Reference values for local arterial stiffness. Part A: carotid artery

Objective:Non-invasive measures of common carotid artery properties, such as diameter and distension, and pulse pressure, have been widely used to determine carotid artery distensibility coefficient - a measure of carotid stiffness (stiffness approximate to 1/distensibility coefficient). Carotid stiffness has been associated with incident cardiovascular disease (CVD) and may therefore be a useful intermediate marker for CVD. We aimed to establish age and sex-specific reference intervals of carotid stiffness.Methods:We combined data on 22708 individuals (age range 15-99 years, 54% men) from 24 research centres worldwide. Individuals without CVD and established cardiovascular risk factors constituted a healthy sub-population (n=3601, 48% men) and were used to establish sex-specific equations for percentiles of carotid distensibility coefficient across age.Results:In the sub-population without CVD and treatment (n=12906, 52% men), carotid distensibility coefficient Z-scores based on these percentile equations were independently and negatively associated, in men and women, respectively, with diabetes {-0.28 [95% confidence interval (CI) -0.41; -0.15] and -0.27 (-0.43; -0.12)}, mean arterial pressure [-0.26 (-0.29; -0.24) and -0.32 (-0.35; -0.29)], total-to-high-density lipoprotein cholesterol ratio [-0.05 (-0.09; -0.02) and -0.05 (-0.11; 0.01)] and BMI [-0.06 (-0.09; -0.04) and -0.05 (-0.08; -0.02)], whereas these were positively associated with smoking [0.30 (0.24; 0.36) and 0.24 (0.18; 0.31)].Conclusions:We estimated age and sex-specific percentiles of carotid stiffness in a healthy population and assessed the association between cardiovascular risk factors and carotid distensibility coefficient Z-scores, which enables comparison of carotid stiffness values between (patient) groups with different cardiovascular risk profiles, helping interpretation of such measures.