Relationship Between C-Reactive Protein and Subclinical Atherosclerosis

Abstract

Elevated levels of C-reactive protein (CRP) are associated with increased risk for incident cardiovascular events on the basis of observations from several prospective epidemiological studies. However, less is known regarding the relationship between CRP levels and atherosclerotic burden. We measured CRP in 3373 subjects 30 to 65 years of age who were participating in the Dallas Heart Study, a multiethnic, population-based, probability sample. Electron-beam CT scans were used to measure coronary artery calcification (CAC) in 2726 of these subjects, and MRI was used to measure aortic plaque in 2393. CRP levels were associated with most traditional cardiovascular risk factors. Subjects with CAC had higher median CRP levels than those without CAC (men: median, 2.4 versus 1.8 mg/L, P<0.001; women: median, 5.2 versus 3.6 mg/L, P<0.001), and there was a modest trend toward increasing CRP levels with increased CAC levels in men (P for trend=0.003) but not in women (P for trend=0.08). Male subjects with aortic plaque also had higher CRP levels than those without (median, 2.3 versus 1.8; P<0.001). In multivariate analysis adjusted for traditional cardiovascular risk factors, body mass index, and estrogen and statin medication use, the associations between CRP levels and CAC and CRP levels and aortic plaque were no longer statistically significant. In a large, population-based sample, subjects with higher CRP levels had a modest increase in the prevalence of subclinical atherosclerosis, but this association was not independent of traditional cardiovascular risk factors. CRP is a poor predictor of atherosclerotic burden.