Validity and reliability of carotid-toe pulse wave velocity as a measure of arterial stiffness in healthy individuals: Comparison to carotid-femoral pulse wave velocity

Purpose: The present investigation evaluated the validity and reliability of carotid-toe PWV (ctPWV) as a non-intrusive measure of systemic arterial stiffness in healthy young adults. Methods: The Validity Trial examined the association and agreement between cfPWV and ctPWV in 33 adults (24 ± 2 years; 14 females), while the Reliability Trial assessed the variability in cfPWV and ctPWV in 13 adults (22 ± 2 years; 5 females) over repeat visits. Proximal pulse waves were acquired (applanation tonometry) from the left common carotid (CCA) for both measures, while distal pulse waves were acquired from the left femoral artery (applanation tonometry) and the second left toe (pulse oximeter) for cfPWV and ctPWV, respectively. Results: cfPWV (5.3 ± 0.7, 3.9–6.5 m/s) and ctPWV (5.4 ± 0.5, 4.6–6.3 m/s) demonstrated a moderate-to-strong positive linear correlation (r = 0.79, P < 0.01) and a strong intra-class correlation (ICC; ICC = 0.86, P < 0.01). The Bland–Altman plot demonstrated agreement between cfPWV and ctPWV with no fixed bias (0.1 m/s, ± 2SD: −0.8 to 0.9 m/s, P > 0.05) and all data points falling within ±2 SD of the mean difference between measures. cfPWV and ctPWV demonstrated reliability across visits as evidenced by low coefficients of variation (cfPWV: 3.4 ± 2.6%, ctPWV: 2.6 ± 2.5%) and strong ICCs (cfPWV: ICC = 0.91, ctPWV: ICC = 0.84, both P < 0.01). Conclusions: Through comparison with cfPWV, this study provides evidence to suggest that ctPWV yields a valid and reliable index of arterial stiffness in healthy young adults.