Demographic Characteristics
A total of 190 family caregivers of people with dementia participated in the study. 66.3% of caregivers are female, with the mean age was 56.3years (SD = 12.81). Almost three quarters (74%) had completed high school. Among the care recipients’ average age was 77.39 years (SD = 9.10), and the majority of them were female (59.5%). Most of the subjects had mild to moderate dementia and over half of participants (53.7%) were under a risk of malnutrition (table 1).
Table 1 Demographics of the Participants and Between-Group Differences
Variables
|
All
(n=190)
|
Sample 1
(n=95)
|
Sample 2
(n=95)
|
/ p value
|
Gender
|
|
|
|
.301
|
Male _n (%)
|
77 (40.5%)
|
35 (36.8%)
|
42 (44.2%)
|
|
Female _n (%)
|
113 (59.5%)
|
60 (63.2%)
|
53 (55.8%)
|
|
Age _ mean (SD)
|
77.39 (9.10)
|
77.65 (10.16)
|
77.13 (7.49)
|
.691
|
Education
|
|
|
|
.908
|
Illiterate _n (%)
|
38 (20.0%)
|
20 (21.0%)
|
18 (18.9%)
|
|
Lower junior high school _n (%)
|
106 (55.8%)
|
53 (55.8%)
|
53 (55.8%)
|
|
Upper junior high school _n (%)
|
46 (24.2%)
|
22 (23.2%)
|
24 (25.3%)
|
|
Marital status
|
|
|
|
.230
|
Marriage (partner) _n (%)
|
123 (64.7%)
|
54 (56.6%)
|
69 (72.6)
|
|
Single _n (%)
|
67 (35.3%)
|
41 (43.2%)
|
26 (27.4%)
|
|
Morbidity years _ mean (SD)
|
7.17 (3.07)
|
7.20 (3.17)
|
7.14 (2.98)
|
.882
|
MMSE (n=170) _ mean (SD)
|
14.51 (5.68)
|
14.28 (5.65)
|
14.75 (5.68)
|
.590
|
CDR (n=51)
|
|
|
|
.428
|
0.5 _n (%)
|
2 (3.9%)
|
0 (0%)
|
2 (7.7%)
|
|
1 _n (%)
|
16 (31.4%)
|
8 (30.2%)
|
8 (30.8%)
|
|
2 _n (%)
|
23 (45.1%)
|
13 (52.0%)
|
10 (38.5%)
|
|
3 _n (%)
|
10 (19.6%)
|
4 (16.0%)
|
6 (23.1%)
|
|
Current eating ability
|
|
|
|
.037
|
Independent _n (%)
|
133 (70%)
|
60 (63.2%)
|
73 (76.8%)
|
|
Assistance _n (%)
|
45 (23.7%)
|
30 (31.6%)
|
15 (15.8%)
|
|
Feed _n (%)
|
12 (6.3%)
|
5 (5.3%)
|
7 (7.4%)
|
|
Food preference change
|
|
|
|
.557
|
No _n (%)
|
110 (57.9%)
|
53 (55.8%)
|
57 (60.0%)
|
|
Yes _n (%)
|
80 (42.1%)
|
42 (44.2%)
|
38 (40.0%)
|
|
MNA score (n=188)
|
|
|
|
.314
|
Normal (>24) _n (%)
|
44 (23.4%)
|
20 (21.1%)
|
24 (25.8%)
|
|
At risk (17-23.5) _n (%)
|
101 (53.7%)
|
49 (51.6%)
|
52 (55.9%)
|
|
Malnutrition (<17) _n (%)
|
43 (22.9%)
|
26 (27.4%)
|
17 (18.3%)
|
|
Notes. SD, standard deviation; MMSE, Mini-Mental State Examination; CDR, Clinical Dementia Rating. *p value < 0.05
Validity
1. Content Validity Index
In the current study, the initial I-CVI ranged from .67 to 1.00 for the 10 initial items. After deleting 2 inappropriate items and 1 item being added based on the comments of the experts, the modified version of the DFAS comprised 9 items. Consequently, the S-CVI/Ave value for relevance was 0.89. Each item was rated by the respondent on a 4-point Likert type scale ranging from 0 to 3, with the total score ranging between 0 and 27, where higher scores reflected more functional limitations.
2. Item analysis.
Table 2 presents the item analyses for the 9-item DFAS. The mean, SD, comparisons of extreme groups, and item-overall score correlation (r) were used in the item analysis for item selection. Considering the results of the overall analysis for the average, standard deviation, composite reliability (CR) value, and correlation of all items, item 6 was deleted due to a low SD, a non-significant CR value, and a low item-total correlation (r=.253) below .30; Item 9 was deleted due to a large mean (mean=2.66>2.58). Therefore, a 7-item DFAS was established at this stage.
