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Snoring in preschool children: prevalence, severity and risk factors
Authors
Claudia E. Kuehni1, Marie-Pierre F. Strippoli1, Emmanuelle S. Chauliac1, Michael Silverman2
Address for correspondence
Dr. Claudia E. Kuehni, Institute of Social and Preventive Medicine, University of Bern,
Finkenhubelweg 11, CH-3012, Bern, Switzerland.
Phone: +41 (0)31 631 35 07, Fax: +41 (0)31 631 35 20, e-mail: kuehni@ispm.unibe. ch
Full names, institution and country of all co-authors
1. Institute of Social and Preventive Medicine, University of Bern, Switzerland
Claudia E. Kuehni
Marie-Pierre F. Strippoli
Emmanuelle S. Chauliac
2. Division of Child Health, Department of Infection, Immunity and Inflammation, University of
Leicester, UK
Michael Silverman
Short title: Snoring in preschool children
1
Table E1A - Reported frequency of snoring in the last 12 months in children aged 1-4 years, by environmental and socioeconomic factors (N=6742)
Reported frequency of snoring
Never
Only with colds
Sometimes without colds
Almost always
n
%
(95 CI)
n
%
(95 CI)
n
%
(95 CI)
n
%
(95 CI)
2714
40.3
(39.1-41.4)
1862
27.6
(26.6-28.7)
1635
24.2
(23.2-25.3)
531
7.9
(7.2-8.5)
None
1878
43.0
(41.5-44.5)
1209
27.7
(26.4-29.0)
990
22.7
(21.4-23.9)
290
6.6
(5.9-7.4)
One parent
621
36.3
(34.0-38.6)
471
27.5
(25.4-29.6)
461
26.9
(24.8-29.0)
158
9.2
(7.9-10.6)
Both parents
215
32.4
(28.8-35.9)
182
27.4
(24.0-30.8)
184
27.7
(24.3-31.1)
83
12.5
(10.0-15.0)
No
2361
41.6
(40.3-42.8)
1589
28.0
(26.8-29.1)
1332
23.4
(22.3-24.5)
400
7.0
(6.4-7.7)
Yes
353
33.3
(30.5-36.1)
273
25.8
(23.1-28.4)
303
28.6
(25.9-31.3)
131
12.4
(10.4-14.3)
No
1198
42.9
(41.0-44.7)
762
27.3
(25.6-28.9)
638
22.8
(21.3-24.4)
196
7.0
(6.1-8.0)
Yes
1516
38.4
(36.9-39.9)
1100
27.9
(26.5-29.3)
997
25.3
(23.9-26.6)
335
8.5
(7.6-9.4)
Electric
900
41.3
(39.3-43.4)
609
28.0
(26.1-29.8)
501
23.0
(21.2-24.8)
168
7.7
(6.6-8.8)
Other
1814
39.7
(38.3-41.2)
1253
27.5
(26.2-28.7)
1134
24.8
(23.6-26.1)
363
8.0
(7.2-8.7)
Central
2514
40.5
(39.2-41.7)
1734
27.9
(26.8-29.0)
1489
24.0
(22.9-25.0)
475
7.6
(7.0-8.3)
Other
200
37.7
(33.6-41.9)
128
24.2
(20.5-27.8)
146
27.5
(23.7-31.4)
56
10.6
(7.9-13.2)
2181
39.5
(38.2-40.7)
1507
27.3
(26.1-28.4)
1389
25.1
(24.0-26.3)
450
8.1
(7.4-8.9)
Total
A- Environmental factors
Parental smoking
Maternal smoking during pregnancy
Exposure to road traffic
Cooking
Heating
Breast feeding > 6 months
No
2
Yes
533
43.9
(41.1-46.7)
355
29.2
(26.7-31.8)
246
20.2
(18.0-22.5)
81
6.7
(5.3-8.1)
No
2537
41.3
(40.0-42.5)
1704
27.7
(26.6-28.8)
1448
23.5
(22.5-24.6)
461
7.5
(6.8-8.2)
Yes
177
29.9
(26.2-33.6)
158
26.7
(23.1-30.3)
187
31.6
(27.8-35.3)
70
11.8
