Introduction
Method
Data
Study 1
Study 2
Variables
Performance Disability
HRQoL
Health State
Other Variables
Study 1 analysis
Step 1: Establishing a measurement model
Step 2: Testing invariance across measurement occasions
Step 3: Testing invariance with respect to exogenous variables
Study 2 analysis
Step 1: Establishing a measurement model
Step 2: Testing invariance across measurement occasions
Step 3: Testing invariance with respect to exogenous variables
Results
Study 1 results
Variable | Study 1 (n = 2,952) | Study 2 (n = 1,767) |
---|---|---|
Sex | ||
Male | 423 (14.33%) | 303 (17.15%) |
Female | 2,031 (68.80%) | 1,464 (82.86%) |
Age, mean (SD) | 40.82 (9.35) | 45.56 (9.31) |
Time since diagnosis in years, mean (SD) | NA | 3.69 (2.12) |
Newly diagnosed | ||
Yes | 1,054 (35.70%) | NA |
No/unknown | 1,898 (64.30%) | |
Relapse | ||
Yes (T1) | NA | 608 (34.41%) |
Yes (T2) | NA | 565 (31.98%) |
Yes (T3) | NA | 555 (31.41%) |
Symptom change | ||
T1 | NA | 3.64 (1.15) |
T2 | NA | 3.61 (1.08) |
T3 | NA | 3.64 (1.04) |
Group membership | ||
Stable | 771 (26.12%) | NA |
Actively relapsing | 1,552 (52.57%) | NA |
Progressing without relapsing | 629 (21.31%) | NA |
Measurement Occasions & Group Membership | Mobility | Hand Function | Fatigue | Cognitive | Bladder/Bowel | Sensory | Spasticity |
---|---|---|---|---|---|---|---|
Study 1—Performance Scales: higher scores indicate more disability
| |||||||
Time 1 | |||||||
Relapsing | 1.52 (1.45) | 1.22 (1.08) | 2.58 (1.31) | 1.62 (1.19) | 1.18 (1.08) | 1.89 (1.19) | 1.51 (1.24) |
Progressive | 1.67 (1.47) | 1.02 (0.98) | 2.39 (1.26) | 1.40 (1.17) | 1.20 (1.04) | 1.65 (1.17) | 1.34 (1.22) |
Stable | 0.82 (1.17) | 0.63 (0.86) | 1.68 (1.22) | 0.99 (1.01) | 0.72 (0.90) | 1.31 (1.03) | 0.82 (1.05) |
Time 2 | |||||||
Relapsing | 1.65 (1.50) | 1.25 (1.09) | 2.68 (1.31) | 1.74 (1.23) | 1.29 (1.15) | 1.83 (1.22) | 1.60 (1.29) |
Progressive | 1.79 (1.56) | 1.10 (1.05) | 2.45 (1.31) | 1.45 (1.12) | 1.24 (1.05) | 1.59 (1.13) | 1.48 (1.27) |
Stable | 0.78 (1.21) | 0.66 (0.89) | 1.70 (1.25) | 1.02 (0.97) | 0.75 (0.91) | 1.13 (0.98) | 0.77 (0.96) |
Time 3 | |||||||
Relapsing | 1.75 (1.55) | 1.31 (1.13) | 2.70 (1.32) | 1.77 (1.21) | 1.37 (1.67) | 1.84 (1.24) | 1.65 (1.28) |
Progressive | 1.91 (1.67) | 1.16 (1.07) | 2.52 (1.28) | 1.52 (1.16) | 1.35 (1.10) | 1.65 (1.16) | 1.50 (1.29) |
