Exhaled nitric oxide in evaluation of young adults with chronic cough.
BACKGROUND
Bronchial asthma (A) is frequently diagnosed in patients with chronic cough. The study was conducted to determine whether an evaluation of fractional exhaled nitric oxide (FeNO) concentration can be used as a screening test for asthma in young adults with chronic cough (CCP).


METHODS
The study was performed on 540 (mean age 26.5; range 18-45 years), nonsmoking young CCP. All patients had resting spirometry within normal limits and no abnormalities on chest radiographs. Skin prick tests with common aeroallergens, bronchial provocation challenge with histamine, and evaluation of FeNO concentration were performed in all patients. One hundred healthy, nonsmoking, nonatopic subjects were used as control subjects (HC).


RESULTS
Asthma (A) was diagnosed in 178 CCP (32.96%). Other frequent diagnoses included rhinitis/sinusitis (R) and gastroesophageal reflux (GERD). The median FeNO concentration in A (86 ppb; 95% CI 72 to 94,5 ppb) was significantly greater than in R (37 ppb; 95% CI 35,6 to 42,9 ppb; p < 0.0001), GERD (14,8 ppb; 95%CI 13.3 to 16.2 ppb; p < 0.0001), or in HC (13 ppb; 95%CI 11 to 15 ppb; p < 0.0001). Significant correlation was found between log(FeNO) and bronchial reactivity expressed as log(PC20) (r = -0.529; 95%CI -0.616 to -0.429; p < 0.0001), but even stronger correlation was demonstrated between log(FeNO) and peripheral blood eosinophilia (r = 0.757; 95%CI 0.717 to 0.792). Receiver Operator Characteristic (ROC) curve analysis revealed that CCP can be screened for A by measuring FeNO concentration. Using 40 ppb as a cut-off value for the FeNO concentration, the specificity 82.6% and sensitivity 88.3% can be achieved.


CONCLUSIONS
In clinical practice, assessment of FeNO concentration can be used as a screening test for asthma in young adults who have chronic cough.
Kowal
Krzysztof
K
Department of Allergology and Internal Medicine, Medical University of Bialystok, Poland. kowalkmd@amb.edu.pl
Bodzenta-Lukaszyk
Anna
A
Zukowski
Sebastian
S
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology; D001249:Asthma / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000378:metabolism; D001773:Blood Cells / Q000473:pathology; D001944:Breath Tests; D016535:Bronchial Hyperreactivity / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D002908:Chronic Disease; D003371:Cough / Q000209:etiology* / Q000378:metabolism; D004802:Eosinophilia / Q000473:pathology; D005541:Forced Expiratory Volume / Q000502:physiology; D005764:Gastroesophageal Reflux / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000276:immunology; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D011237:Predictive Value of Tests; D012372:ROC Curve; D012221:Rhinitis, Allergic, Perennial / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D012680:Sensitivity and Specificity; D012882:Skin Tests; D055815:Young Adult
D000485:Allergens; D009569:Nitric Oxide