Personalized Protocol for the Dynamic Assessment of Functional Biomarkers of Vascular Stiffness: A Novel Diagnostic Tool in P4 Medicine

Background/Objectives: Functional biomarkers of vascular stiffness (FBM-VS) may serve as an effective tool for predicting and monitoring the effectiveness of preventive strategies against accelerated vascular ageing in healthy populations within the framework of P4 medicine. The aim of this study was to perform a comparative analysis of a standardized to hydrostatic column height passive head-up tilt test (stHUTT) and a simplified supine-to-sitting test (SST) for measuring FBM-VS in a paired sample of young healthy subjects. Materials and Methods: This observational cross-sectional study included 95 healthy adults aged 18–20 years (54 women and 41 men). Brachial–ankle pulse wave velocity (baPWV) was measured in three positions: baseline supine position (baPWVb), during stHUTT (baPWVst), and after transitioning to a sitting position (baPWVsit). The functional reserve of orthostatic circulatory regulation (FR) and the functional reserve coefficient (FRC) were calculated for the stHUTT (FRst and FRCst) and during the supine-to-sitting test (FRsit and FRCsit). Results: The results showed unidirectional orthostatic changes in baPWV during both tests (significant increase compared to baseline supine values): baPWVst and baPWVsit in stHUTT and during the SST increased from 8.6 [8.1; 9.1] m/s to 13.4 [12.1; 14.4] m/s and to 15.2 [13.4; 16.1] m/s (p < 0.001), respectively. FBM-VS values in the SST were higher compared to stHUTT: FRsit = 6.4 [5.25; 7.75] m/s vs. FRst = 4.85 [3.7; 5.75] m/s (p < 0.001), and FRCsit = 0.74 [0.59;0.9] vs. FRCst = 0.55 [0.45; 0.68] (p < 0.001). The variance of these parameters was also significantly higher in the SST. Spearman rank correlation analysis demonstrated significant positive correlations between biomarkers measured during both orthostatic tests. Conclusions: The supine-to-sitting test may be used for the personalized quantitative assessment of FBM-VS in healthy populations. To assess their prognostic value and to provide personalized long-term monitoring to control the effectiveness of preventive measures against vascular ageing in healthy individuals, a prospective cohort study is required.