Stable | 0.81 (1.24) | 0.67 (0.88) | 1.63 (1.25) | 1.02 (1.25) | 0.76 (0.91) | 1.06 (0.96) | 0.82 (0.99) |
Measurement Occasions | PF | RF | BP | GH | VT | SF | RE | MH |
---|---|---|---|---|---|---|---|---|
Study 2—SF-12: higher scores indicate better health
| ||||||||
Time 1 | 6.80 (2.34) | 6.26 (2.47) | 5.40 (2.52) | 4.30 (1.93) | 3.13 (2.04) | 7.17 (2.38) | 7.42 (2.28) | 5.87 (1.73) |
Time 2 | 6.86 (2.17) | 6.34 (2.32) | 5.41 (2.54) | 4.37 (1.95) | 3.16 (1.96) | 7.03 (2.43) | 6.98 (2.38) | 5.81 (1.65) |
Time 3 | 6.70 (2.44) | 6.23 (2.50) | 5.52 (2.68) | 4.32 (1.93) | 3.05 (2.07) | 7.13 (2.43) | 7.50 (2.31) | 5.92 (1.72) |
Step 1: Establishing a measurement model
CHISQ (df) | RMSEA (90% CI) | ECVI (90% CI) | Comparison models | CHISQ DIFF (df) |
P
| ECVI DIFF (90% CI) | CFI | TLI | ||
---|---|---|---|---|---|---|---|---|---|---|
Study 1—Performance Scales
| ||||||||||
Models–Study 1 | ||||||||||
1.1.1 | Unidimensional measurement model | 1,675.4 (495) | 0.049 (0.047; 0.052) | 0.75 (0.71; 0.79) | 0.99 | 0.99 | ||||
1.1.2 | 2 factor measurement model | 899.2 (414) | 0.035 (0.031; 0.028) | 0.54 (0.51; 0.57) | 1.00 | 0.99 | ||||
1.2.1 | Across occasion constraints on factor loadings and intercepts | 1,281.6 (534) | 0.038 (0.035; 0.040) | 0.59 (0.55; 0.63) | 1.2.1 vs. 1.1.2 | 382.4 (120) | <0.0001 | 0.04 (0.03; 0.07) | 0.99 | 0.99 |
1.2.2 | Sensory intercept, time 1 free, stable group | 1,224.8 (533) | 0.036 (0.034; 0.039) | 0.57 (0.51; 0.58) | 1.2.2 vs 1.2.1 | 56.8 (1) | <0.0001 | 0.02 (0.01; 0.03) | 0.99 | 0.99 |
1.2.3 | Sensory intercept, time 1 free, relapse group | 1,150.6 (532) | 0.034 (0.032; 0.037) | 0.54 (0.49; 0.56) | 2.2.3 vs 1.2.2 | 74.2 (1) | <0.0001 | 0.03 (0.02; 0.04) | 1.00 | 0.99 |
1.3.1 | As Model 1.2.2 but with addition of exogenous variables | 1,461.8 (757) | 0.031 (0.028; 0.033) | 0.75 (0.69; 0.76) | 0.99 | 0.99 | ||||
1.3.2 | Time lag restricted model | 1,579.1 (808) | 0.031 (0.029; 0.033) | 0.76 (0.72; 0.80) | 1.3.2 vs. 1.3.1 | 114.1 (50) | <0.0001 | <0.01 (−0.01; 0.01) | 0.99 | 0.99 |
Study 2—SF-12
| ||||||||||
Models–study 2 | ||||||||||
2.1.1 | Measurement model from manual | 2,305.3 (213) | 0.076 (0.073; 0.079) | 1.47 (1.37; 1.55) | 0.94 | 0.93 | ||||
2.1.2 | Modified measurement model | 1,147.1 (192) | 0.053 (0.050; 0.059) | 0.80 (0.73; 0.85) | 2.1.2 vs. 2.1.1 | 1,158.2 (21) | <0.0001 | 0.63 (0.57; 0.70) | 0.97 | 0.96 |
