592
P. Enthoven et al.
with (all) χ 2 (9)=64.309, p < 0.001, SRMR = 0.027,
(WAD) χ 2 (9)=16.856, p = 0.051, SRMR = 0.031, (CR)
χ 2 (9)=42.002, p < 0.001, SRMR = 0.038, and (MixCP)
χ 2 (9)=37.057, p < 0.001, SRMR = 0.038, respectively
(Table V). Furthermore, all standardized residual cor-
relations were small (< 0.10). However, in the WAD
group 1 residual correlation was at 0.12 and in the
MixCP group 1 residual correlation was at 0.10, but
can be considered small. Standardized factor pattern
loadings ranged from 0.706 to 0.932.
Table V. Confirmatory factor analysis, including all items of the
Patient Enablement Instrument (PEI) for all groups
All
WAD
CR
MixCP
(n = 516) (n = 116) (n = 115) (n = 285)
Factor 1 Factor 1 Factor 1 Factor 1
χ 2 test of model fit
Degrees of freedom (df)
p-value
SRMR 64.309
(9)
< 0.001
0.027 Residual correlations
Standardized factor loadings
PEI1, able to cope with life
PEI2, able to understand your illness
PEI3, able to cope with your illness
PEI4, able to keep yourself healthy
PEI5, confident about your health
PEI6, able to help yourself < 0.1 < 0.1 a < 0.1 < 0.1 b
0.870
0.788
0.916
0.880
0.895
0.882 0.813
0.706
0.924
0.804
0.907
0.927 0.889
0.855
0.932
0.905
0.927
0.907 0.892
0.752
0.879
0.891
0.821
0.882
16.856
(9)
0.051
0.031
42.002
(9)
< 0.001
0.038
37.057
(9)
< 0.001
0.038
Internal consistency. For all participants the PEI
(n = 516) had a Cronbach’s alpha of 0.907. In the WAD,
the CR and the MixCP group the Cronbach’s alpha was
0.890, 0.929 and 0.878, respectively.
a
Residual correlation PEI2 – PEI4 = 0.128, b residual correlation PEI3 – PEI5 = 0.100.
WAD: whiplash-associated disorders; CR: cervical radiculopathy; MixCP: mixed
chronic pain; SRMR: standardized root mean square residual.
Correlations between Patient Enablement
Instrument and other measures
2 “able to understand your illness” (CR group, 8%,
n = 11) and question 6 “able to help yourself” (MixCP
group, 1.9%, n = 6), respectively.
For all participants the correlations between PEI score
and health (EQ-5D Index and EQ VAS) after treatment
were moderate (r Sp = 0.507–0.581, Table VI). For the
CR group the correlation between the PEI score and
Construct validity. Results showed the 1-factor PEI
model had approximate fit to the data for all 4 groups,
Table VI. Correlations between the Patient Enablement Instrument (PEI) score after treatment with self-reported health after treatment
and changes from baseline to after treatment
Patient Enablement Instrument
Variables
Baseline
Age, years
Sex (men, women)
BMI
Country of birth (Sweden, Scandinavian country outside Sweden,
non-Scandinavian country)
Level of education (Compulsory, High school, University/college)
Living alone (yes, no)
Disability (NDI or FRI)
After treatment
Change from baseline to after treatment
Anxiety (HADS)
After treatment
Change from baseline to after treatment
Depression (HADS)
After treatment
Change from baseline to after treatment
PCS
After treatment
Change from baseline to after treatment
SES
After treatment
Change from baseline to after treatment
CSQ Catastrophizing
After treatment
Change from baseline to after treatment
EQ-5D index
After treatment
Change from baseline to after treatment
EQ VAS
After treatment
Change from baseline to after treatment
Self-reported current work ability
After treatment (n = 103, 275)
Change from baseline to after Treatment (n = 93; 273)
All (n = 485–504) WAD (n = 113–116) CR (n = 108–115) MixCP (n = 262–276)
r Sp r Sp r Sp
p-value
0.037
–0.012
–0.070
p-value
r Sp
p-value
0.413
0.790
0.790 0.126
0.108
0.035 0.177
0.247
0.713 –0.082
0.035
–0.162 0.464
0.690
0.064 –
–
–0.053 –
–
0.627 0.069
0.039
–0.172
p-value
0.383
0.712
0.087 0.016
0.090
–0.054 0.795
0.135
0.382
0.574 –0.103
0.099
0.062 0.090
0.100
0.304
–
–
–0.022 –
– –
– –
– –0.387
–0.452 < 0.001
< 0.001 –0.579
–0.554 < 0.001
< 0.001 –0.383
–0.274 < 0.001
< 0.001
–
– –
– –
– –
– –
– –
– –0.276
–0.286 < 0.001
< 0.001
–
– –
– –
– –
– –
– –
– –0.335
–0.293 < 0.001
< 0.001
–
– –
– –0.332
–0.353 < 0.001
< 0.001 –
– –
– –
– –
–
–
– –
– 0.250
0.260 0.008
0.005 –
– –
– –
– –
–
–
– –
– –
– 0.552
0.388 < 0.001
< 0.001 –
– –
-
0.505
–0.248 < 0.001
< 0.001 0.252
0.137 0.007
0.065 0.543
0.209 < 0.001
0.030 0.432
0.200 < 0.001
0.001
0.576
0.490 < 0.001
< 0.001 0.403
0.297 < 0.001
0.001 0.618
0.494 < 0.001
< 0.001 0.530
0.384 < 0.001
< 0.001
–
– 0.201
0.201 0.040
0.053 –
– 0.356
0.167 < 0.001
0.006
–
–
–
–
–
–
WAD: whiplash-associated disorders; CR: cervical radiculopathy; MixCP: mixed chronic pain; NDI: Neck Disability Index; FRI: Functional Rating Index; HADS:
Hospital Anxiety and Depression Scale; EQ-5D: European Quality of Life-5 Dimensions; VAS: visual analogue scale; rSp: Spearman’s rho.
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