Unveiling the Utility of Fractional Exhaled Nitric Oxide (FeNO) in Asthma Diagnosis and Inflammatory Phenotyping: A Dissociation from Lung Function and Asthma Control

Abstract

Objective: This study aims to examine the association and clinical relevance of fractional exhaled nitric oxide (FENO) with lung function, sputum eosinophils, blood eosinophils, blood total IgE (TIgE), and asthma control test (ACT) score. Methods: A total of 189 participants, consisting of 99 asthmatic out-patients and 90 healthy individuals, were recruited for the study conducted between May 2013 and December 2013. The study aimed to investigate the correlation between various factors, including the levels of FeNO, FEV1%pred, ACT scores, sputum eosinophils, blood eosinophils, and TIgE, in asthma patients. Results: The results revealed that the levels of FeNO, blood eosinophils, and TIgE were significantly higher in asthma patients compared to healthy individuals (P<0.05). Additionally, the level of FEV1%pred was significantly lower in asthma patients compared to healthy individuals (P<0.05).There was no significant correlation between FeNO 1evel and FEV1%Pred（r=0.004，P>0.05），nor between FeNO level and ACT scores（r=-0.195，P>0.05）. Correlation analysis showed that，FENO level was positive correlated with sputum eosinophils（r=0.473, P<0.05）, blood eosinophils（r=0.315, P<0.05） and TIgE（r=0.305, P<0.05）. Conclusion: The FENO can assist diagnosis of asthma because the level of FENO is increased in asthma patients. FENO is no significant correlation with FEV1%Pred and ACT score, but the FENO level is positive correlated with sputum eosinophils, blood eosinophils and TIgE. FENO could reflect airway inflammatory level, especially esoinophilic airway inflammation.