Persistently high exhaled nitric oxide and loss of lung function in controlled asthma.
BACKGROUNDS
It remains unclear whether a persistently high exhaled nitric oxide fraction (FeNO) in patients with controlled asthma is associated with the progressive loss of lung function.


METHODS
This was a 3-year prospective study. We examined the changes in pre- and post-bronchodilator forced expiratory volume in 1 s (FEV1) and FeNO in 140 patients with controlled asthma. We initially determined the FeNO cut-off point for identifying patients with a rapid decline in FEV1 (>40 mL/yr). Next, a total of 122 patients who maintained high or non-high FeNO were selected, and the associations between the FeNO trend and changes in FEV1 and bronchodilator response (BDR) were investigated.


RESULTS
A FeNO level >40.3 ppb yielded 43% sensitivity and 86% specificity for identifying patients with a rapid decline in FEV1. Patients with persistently high FeNO had higher rates of decline in FEV1 (42.7 ± 37.5 mL/yr) than patients with non-high FeNO (16.7 ± 31.5 mL/yr) (p < 0.0005). The changes in BDR from baseline to the end of the study, in patients who had high or non-high levels of FeNO were -0.8% and 0.1%, respectively (p < 0.01). In a multivariate analysis adjusted by age, body mass index, asthma control, blood eosinophil numbers, and FEV1% of predicted, a FeNO level of ≥40 ppb was independently associated with an accelerated decline in FEV1 (p < 0.05).


CONCLUSIONS
This study suggests that FeNO is potentially valuable tool for identifying individuals who are at risk of a progressive loss of lung function among patients with controlled asthma.
['Matsunaga|Kazuto|K|', 'Hirano|Tsunahiko|T|', 'Oka|Asako|A|', 'Ito|Kousuke|K|', 'Edakuni|Nobutaka|N|']
D000328:Adult D001249:Asthma D018450:Disease Progression D045853:Exhalation D005260:Female D005500:Follow-Up Studies D005541:Forced Expiratory Volume D006801:Humans D008297:Male D008875:Middle Aged D009569:Nitric Oxide D011446:Prospective Studies D012372:ROC Curve D012129:Respiratory Function Tests D012307:Risk Factors D012680:Sensitivity and Specificity
Exhaled nitric oxide Adult asthma Airflow limitation Airway inflammation Remodeling