Table 2 Item Analysis of the 9-Item Diet Function Assessment Scale
Items
|
Mean (SD)
|
t
(CR value)
|
Corrected Item-Total Correlation
|
1.
|
Decides that he/she needs to eat
|
1.71 (0.99)
|
-8.59***
|
.60
|
2.
|
Chooses appropriate utensils when eating
|
1.46 (0.77)
|
-7.83***
|
.70
|
3.
|
Eats an appropriate amount of food
|
1.91 (0.92)
|
-4.92***
|
.49
|
4.
|
Uses a spoon to eat
|
1.57 (0.90)
|
-8.60***
|
.58
|
5.
|
Needs to have foods cut into small pieces
|
1.73 (0.94)
|
-7.45***
|
.53
|
6.
|
Only uses fingers to eat food
|
1.08 (0.40)
|
-1.79
|
.25
|
7.
|
Relies on others to be fed
|
1.34 (0.72)
|
-5.11***
|
.65
|
8.
|
Decides to prepare a light meal or snack for self
|
2.57 (0.81)
|
-18.62***
|
.62
|
9.
|
Prepares or cooks a light meal or snack safely
|
2.66 (0.74)
|
-7.18***
|
.52
|
|
Overall
Mean ± 1.5 SD
|
1.78 (0.53)
(2.58, 0.99)
|
|
|
Notes. N = 95 (Sample 1). *p value < 0.05,**p value < 0.01,***p value < 0.0001
3. Exploratory factor analysis (EFA)
The EFA using a principal component analysis (PCA) with a varimax rotation was performed for Sample 1. The Kaiser–Meyer–Olkin value for the 8 items was .734, and the Bartlett’s test of sphericity value showed statistical significance ( = 279.530, df = 28, p < .000), which indicated that the data were suitable for the factor analysis. Seven items were analyzed through an EFA; two factors were extracted based on the screen plot; eigenvalues greater than 1.0 indicated an appropriate factor structure (Table 3). Factor 1: self-eating ability included four items (1, 2, 3, and 8); Factor 2: dietary executive function included three items (5, 4, and 7). The cumulative explanatory power of the second factor analysis was 56.94%.
Table 3 The Results of the Exploratory Factor Analyses
Factor/ Item
|
Factor loading
|
Cumulative Variance (%)
|
Cronbach’s
alpha
|
1
|
2
|
Factor 1: Self-eating ability
|
|
|
42.96
|
.70
|
1.Decides that he/she needs to eat
|
.77
|
.12
|
|
|
3.Eats an appropriate amount at meals
|
.68
|
.11
|
|
|
2.Chooses appropriate utensils when eating
|
.67
|
.45
|
|
|
8.Decides to prepare a light meal or snack for him/herself
|
.63
|
.19
|
|
|
Factor 2: Dietary executive function
|
|
|
13.98
|
.69
|
4.Uses a spoon to eat
|
.16
|
.79
|
|
|
5.Need to have food cut up into small pieces
|
.10
|
.77
|
|
|
7.Relies on others to be fed
|
.34
|
.73
|
|
|
Total Variance Explained /Cronbach’s alpha
|
|
|
56.94
|
.74
|
Note. N = 95 (Sample 1).. The number in bold indicates the factor loading of including in Diet Function Assessment Scale items.
3. Confirmatory factor analysis (CFA).
This 2-factor model provided a good fit based on the results of an analysis using Sample 2. The results indicated a Chi-square ( ) = 17.511; degrees of freedom (df) = 13; / df (CMIN/DF) = 1.35 (p = .18); standardized root mean square residual (SRMR) = .05; a root mean square error of approximation (RMSEA) = .06; Tucker-Lewis index (TLI) = .96 and a comparative fit index (CFI) = .97. Table 4 presents the standardized factor loadings (SFLs), standardized error, squared multiple correlation (R2), CR, and average variance extracted (AVE) for the 7-item DFAS. Most of SFLs were over .50 (ranging from .33 to .85), except for item 3 (SLF=.33), which was considered to be a reliable item for measuring self-eating ability, and we therefore retained. The CFA results supported the factor structure of the 7-item DFAS (table 4).
Table 4 SFL, R2, CR, and AVE of the DFAS
Dimension
|
Items
|
SFL
|
R2
|
CR/AVE
|
Self-eating ability
|
1
|
Decides that he/she needs to eat
|
0.77
|
0.59
|
0.66/0.35
|
3
|
Eats an appropriate amount at meals
|
0.33
|
0.11
|
2
|
Chooses appropriate utensils when eating
|
0.68
|
0.46
|
8
|
Decides to prepare a light meal or snack for self
|
0.50
|
0.24
|
Dietary executive function
|
4
|
Uses a spoon to eat
|
0.60
|
0.36
|
0.73/0.48
|
5
|
Need to have foods cut into small pieces
|
0.62
|
0.38
|
7
|
Relies on others to be fed
|
0.85
|
0.71
|
Notes. N = 95 (Sample 2). CR = composite reliability; AVE = average variance extracted; SFL = standardized factor loadings; R2 = squared multiple correlation.
5. Criterion-related validity.
The results showed a significant and negative correlation (r = -0.528, p < 0.01) between the DFAS score and the MNA score.
Reliability
1. Internal consistency
The Cronbach's α value for each factor ranged between .69 and .70, and the overall Cronbach's α value for the 7 items was .74.
2. The optimal Cut-off value
To evaluate the optimal cut-off value of the DFAS score to detect risks related to dietary functioning in people with dementia, a ROC curve analysis was performed using an MNA cut-off value of ≤ 23.5 (at risk for malnutrition) and ≤ 17 (malnutrition) as the gold standard. The optimal cut-off value was selected based on the criterion based from Youden’s Index (Hajian-Tilaki, 2018) and defined as YI = maxc Se (c) + Sp (c) − 1, which maximizes the sensitivity and specificity of the results. The AUC was 0.51, and the optimal cut-off score to determine risks related to dietary functions was 11. The cutoff yielded sensitivity/specificity values of 0.87/0.21. The AUC was 0.74, and the optimal cut-off score to determine poor dietary functioning was 13, with the cutoff yielding sensitivity/specificity values of 1.00/0.53.