Study population
During the study period, a total of 589 children presenting with ‘snoring and/or mouth breathing’ were included in the study. Among them, 368 were male and 221 were female. The male to female ratio was approximately 1.66:1. The patient age ranged from 2.7 years to 15.5 years, with a median patient age of 6.0 years (IQR: 4.9–7.8 years).
Patients were grouped by age as follows: < 7 y-382 cases (64.9%) and ≥ 7 y-207 cases (53.1%). Patients were classified by the season as follows: 146 cases were detected in spring (24.8%), 165 cases were detected in summer (28.0%), 117 cases were detected in autumn (19.9%), and 161 cases were detected in winter (27.3%).
Among the 589 patients, BMI ranged from 9.60 kg/m2 to 38.48 kg/m2, with a median BMI of 16.2 kg/m2 (IQR: 14.93–18.16 kg/m2). Among these patients, 108 (18.3%) were overweight and 92 (15.6%) were obese. Further, there were 438 cases (74.4%) of tonsillar hypertrophy, 526 cases (89.3%) of adenoid hypertrophy, 410 cases (69.6%) of rhinitis/sinusitis, and 77 cases (13.1%) of asthma.
There was no significant difference in gender and age among groups in different seasons (Table 1).
Table 1
Demographic characteristics of patients presenting with snoring
|
Spring
N = 146 n (%)
|
Summer
N = 165 n (%)
|
Autumn
N = 117 n (%)
|
Winter
N = 161 n (%)
|
H/χ2
|
P
|
M/F
|
89/57
|
104/61
|
79/38
|
96/65
|
1.993b
|
0.574
|
Age (y)
|
5.3 (4.4, 6.0)
|
5.1 (4.5, 5.9)
|
5.3 (4.5, 5.8)
|
5.5 (4.2, 5.8)
|
3.136a
|
0.371
|
Note: a: H-value from the Kruskal-Wallis H-test; b: χ2-value from the Pearson test |
Diagnostic rate of OSAHS in children in different seasons
Of the 589 patients, 301 cases (51.1%) were diagnosed with OSAHS. Among them, 77 cases (25.6%) were detected in spring, 74 cases (24.6%) were detected in summer, 59 cases (19.6%) were detected in autumn, and 91 cases (30.2%) were detected in winter. There was no difference in the diagnostic rate of OSAHS and primary snoring (PS) in different seasons (Table 2).
Table 2
Influence of season on the diagnostic rate of snoring in children
|
Seasons
|
Test value
|
P
|
Spring
N = 146
n (%)
|
Summer
N = 165
n (%)
|
Autumn
N = 117
n (%)
|
Winter
N = 161
n (%)
|
PS
|
69 (24.0%)
|
91 (31.6%)
|
58 (20.1%)
|
70 (24.3%)
|
4.653
|
0.20
|
OSAHS
|
77 (25.6%)
|
74 (24.6%)
|
59 (19.6%)
|
91 (30.2%)
|
Note: p values obtained from the Pearson test. |
Of the 301 patients, 238 cases (79.1%) had tonsil hypertrophy, 276 cases (91.7%) had adenoid hypertrophy, 215 cases (71.4%) had rhinitis/sinusitis, and 36 cases (12.0%) had asthma. There was no significant difference in BMI among children with OSAHS in different seasons, but the proportion of rhinitis/sinusitis and tonsil hypertrophy in spring was higher than that in summer (P = 0.015 and 0.036, respectively), and the proportion of adenoid hypertrophy in winter was higher than that in summer (P = 0.024) (Table 3).
