. Author manuscript; available in PMC: 2019 Jun 1.

Published in final edited form as: J Allergy Clin Immunol. 2017 Oct 5;141(6):2249–2255.e2. doi: 10.1016/j.jaci.2017.08.028

Table 2.

Effect of NO₂ above 8ppb on spirometry and asthma outcomes in school age children with asthma

	Univariate model		Multivariate model^b
	Odds ratio	95% Confidence interval (CI)	Odds ratio	95% Confidence interval (CI)
Maximum Symptom Days^a	1.31	0.90, 1.90	1.15	0.80, 1.64
	Beta	95% CI	Beta	95% CI
FEV₁/FVC	−0.049^*	−0.077, −0.021	−0.049^*	−0.078, −0.021
FEV₁%	−5.5	−12.0, 0.9	−5.5	−11.7, 0.8
FVC%	−0.7	−5.8, 4.4	−0.5	−5.5, 4.5
FEF_25-75%	−22.8^*	−36.0, −9.7	−22.8^*	−36.0, −9.7
FeNO	3.5	−6.9, 13.9	−0.5	−12.0, 11.0

Maximum symptom days = the greatest result of the following three variables in the 2 weeks prior to each follow-up survey: 1) number of days with wheezing, chest tightness, or cough; 2) number of days on which child had to slow down or discontinue play activities due to wheezing, chest tightness, or cough, and; 3) number of nights with wheezing, chest tightness, or cough leading to disturbed sleep;

Multivariate model: Maximum symptom days adjusted for Age, Race, Gender and season; spirometry and FeNO adjusted for race and time. Results scaled to each 10 ppb increment of NO₂ above 8ppb.

p-value = 0.001.

FEV₁: forced expiratory volume in 1 second; FVC: forced vital capacity; FEF_25-75: forced expiratory flow between the 25^th and 75^th percent of FVC; FeNO: fractional exhaled Nitric Oxide.