Table 2.

Distance between residence and nearest major roadway as a predictor of selected respiratory outcomes

	All subjects			Subjects on home respiratory supportb
	Odds ratioa (95% CI)	N	P value	Odds rratio (95% CI)	N	P value
Emergency department visit	0.96	694 (1583 forms)	.72	1.00	275 (739 forms)	1.00
	(0.78–1.18)			(0.70–1.42)
Inpatient hospitalization	1.01	695 (1584 forms)	.94	1.13	276 (739 forms)	.47
	(0.80–1.28)			(0.80–1.60)
Systemic steroid use	0.97	692 (1575 forms)	.80	1.18	275 (737 forms)	.30
	(0.78–1.21)			(0.87–1.61)
Antibiotic use	1.14	694 (1577 forms)	.24	1.16	276 (736 forms)	.42
	(0.92–1.41)			(0.81–1.66)
Cough or wheeze	0.94	687 (1546 forms)	.59	0.93	273 (722 forms)	.68
	(0.76–1.17)			(0.64–1.33)
Rescue β-agonist use	0.92	686 (1520 forms)	.43	1.07	272 (708 forms)	.69
	(0.73–1.14)			(0.76–1.50)
Activity limitations	0.65	680 (1501 forms)	.005	0.69	270 (700 forms)	.09
	(0.49–0.88)			(0.46–1.05)
Nighttime symptoms	0.78	686 (1541 forms)	12	0.61	272 (719 forms)	.06
	(0.58–1.06)			(0.37–1.02)

Abbreviation: CI, confidence interval.

^aOdds ratios for respiratory outcomes (dependent variable) given reported proximity to major roadway (independent continuous variable) were generated through logistic regression and adjusted for potential confounders, including race or ethnicity, (log of) population density, (log of) median household income, and age at the time of respiratory outcomes questionnaire completion. All regressions were clustered by subject as subjects may have completed separate forms at serial visits. Adjusted odds ratios <1 suggest that poor respiratory outcomes are less likely the further the residence is from a major roadway.

^bOf the 784 subjects in this study, 281 were on supplemental oxygen via nasal cannula, 24 were on home ventilators, and 9 had a tracheostomy without ventilator use. Odds ratios were calculated in a similar manner to all subjects regressions.