Background
Methods
Study design
Subjects
Study I: sensitivity and experimental concurrent validity
n | UPDRS | Age | Medications | |
---|---|---|---|---|
Study I | 13 PD | 28.1(±11.2) | 60.4 ± 8.5 years | None |
12 CTRL | 60.2 ± 8.2 years | |||
Study II | 17 PD | 28.3 (±10.4) | 67.1 ± 7.3 years | PD ON medication |
17 CTRL | 67.9 ± 6.1 years |
Study II: test-retest reliability and clinical concurrent validity
Measurement protocol and data acquisition
Study I: sensitivity and experimental concurrent validity
Study II: test-retest reliability and clinical concurrent validity
Automatic instrumented Sway in the clinic: ISway
Measure abbreviation
|
Description
|
---|---|
JERK | Sway jerkiness, time derivative of acceleration[m2/s5] |
Time-domainmeasures
| |
DIST | Mean distance from center of COP (ACC) trajectory[mm] ([m/s2]) |
RMS | Root mean square of COP (ACC) time series [mm]([m/s2]) |
PATH | Sway path, total length of COP (ACC) trajectory[mm] ([m/s2]) |
RANGE | Range of COP displacement (acceleration) [mm]([m/s2]) |
MV | Mean velocity COP: PATH/trial duration [m/s];ACC: [mm/s] |
MF | Mean frequency, the number, per second, of loopsthat have to be run by the COP (ACC), to cover atotal trajectory equal to PATH (MF = PATH/(2*π*DIST*trial duration) (Hz) |
AREA | Sway area, computed as the area spanned fromthe COP (ACC) per unit of time [mm2/s] ([m2/s5]) |
Frequency-domainmeasures
| |
PWR | Total power [mm2] ([m2/s4]) |
F50 | Median frequency, frequency below which the50% of PWR is present (Hz) |
F95 | 95% power frequency, frequency below which the95% of PWR is present (Hz) |
CF | Centroidal frequency (Hz) |
FD | Frequency dispersion (−) |
Data analysis
Results
Study I: sensitivity and experimental concurrent validity
COP | ACC | Correlation | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Control | PD | p values | Control | PD | p values | r | p | |||||
Mean | SEM | Mean | SEM | Mean | SEM | Mean | SEM | |||||
Jerk | NA | 0.241 | 0.023 | 0.394 | 0.053 |
0.0003
| ||||||
Trajectory Measures
| ||||||||||||
DIST |
4.370
|
0.329
|
6.261
|
0.423
|
0.002
|
0.062
|
0.005
|
0.088
|
0.010
|
0.02
|
0.73
| 0.0001 |
RMS |
5.141
|
0.371
|
7.329
|
0.552
|
0.003
|
0.073
|
0.006
|
0.106
|
0.012
|
0.02
|
0.74
| 0.0000 |
PATH | 944.015 | 89.277 | 817.707 | 62.661 | 0.25 | 17.183 | 1.028 | 22.035 | 2.128 | 0.05 | 0.46 | 0.200 |
RANGE | 32.247 | 2.750 | 40.824 | 3.385 | 0.06 |
0.421
|
0.031
|
0.610
|
0.065
|
0.01
|
0.64
| 0.0007 |
MV | 7.867 | 0.744 | 6.814 | 0.522 | 0.26 | 1.328 | 0.229 | 1.789 | 0.241 | 0.18 | 0.12 | 0.56 |
MF |
0.290
|
0.018
|
0.181
|
0.016
|
0.0001
| 0.393 | 0.029 | 0.378 | 0.045 | 0.78 | 0.33 | 0.11 |
Area Measures
| ||||||||||||
AREA | 10.699 | 1.581 | 13.138 | 2.121 |
0.36
|
0.002
|
0.0003
|
0.005
|
0.001
|
0.004
|
0.68
| 0.002 |
Frequency Measures
| ||||||||||||
PWR |
9870.8
|
1761.7
|
12966.1
|
1585.1
| 0.2 |
2.009
|
0.269
|
3.178
|
0.479
|
0.04
| 0.41 | 0.05 |
