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Exhaled nitric oxide continues to reflect airway hyperresponsiveness and disease activity in inhaled corticosteroid‐treated adult asthmatic patients
Author(s) -
REID David W,
JOHNS David P,
FELTIS Bryce,
WARD Chris,
WALTERS E. Haydn
Publication year - 2003
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1046/j.1440-1843.2003.00495.x
Subject(s) - medicine , exhaled nitric oxide , asthma , methacholine , bronchial hyperresponsiveness , corticosteroid , immunology , airway , gastroenterology , sputum , spirometry , respiratory disease , anesthesia , lung , pathology , tuberculosis
Objective: Exhaled nitric oxide (eNO) has been used as a surrogate of airway inflammation in mild asthma. However, whether eNO levels reflect disease activity in symptomatic asthmatics receiving moderate doses of inhaled corticosteroid (ICS) is more uncertain. Methodology: To examine the relationship between eNO levels, sputum and blood eosinophils (SpE and PbE), PD 20 methacholine as a marker of airway hyperresponsiveness (AHR) and clinical status in 28 ICS‐treated asthmatic subjects with persistent asthma compared to that in 25 symptomatic asthmatics managed with β 2 ‐agonists alone. Results: As expected, eNO levels were normalized in ICS‐treated subjects and significantly elevated in the β 2 ‐agonist only group ( P < 0.001). SpE, PbE and PD 20M did not differ between asthmatic groups but FEV 1 was significantly worse in ICS‐treated subjects ( P < 0.01). Exhaled NO levels correlated with PbE within both asthmatic groups ( P < 0.005), but with SpE only in ICS‐untreated subjects (r (s) = 0.6, P < 0.05). In contrast, PD 20M was negatively correlated with eNO and PbE in ICS‐treated subjects only (r (s) = − 0.4, r (s) = − 0.4, respectively, P < 0.05). SpE and PbE were strongly correlated in both asthmatic groups (r (s) = 0.8, r (s) = 0.7, respectively, P < 0.005). Exhaled NO levels, SpE and PbE were all positively associated with increased nocturnal awakenings ( P < 0.05) in ICS‐treated subjects, but not in ICS‐untreated subjects. Conclusions: In ICS‐treated asthma, eNO reflects clinical activity, PbE and AHR but not eosinophilic airway inflammation. Exhaled NO levels are quantitatively and relationally different in asthmatic subjects treated with ICS and continue to have potential for use as a surrogate of asthma pathophysiology in this group.