Table 3
Rhinitis/sinusitis, asthma, adenoid/tonsillar hypertrophy, and BMI distribution in children with OSAHS in different seasons
|
Seasons
|
Test value
|
P
|
Spring
N = 77
n (%)
|
Summer
N = 74
n (%)
|
Autumn
N = 59
n (%)
|
Winter
N = 91
n (%)
|
Rhinitis/sinusitis
|
65(84.4)▲
|
46(62.2)
|
40(67.8)
|
64(70.3)
|
9.912a
|
0.019
|
Asthma
|
5(6.5)
|
8(10.8)
|
7(11.9)
|
16(17.6)
|
5.010a
|
0.170
|
Tonsil hypertrophy
|
66(85.7)▲
|
50(67.6)
|
46(78.0)
|
76(83.5)
|
9.101a
|
0.027
|
Adenoid hypertrophy
|
69(89.6)
|
64(86.5)
|
53(89.8)
|
90(98.9)▲
|
11.572b
|
0.007
|
BMI (kg/2)
|
16.1 (15.0, 17.9)
|
16.5 (14.7, 20.1)
|
17.0 (15.4, 19.7)
|
16.2 (15.2,18.5)
|
2.962c
|
0.403
|
Note: ▲ statistically significant compared with summer, P < 0.05; a:χ2 values obtained from the Pearson test. b: χ2 values obtained from the Fisher accurate probability method. c: H value obtained by Kruskal-Wallis H test. |
Comparison of the severity of OSAHS in children in different seasons
The diagnostic rate of severe OSAHS in winter was higher than that in summer (χ2 = 7.05, ,P = 0.008) (Table 4). There was no difference in gender, age, and BMI among children with different severities of OSAHS (all p>0.05) (Table 5).
Table 4
Comparison of the severity of OSAHS in children in different seasons
|
Seasons
|
Test value
|
P
|
Spring
N = 77
n (%)
|
Summer
N = 74
n (%)
|
Autumn
N = 59
n (%)
|
Winter
N = 91
n (%)
|
Mild OSAHS
|
47 (61.0)
|
53 (71.6)
|
33 (56.0)
|
50 (54.9)
|
6.051b
|
0.109
|
Moderate OSAHS
|
14 (18.2)
|
15 (20.3)
|
9 (15.3)
|
22 (20.9)
|
0.210b
|
0.976
|
Severe OSAHS
|
16 (20.8)
|
6 (8.1)
|
14 (23.7)
|
22 (24.2)▲
|
8.201b
|
0.042
|
Note: ▲ statistically significant compared with summer, P < 0.05; b: χ2 values obtained from the Pearson test. |
Table 5
Gender, age, and BMI distribution of children with different severities of OSAHS
|
Severity
|
Test value
|
P
|
Mild
N = 183
n (%)
|
Moderate
N = 60
n (%)
|
Severe
N = 58
n (%)
|
M/F
|
120 (61.5)
|
40 (66.7)
|
35 (60.3)
|
0.644b
|
0.740
|
Age (y)
|
5.8(4.9,7.4)
|
5.9(4.6,7.6)
|
6.4(5.2,8.3)
|
3.674a
|
0.159
|
BMI (kg/2)
|
16.5(15.2,18.8)
|
16.1(15.0,19.2)
|
16.7(14.8,19.7)
|
0.112a
|
0.946
|
Note: a:H value obtained by Kruskal-Wallis H test b: χ2 values obtained from the Pearson test. |
Effects of seasons on respiratory events/microarousal events in children with OSAHS
The respiratory arousal index in winter was higher than that in summer (H = -39.297, P = 0.018), and the spontaneous arousal index in spring was higher than that in autumn (H = 44.059, P = 0.020). It was found that the rapid eye movement (REM)- apnea index (AI) in spring and winter was higher than that in autumn (H = 52.292, -52.554; all P < 0.05) (Table 6).
Table 6
Comparison of respiratory events/awakening events in children with OSAHS in different seasons
Items
|
Spring
N = 77
|
Summer
N = 74
|
Autumn
N = 59
|
Winter
N = 91
|
Test value
|
P
|
ODI3%
(/hrTST)
|
2.15 (1.10, 6.35)
|
2.10 (0.85, 4.20)
|
2.90 (0.90, 11.75)
|
1.70 (0.58, 4.73)
|
6.284a
|
0.099
|
OAHI (/hrTST)
|
3.5 (1.98, 8.65)
|
3.0 (1.6, 6.1)
|
4.0 (1.6, 15.3)
|
4.3 (2.0, 9.29)
|
4.754
|
0.191
|
LSPO2 (%)
|
88.00 (82.25, 91.00)
|
89.00 (86.00, 92.00)
|
88.00 (83.00, 91.00)
|
89.00 (85.00, 92.00)
|
6.377a
|
0.095
|
Respiratory arousal index
|
0.20 (0.00, 0.70)
|
0.10 (0.00, 0.30)▮
|
0.10 (0.00, 0.60)
|
0.30 (0.10, 0.70)
|
10.087a
|
0.018
|
Spontaneous arousal index
|
5.35 (2.98, 8.48)
|
3.80 (2.55, 6.05)
|
3.60 (1.95, 5.40)▲
|
4.20 (2.90, 6.70)
|
10.639a
|
0.015
|
REM-AI (/hrTST)
|
4.50 (1.70, 9.78)
|
3.0 (1.35, 5.95)
|
1.90 (0.60, 4.60)▲▮
|
4.40 (2.70, 7.60)
|
18.789a
|
0.000
|
Note:▲ statistically significant compared with spring;▮statistically different compared with winter; a:H value obtained by Kruskal-Wallis H test. |
Comparison of PSG results of children with OSAHS aged < 7 years in different seasons
The respiratory arousal index in winter was higher than that in summer (H = -35.570, P = 0.008). There was no significant difference in the spontaneous arousal index between the two groups (all P > 0.05). The REM-AI in winter and spring was higher than that in summer and autumn, respectively (H = -33.929 and − 38.632; H = 30.665 and 35.368, all P < 0.05) (Table 7).
