Abstract
BackgroundFractional exhaled nitric oxide (FeNO) is a marker of type-2 inflammation used both to support diagnosis of asthma and follow up asthma patients. The associations of FeNO with lung function decline and bronchodilator (BD) response have been studied only scarcely in large populations. ObjectivesTo study the association between FeNO and a) retrospective lung function decline over 20 years, and b) lung function response to BD among asthmatic subjects compared with non-asthmatic subjects and with regards to current smoking and sex. MethodsLongitudinal analyses of previous lung function decline and FeNO level at follow-up and cross-sectional analyses of BD response and FeNO levels in 4257 participants (651 asthmatics) from the European Community Respiratory Health Survey. ResultsAmong asthmatic subjects, higher percentage declines of FEV1 and FEV1/FVC were associated with higher FeNO levels (p = 0.001 for both) at follow-up. These correlations were found mainly among non-smoking individuals (p = 0.001) and females (p = 0.001) in stratified analyses.Percentage increase in FEV1 after BD was positively associated with FeNO levels in non-asthmatic subjects. Further, after stratified for sex and smoking separately, a positive association was seen between FEV1 and FeNO levels in non-smokers and women, regardless of asthma status. ConclusionsWe found a relationship between elevated FeNO and larger FEV1 decline over 20 years among subjects with asthma who were non-smokers or women. The association between elevated FeNO levels and larger BD response was found in both non-asthmatic and asthmatic subjects, mainly in women and non-smoking subjects.
Highlights
Fractional exhaled nitric oxide (FeNO) is based on a non-invasive method to measure nitric oxide (NO) in exhaled air and is a biomarker of type-2 inflammation,[1] reflecting activation of IL-4/-13driven mechanisms.[2]
We found a relationship between elevated FeNO and larger forced expiratory volume in 1 sec (FEV1) decline over 20 years among subjects with asthma who were non-smokers or women
The main finding of the present study was that a larger previous lung function decline over 20 years was associated with higher FeNO levels in asthmatics in ECRHS III
Summary
Fractional exhaled nitric oxide (FeNO) is based on a non-invasive method to measure nitric oxide (NO) in exhaled air and is a biomarker of type-2 inflammation,[1] reflecting activation of IL-4/-13driven mechanisms.[2]. Identification of subjects at risk of accelerated decline in lung function is important, as irreversible airflow obstruction is known to be associated with increased morbidity and mortality.[6] Lung function decline is faster in asthmatics than in healthy subjects.[7,8] Factors contributing to accelerated lung function decline in patients with asthma are smoking,[7] recurrent exacerbations,[9] and low baseline FEV1.10 Evidence suggests that airway inflammation may play an important role in the progression of lung function impairment in asthma.[11,12] Eosinophil inflammation appears to relate to accelerated lung function decline[13] in both asthmatic and non-asthmatic individuals. Fractional exhaled nitric oxide (FeNO) is a marker of type-2 inflammation used both to support diagnosis of asthma and follow up asthma patients.The associations of FeNO with lung function decline and bronchodilator (BD) response have been studied only scarcely in large populations
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