Associations between Lipoprotein(a) Levels and Cardiovascular Outcomes in African Americans and Caucasians: The Atherosclerosis Risk in Communities (ARIC) Study
Background—Based on studies with limited statistical power, lipoprotein(a) [Lp(a)] is not considered a risk factor for cardiovascular disease (CVD) in African Americans. We evaluated associations between Lp(a) and incident CVD events in African Americans and Caucasians in the Atherosclerosis Risk in Communities (ARIC) study.
Methods and Results—Plasma Lp(a) was measured in African Americans (n=3,467) and Caucasians (n=9,851). Hazards ratios (HRs) for incident CVD events (coronary heart disease [CHD] and ischemic strokes) were calculated. Lp(a) levels were higher with wider interindividual variation in African Americans (median [interquartile range]: 12.8 [7.1-21.7] mg/dl) than Caucasians (4.3 [1.7-9.5] mg/dl; p <0.0001). At 20 years of follow-up, 676 CVD events occurred in African Americans and 1,821 events occurred in Caucasians. Adjusted HRs (95% confidence interval [CI]) 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 CHD, and 1.21 (1.06-1.39) for ischemic strokes in African Americans. For Caucasians, the respective HRs (95% CIs) 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%CI] 1.35 [1.06-1.74] for African Americans; HR 1.27 [1.10-1.47] for Caucasians). Similar results were obtained using Lp(a) cut-offs of ≤10 mg/dl, >10-≤20 mg/dl, >20-≤30 mg/dl, and >30 mg/dl.
Conclusions—Lp(a) levels were positively associated with CVD events. Associations were at least as strong, with a larger range of Lp(a) concentrations, in African Americans compared with Caucasians.
- Received May 20, 2011.
- Accepted October 31, 2011.
- Copyright © 2011, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited