Direct means of obtaining CAVI 0 —a corrected cardio-ankle vascular stiffness index (CAVI)—from conventional CAVI measurements or their underlying variables

Objective : Cardio-ankle vascular index (CAVI) as measured using the VaSera device (CAVI VS , Fukuda Denshi), has been proposed as a stiffness index that does not depend on blood pressure. We have recently shown theoretically that CAVI VS still exhibits blood pressure dependence, and proposed the corrected index CAVI 0 . The present study aims to establish a method of calculating C A V I 0 either (i) from VaSera-reported values of cardiac-brachial and brachial-ankle pulse transit times (tb and tba, respectively) and blood pressure, or (ii) directly from CAVI VS . To derive this method, the relationship among CAVI VS and its scale constants a and b , tb, tba, and blood pressure has to be established. Approach : From data of 497 subjects, eight candidate CAVI parameters were defined and calculated, containing all combinations of left or right tb/tba/blood pressure. Candidates were evaluated through correlation with measured left and right CAVI VS . Correlations were compared statistically. Once the correct candidates were determined, two constants ( a and b ) required for converting CAVI VS to CAVI 0 were estimated through linear regression. Main results : Left and right CAVI VS are calculated using left and right tba; however, both left and right CAVI VS are calculated using right brachial blood pressures and right tb. Constants a and b for conversion of CAVI VS to CAVI 0 were estimated to be 0.842 [0.836 0.848] and 0.753 [0.721 0.786] (mean [95%CI]), respectively. Equations to estimate CAVI 0 from CAVI VS , and to directly calculate CAVI 0 from the VaSera output are provided in this paper, as well as in a directly usable spreadsheet supplement. Significance : Our results permit straightforward calculation of C A V I 0 during a study, as well as retrospective estimation of C A V I 0 from CAVI VS in already published studies or where the original transit time values are not available, paving the way for thorough comparison of CAVI 0 to CAVI VS in clinical and research settings. Novelty and significance Cardio-ankle vascular index (CAVI) as measured using the VaSera device (CAVI VS , Fukuda Denshi), has been proposed as a blood pressure-independent arterial stiffness index. We have recently shown theoretically that CAVI VS still exhibits pressure dependence, and proposed a corrected index, CAVI 0 . In the present study, we derived equations to directly obtain CAVI 0 using data from the VaSera device. Our results permit straightforward calculation of C A V I 0 during a study, as well as retrospective estimation of