Aim: Pulse wave velocity (PWV), augmentation index (AIx) and time to first wave reflection (Tr) are all measures of arterial stiffness, but whether these parameters behave similarly in different populations is not well-understood. Given the large burden of cardiovascular disease in individuals with chronic kidney disease (CKD), assessing the relationship between vascular stiffness parameters in this population is important.
Method: A subset of 152 participants enrolled in the Chronic Renal Insufficiency Cohort Study had vascular stiffness parameters (aortic PWV, central AIx, and Tr) measured using the SphygmoCor system. Linear association between these parameters was assessed using Pearson correlation coefficients. Reproducibility across operators of the device was also tested within individuals.
Results: Association was largest between PWV and heart rate-adjusted AIx (AIx-75). The correlation coefficient was 0.371 (p = 0.0003) for ideal studies and 0.305 (p = 0.0001) for all technically acceptable studies. The association between ideal PWV and AIx-75 measurements was 0.361 (p = 0.005) for men and 0.423 (p = 0.01) for women. Bland-Altman plots comparing the mean value of PWV (n = 31) or AIx-75 (n = 21) when measured by 2 different individuals against the difference in their respective values demonstrate that both measures of arterial stiffness are reproducible across multiple technicians.
Conclusions: Thus, we conclude that PWV and AIx-75, despite measuring different quantities in different units, are related measures of arterial stiffness and are reproducible across multiple operators in the population with CKD.