Associations between lipoprotein(a) levels and cardiovascular outcomes in black and white subjects: the Atherosclerosis Risk in Communities (ARIC) Study.

Abstract

On the basis of studies with limited statistical power, lipoprotein(a) [Lp(a)] is not considered a risk factor for cardiovascular disease (CVD) in blacks. We evaluated associations between Lp(a) and incident CVD events in blacks and whites in the Atherosclerosis Risk in Communities (ARIC) study. Plasma Lp(a) was measured in blacks (n=3467) and whites (n=9851). Hazards ratios (HRs) for incident CVD events (coronary heart disease and ischemic strokes) were calculated. Lp(a) levels were higher with wider interindividual variation in blacks (median [interquartile range], 12.8 [7.1-21.7] mg/dL) than whites (4.3 [1.7-9.5] mg/dL; P<0.0001). At 20 years of follow-up, 676 CVD events occurred in blacks, and 1821 events occurred in whites. Adjusted HRs (95% confidence interval) per race-specific 1-SD-greater log-transformed Lp(a) were 1.13 (1.04-1.23) for incident CVD, 1.11 (1.00-1.22) for incident coronary heart disease, and 1.21 (1.06-1.39) for ischemic strokes in blacks. For whites, the respective HRs (95% confidence intervals) were 1.09 (1.04-1.15), 1.10 (1.05-1.16), and 1.07 (0.97-1.19). Quintile analyses showed that risk for incident CVD was graded but statistically significant only for the highest compared with the lowest quintile (HR [95% confidence interval], 1.35 [1.06-1.74] for blacks and 1.27 [1.10-1.47] for whites). Similar results were obtained with the use of Lp(a) cutoffs of ≤10 mg/dL, >10 to ≤20 mg/dL, >20 to ≤30 mg/dL, and >30 mg/dL. Lp(a) levels were positively associated with CVD events. Associations were at least as strong, with a larger range of Lp(a) concentrations, in blacks compared with whites.