Exhaled nitric oxide as a diagnostic test for asthma in rhinitic patients with asthmatic symptoms.
BACKGROUND
Rhinitis is a major risk factor for asthma, so that evaluation of the lower airways is recommended in patients with rhinitis. Exhaled nitric oxide (FE(NO)) is considered a marker of airway inflammation and it has been found to be useful for the screening of patients with suspected diagnosis of asthma. Our aim was to assess the validity and accuracy of FE(NO) to identify patients with asthma in 48 non-smoking patients with persistent rhinitis and asthma-like symptoms.


METHODS
Asthma was diagnosed on the basis of 12% improvement in FEV1 after salbutamol or a methocholine PD(20)FEV1<800 microg. Prior to lung function FE(NO) was measured with the single exhalation method at 50 ml/s.


RESULTS
The geometric mean (95% confidence interval) FE(NO) was significantly higher in the 18/48 asthmatics than in the non-asthmatic patients (60 ppb, CI 95%: 50-89, versus 30 ppb, CI 95%: 28-45, P=0.001). Receiver operating characteristic (ROC) curve for the diagnosis of asthma indicated that FE(NO) is an acceptable discriminator between patients with and without asthma (area under the ROC curve=0.78). None of the asthmatic patients had FE(NO) values<25 ppb and all the patients with FE(NO)>100 ppb (n=5) were asthmatics. The sensitivity and specificity of FE(NO) for detecting asthma, using 36 ppb as cut-off point, were 78% and 60% and the positive and negative predictive values were 54% and 82%, respectively.


CONCLUSIONS
Measuring FE(NO) may be useful for the screening of rhinitic patients with asthma-like symptoms.
Heffler
Enrico
E
Allergologia e Immunologia Clinica, University of Torino, Ospedale Mauriziano Umberto I, Largo Turati 62, 10128 Torino, Italy.
Guida
Giuseppe
G
Marsico
Pietro
P
Bergia
Roberta
R
Bommarito
Luisa
L
Ferrero
Nicoletta
N
Nebiolo
Franco
F
De Stefani
Antonella
A
Usai
Antonio
A
Bucca
Caterina
C
Rolla
Giovanni
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D015415:Biomarkers / Q000032:analysis; D001944:Breath Tests / Q000379:methods; D002648:Child; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D012220:Rhinitis / Q000150:complications* / Q000503:physiopathology; D012307:Risk Factors; D012680:Sensitivity and Specificity
D015415:Biomarkers; D009569:Nitric Oxide