Increased carotid artery intima-media thickness (IMT) has been widely used as a surrogate marker of atherosclerosis and has been shown to predict cardiovascular disease (CVD). However, the interpretation of IMT values, as measured across different age, sex and risk groups, has been hampered by the absence of normal and reference values comparators. The aim of the present study is therefore to establish normal and reference values for IMT based on a wide population.

We combined common carotid IMT data from 25 research centres worldwide as obtained with the use of an echo-tracking system. The total population consisted of 29,975 individuals (54% men), with ages ranging from 15 to 101 years-old, of whom 21% had established CVD, 56% had hypertension, 11% had diabetes, 25% had hypercholesterolemia, 20% was current smoker and 32 and 16% were on blood pressure (BP)- and/or lipid lowering treatment respectively.

Sex- and age-specific normal values of IMT were established in the ‘normal population’, which consisted of 2,762 individuals without overt CVD, and who had optimal or normal BP (i.e. <130/85 mm Hg) and no acquired cardiovascular risk factors [i.e. diabetes, use of BP- and/or lipid lowering medication, hypercholesterolemia, current smoking] (Fig 1). Multiple linear regression analyses will be used to investigate the influence of, and establish reference IMT values across categories of the cardiovascular risk factors mentioned above.

Fig 1

Normal values of IMT for age categories in men and women

In conclusion, this unique study enables the definition of normal and reference values for IMT to help interpretation of such measures as obtained in both research and clinical settings.