Background
Motor examination of the unified Parkinson's disease rating scale
Previous analyses
Modelling approach
Methods
Participants
Measures
PD-On
|
PD-Off
|
PSP
| ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
UPDRS Motor Items
|
M
|
SD
|
Skew
|
Kurt.
|
M
|
SD
|
Skew
|
Kurt.
|
M
|
SD
|
Skew
|
Kurt.
| ||
1 | Speech |
1.40
| 0.91 | 0.37 | -.06 |
1.72
| 0.93 | 0.33 | .03 |
2.45
| 1.00 | 0.07 | -.92 | |
2 | Facial Expression |
1.55
| 0.89 | 0.44 | .11 |
2.15
| 0.85 | 0.06 | -.25 |
2.67
| 1.02 | -0.33 | -.58 | |
3 | Tremor-at-rest: | H/N |
0.48
| 0.73 | 1.42 | 1.45 |
0.36
| 0.76 | 2.24 |
4.71
|
0.02
| 0.24 |
11.69
|
142.73
|
4 | RUE |
0.81
| 0.93 | 0.75 | -.52 |
1.01
| 1.19 | 0.80 | -.58 |
0.10
| 0.42 |
4.56
|
22.08
| |
5 | RLE |
0.55
| 0.76 | 1.15 | .35 |
0.65
| 1.01 | 1.28 | .44 |
0.03
| 0.21 |
6.86
|
51.53
| |
6 | LUE |
0.69
| 0.87 | 0.91 | -.38 |
0.94
| 1.19 | 1.08 | .10 |
0.10
| 0.41 |
4.72
|
23.60
| |
7 | LLE |
0.52
| 0.73 | 1.24 | .74 |
0.65
| 1.10 | 1.60 | 1.52 |
0.03
| 0.25 |
10.47
|
118.78
| |
8 | Postural tremor | R |
0.66
| 0.68 | 0.87 | 1.33 |
0.93
| 0.87 | 0.69 | .02 |
0.34
| 0.55 | 1.40 | 1.02 |
9 | L |
0.64
| 0.63 | 0.46 | -.66 |
0.98
| 0.95 | 0.69 | -.28 |
0.34
| 0.57 | 1.65 |
2.69
| |
10 | Rigidity | H/N |
1.24
| 0.80 | 0.19 | .00 |
1.89
| 1.07 | 0.03 | -.55 |
2.40
| 1.19 | -0.22 | -.91 |
11 | RUE |
1.68
| 0.78 | -0.24 | .16 |
1.84
| 0.90 | -0.21 | .07 |
1.70
| 0.98 | 0.30 | .11 | |
12 | RLE |
1.36
| 0.80 | 0.29 | .29 |
1.58
| 1.06 | 0.01 | -.74 |
1.34
| 1.01 | 0.35 | -.69 | |
13 | LUE |
1.63
| 0.78 | 0.26 | .54 |
1.96
| 0.91 | -0.25 | -.01 |
1.61
| 1.03 | 0.23 | -.24 | |
14 | LLE |
1.39
| 0.82 | 0.44 | .60 |
1.68
| 1.11 | 0.07 | -.76 |
1.37
| 1.04 | 0.26 | -.83 | |
15 | Finger taps | R |
1.58
| 0.78 | 0.34 | .55 |
2.20
| 0.93 | 0.17 | -.46 |
1.54
| 1.04 | 0.42 | -.37 |
16 | L |
1.59
| 0.82 | 0.69 | 1.05 |
2.38
| 1.01 | -0.28 | -.32 |
1.69
| 1.12 | 0.40 | -.59 | |
17 | Hand movements | R |
1.50
| 0.83 | 0.58 | .57 |
1.72
| 0.94 | 0.48 | -.04 |
1.59
| 0.98 | 0.61 | -.04 |
18 | L |
1.51
| 0.84 | 0.79 | 1.06 |
1.98
| 1.00 | 0.08 | -.49 |
1.65
| 1.02 | 0.55 | -.22 | |
19 | Rapid Alternating. Movements. | R |
1.45
| 0.82 | 0.35 | .35 |
1.85
| 0.97 | 0.20 | -.29 |
1.66
| 1.06 | 0.43 | -.31 |
20 | L |
1.50
| 0.80 | 0.71 | 1.14 |
2.21
| 1.04 | -0.16 | -.47 |
1.76
| 1.15 | 0.53 | -.50 | |
21 | Leg agility | R |
1.44
| 0.83 | 0.73 | .91 |
2.05
| 1.03 | 0.02 | -.64 |
1.57
| 1.13 | 0.42 | -.47 |
22 | L |
1.50
| 0.85 | 0.81 | 1.03 |
2.25
| 1.03 | -0.17 | -.55 |
1.72
| 1.18 | 0.37 | -.59 | |
23 | Arise from chair |
1.23