(9.2-14.4)
No
1303
40.7
(39.0-42.4)
946
29.5
(27.9-31.1)
737
23.0
(21.5-24.5)
219
6.8
(6.0-7.7)
Yes
1411
39.9
(38.3-41.5)
916
25.9
(24.5-27.3)
898
25.4
(24.0-26.8)
312
8.8
(7.9-9.8)
No
1060
42.3
(40.3-44.2)
727
29.0
(27.2-30.8)
559
22.3
(20.7-23.9)
161
6.4
(5.5-7.4)
Yes
1654
39.1
(37.6-40.5)
1135
26.8
(25.5-28.1)
1076
25.4
(24.1-26.7)
370
8.7
(7.9-9.6)
No
2049
39.8
(38.4-41.1)
1465
28.4
(27.2-29.7)
1255
24.4
(23.2-25.5)
384
7.5
(6.7-8.2)
Yes
665
41.9
(39.4-44.3)
397
25.0
(22.9-27.1)
380
23.9
(21.8-26.0)
147
9.3
(7.8-10.7)
Low deprivation
1020
41.4
(39.4-43.3)
715
29.0
(27.2-30.8)
572
23.2
(21.5-24.9)
159
6.4
(5.5-7.4)
Medium deprivation
894
39.5
(37.5-41.5)
647
28.6
(26.7-30.5)
546
24.1
(22.4-25.9)
175
7.7
(6.6-8.8)
High deprivation
750
39.5
(37.3-41.7)
469
24.7
(22.8-26.7)
487
25.7
(23.7-27.6)
191
10.1
(8.7-11.4)
B- Socioeconomic factors
Single parent
Poor maternal education (≤ 16 yrs)
Poor paternal education (≤ 16 yrs)
Crowding (>1 person per room)
Townsend score
3
Table E1B - Reported frequency of snoring in the last 12 months in children aged 1-4 years, by clinical and biological features (N=6742)
Reported frequency of snoring
Never
Only with colds
Sometimes without colds
Almost always
n
%
(95 CI)
n
%
(95 CI)
n
%
(95 CI)
n
%
(95 CI)
2714
40.3
(39.1-41.4)
1862
27.6
(26.6-28.7)
1635
24.2
(23.2-25.3)
531
7.9
(7.2-8.5)
1
1719
40.9
(39.4-42.3)
1259
29.9
(28.5-31.3)
953
22.7
(21.4-23.9)
276
6.6
(5.8-7.3)
2
319
39.5
(36.1-42.9)
225
27.8
(24.7-30.9)
208
25.7
(22.7-28.8)
56
6.9
(5.2-8.7)
3
331
38.5
(35.2-41.7)
198
23.0
(20.2-25.8)
245
28.5
(25.5-31.5)
86
10.0
(8.0-12.0)
4
345
39.8
(36.5-43.1)
180
20.8
(18.1-23.5)
229
26.4
(23.5-29.4)
113
13.0
(10.8-15.3)
Female
1387
43.0
(41.3-44.7)
897
27.8
(26.3-29.4)
708
21.9
(20.5-23.4)
234
7.3
(6.4-8.1)
Male
1327
37.7
(36.1-39.3)
965
27.4
(26.0-28.9)
927
26.4
(24.9-27.8)
297
8.4
(7.5-9.4)
White
1907
38.6
(37.3-40.0)
1390
28.1
(26.9-29.4)
1229
24.9
(23.7-26.1)
412
8.3
(7.6-9.1)
South Asian
807
44.7
(42.4-47.0)
472
26.2
(24.1-28.2)
406
22.5
(20.6-24.4)
119
6.6
(5.4-7.7)
None
2140
45.0
(43.6-46.4)
1279
26.9
(25.7-28.2)
1024
21.5
(20.4-22.7)
309
6.5
(5.8-7.2)
1-10 attacks
545
29.3
(27.2-31.4)
562
30.2
(28.1-32.3)
566
30.4
(28.4-32.5)
186
10.0
(8.6-11.4)
> 10 attacks
29
22.1
(14.9-29.3)
21
16.0
(9.7-22.4)
45
34.4
(26.1-42.6)
36
27.5
(19.7-35.2)
1819
44.1
(42.6-45.6)
1107
26.9
(25.5-28.2)
911
22.1
(20.8-23.4)
285
6.9
(6.1-7.7)
Total
Demographic variables
Age (years)
Sex
Ethnicity
Atopic disorders
Attacks of wheeze*
Eczema ever
No
4
Yes
895
34.2
(32.3-36.0)
755
28.8
(27.1-30.6)
724
27.6
(25.9-29.3)
246
9.4
(8.3-10.5)
No
2316
42.4
(41.0-43.7)
1512
27.7
(26.5-28.8)
1248
22.8
(21.7-23.9)
392
7.2
(6.5-7.9)
