Objective: Chronic low-grade inflammation is associated with atherosclerosis. Ultrasound imaging allows measurement of intima-media thickness (IMT) and plaque. We investigated the association between inflammatory markers and carotid and femoral atherosclerosis.
Methods: We studied 554 subjects with primary dyslipidemia (57% men, median age 49 years) and 246 age- and sex-matched normolipidemic subjects. Carotid and femoral arteries were imaged bilaterally with a standardized protocol. Mean and maximum common carotid IMT (CC-IMT and MaxCC-IMT) and common femoral IMT (F-IMT and MaxF-IMT), and carotid and femoral plaque were assessed. Carotid atherosclerosis was defined by CC-IMT and/or plaque height >75th percentile of a reference population. White blood cell count (WBCC) was measured in all subjects. High-sensitivity C-reactive protein (CRP) was measured in 330 dyslipidemic subjects.
Results: The age- and sex-adjusted probability of carotid atherosclerosis and femoral plaque increased by 20% (odds ratio [OR] 1.20; 95% CI, 1.10-1.31) and 25% (1.25; 1.13-1.38), respectively, for each 1000/mm(3) WBCC increment. WBCC was associated with age- and sex-adjusted CC-IMT and MaxCC-IMT (p<0.05, both), and F-IMT and MaxF-IMT (p<0.001, both). Adjustment for cardiovascular risk factors did not influence these associations. CRP was associated with CC-IMT and MaxCC-IMT (p<0.05, both), but the associations disappeared after adjustment for body mass index. CRP was unrelated to carotid plaque or measures of femoral atherosclerosis.
Conclusions: WBCC, but not CRP, related to early and advanced measures of atherosclerosis independently of risk factors. Our findings support using the heretofore undervalued WBCC as an easy-to-measure, low-cost diagnostic marker of atherosclerosis.
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