Relationship among pulmonary function, bronchial reactivity, and exhaled nitric oxide in a large group of asthmatic patients.
BACKGROUND
Bronchial reactivity and exhaled nitric oxide (eNO) are not often used to monitor control and severity of asthma in clinical practice.


OBJECTIVE
To evaluate the relationship among different physiologic measures (pulmonary function, nonspecific bronchial reactivity, and eNO) in asthmatic patients.


METHODS
Cross-sectional, hospital-based study conducted in patients with varied asthma severity.


RESULTS
A total of 392 patients participated in the study. There was no difference in eNO levels between patients taking inhaled corticosteroids (ICS group) and patients not receiving inhaled corticosteroids (NICS group). However, the percentage of predicted forced expiratory volume in 1 second (FEV1) and the provocative dose of methacholine causing a 20% decrease in FEV1 were significantly lower in the ICS group compared with the NICS group (mean, 83.2%; 95% confidence interval [CI], 80.4%-86.0%; vs mean, 94.1%; 95% CI, 91.1%-97.1%; P = .001; and geometric mean, 0.32 mg; 95% CI, 0.23-0.45 mg; vs geometric mean, 0.58 mg; 95% CI, 0.42-0.81 mg; P = .01; respectively). Patients with more severe bronchial hyperresponsiveness had a lower percentage of predicted FEV1 values (P < .001) and levels of eNO were significantly increased with increasing bronchial hyperresponsiveness (P < .001). There was no relationship between the percentage of predicted FEV1 and eNO. Atopic patients had significantly higher eNO levels than nonatopic patients (geometric mean, 11.21 ppb; 95% CI, 10.07-12.49 ppb; vs geometric mean, 7.76 ppb; 95% CI, 6.11-9.85 ppb; P = .006; respectively).


CONCLUSIONS
eNO values are not related to the degree of airway obstruction but are related to airway reactivity and atopic status independent of inhaled corticosteroid use. Higher values of eNO are seen with increased airway reactivity.
Medicines Evaluation Unit, North West Lung Research Centre, Wythenshawe Hospital, Manchester, England. slangley@meu.org.uk
Stephen J
SJ
Langley
Sophie
S
Goldthorpe
Adnan
A
Custovic
Ashley
A
Woodcock
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001944:Breath Tests; D016535:Bronchial Hyperreactivity; D001985:Bronchial Provocation Tests; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006760:Hospitalization; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000502:physiology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index
D009569:Nitric Oxide