Value of fractional exhaled nitric oxide in assessing the severity of chronic cough symptom

Abstract

Objective To evaluate the values of fractional exhaled nitric oxide(FeNO) in assessing the severity of chronic cough. Methods Totally 68 patients with chronic cough were recruited from Department of Respiratory Medicine from June 2014 to February 2015.All patients are grouped according to the FeNO levels, the differences of leicester cough questionnaire (LCQ) and cough symptom scores among groups are evaluated, FeNO tests, LCQ and cough symptom scores before and after treatment for 4 weeks are recorded. Results LCQ and daytime cough symptom score showed significant differences among groups according to FeNO levels (P<0.01). There was significant difference in FeNO levels among 3 groups[cough variant asthma (CVA), eosinophilic bronchitis (EB), other causes], those with CVA [(67.5±17.1) ppb]or EB[(34.6±9) ppb]had a significantly higher median FeNO level than those with other etiology [(23.4±8.9) ppb], and CVA were also higher than EB (Z=-4.9, P<0.01), FeNO levels, LCQ scores and cough symptom scores all showed significant improvements After 4 weeks treatment (Z=-3.975, P<0.01), significant differences in the improvements rates were noticed among three groups in which CVA group showed the highest rate (33.2±3.9)%.On the whole, there were significant correlations between the change of FeNO decrease and the increase of LCQ (r=0.48, P<0.01) especially in CVA(r=0.55, P<0.01) and EB (r=0.66, P<0.01) groups. Conclusions FeNO showed a important value in the evaluation of chronic cough symptom severity base on our finding that FeNO decrease is correlated with the improvement of life quality score and cough symptom score. Key words: Chronic cough; Exhaled nitric oxide; Life quality score