F50 |
0.410
|
0.015
|
0.298
|
0.012
|
0.00009
|
0.385
|
0.014
|
0.305
|
0.012
|
0.0003
|
0.86
| 0.000001 |
F95 |
1.518
|
0.069
|
0.990
|
0.057
|
0.0007
| 1.849 | 0.121 | 1.523 | 0.128 |
0.07
|
0.49
| 0.01 |
CF |
0.666
|
0.032
|
0.451
|
0.023
|
0.0002
|
0.722
|
0.043
|
0.591
|
0.038
|
0.03
|
0.47
| 0.02 |
FD |
0.767
|
0.009
|
0.827
|
0.009
|
0.00005
|
0.777
|
0.009
|
0.839
|
0.008
|
0.0003
|
0.89
| 0.000001 |
Study II: test-retest reliability and clinical concurrent validity
CTRL
|
PD
| |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Test I | Test II | ICC(1-1) | 95%Cl bounds | Test I | Test II | ICC(1-1) | 95%Cl bounds | |||||||
Mean | SEM | Mean | SEM | ρ | lower | upper | Mean | SEM | Mean | SEM | ρ | lower | upper | |
Jerk |
0.065
|
0.007
|
0.067
|
0.007
|
0.87
| 0.67 | 0.95 |
0.235
|
0.110
|
0.188
|
0.066
|
0.86
| 0.66 | 0.95 |
Trajectory Measures
| ||||||||||||||
DIST |
0.043
|
0.003
|
0.048
|
0.004
|
0.70
| 0.34 | 0.88 |
0.089
|
0.020
|
0.074
|
0.014
|
0.84
| 0.61 | 0.94 |
RMS |
0.052
|
0.003
|
0.057
|
0.005
|
0.71
| 0.35 | 0.89 |
0.108
|
0.026
|
0.089
|
0.017
|
0.83
| 0.59 | 0.93 |
PATH |
4.428
|
0.220
|
4.484
|
0.234
|
0.89
| 0.72 | 0.96 |
8.232
|
1.285
|
7.286
|
0.909
|
0.81
| 0.56 | 0.93 |
RANGE |
0.275
|
0.016
|
0.283
|
0.020
|
0.74
| 0.41 | 0.90 |
0.567
|
0.150
|
0.494
|
0.102
|
0.82
| 0.58 | 0.93 |
MV | 0.104 | 0.012 | 0.122 | 0.013 | 0.68 | 0.31 | 0.87 |
0.211
|
0.049
|
0.176
|
0.029
|
0.75
| 0.44 | 0.90 |
MF | 0.58 | 0.03 | 0.55 | 0.05 | 0.60 | 0.17 | 0.84 | 0.54 | 0.04 | 0.54 | 0.04 | 0.55 | 0.12 | 0.81 |
Area Measures
| ||||||||||||||
AREA |
0.0019
|
0.0002
|
0.0021
|
0.0002
|
0.76
| 0.45 | 0.91 |
0.0127
|
0.0059
|
0.0078
|
0.0031
|
0.73
| 0.40 | 0.89 |
Frequency Measures
| ||||||||||||||
PWR | 0.41 | 0.04 | 0.47 | 0.08 | 0.61 | 0.19 | 0.84 |
3.54
|
2.24
|
2.04
|
1.33
|
0.85
| 0.64 | 0.94 |
F50 | 0.43 | 0.03 | 0.41 | 0.05 | 0.30 | -0.20 | 0.68 | 0.36 | 0.01 | 0.37 | 0.02 | 0.35 | -0.13 | 0.70 |
F95 | 1.95 | 0.10 | 1.92 | 0.10 | 0.59 | 0.17 | 0.83 | 1.78 | 0.16 | 2.00 | 0.14 | 0.67 | 0.31 | 0.87 |
CF | 0.78 | 0.05 | 0.76 | 0.05 | 0.61 | 0.19 | 0.84 | 0.69 | 0.05 | 0.76 | 0.06 | 0.69 | 0.34 | 0.87 |
FD | 0.76 | 0.01 | 0.79 | 0.02 | 0.25 | -0.25 | 0.65 | 0.78 | 0.01 | 0.80 | 0.01 | 0.61 | 0.20 | 0.84 |
UPDRS III
|
PIGD
| |
---|---|---|
JERK
| 0.29 (p = 0.29) |
0.55 (p = 0.03)
|
Time-domain measures
| ||
DIST
| 0.29 (p = 0.29) |
0.57 (p = 0.02)
|
RMS
| 0.29 (p = 0.28) |
0.57 (p = 0.02)
|
PATH
| 0.22 (p = 0.42) |
0.50 (p = 0.05)
|
RANGE
| 0.29 (p = 0.30) |
0.56 (p = 0.03)
|
MV
| 0.29 (p = 0.28) |
0.63 (p = 0.01)
|
MF
| −0.09 (p = 0.72) | −0.37 (p = 0.17) |
AREA
| 0.29 (p = 0.29) |
0.55 (p = 0.03)
|
Frequency-domain measures
| ||
PWR
| 0.30 (p = 0.27) |
0.54 (p = 0.04)
|
F50
| −0.17 (p = 0.54) | −0.18 (p = 0.49) |
F95
| −0.24 (p = 0.38) | −0.42 (p = 0.12) |
CF
| −0.18 (p = 0.50) | 0.34 (p = 0.20) |
FD
| 0.23 (p = 0.41) | 0.31 (p = 0.26) |