| 1.05 | 1.07 | .88 |
1.70
| 1.45 | 0.33 | -1.28 |
2.40
| 1.24 | -0.11 | -1.20 | |
24 | Posture |
1.35
| 0.86 | 0.67 | .66 |
1.75
| 1.10 | 0.26 | -.56 |
1.47
| 1.14 | 0.31 | -.61 | |
25 | Gait |
1.28
| 0.91 | 0.66 | .29 |
2.12
| 1.13 | 0.02 | -.71 |
2.60
| 1.14 | -0.42 | -.63 | |
26 | Postural stability |
0.89
| 1.01 | 1.17 | .96 |
1.95
| 1.23 | 0.09 | -.97 |
2.67
| 1.12 | -0.28 | -.92 | |
27 | Body bradykinesia |
1.45
| 0.97 | 0.73 | .14 |
2.46
| 1.05 | -0.15 | -.69 |
2.39
| 0.98 | -0.26 | -.92 | |
Motor Total |
32.9
| 14.8 | 0.38 |
44.9
| 15.0 | 0.75 |
39.2
| 13.9 | 0.64 |
Preliminary statistical analyses
Simultaneous factor analyses
General model search
Model search across samples
Results
Simultaneous analysis of the PD-On group and PD-Off group
Model | Description | χ2
|
df
| RMSEA | TLI | CFI | St.RMR | Comments |
---|---|---|---|---|---|---|---|---|
PD1 | Six factors based on component solutions -no constraints across groups; correlated residuals Facial and Speech | 1318 | 592 | 0.071 | .92 | .93 | 0.08 |
BASELINE MODEL with
95% confidence interval of RMSEA:
0.065 – 0.077
|
PD2 | As PD1: Within a factor all loadings equal | 1578 | 634 | 0.078 | .90 | .91 | 0.10 | Outside interval. PD2; too simple |
PD3 | As PD1: Loadings PD-On = Loadings PD-Off | 1377 | 613 | 0.071 | .92 | .93 | 0.07 | Simpler model than PD2 |
PD4
|
As PD3:
Also equal factor covariance matrices
|
1450
|
634
|
0.072
|
.92
|
.92
|
0.09
|
Preferred model: Very simple; easy interpretation;
|
PD5 | As PD4: Also residual variances and residual covariances equal across groups | 2497 | 674 | 0.100 | .82 | .83 | 0.13 | Rejected: Oversimplification |
Baseline model
Restricting the baseline model
Conclusion
Model development: PD groups and PSP-group
χ2
|
df
| RMSEA | TLI | CFI | St.RMR | Comments | ||
---|---|---|---|---|---|---|---|---|
PP1 | Same model as PD1 | -- | -- | -- | -- | -- | -- | Empirically not identified |
PP2 | As PP1: Loadings PD-On = Loadings PD-Off = Loadings PSP | 1949 | 930 | 0.070 | 0.97 | 0.97 | 0.09 |
Baseline model
95% Confidence Interval of RMSEA:
0.065 – 0.075
|
PP3 | As PP2: Also factor correlation matrices equal1
| 2376 | 972 | 0.081 | 0.89 | 0.90 | 0.22 | Outside confidence limits PP2 |
PP4
|
As PP3:
In PSP all factor (co)variances related to the factor Tremor estimated rather than set equal to those of the PD groups
|
2099
|
966
|
0.073
|
0.96
|
0.97
|
0.14
|
Within confidence limits of PP2
Preferred model
|
Conclusion of the model search
Model fit
1 | 2 | 3 | 4 | 5 | 6 | Residual variances | |||||
---|---|---|---|---|---|---|---|---|---|---|---|