Yes
398
31.2
(28.7-33.8)
350
27.5
(25.0-29.9)
387
30.4
(27.8-32.9)
139
10.9
(9.2-12.6)
No
2204
44.5
(43.1-45.8)
1406
28.4
(27.1-29.6)
1050
21.2
(20.0-22.3)
297
6.0
(5.3-6.7)
Yes
510
28.6
(26.5-30.7)
456
25.5
(23.5-27.6)
585
32.8
(30.6-35.0)
234
13.1
(11.5-14.7)
< 4 colds
1602
48.9
(47.2-50.6)
801
24.4
(23.0-25.9)
687
21.0
(19.6-22.4)
188
5.7
(4.9-6.5)
4-6 colds
789
34.5
(32.6-36.5)
707
31.0
(29.1-32.9)
596
26.1
(24.3-27.9)
192
8.4
(7.3-9.5)
≥ 7 colds
323
27.4
(24.8-29.9)
354
30.0
(27.4-32.6)
352
29.8
(27.2-32.4)
151
12.8
(10.9-14.7)
No
2050
44.5
(43.1-46.0)
1324
28.8
(27.4-30.1)
958
20.8
(19.6-22.0)
272
5.9
(5.2-6.6)
Yes
664
31.1
(29.1-33.0)
538
25.2
(23.3-27.0)
677
31.7
(29.7-33.6)
259
12.1
(10.7-13.5)
None
1775
44.9
(43.4-46.5)
1076
27.2
(25.8-28.6)
848
21.5
(20.2-22.7)
252
6.4
(5.6-7.1)
1 episode
575
35.5
(33.2-37.9)
470
29.0
(26.8-31.3)
439
27.1
(25.0-29.3)
134
8.3
(6.9-9.6)
> 1 episode
364
31.0
(28.4-33.7)
316
26.9
(24.4-29.5)
348
29.7
(27.0-32.3)
145
12.4
(10.5-14.2)
Normal
1928
40.2
(38.8-41.5)
1336
27.8
(26.6-29.1)
1165
24.3
(23.1-25.5)
372
7.7
(7.0-8.5)
Underweight
119
45.2
(39.2-51.3)
59
22.4
(17.4-27.5)
67
25.5
(20.2-30.8)
18
6.8
(3.8-9.9)
Overweight
357
38.6
(35.5-41.8)
267
28.9
(26.0-31.8)
223
24.1
(21.4-26.9)
77
8.3
(6.5-10.1)
Obese
110
41.2
(35.3-47.1)
75
28.1
(22.7-33.5)
61
22.8
(17.8-27.9)
21
7.9
(4.6-11.1)
Maternal history of wheeze or asthma
Other respiratory symptoms
Cough at night*
Frequency of colds*
Chronic rhinitis*
Otitis media*
Body mass index
Low birthweight (< 2500g)
5
No
2514
40.2
(39.0-41.4)
1728
27.6
(26.5-28.7)
1520
24.3
(23.2-25.4)
494
7.9
(7.2-8.6)
Yes
200
41.2
(36.8-45.5)
134
27.6
(23.6-31.6)
115
23.7
(19.9-27.5)
37
7.6
(5.2-10.0)
None
866
49.4
(47.1-51.7)
447
25.5
(23.5-27.5)
337
19.2
(17.4-21.1)
103
5.9
(4.8-7.0)
A little
1503
38.0
(36.5-39.5)
1129
28.6
(27.1-30.0)
1012
25.6
(24.2-27.0)
310
7.8
(7.0-8.7)
A lot
345
33.3
(30.5-36.2)
286
27.6
(24.9-30.4)
286
27.6
(24.9-30.4)
118
11.4
(9.5-13.3)
Posseting† during 1st year of life
* during the past 12 months
† regurgitation, a common form of gastro-oesophageal reflux in infants
6
Table E2A - Environmental and socioeconomic factors associated with snoring sometimes without colds in the last 12 months (N=4349)
Base model
OR
95% CI
Partially adjusted model I
p
OR
95% CI
p
Fully adjusted model
OR
95% CI
p
A- Environmental factors
Parental smoking
One parent vs. none
1.41 (1.22- 1.63)
Both parents vs. none
1.55 (1.25- 1.93) <0.001 1.42 (1.13- 1.78) <0.001
1.30 (1.12- 1.51)
Maternal smoking during pregnancy
1.44 (1.21- 1.72) <0.001
Exposure to road traffic
1.25 (1.10- 1.42) 0.001
1.19 (1.04- 1.36) 0.010
No electric cooking
1.23 (1.07- 1.42) 0.003
