Participants
The average age of the 432 children was 2years 1months ± 7months ranging from 6 months~3 years. The mean age for 242(56.02%) boys was 2years with (standard deviation =6months), the mean age for 190(43.98%) girls was 2years with (standard deviation =7months) . The rates for 188 infants <24 months was 43.5%.
Reliability analysis
The Cronbach's alpha value for the 23 items scores was 0.838, indicating a good reliability of the scale. The Cronbach’s alpha value for all dimensions ranged from 0.576 to 0.835. Except for item 1 and 24, item-total correlations were greater than 0.3. After eliminating any of these two item, the alpha was unchanged(see Table 1).
Table 1 Item-total correlation analysis and Exploratory Factor Analysis of the SDSC-I
|
Item-total correl
|
Alpha if deleted
|
Variance Explained(%)
|
Factor loading
|
Factor 1: Disorders of initiating sleep (DIS)
|
|
|
11.747
|
|
D1.Sleep duration
|
0.155
|
0.839
|
|
0.463
|
D2.Sleep latency
|
0.423
|
0.830
|
|
0.328
|
D3.Going to bed reluctantly
|
0.511
|
0.826
|
|
0.679
|
D4.Difficulty to fall asleep
|
0.610
|
0.821
|
|
0.721
|
D5.Needs parent in room to sleep
|
0.351
|
0.835
|
|
0.849
|
D6.Anxiety when falling asleep alone
|
0.412
|
0.835
|
|
0.817
|
Factor 2: Disorders of Maintaining Sleep (DMS)
|
|
|
11.129
|
|
M7.Night awakenings more than twice
|
0.431
|
0.830
|
|
0.586
|
M8.Difficulty to fall asleep after waking
|
0.518
|
0.827
|
|
0.660
|
M9.Noctural hyperkinesia
|
0.473
|
0.829
|
|
0.419
|
Factor 3: Sleep Hyperhidrosis (SHY)
|
|
|
10.994
|
|
H10.Falling asleep sweating
|
0.473
|
0.828
|
|
0.837
|
H11.Night sweating
|
0.497
|
0.827
|
|
0.824
|
Factor 4: Sleep Breathing Disorders (SBD)
|
|
|
9.061
|
|
B12. Breathing problems
|
0.344
|
0.834
|
|
0.765
|
B13.Sleep apnoea
|
0.229
|
0.837
|
|
0.806
|
B14.Snoring
|
0.418
|
0.831
|
|
0.603
|
Factor 5: Parasomnias (PARA)
|
|
|
8.112
|
|
P15.Startles or jerks while falling asleep
|
0.456
|
0.830
|
|
0.668
|
P16. Sleep terrors or Nightmares
|
0.551
|
0.826
|
|
0.735
|
P17.Sleeptalking
|
0.368
|
0.833
|
|
0.545
|
P18.The child grinds teeth during sleep
|
0.257
|
0.836
|
|
0.421
|
Factor 6: Non-Restorative Sleep and Excessive Somnolence (NRSES)
|
|
|
7.232
|
|
N19.Unusually difficult to wake up in the morning
|
0.282
|
0.836
|
|
0.638
|
N20.Feeling tired with non-restorative sleep
|
0.445
|
0.831
|
|
0.787
|
N21.Sleep paralysis
|
0.387
|
0.833
|
|
0.773
|
N22.Daytime somnolence
|
0.381
|
0.833
|
|
0.664
|
N23.Sleep attacks
|
0.276
|
0.845
|
|
0.543
|
A Shapiroe-Wilks test of the total scale and subscale scores demonstrated a non-normal distribution.The correlation analysis was performed by nonparametric Spearman Rho.The correlation between subscale(DIS, DMS, SHY, SBD, PARA and NRSES) of the SDSC-I were <0.40, except a correlation between DIS and DMS was 0.525. Between the total score and subscales, a strong correlation was observed ranging from 0.501(SBD) to 0.820(DIS).
Construct validity
This scale was suitable for EFA using geomin rotation,with KMO value=0.82 and Bartlett's test of sphericity of χ 2 value=3088.36(P<0.001). Based on the eigenvalues, a six-factor solution explained 58.27% of the total variance.The factor loads of all the items varied between 0.328(item2) and 0.849(item5). The 23-item scale, the factor loadings and the 6 factors are depicted in Table 1. In the model described in CFA, χ2/DF=3.556, CFI =0.809, SRMR=0.070, and the RMESA=0.077 values were determined. The factor loading of the 23 items was from 0.22 to 0.87(see Figure 1). The factor structure of the chinese SDSC in infants was consistent with previous studies and appeared to be compatible.
