Journal of Rehabilitation Medicine 51-8 | Page 35

Rasch analysis of UK FIM+FAM in patients with TBI
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Table III. Frequency distribution of responses and Rasch model fit statistics for the UKFIM+FAM items (n  = 320). See Table SI 1 for an
equivalent table for individual items the full dataset (n  = 1,956)
Frequency distribution across scoring categories
Description
Motor
Eating
Swallowing*
Grooming*
Bathing*
Dressing – upper*
Dressing – lower*
Toileting*
Bladder
Bowel*
Bed transfers*
Toilet transfers*
Bath transfers
Car transfers
Locomotion
Stairs
Community mobility
Communication
Comprehension
Expression
Reading*
Writing*
Speech intelligibility
Psychosocial
Social interaction*
Emotional status*
Adjustment to limitations
Use of leisure time
Problem solving
Memory*
Orientation
Concentration
Safety awareness
Domain subtests
Motor
Communication
Psychosocial
Location Fit Residual χ 2 ** Cat 1 Cat 2 Cat 3 Cat 4 Cat 5 Cat 6 Cat 7 % Cat 1+7
–0.56
–0.69
–0.21
0.05
–0.23
–0.05
–0.15
–0.25
–0.24
–0.17
–0.12
0.10
0.29
0.08
0.54
0.93 –0.71
4.23
–4.56
–4.54
–4.74
–4.58
–5.24
–1.71
–2.80
–3.62
–3.59
–0.49
0.55
–1.53
0.79
1.25 8.34
29.30
34.33
33.87
33.27
33.17
31.61
7.08
11.17
15.82
18.48
3.12
8.11
6.78
8.67
1.99 37
28
43
50
43
51
58
57
58
55
60
72
112
72
138
132 7
9
16
24
21
22
17
12
10
9
8
10
7
12
4
28 7
7
16
14
13
20
17
12
14
23
20
16
11
6
4
39 8
3
23
36
24
26
10
11
9
13
15
20
21
12
4
10 30
17
44
47
39
40
25
16
15
30
28
42
13
40
24
29 35
27
47
45
36
33
32
27
26
36
37
38
31
57
60
27 170
203
105
78
118
102
135
159
162
128
126
96
99
94
60
29 70.4
78.6
50.3
43.5
54.8
52.0
65.6
73.5
74.8
62.2
63.3
57.1
71.8
56.7
67.3
54.8
–0.42
–0.36
0.02
0.23
–0.67 –0.41
–0.30
4.03
2.90
2.09 2.06
5.52
38.31
33.34
7.68 22
29
59
84
20 16
16
8
10
11 16
15
10
22
18 14
18
23
31
11 76
55
60
33
35 68
66
45
34
40 82
95
89
80
159 35.4
42.2
50.3
55.8
60.9
–0.36
0.01
0.39
0.38
0.59
0.34
–0.03
0.04
0.54 3.55
9.35
1.14
0.52
–0.68
2.67
0.64
0.42
–0.42 18.71
89.26
7.76
1.61
5.16
16.23
4.77
1.69
4.17 24
45
51
56
73
58
47
33
54 17
33
50
44
32
48
36
42
77 16
18
40
29
27
29
21
27
34 22
16
31
21
32
32
29
22
18 52
37
40
39
53
36
24
59
32 62
71
45
69
51
47
41
51
42 101
74
37
36
26
44
96
60
37 42.5
40.5
29.9
31.3
33.7
34.7
48.6
31.6
31.0
0.01
–0.07
0.06 –1.28
–0.08
0.99 11.43
18.95
6.34
*Significant misfit to the Rasch model (p  < 0.05, Bonferroni-adjusted); Response options in bold were endorsed by less than 10 people.
**χ 2 degrees of freedom for items (df = 4) and for subtests (df = 8)
Percent cat 1+7: response category scores in the lower and upper end of the scale
(Cronbach’s alpha=0.78), strict uni-dimensionality
(< 5% t-tests significant at < 0.05), and no local de-
pendency. However, the item-trait interaction was
significant (χ 2 (df24) =159.1, p < 0.001) confirming the
expected inflation of χ 2 statistics due to large sample
size. As with our previous analysis for stroke (17),
neither uniform re-scoring of items nor exclusion of
participants with extreme scores improved the fit of
the model, so these data are not presented.
Analysis of DIF showed no significant DIF by any
of the personal factors. At the individual super-item
level there were no signs of local dependency and all
showed acceptable fit residual and χ 2 values (Table III).
Fig. S1 1 shows the person-item threshold distribution
for the final analysis with the full sample and indicates
http://www.medicaljournals.se/jrm/content/?doi=10.2340/16501977-2580
1
Table IV. The UK FIM FAM: Rasch model summary statistics (overall fit of the scale)
UK FIM+FAM Item – trait interaction Rasch model χ 2 /df p-value PSI Uni-dimensionality
(Sig. t-tests in %) Local dependency
521.36/120
2,253.69/120 < 0.001
< 0.001 0.94
0.94 No (> 35)
No (> 35) Yes
36.72/24
159.11/24 0.05
< 0.001 0.78
0.81 Yes (2.19)
Yes (2.51)
Pathway 1: Initial all 30 items
Sub-sample (n  = 320)
Full dataset (n  =1,956)
Pathway 2: Three super-items
Sub-sample (n  =320)
Full dataset (n  =1,956)
No
a
UK FIM+FAM; UK Functional Assessment Measure; df: degrees of freedom; PSI: Person Separation Index (without extremes). Super-item 1=Communication;
Super-item 3 is Psychosocial domain. FIM: Functional Independence Measure; FAM: Functional Assessment Measure.
J Rehabil Med 51, 2019