Differences in the role of black race and stroke risk factors for first vs recurrent stroke

OBJECTIVES: To assess whether black race and other cerebrovascular risk factors have a differential effect on first vs. recurrent stroke events. METHODS: Estimate the differences in the magnitude of the association of demographic (age, back race, sex) or stroke risk factors (hypertension, diabetes, cigarette smoking, atrial fibrillation, left ventricular hypertrophy, or heart disease) for first vs. recurrent stroke from a longitudinal cohort study of 29,682 black or white participants aged 45 years and older. RESULTS: Over an average 6.8 years follow-up, 301 of 2,993 participants with a previous stroke at baseline had a recurrent stroke, while 818 of 26,689 participants who were stroke-free at baseline had a first stroke. Among those stroke-free at baseline, there was an age-by-race interaction (p = 0.0002), with a first stroke risk 2.70 (95% confidence interval: 1.86-3.91) times greater for black than white participants at age 45, but no racial disparity at age 85 (hazard ratio = 0.91; 95% confidence interval: 0.70-1.18). In contrast, there was no evidence of a higher risk of recurrent stroke at any age for black participants (p > 0.05). The association of traditional stroke risk factors was generally similar for first and recurrent stroke. CONCLUSION: The association of age and black race differs substantially on first vs. recurrent stroke risk, with risk factors playing a similar role.