Axial Dysfunctioning | Tremor-at-rest | Postural tremor | Rigidity | Brady-kinesia Right | Brady-kinesia Left | On | Off | PSP | |||
3 | Tremor-at-rest: | H/N | 0.78 | 0.39 | 0.63 | 0.13 | |||||
4 | R Upper | 0.69 | 0.50 | 0.85 | 0.19 | ||||||
6 |
Extremities:
| L Upper | 0.74 | 0.33 | 0.88 | 0.18 | |||||
5 | R Lower | 0.70 | 0.37 | 1.09 | 0.06 | ||||||
7 | L Lower | 0.73 | 0.21 | 1.17 | 0.08 | ||||||
8 | Postural tremor | R | 0.90 | 0.13 | 0.42 | 0.04 | |||||
9 | L | 0.75 | 0.27 | 0.81 | 0.31 | ||||||
10 | Rigidity | Head/Neck | 0.67 | 0.22 | 0.65 |
1.02
| |||||
11 | R Upper | 0.68 | 0.40 | 0.62 | 0.69 | ||||||
12 |
Extremities:
| L Upper | 0.76 | 0.24 | 0.64 | 0.49 | |||||
13 | R Lower | 0.70 | 0.38 | 0.59 | 0.66 | ||||||
14 | L Lower | 0.77 | 0.20 | 0.64 | 0.50 | ||||||
15 | Finger taps | R | 0.81 | 0.21 | 0.44 | 0.45 | |||||
16 | L | 0.82 | 0.22 | 0.39 | 0.47 | ||||||
17 | Hand movements | R | 0.90 | 0.14 | 0.29 | 0.18 | |||||
18 | L | 0.90 | 0.15 | 0.27 | 0.18 | ||||||
19 | Rapid alt. mov. | R | 0.82 | 0.18 | 0.49 | 0.40 | |||||
20 | L | 0.83 | 0.15 | 0.45 | 0.40 | ||||||
21 | Leg agility | R | 0.72 | 0.22 | 0.67 | 0.71 | |||||
22 | L | 0.68 | 0.31 | 0.64 | 0.79 | ||||||
23 | Arise from chair | 0.82 | 0.22 | 0.45 | 0.34 | ||||||
24 | Posture | 0.72 | 0.20 | 0.42 |
1.04
| ||||||
25 | Gait | 0.82 | 0.15 | 0.38 | 0.60 | ||||||
26 | Postural stability | 0.77 | 0.28 | 0.49 | 0.49 | ||||||
27 | Body bradykinesia | 0.79 | 0.34 | 0.40 | 0.45 | ||||||
1 | Speech | 0.60 | 0.50 | 0.69 | 0.80 | ||||||
2 | Facial expression | 0.60 | 0.53 | 056 | 0.92 |
Model characteristics
Residual variances
Factor correlations
2 (PSP) | 2 (PD) | 3 | 1 | 4 | 5 | 6 | ||
---|---|---|---|---|---|---|---|---|
Tremor-at-rest | Tremor-at-rest | Postural Tremor | Axial Dysfunctioning | Rigidity | Brady-kinesia Right | Brady-kinesia Left | ||
2 | Tremor-at-rest | (0.01) † | (0.33) | |||||
3 | Postural Tremor | 0.04†† |
0.61
| (0.40) | ||||
1 | Axial Dysfunctioning | -0.03†† | 0.13 | 0.14 | (0.61) | |||
4 | Rigidity | 0.01†† | 0.29 | 0.26 |
0.61
| (0.44) | ||
5 | Bradykinesia Right | 0.00†† | 0.24 | 0.18 |
0.60
|
0.67
| (0.53) | |
6 | Bradykinesia Left | 0.00†† | 0.22 | 0.14 |
0.60
|
0.67
|
0.74
| (0.60) |
Residual covariances
Residual correlation between | Finger taps | Hand movements | Rapid alternating movements | Leg Agility | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
On | Off | PSP | On | Off | PSP | On | Off | PSP | On | Off | PSP | |
Right and left-hand side | 0.13 | 0.20 | 0.30 | 0.11 | 0.13 | 0.11 | 0.09 | 0.24 | 0.29 | 0.16 | 0.42 | 0.57 |