2.2.1 | Across occasion constraints on factor loadings and intercepts | 1,303.8 (218) | 0.053 (0.050; 0.056) | 0.86 (0.80; 0.93) | 2.2.1 vs. 2.1.2 | 156.7 (26) | <0.0001 | 0.06 (0.04; 0.08) | 0.97 | 0.96 |
2.2.2 | Factor loadings and intercepts of RE free | 1,224.8 (214) | 0.052 (0.049; 0.055) | 0.82 (0.76; 0.88) | 2.2.2 vs. 2.2.1 | 79.0 (4) | <0.0001 | −0.67 (−0.70; −0.62) | 0.97 | 0.96 |
2.3.1 | As Model 2.2.2 but with addition of exogenous variables | 1,653.7 (376) | 0.044 (0.042; 0.046) | 1.188 (1.118; 1.262) | 0.97 | 0.95 | ||||
2.3.2 | Free direct effects of age on MH | 1,595.8 (373) | 0.043 (0.041; 0.045) | 1.159 (0.090; 1.231) | 2.3.2 vs. 2.3.1 | 58.0 (3) | <0.0001 | 0.03 (0.02; 0.05) | 0.97 | 0.96 |
2.3.3 | Free direct effects of age on VT | 1,555.0 (370) | 0.043 (0.040; 0.045) | 1.139 (1.072; 1.211) | 2.3.3 vs. 3.3.2 | 40.8 (3) | <0.0001 | 0.02 (0.01; 0.03) | 0.97 | 0.96 |
Step 2: Testing measurement invariance across measurement occasions
Step 3: Testing measurement invariance with respect to exogenous variables
Visible–T1 | Internal–T1 | Visible–T2 | Internal–T2 | Visible–T3 | Internal–T3 | |
---|---|---|---|---|---|---|
Variance/covariances
| ||||||
Visible–T1 | ||||||
Stable | 1.10 | |||||
Progressive | 1.17 | |||||
Relapsing | 1.52 | |||||
Internal–T1 | ||||||
Stable | 0.38 | 0.52 | ||||
Progressive | 0.35 | 0.60 | ||||
Relapsing | 0.56 | 0.73 | ||||
Visible–T2 | 1.26 | |||||
Stable | 0.99 | 0.36 | 1.98 | |||
Progressive | 1.58 | 0.35 | 1.82 | |||
Relapsing | 1.43 | 0.56 | ||||
Internal–T2 | ||||||
Stable | 0.35 | 0.40 | 0.42 | 0.47 | ||
Progressive | 0.28 | 0.52 | 0.37 | 0.67 | ||
Relapsing | 0.50 | 0.63 | 0.65 | 0.77 | ||
Visible–T3 | ||||||
Stable | 0.97 | 0.34 | 1.20 | 0.39 | 1.22 | |
Progressive | 1.65 | 0.26 | 2.05 | 0.25 | 2.29 | |
Relapsing | 1.41 | 0.52 | 1.77 | 0.58 | 1.93 | |
Internal–T3 | ||||||
Stable | 0.32 | 0.39 | 0.38 | 0.42 | 0.40 | 0.48 |
Progressive | 0.25 | 0.52 | 0.30 | 0.61 | 0.35 | 0.69 |
Relapsing | 0.51 | 0.61 | 0.64 | 0.69 | 0.65 | 0.79 |
Sex | ||||||
Stable | −0.01 | 0.01 | −0.02 | 0.01 | −0.03 | 0.01 |
Progressive | −0.09 | <0.01 | −0.08 | −0.01 | −0.09 | −0.01 |
Relapsing | −0.08 | −0.02 | −0.07 | −0.01 | −0.08 | −0.01 |
Age | ||||||
Stable | 0.32 | 0.07 | 0.34 | 0.09 | 0.35 | 0.08 |
Progressive | 0.43 | 0.04 | 0.50 | 0.02 | 0.51 | 0.01 |
