Impact of air pollution on respiratory diseases in children with recurrent wheezing or asthma

BMC Pulmonary Medicine

Table 2 Respiratory symptoms during follow-up in children with recurrent wheezing or asthma and healthy children ^a

Clinical characteristics	Wheezing/asthma (n = 329)		Healthy children (n = 364)		p-value
	N	%	N	%
Days with fever (≥37°), mean ± SD	7.3 ± 7.3		5.9 ± 6.4		0.009
0	66	20.1	92	25.3
1-4	87	26.4	99	27.2
5-9	74	22.5	101	27.7
≥10	102	31.0	72	19.8	0.005
Days with cough, mean ± SD	31.7 ± 29.9		17.9 ± 23.7		<0.001
0	20	6.1	81	22.2
1-6	33	10.0	68	18.7
7-20	107	32.5	108	29.7
≥21	169	51.4	107	29.4	<0.001
Rhinitis
0	270	82.1	321	88.2
1	38	11.5	23	6.3
≥2	21	6.4	20	5.5	0.04
Rhinosinusitis
0	315	95.7	351	96.4
≥1	14	4.3	13	3.6	0.64
Pharyngitis
0	239	72.6	274	75.3
1	52	15.8	56	15.4
≥2	38	11.6	34	9.3	0.61
Acute otitis media
0	263	79.9	313	86.0
1	40	12.2	28	7.7
≥2	26	7.9	23	6.3	0.09
Laryngitis
0	304	92.4	338	92.9
≥1	25	7.6	26	7.1	0.82
Tracheitis
0	294	89.4	344	94.5
≥1	35	10.6	20	5.5	0.01
Asthmatic attacks
0	170	51.7	335	92.0
1	63	19.1	19	5.2
2	46	14.0	4	1.1
≥3	50	15.2	6	1.7	<0.001
Pneumonia
0	221	67.2	309	84.9
1	61	18.5	31	8.5
≥2	47	14.3	24	6.6	<0.001
Hospitalizations
No	306	93.0	353	97.0
Yes	23	7.0	11	3.0	0.02
Subjects with a complete follow-up ^a	306	93.0	346	95.0	0.25
Months of follow-up, mean ± SD ^a	11.9 ± 0.6		11.9 ± 0.5		0.26

^aAnalyses were based on subjects with available information for at least 9 months of follow-up. SD: standard deviation; p-values were calculated using the χ ² test or Wilcoxon’s rank-sum test, as appropriate. Parental-eport of physician-diagnosed episodes.

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