Table 7.
Studies assessing the repeatability or reproducibility of PPG-derived parameters of vascular age
| Study | PPG Parameter | Subjects | Delay | Findings |
|---|---|---|---|---|
| Pulse wave velocity (PWV) | ||||
| Loukogeorgakis et al. (89) | PWV along: carotid-femoral, arm and leg |
Healthy 10 min: 10 3 h: 5 |
10 min 3 h |
Coefficient of variation (CV): -carotid-femoral: 5.7% (10 min), 6.3% (3 h) -arm: 5.6% (10 min), 13.0% (3 h) -leg: 4.6% (10 min), 16.1% (3 h) |
| Tsai et al. (94) | Finger-toe PWV | 20 healthy | 20 min | Intra-class correlation coefficient (ICC): 0.959 Limits of agreement: 0.09 ± 0.69 m/s CV: 5.8% |
| Nabeel et al. (170) | Local carotid PWV | 35 healthy | Beat-to-beat 10 s |
CV: from 4.15% to 11.38% (beat-to-beat) Limits of agreement: 0.02 ± 0.22 m/s (10 s) Correlation coefficient: 0.96 (10 s) |
| Jang et al. (140) | Brachial-ankle PWV (estimated) | HealthyIndividual: 123 Average: 47 |
None | CV (individual pulse waves analyzed): 2.52% CV (average from several pulse waves): 0.27% |
| Liu et al. (121) | Heart-ear, heartfinger, heart-toe PWV (bilateral) | 15 healthy | 3 mo | Technical error of measurement (TEM) and relative TEM (rTEM): -heart-ear: TEM 0.005 and 0.0058, rTEM 4.7% and 5.4% -heart-finger: TEM 0.0538 and 0.0601, rTEM 1.2% and 1.2% -heart-toe: TEM 0.054 and 0.0661, rTEM 1.1% and 1.3% |
| Nabeel et al. (173) | Local carotid PWV | 25 healthy | 10 s | Correlation coefficient: 0.97 Limits of agreement: −0.01 ± 0.19 m/s |
| Alivon et al. (86) | Finger-toe PWV | 38 unhealthy, 7 healthy | 5 min | CV: 4.52% Limits of agreement: 0.02 ± 0.98 m/s |
| Systolic (SBP), diastolic (DBP) and mean (MBP) blood pressure (BP) | ||||
| Scanlon et al. (124) | Toe BP, toe-brachial index (TBI) | 60 patients with diabetes | 7 days | ICC and standard error of measurement (SEM): -toe BP intrarater reliability: ICC 0.78–0.79, SEM 8 mmHg -toe BP interrater reliability: ICC 0.93, SEM 4 mmHg -TBI intrarater reliability: ICC 0.51–0.72, SEM 0.08 -TBI interrater reliability: ICC 0.85, SEM 0.07 |
| Hoyer et al. (155) | Ankle and toe SBPs | 60 unhealthy | 3 mo | CV of toe SBP: Vicorder device 5.63%, Falcon device 6.36% CV of ankle SBP: Vicorder device 3.43%, Falcon device 4.01% |
| Single PPG pulse wave parameters | ||||
| von Wowern et al. (139) | Finger PPG indices | 112 Healthy and unhealthy | Consecutive measurements | Good repeatability (ICC ≥ 0.80): aging index (AGI), dicrotic index, dicrotic dilatation index, cardiac ejection elasticity index, b/a, e/a. Moderate repeatability (ICC: 0.50–0.79): elasticity index, c/a, d/a, a–b and a–e intervals. Poor repeatability (ICC < 0.50): ejection time compensated, dicrotic elasticity index, a-c and a-d intervals. |
| Peltokangas et al. (27) | AGI and amplitude ratios from 5 body locations | Atherosclerotic, healthy | Beat-to-beat Single session 3 days |
Beat-to-beat: ICCs mostly >0.8. Single session: ICCs mostly >0.95, average intra-subject CV < 0.1. 3 days: ICCs for some indices >0.6, with few >0.8. |
| Millasseau et al. (73) | Finger stiffness index (SI) | 8 healthy | 1 wk | Within-subject CV: 9.6% |
| Millasseau et al. (91) | Finger PPG indices | 8 healthy | Short-term: same day Long-term: ≥ 3 days |
Within-subject CV: high short-term repeatability (<5%): SI, reflection index, b/a low short-term repeatability (>10%): c/a, d/a, e/a high long-term repeatability (<10%): SI, b/a low long-term repeatability (>10%): reflection index, c/a, d/a, e/a |
| Kulin et al. (85) | Finger PPG indices | Pulse wave simulator, 10 healthy | minutes | Pulse wave simulator: very low CVs (<1%) for all parameters in “normal” mode; high CVs (>10%) for AGI, d/a and c–d detection ratio in “abnormal” mode. Healthy subjects: low CVs (<5%) for left ventricular ejection time, heart rate, interbeat interval, b/a, SI; moderate CV (7.4%) for reflection index; high CVs (>10%) for AGI, c–d detection ratio, d/a. |
| Gunarathne et al. (108) | Finger SI | 100 healthy | 5 min weeks |
Limits of agreement: 0.09 ± 1.32 m/s (5 min), 0.12 ± 1.86 m/s (6 wk) |
| Other parameters | ||||
| Tanaka et al. (116) | Finger MBP, finger arterial SI and elasticity index | 6 healthy | day(s) | Mean CV: MBP 4.51%, SI 5.72%, elasticity index 8.20% |
| LopezBeltran et al. (145) | Peripheral vascular compliance index | 9 healthy | Single session | CV: from 11.3% to 15.1% depending on MBP |
PPG, photoplethysmogram.