Arterial stiffness index based on home (HASI) vs. ambulatory (AASI) blood pressure measurements

Ambulatory arterial stiffness index (AASI) is a novel index derived from the linear relationship between 24-h ambulatory systolic and diastolic blood pressure (BP) measurements. This study investigated whether ‘home arterial stiffness index’ (HASI) based on self-home BP measurements is similar to AASI. A total of 483 hypertensive subjects underwent 24-h ambulatory and 6-day home BP monitoring. AASI and HASI were defined as one minus the respective regression slope of diastolic on systolic BP. Mean HASI (0.66±0.17) was higher than 24-h (0.33±0.15) daytime (0.50±0.18) and nighttime AASI (0.37±0.19, P<0.001 for all comparisons vs. HASI) and was weakly correlated with 24-h (r=0.14, P<0.01) daytime (r=0.14, P<0.01) and nighttime AASI (r=0.09, P=0.05). Compared to 24-h AASI, HASI was less closely associated with age (r=0.46 and 0.10 respectively, P<0.001 for difference), systolic home BP (r=0.30 and 0.09, P<0.001) and pulse pressure (r=0.52 and 0.20, P<0.001), as well as with 24-h ambulatory systolic BP (r=0.21 and 0.05, P<0.05) and pulse pressure (r=0.56 and 0.25, P<0.001). No satisfactory agreement was observed between HASI and 24-h (agreement 63%, κ 0.02) daytime (agreement 65%, κ 0.1) or nighttime AASI (agreement 63%, κ 0.03) in detecting subjects at the top quartile of the respective distributions. HASI appears to be similar but also has important differences from AASI and is less closely associated with markers of arterial stiffness. These data do not support the view that home BP measurements can replace ambulatory monitoring in the assessment of the arterial stiffness index.