1.21 (1.05- 1.39) 0.009
No central heating
1.22 (0.97- 1.53) 0.083
Breast feeding > 6 months
0.73 (0.62- 0.87) <0.001 0.80 (0.68- 0.95) 0.011
1.30
(1.11-
1.53)
1.47
(1.16-
1.85)
<0.001
1.21
(1.05-
1.41)
0.011
1.29
(1.01-
1.66)
0.042
1.23
(1.03-
1.46)
B- Socioeconomic factors
Single parent
1.76 (1.41- 2.18) <0.001 1.53 (1.21- 1.93) <0.001
Poor maternal education (≤ 16 yrs)
1.10 (0.97- 1.24) 0.146
Poor paternal education (≤ 16 yrs)
1.18 (1.03- 1.34) 0.017
Crowding (>1 person per room)
1.00 (0.86- 1.16) 0.954
Townsend score (tertiles)
Whites
Medium deprivation vs. low
1.27 (1.07- 1.49)
High deprivation vs. low
1.76 (1.45- 2.14) <0.001 1.35 (1.10- 1.67) 0.017
1.28
(1.03-
1.60)
Medium deprivation vs. low
0.58 (0.41- 0.83)
0.56 (0.39- 0.80)
0.63
(0.44-
0.92)
High deprivation vs. low
0.58 (0.42- 0.79) 0.002
0.52 (0.38- 0.72) <0.001
0.63
(0.45-
0.89)
1.15 (0.97- 1.36)
0.026
Asians
0.022
7
Base model: adjusted for age, sex and ethnic group
Partially adjusted model I: adjusted for age, sex, ethnic group and all environmental and socioeconomic factors (all variables in Table E2A)
Fully adjusted model: adjusted for age, sex, ethnic group, all environmental and socioeconomic factors and clinical features simultaneously (variables
in partially adjusted model of Table E2A and partially adjusted model of Table E3A simultaneously)
p-values refer to Wald test for the whole variable included in the model
8
Table E3A - Clinical and biological features associated with snoring sometimes without colds in the last 12 months (N=4349)
Base model
Partially adjusted model II
Fully adjusted model
OR
95% CI
p
OR
95% CI
p
OR
95% CI
p
Male sex
1.36
(1.20- 1.54)
<0.001
1.33
(1.17- 1.52)
<0.001
1.33
(1.17-
1.52)
<0.001
Age ≥ 2 years
1.30
(1.14- 1.48)
<0.001
1.34
(1.17- 1.54)
<0.001
1.38
(1.20-
1.59)
<0.001
South Asian ethnicity
0.74
(0.64- 0.86)
<0.001
0.78
(0.67- 0.91)
0.001
1.27
(0.93-
1.75)
0.135
Attacks of wheeze* (1-10 attacks vs. none)
2.21
(1.93- 2.55)
1.48
(1.27- 1.73)
1.42
(1.21-
1.66)
(> 10 attacks vs. none)
3.19
(1.98- 5.13)
<0.001
1.40
(0.85- 2.32)
<0.001
1.22
(0.73-
2.04)
<0.001
Eczema ever
1.57
(1.39- 1.79)
<0.001
1.29
(1.13- 1.48)
<0.001
1.32
(1.15-
1.52)
<0.001
Maternal history of wheeze or asthma
1.78
(1.52- 2.09)
<0.001
1.39
(1.17- 1.64)
<0.001
1.39
(1.17-
1.65)
<0.001
Cough at night*
2.41
(2.10- 2.78)
<0.001
1.65
(1.41- 1.92)
<0.001
1.62
(1.39-
1.90)
0.001
Frequency of colds* (4-6 colds vs. <4 colds)
1.78
(1.55- 2.05)
1.34
(1.15- 1.56)
1.40
(1.20-
1.63)
(≥ 7 colds vs. <4 colds)
2.62
(2.19- 3.13)
<0.001
1.57
(1.29- 1.92)
<0.001
1.62
(1.33-
1.99)
<0.001
Chronic rhinitis*
2.21
(1.93- 2.52)
<0.001
1.61
(1.40- 1.86)
<0.001
1.57
(1.36-
1.81)
<0.001
