.

CONCLUSIONS

In this study of community-dwelling stroke survivors, ethnic differences exist in the prevalence of stroke risk factors and income may explain the association between ethnicity and stroke.