C-reactive protein (CRP) is an inflammatory biomarker used in vascular risk prediction, though with less data in people of color. Blacks have higher stroke incidence and also higher CRP than whites. We studied the association of CRP with ischemic stroke risk in blacks and whites.

REGARDS, an observational cohort study, recruited and followed 30,239 black and white Americans 45 years and older for ischemic stroke. We calculated hazard ratios and 95% CIs of ischemic stroke by CRP category (<1, 1-3, 3-10, and ≥10 mg/L) adjusted for age, sex and stroke risk factors.

There were 292 incident ischemic strokes among blacks and 439 in whites over 6.9 years of follow-up. In whites, the risk was elevated for CRP in the range from 3 to 10 mg/L and even higher for CRP >10 mg/L, whereas in blacks, an association was only seen for CRP >10 mg/L. Considered as a continuous variable, the risk factor–adjusted hazard ratios per SD higher lnCRP were 1.18 (95% CI 1.09-1.28) overall, 1.14 (95% CI 1.00-1.29) in blacks, and 1.22 (95% CI 1.10-1.35) in whites. Spline regression analysis visually confirmed the race difference in the association.

CRP may not be equally useful in stroke risk assessment in blacks and whites. Confirmation, similar study for coronary heart disease, and identification of reasons for these racial differences require further study.