Content validity
The inter-rater reliability of the SDSC-I was 0.87, I-CVI being >0.78, Kappa values >0.74, S-CVI/UA being 0.87, S-CVI/Ave being 0.98, all met the requirements, and the scale content validity was ideal presented in Table 2.
Table 2 Content validity analysis of each item for Chinese version of SDSC-I
Item
|
Expert Rating (score)
|
I-CVI
|
Kappa
|
A
|
B
|
C
|
D
|
E
|
F
|
|
|
D1
|
4
|
3
|
4
|
4
|
4
|
4
|
1.00
|
1.00
|
D2
|
4
|
4
|
4
|
4
|
4
|
4
|
1.00
|
1.00
|
D3
|
3
|
3
|
4
|
3
|
3
|
4
|
1.00
|
1.00
|
D4
|
4
|
4
|
3
|
3
|
3
|
4
|
1.00
|
1.00
|
D5
|
3
|
3
|
4
|
2
|
4
|
4
|
0.83
|
0.81
|
D6
|
3
|
2
|
4
|
3
|
4
|
3
|
0.83
|
0.81
|
M7
|
4
|
3
|
4
|
3
|
4
|
3
|
1.00
|
1.00
|
M8
|
4
|
4
|
4
|
3
|
4
|
3
|
1.00
|
1.00
|
M9
|
4
|
4
|
4
|
4
|
4
|
3
|
1.00
|
1.00
|
H10
|
4
|
4
|
4
|
4
|
3
|
3
|
1.00
|
1.00
|
H11
|
4
|
4
|
4
|
3
|
3
|
4
|
1.00
|
1.00
|
B12
|
3
|
3
|
4
|
4
|
3
|
3
|
1.00
|
1.00
|
B13
|
3
|
3
|
4
|
4
|
4
|
3
|
1.00
|
1.00
|
B14
|
4
|
4
|
4
|
3
|
4
|
3
|
1.00
|
1.00
|
P15
|
4
|
4
|
4
|
2
|
4
|
4
|
0.83
|
0.81
|
P16
|
4
|
4
|
4
|
3
|
4
|
4
|
1.00
|
1.00
|
P17
|
4
|
4
|
4
|
3
|
4
|
4
|
1.00
|
1.00
|
P18
|
4
|
3
|
4
|
4
|
3
|
4
|
1.00
|
1.00
|
N19
|
4
|
4
|
4
|
3
|
4
|
4
|
1.00
|
1.00
|
N20
|
4
|
4
|
4
|
3
|
4
|
4
|
1.00
|
1.00
|
N21
|
3
|
3
|
4
|
3
|
4
|
3
|
1.00
|
1.00
|
N22
|
4
|
4
|
4
|
3
|
3
|
4
|
1.00
|
1.00
|
N23
|
4
|
4
|
4
|
3
|
4
|
4
|
1.00
|
1.00
|
Item Analysis
According to the total score, the critical ratio method was used to divide 27% into the high group (n = 132, ≥48 points, numbered 2) and the low group (n = 129, ≤37 points, numbered 1), and t-tests were conducted to examine the differences between the two groups on each entry score. The results showed statistically significant differences between the high and low subgroups (P < 0. 05, see Table 3), indicating a strong differentiation in each dimension.