Otitis media* (1 episode vs. none)
1.58
(1.36- 1.83)
1.34
(1.14- 1.56)
1.34
(1.14-
1.57)
1.94
(1.63- 2.29)
1.29
(1.07- 1.55)
1.30
(1.08-
1.57)
Underweight vs. normal
1.00
(0.73- 1.37)
Overweight vs. normal
1.05
(0.87- 1.26)
Obese vs. normal
0.95
(0.69- 1.32)
0.942
Low birthweight (<2500g)
1.01
(0.80- 1.29)
0.915
Demographic variables
Atopic disorders
Other respiratory symptoms
(>1 episode vs. none)
<0.001
<0.001
<0.001
Body mass index
Posseting† during 1st year of life
9
A little vs. none
1.72
(1.48- 2.00)
A lot vs. none
2.07
(1.69- 2.54)
<0.001
1.46
(1.25- 1.71)
1.44
(1.16- 1.79)
<0.001
1.44
(1.23-
1.69)
1.39
(1.11-
1.73)
<0.001
*during the past 12 months; † regurgitation, a common form of gastro-oesophageal reflux in infants
Base model: adjusted for age, sex and ethnic group
Partially adjusted model II: adjusted for age, sex, ethnic group and all other clinical and biological features (all variables in Table E3A)
Fully adjusted model: adjusted for age, sex, ethnic group, all other clinical and biological features and all environmental and socioeconomic
simultaneously (variables in partially adjusted model of Table E3A and partially adjusted model of Table E2A simultaneously)
p-values refer to Wald test for the whole variable included in the model
10
Table E2B - Environmental and socioeconomic factors associated with snoring only with colds in the last 12 months (N=4576)
Base model*
OR
95% CI
Partially adjusted model I*
p
OR
95% CI
p
Fully adjusted model*
OR
95% CI
p
A- Environmental factors
Parental smoking
One parent vs. none
1.18 (1.03- 1.36)
1.18 (1.02- 1.36)
Both parents vs. none
1.25 (1.01- 1.55) 0.017
1.30 (1.05- 1.62)
Maternal smoking during pregnancy
1.09 (0.92- 1.30) 0.334
Exposure to road traffic
1.17 (1.03- 1.31) 0.013
No electric cooking
1.09 (0.95- 1.24) 0.212
No central heating
0.92 (0.73- 1.16) 0.481
Breast feeding > 6 months
0.97 (0.83- 1.12) 0.654
1.23
(1.06-
1.42)
0.010
1.30
(1.04-
1.62)
0.004
1.16 (1.02- 1.30)
0.019
1.14
(1.00-
1.28)
0.045
0.87
(0.77-
0.99)
0.030
B- Socioeconomic factors
Single parent
1.31 (1.04- 1.64) 0.019
1.31 (1.05- 1.65)
0.019
Poor maternal education (≤ 16 yrs)
0.89 (0.79- 1.00) 0.053
0.84 (0.74- 0.95)
0.004
Poor paternal education (≤ 16 yrs)
0.97 (0.85- 1.09) 0.585
Crowding (>1 person per room)
0.89 (0.77- 1.03) 0.119
Townsend score (tertiles)
Medium deprivation vs. low
1.06 (0.92- 1.22)
High deprivation vs. low
0.98 (0.83- 1.15) 0.546
Base model: adjusted for age, sex and ethnic group
Partially adjusted model I: adjusted for age, sex, ethnic group and all environmental and socioeconomic factors (all variables in Table E2B)
11