Table 7
Comparison of PSG results of children with OSAHS aged < 7 years in different seasons
Items
|
Spring
N = 60
|
Summer
N = 45
|
Autumn
N = 38
|
Winter
N = 58
|
Test value
|
P
|
ODI3%
(/hrTST)
|
2.25 (1.10, 6.35)
|
1.90 (1.20, 3.50)
|
2.70(0.60, 11.75)
|
1.70 (0.70, 4.25)
|
2.287a
|
0.515
|
LSPO2 (%)
|
88.0 (82.00, 91.00)
|
90.00 (85.00, 91.00)
|
88.00 (82.50, 91.00)
|
88.00 (84.70, 92.00)
|
4.323a
|
0.229
|
Respiratory arousal index
|
0.2 (0.00, 0.68)
|
0.1 (0.00, 0.20)▮
|
0.20 (0.00, 0.70)
|
0.30 (0.10, 0.73)
|
11.236a
|
0.011
|
Spontaneous arousal index
|
6.20 (3.38, 9.30)
|
4.00 (2.70, 6.80) ▲
|
3.8 (2.60, 6.00) ▲
|
4.70 (3.28, 7.23)
|
8.476a
|
0.037
|
REM-AI (/hrTST)
|
4.90 (2.40,9.65)
|
2.90 (1.15,6.18) ▮▲
|
1.90 (0.28,7.75)▮ ▲
|
4.90 (3.70, 8.18)
|
17.769a
|
0.000
|
Note:▲ statistically significant compared with spring,;▮statistically different compared with winter༛a:H value obtained by the Kruskal-Wallis H test. |
Comparison of PSG results of children with OSAHS aged ≥ 7 years in different seasons
There was no significant difference in PSG results of children with OSAHS aged ≥ 7 years in different seasons (all P > 0.05) (Table 8).
Table 8
Comparison of PSG results of children with OSAHS aged ≥ 7 years in different seasons
Items
|
Spring
N = 17
|
Summer
N = 29
|
Autumn
N = 21
|
Winter
N = 33
|
Test value
|
P
|
ODI3%
(/hrTST)
|
1.90 (1.03,7.13)
|
2.95 (0.67,5.63)
|
4.45 (1.65,13.3)
|
1.70 (0.25,6.45)
|
4.535a
|
0.209
|
LSPO2 (%)
|
89.50 (84.25, 91.50)
|
89.00(86.00,92.00)
|
87.50 (83.75, 91.75)
|
89.00 (88.00,92.50)
|
2.549a
|
0.466
|
Respiratory arousal index
|
0.15 (0.00, 1.08)
|
0.15 (0.00, 0.43)
|
0.50 (0.00, 0.45)
|
0.20 (0.05, 0.50)
|
2.149a
|
0.542
|
Spontaneous arousal index
|
3.90 (2.05, 5.40)
|
3.70 (2.15, 4.80)
|
2.90 (1.83, 4.78)
|
3.40 (2.35, 5.15)
|
1.682a
|
0.641
|
REM-AI (/hrTST)
|
1.70 (1.40,11.65)
|
3.05 (1.68, 5.13)
|
1.70 (0.00, 3.35)
|
2.80 (1.65,6.30)
|
5.398a
|
0.145
|
Note: ▮statistically different compared with winter; a: H value obtained by the Kruskal-Wallis H test |