Table 3 Item analysis for Chinese version of SDSC-I
Item
|
high group
|
low group
|
t
|
P
|
D1
|
1.61±0.627
|
1.27±0.48
|
4.85
|
<0.001
|
D2
|
3.3±1.089
|
1.95±0.774
|
11.56
|
<0.001
|
D3
|
2.99±1.169
|
1.47±0.638
|
13.14
|
<0.001
|
D4
|
3.12±1.153
|
1.35±0.525
|
16.04
|
<0.001
|
D5
|
4.76±0.594
|
3.28±1.576
|
9.98
|
<0.001
|
D6
|
4.36±1.12
|
2.1±1.468
|
13.93
|
<0.001
|
M7
|
2.8±1.298
|
1.45±0.637
|
10.73
|
<0.001
|
M8
|
2.05±1.036
|
1.09±0.28
|
10.35
|
<0.001
|
M9
|
4.26±0.879
|
2.26±1.241
|
14.95
|
<0.001
|
H10
|
3.03±1.278
|
1.29±0.575
|
14.27
|
<0.001
|
H11
|
2.67±1.275
|
1.19±0.452
|
12.56
|
<0.001
|
B12
|
1.39±0.749
|
1.00±0.00
|
6.04
|
<0.001
|
B13
|
1.15±0.502
|
1.00±0.00
|
3.47
|
0.001
|
B14
|
1.97±1.018
|
1.2±0.422
|
7.99
|
<0.001
|
P15
|
1.99±1.008
|
1.21±0.408
|
8.26
|
<0.001
|
P16
|
2.38±0.937
|
1.3±0.494
|
11.65
|
<0.001
|
P17
|
1.86±0.909
|
1.23±0.459
|
7.02
|
<0.001
|
P18
|
1.48±0.776
|
1.1±0.327
|
5.23
|
<0.001
|
N19
|
1.85±1.129
|
1.16±0.556
|
6.25
|
<0.001
|
N20
|
1.7±0.863
|
1.04±0.231
|
8.56
|
<0.001
|
N21
|
1.52±0.842
|
1.02±0.151
|
6.60
|
<0.001
|
N22
|
1.68±0.859
|
1.09±0.317
|
7.38
|
<0.001
|
N23
|
1.55±0.775
|
1.21±0.51
|
4.24
|
<0.001
|
Scale score distribution
The minimum scores of the scale was 23, and for the subscales of DIS, DMS, SHY, SBD, PARA, and NRSES was 6, 3, 2, 3, 4, and 5, respectively.And the maximum scores of the total scale and subscales were 78, 27, 15, 10, 11, 15, and 20, respectively.And correspondingly, The percentages of the lowest scores were: 0.20%, 0.70%, 6.5%, 37.5%, 58.3%, 22.2%, 48.8%, and the percentages of the highest scores were: 0. 20%, 0. 70%, 0.20%, 3.5%, 0.20%, 0.70%, 0.20%, all of which were low. All the total scores demonstrated left-tailed distribution (Wilk's W=0.973, P=0.000)(see Figure 2). Differences in total score by age and gender were not found.
Other measurements
As previously done in the similar studies [10], most of the infants (62.0%) slept >9 h per night and that none slept <5 h. 59.7% of the young children fell asleep 30min after going to bed. The highest prevalence of frequencies of parent-reported sleeping disturbances symptoms was item5 (77.3%) , and the lowest was item1(0.2%) and item13(0.2%)(see Table 4). The analysis of the respondents' compliance and the completion time of the scale showed that most of the parents could fill out the questionnaire issued in this study and complete it within 10-15 min, and the return rate of the questionnaire was over 90%.
Table 4 Frequencies (%) of parent-reported sleeping disturbances in infants.
Item
|
Never
|
Occasionally
1~2x/month
|
Sometimes
1~2x/week
|
Often
3~5x/week
|
Always
|
D1
|
62.000
|
33.100
|
4.600
|
0.200
|
0.000
|
D2
|
13.900
|
45.800
|
23.400
|
8.800
|
8.100
|
D3
|
32.200
|
37.300
|
16.900
|
8.600
|
5.100
|
D4
|
33.600
|
37.300
|
15.300
|
9.300
|
4.600
|
D5
|
6.900
|
8.800
|
6.900
|
14.800
|
62.500
|
D6
|
23.400
|
14.800
|
8.300
|
12.700
|
40.700
|
M7
|
37.300
|
38.900
|
9.700
|
9.700
|
4.400
|
M8
|
64.100
|
25.000
|
7.900
|
2.300
|
0.700
|
M9
|
11.100
|
22.200
|
12.300
|
30.600
|
23.800
|
H10
|
42.400
|
26.900
|
13.900
|
9.000
|
7.900
|
H11
|
50.200
|
27.800
|
10.600
|
7.400
|
3.900
|
B12
|
88.200
|
7.600
|
2.800
|
0.900
|
0.500
|
B13
|
95.600
|
3.000
|
1.200
|
0.200
|
0.000
|
B14
|
62.000
|
28.000
|
6.700
|
2.300
|
0.900
|
P15
|
55.800
|
35.600
|
4.900
|
3.000
|
0.700
|
P16
|
40.500
|
44.400
|
10.600
|
4.200
|
0.200
|
P17
|
58.100
|
32.900
|
6.900
|
2.100
|
0.000
|
P18
|
78.900
|
16.400
|
3.500
|
1.200
|
0.000
|
N19
|
73.600
|
14.400
|
7.200
|
3.000
|
1.900
|
N20
|
78.200
|
15.700
|
4.600
|
1.400
|
0.000
|
N21
|
85.200
|
10.900
|
3.000
|
0.500
|
0.500
|
N22
|
75.900
|
18.800
|
4.200
|
0.900
|
0.200
|
N23
|
74.100
|
19.200
|
5.600
|
1.200
|
0.000
|