Fully adjusted model: adjusted for age, sex, ethnic group, all environmental and socioeconomic factors and clinical features simultaneously (variables
in partially adjusted model of Table E2B and partially adjusted model of Table E3B simultaneously)
p-values refer to Wald test for the whole variable included in the model
12
Table E3B - Clinical and biological features associated with snoring only with colds in the last 12 months (N=4576)
Base model
Partially adjusted model II
OR
95% CI
p
OR
95% CI
Male sex
1.12
(1.00- 1.26)
0.053
1.09
(0.97-
Age ≥ 2 years
0.86
(0.76- 0.98)
0.019
0.90
South Asian ethnicity
0.83
(0.72- 0.95)
0.007
Attacks of wheeze* (1-10 attacks vs. none)
1.68
(1.46- 1.92)
(> 10 attacks vs. none)
1.15
(0.65- 2.03)
Eczema ever
1.39
Maternal history of wheeze or asthma
Fully adjusted model
p
OR
95% CI
p
1.23)
0.159
1.10
(0.97-
1.24)
0.141
(0.79-
1.03)
0.122
0.90
(0.79-
1.03)
0.127
0.85
(0.74-
0.98)
0.026
0.85
(0.74-
0.98)
0.028
1.38
(1.19-
1.59)
1.36
(1.17-
1.57)
<0.001
0.73
(0.41-
1.31)
<0.001
0.70
(0.39-
1.26)
<0.001
(1.23- 1.57)
0.001
1.23
(1.09-
1.40)
0.001
1.24
(1.09-
1.41)
0.001
1.31
(1.12- 1.54)
0.001
Cough at night*
1.45
(1.26- 1.68)
<0.001
1.18
(1.00-
1.37)
0.037
1.18
(1.02-
1.38)
0.029
Frequency of colds* (4-6 colds vs. <4 colds)
1.77
(1.55- 2.03)
1.57
(1.36-
1.80)
1.57
(1.37-
1.81)
(≥ 7 colds vs. <4 colds)
2.19
(1.84- 2.61)
0.001
1.85
(1.53-
2.23)
1.85
(1.54-
2.23)
Chronic rhinitis*
1.27
(1.11- 1.45)
<0.001
Otitis media* (1 episode vs. none)
1.33
(1.15- 1.53)
1.21
(1.05-
1.41)
1.22
(1.05-
1.41)
1.39
(1.17- 1.65)
1.07
(0.90-
1.28)
1.07
(0.89-
1.28)
Underweight vs. normal
0.80
(0.58- 1.10)
Overweight vs. normal
1.06
(0.89- 1.26)
Obese vs. normal
0.98
(0.72- 1.33)
0.486
Low birthweight (<2500g)
1.00
(0.80- 1.26)
0.969
Demographic variables
Atopic disorders
Other respiratory symptoms
(>1 episode vs. none)
<0.001
<0.001
0.036
<0.001
0.032
Body mass index
Posseting† during 1st year of life
13
A little vs. none
1.44
(1.26- 1.66)
A lot vs. none
1.56
(1.28- 1.90)
0.001
1.32
(1.15-
1.52)
1.32
(1.08-
1.61)
<0.001
1.31
(1.14-
1.51)
1.31
(1.07-
1.60)
0.001
*during the past 12 months; † regurgitation, a common form of gastro-oesophageal reflux in infants
Base model: adjusted for age, sex and ethnic group
Partially adjusted model II: adjusted for age, sex, ethnic group and all other clinical and biological features (all variables in Table E3B)
Fully adjusted model: adjusted for age, sex, ethnic group, all other clinical and biological features and all environmental and socioeconomic
simultaneously (variables in partially adjusted model of Table E3B and partially adjusted model of Table E2B simultaneously)
p-values refer to Wald test for the whole variable included in the model
14
15