Relapsing | 0.37 | 0.12 | 0.43 | 0.14 | 0.43 | 0.13 |
Newly diagnosed | −0.26 | −0.12 | −0.26 | −0.12 | −0.26 | −0.12 |
Time between T1 and T2 | 0.10 | 0.01 | 0.10 | 0.01 | ||
Time between T2 and T3 | 0.10 | 0.01 |
Residual variances | Mobility | Spasticity | Bladder/bowel | Hand function | Sensory | Fatigue | Cognitive |
---|---|---|---|---|---|---|---|
Stable | |||||||
T1 | 0.27 | 0.59 | 0.53 | 0.40 | 0.61 | 0.74 | 0.48 |
T2 | 0.23 | 0.45 | 0.51 | 0.42 | 0.55 | 0.80 | 0.48 |
T3 | 0.30 | 0.43 | 0.51 | 0.38 | 0.51 | 0.88 | 0.51 |
Progressive | |||||||
T1 | 0.41 | 0.82 | 0.77 | 0.60 | 0.82 | 0.79 | 0.75 |
T2 | 0.44 | 0.87 | 0.70 | 0.61 | 0.72 | 0.80 | 0.64 |
T3 | 0.40 | 0.81 | 0.80 | 0.60 | 0.76 | 0.80 | 0.67 |
Stable | |||||||
T1 | 0.57 | 0.83 | 0.76 | 0.58 | 0.76 | 0.77 | 0.72 |
T2 | 0.40 | 0.83 | 0.79 | 0.58 | 0.79 | 0.74 | 0.73 |
T3 | 0.43 | 0.76 | 0.86 | 0.61 | 0.78 | 0.73 | 0.67 |
Study 1 conclusion
Study 2 results
Step 1: Establishing a measurement model
Step 2: Testing measurement invariance across measurement occasions
Step 3: Testing measurement invariance with respect to exogenous variables
PHYS HRQoL –T1 | MENT HRQoL –T1 | PHYS HRQoL –T2 | MENT HRQoL –T2 | PHYS HRQoL –T3 | MENT HRQoL –T3 | |
---|---|---|---|---|---|---|
Variance/Covariances | ||||||
PHYS HRQoL –T1 | 1 | |||||
MENT HRQoL –T1 | 0.87 | 1 | ||||
PHYS HRQoL –T2 | 0.87 | 0.78 | 0.94 | |||
MENT HRQoL –T2 | 0.81 | 0.81 | 0.84 | 0.95 | ||
PHYS HRQoL –T3 | 0.91 | 0.80 | 0.90 | 0.83 | 1.05 | |
MENT HRQoL –T3 | 0.77 | 0.78 | 0.77 | 0.81 | 0.91 | 0.98 |
Sex | −0.03 | 0.002 | −0.01 | −0.01 | −0.02 | −0.005 |
Age | −0.25 | −0.12 | −0.21 | −0.13 | −0.26 | −0.13 |
Time since diagnosis | −0.04 | 0.02 | 0.01 | −0.05 | −0.02 | −0.03 |
Symptom change–T1 | 0.63 | 0.52 | 0.52 | 0.48 | 0.52 | 0.39 |
Symptom change–T2 | 0.52 | 0.42 | 0.61 | 0.53 | 0.57 | 0.41 |
Symptom change–T3 | 0.41 | 0.36 | 0.42 | 0.39 | 0.60 | 0.49 |
Relapse–T1 | −0.15 | −0.15 | −0.13 | −0.12 | −0.13 | −0.12 |
Relapse–T2 | −0.13 | −0.13 | −0.15 | −0.14 | −0.14 | −0.12 |
Relapse–T3 | −0.12 | −0.11 | −0.13 | −0.11 | −0.17 | −0.14 |
PF | RP | BP | GH | VT | SF | RE | MH | |
---|---|---|---|---|---|---|---|---|
Residual variances | ||||||||
T1 | 2.27 | 1.66 | 3.24 | 1.68 | 1.97 | 1.31 | 2.65 | 1.76 |
T2 | 1.99 | 1.62 | 3.28 | 1.65 | 1.82 | 1.56 | 2.61 | 1.67 |
T3 | 2.51 | 1.60 | 3.91 | 1.64 | 2.02 | 1.62 | 2.59 | 1.79 |