Exhaled nitric oxide predicts asthma relapse in children with clinical asthma remission.
BACKGROUND
Nitric oxide in exhaled air (FE(NO)) is a marker of eosinophilic airway inflammation. A study was undertaken to determine whether FE(NO) predicts asthma relapse in asymptomatic asthmatic children in whom inhaled corticosteroids are discontinued.


METHODS
Forty children (21 boys) of mean age 12.2 years on a median dose of 400 mug budesonide or equivalent (range 100-400) were included. FE(NO) was measured before and 2, 4, 12, and 24 weeks after withdrawal of steroids. A relapse was defined as more than one exacerbation per month, or need for beta agonist treatment on 4 days per week for at least 2 weeks, or diurnal peak flow variability of >20%. FE(NO) measurements were performed online with an expiratory flow of 50 ml/s.


RESULTS
Nine patients relapsed. Two and 4 weeks after withdrawal of steroids geometric mean FE(NO) in children who were about to relapse was higher than in those who did not relapse: 35.3 ppb v 15.7 ppb at 2 weeks (ratio 2.3; 95% CI 1.2 to 4.1; p = 0.01) and 40.8 ppb v 15.9 ppb at 4 weeks (ratio 2.6; 95% CI 1.3 to 5.1). An FE(NO) value of 49 ppb at 4 weeks after discontinuation of steroids had the best combination of sensitivity (71%) and specificity (93%) for asthma relapse.


CONCLUSIONS
FE(NO) 2 and 4 weeks after discontinuation of steroids in asymptomatic asthmatic children may be an objective predictor of asthma relapse.
Pijnenburg
M W
MW
Department of Paediatrics/Paediatric Respiratory Medicine, Erasmus Medical Centre/Sophia Children's Hospital, P O Box 2060, 3000 CB Rotterdam, The Netherlands.
Hofhuis
W
W
Hop
W C
WC
De Jongste
J C
JC
D000280:Administration, Inhalation; D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests; D001993:Bronchodilator Agents / Q000008:administration & dosage; D019819:Budesonide / Q000008:administration & dosage; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D011446:Prospective Studies; D012008:Recurrence; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D014797:Vital Capacity / Q000502:physiology
D015415:Biomarkers; D001993:Bronchodilator Agents; D009569:Nitric Oxide; D019819:Budesonide
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