Agreement Of Seated And Supine Pulse Wave Velocity Measurements With Prolonged Sitting

Abstract

During prolonged sitting research, measuring pulse wave velocity (PWV) in the seated posture would minimize participant burden and preserve the detrimental vascular effects of inactivity. However, PWV is validated in the supine position and it is unknown how supine and seated PWV measures compare. PURPOSE: This study evaluated agreement between the following seated and supine measures of PWV: carotid-femoral (cf), brachial-femoral (bf), and femoral-ankle (fa). We evaluated: (i) the overall agreement between seated and supine measures and (ii) the repeated measures agreement. METHODS: cfPWV, bfPWV, and faPWV were recorded while supine and then seated, and then following a three-hour period of uninterrupted sitting, all measurements were repeated. Mixed model regression was used to calculate agreement between the supine and seated measures. For each PWV outcome, the supine measures were regressed against the seated measures and nested within subject and time (pre vs. post sitting), with subject and time specified as random. The random variance components were used to calculate intraclass correlation coefficients (ICC) with 95% confidence intervals. Overall agreement and repeated-measures ICCs were calculated. An ICC ≥ 0.70 represented strong agreement, and ICC ≥ 0.90 represented a very strong agreement. RESULTS: A total of 18 subjects were included in the final analysis (age: 22.6 ± 3.1 years, female: 6, cfPWV: 6.1 ± 0.9 m/s). The overall agreement between seated and supine measures was strong for cfPWV (ICC: 0.77, 95%CI: 0.63-0.86), weak but significant for bfPWV (ICC: 0.37, 95%CI: 0.11-0.58), and non-significant and weak for faPWV (ICC: 0.26, 95%CI: -0.02-0.49). The cfPWV measurement had strong repeated-measure (i.e., change in pre-sit vs change in post-sit) agreement (ICC: 0.87, 95%CI: 0.78-0.92). There was a very strong repeated measures agreement in bfPWV (ICC: 0.96, 95%CI: 0.93-0.98) and faPWV (ICC: 0.93, 95%CI: 0.88-0.96). CONCLUSIONS: There was strong overall seated and supine agreement for cfPWV but weak overall agreement for bfPWV and faPWV, which indicated that seated and supine measurements are only comparable for cfPWV. Strong to very-strong repeated-measures agreement for all measures suggest that change in PWV is comparable regardless of posture.