Asthma incidence in children growing up close to traffic: a registry-based birth cohort

Table 2 Adjusted HR (95% CI) for asthma medication and diagnoses, in relation to traffic-related exposure, n = 7898

	Inhaled asthma medication^a				Diagnoses^a
	β₂-agonist	β₂-agonist	Corticosteroid	Corticosteroid	Bronchiolitis	Obstructive bronchitis	Asthma
	1st purchase	3rd year	1st purchase	3rd year	Bronchiolitis	Obstructive bronchitis	Asthma
Heaviest road ≤100 m, birth address ^b
0–8640 cars/day	1.0	1.0	1.0	1.0	1.0	1.0	1.0
≥8640 cars/day	0.9 (0.8–1.0)	0.7 (0.6– 0.9)	0.8 (0.7–0.9)	0.8 (0.6–1.0)	0.7 (0.6–0.9)	1.0 (0.9–1.2)	0.7 (0.6–0.9)
Heaviest road ≤100 m, never moved ^b
0–8640 cars/day	1.0	1.0	1.0	1.0	1.0	1.0	1.0
≥8640 cars/day	0.9 (0.7–1.0)	0.7 (0.5–1.0)	0.8 (0.6–0.9)	0.9 (0.6–1.2)	0.7 (0.6–0.9)	1.0 (0.8–1.2)	0.7 (0.6–0.9)
NO _X, birth address ^c
≤15 μg/m³	1.0	1.0	1.0	1.0	1.0	1.0	1.0
15–25	0.8 (0.7–1.0)	0.7 (0.5–0.8)	0.8 (0.7–0.9)	0.7 (0.5–0.9)	0.6 (0.5–0.8)	1.1 (0.9–1.3)	0.8 (0.7–0.9)
>25	0.7 (0.6–0.9)	0.6 (0.4–0.8)	0.7 (0.5–0.9)	0.6 (0.4–0.8)	0.5 (0.4–0.8)	1.1 (0.8–1.4)	0.7 (0.5–0.9)
NO _X , never moved ^c
≤15 μg/m³	1.0	1.0	1.0	1.0	1.0	1.0	1.0
15–25	0.8 (0.7–1.0)	0.6 (0.4–0.8)	0.8 (0.7–0.9)	0.6 (0.4–0.8)	0.6 (0.5–0.8)	1.1 (0.9–1.3)	0.8 (0.7–0.9)
>25	0.8 (0.6–1.0)	0.5 (0.3–0.9)	0.6 (0.5–0.8)	0.5 (0.3–0.9)	0.5 (0.4–0.8)	1.1 (0.8–1.5)	0.7 (0.5–0.9)
NO _X, lifetime mean ^d
≤15 μg/m³	1.0	1.0	1.0	1.0	1.0	1.0	1.0
15–25	0.8 (0.7–0.9)	0.7 (0.6–0.9)	0.7 (0.6–0.9)	0.7 (0.6–0.9)	0.7 (0.5–0.8)	0.9 (0.8–1.1)	0.7 (0.6–0.9)
>25	0.8 (0.6–1.1)	0.5 (0.3–0.9)	0.6 (0.5–0.9)	0.5 (0.3–0.9)	0.7 (0.5–1.0)	1.0 (0.7–1.3)	0.7 (0.5–1.0)

^aadjusted for sex, ETS, breastfeeding, parental allergy, parental origin, parental education, and year of birth.
^bn = 6007 children had complete covariate information and traffic exposure assessments.
^cn = 6005 children had complete covariate information and modeled NO_X concentrations.
^dnumber of children with complete covariate information and modeled mean NO_X during time at risk varies between n = 5194-5248 depending on outcome.

ISSN: 1476-069X