Association between Ambulatory Arterial Stiffness Index and Blood Pressure Variability: A Cross-Section Study

Abstract

Ambulatory arterial stiffness index (AASI), a surrogate marker of arterial stiffness derived from ambulatory blood pressure (BP), which is calculated as 1 minus the linear slope of diastolic BP on systolic BP. Our study aim was to investigate the association between AASI and BP variation parameters, evaluated by both circadian rhythms and 24h coefficient of variation (CoV) in a population of normotension, untreated hypertension, controlled hypertension, uncontrolled hypertension, white coat hypertension and white coat uncontrolled hypertension. 610 subjects (48.7% female, age 60.9 ± 13.2 years), who underwent 24h ambulatory blood pressure monitoring were included; AASI was significantly higher in reverse-dipping than other dipping patterns, both in systolic and diastolic BP (p< .05). In a multiple linear regression analysis, circadian rhythms and 24h CoV in diastolic BP were independently associated with AASI after adjusted for multiple confounders (β=-0.002, 95% Cl -0.004~-0.001, P= .0004; β=-0.56, 95% Cl -0.78~-0.33, P< .001); the association between circadian rhythms and AASI were consistent across subgroups defined according to age, sex, BP phenotypes, smoking status, and white coat effect (p for interaction all>0.05). In conclusion, in subjects of different BP phenotypes, AASI was significantly associated with circadian rhythms and 24h CoV.