Reproducibility of arterial compliance and carotid wall thickness measurements in normal subjects

1. Non-invasive techniques to measure indices of arterial function and wall thickness are frequently used as surrogate markers of cardiovascular disease. Reproducibility of measurements of arterial compliance has been infrequently reported and little is known about the interrelationships of the various indices in vivo. 2. The present study was designed to assess reproducibility and interrelationships of indices of systemic arterial compliance, pulse wave velocity, carotid compliance and intima-media thickness (IMT). 3. Fifty healthy volunteers (20 male and 30 female; aged 20-70 years, mean 46.5 years), participated in the present study. Each subject was studied on two occasions by the same investigators, using an identical protocol at an interval of 1-5 weeks (mean 2.5 weeks) without lifestyle change. 4. There were no significant differences between visits for any recorded general data, except resting blood pressure, which was lower on the second occasion. There were no systematic differences within each pair over the range of measurements for any of the variables. Bland-Altman plots of repeatability of changes in indices showed that the mean values between visits were not significantly different. All indices of central arterial compliance were significantly related to age and IMT. 5. Thus, under controlled experimental conditions, there was satisfactory repeatability of measurements of indices of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance and IMT), This type of information will permit the construction of sample size tables for clinical trials using these indices. 6. Central arterial compliance may be an important determinant of IMT.