Test-retest reliability of pulse wave velocity in individuals with chronic spinal cord injury

Background: Pulse wave velocity (PWV), which reflects arterial stiffness, is an important predictor of future coronary artery disease. The test-retest reliability of PWV has not been investigated in people with spinal cord injury (SCI). Purpose: To report the test-retest (cay-to-day) reliability of PWV measurements among people with SCI, and to determine the smallest real difference (SAD) of PWV values. Participants: Twenty men (n = 19) and a woman (n = 1) with SCI (C4-T10; AIS A-D; >= 1-year post-injury; 10 with paraplegia and 10 with tetraplegia; time post-injury: 11.8 +/- 8.7 years; age: 43.0 +/- 12.6 years). Methods: On two occasions within a 2-week period, aortic PWV (between the common carotid and femoral artery), arm PWV (between the brachial and radial artery), and leg PWV (between femoral and posterior tibial artery) were assessed at the same time of day using Doppler flowmeters. Results: No statistically significant differences were found between days 1 and 2 in aortic PWV (day 1: 941 +/- 185 cm/seconds, day 2: 917 +/- 160 cm/seconds, P = 0.257), leg PWV (day 1: 1088 +/- 141 cm/seconds, day 2: 1122 +/- 165 cm/seconds, P = 0.099) and arm PWV (day 1: 1283 +/- 185 cm/seconds, day 2: 1358 +/- 256 cm/seconds, P = 0.180). The aortic and leg PWVs had high test-retest reliability (intraclass correlation coefficient: ICC = 0.920 and 0.913 respectively; P < 0.001 for both) and arm PWV had moderate test retest reliability (ICC = 0.598, P = 0.03). SRDs for each PWV were 104 cm/seconds (aortic PWV), 97 cm/seconds (leg PWV) and 143 cm/seconds (a-m PWV). Conclusion: The test retest reliability of PWV assessment is high among patients with chronic SCI. Changes in aortic PWV values above 104 cm/seconds with repeated testing like represent true changes in health status.