Association between fractional exhaled nitric oxide (FeNO) cutoff values (25 ppb) and risk factors of cough

Abstract

The cutoff values of FeNO (≥25 ppb or <25 ppb) are useful for etiological detection of cough with high sensitivity.

<p>Association Between FeNO, Total Blood IgE, Peripheral Blood Eosinophil and Inflammatory Cytokines in Partly Controlled Asthma</p>

“…The higher predictive ability was detected at FeNO >50 ppb where the best cutoff point for total IgE was ≥350 (sensitivity 66.7%, specificity 63.6%). A recent study by Qian et al reported that FeNO 25 ppb had a significant correlation with serum IgE between 200 and <200 IU/mL level l. 27 …”

“…A study by Qian et al reported that FeNO 25 ppb significantly correlated with FEV 1 /FVC ratio ( p =0.032) 27 while a recent study carried out on 160 Korean school children with asthma being monitored a FeNO value ≥35 ppb synchronized with asthma exacerbation. FEV 1 /FVC ratio as well as FEF25%–75% was significantly less than baseline in these children.…”

“…30 In a recent study, a FeNO cutoff of 25 ppb showed a significant correlation with eosinophils between >5% and <5%. 27 BTS/SIGN British guidelines approve use of FeNO as an evidence of eosinophilic inflammation. 20 The ATS has recommended using FeNO for monitoring eosinophilic airway inflammation and the control of asthma.…”

WAO-ARIA consensus on chronic cough – Part III: Management strategies in primary and cough-specialty care. Updates in COVID-19

“…59,103 This lack of clear cut-off levels of FeNO for the etiological diagnosis of asthma, CVA and NAEB in chronic cough [105][106][107] limits its usefulness as a routine diagnostic modality and follow-up assessment tool for chronic cough and compels its validation in future studies. 59,62,108,109 In the upper airways, an abnormally low nasal nitric oxide (nNO) is reportedly a predictor of nasal polyposis in severe asthmatic patients even when blood eosinophils are normal or low. 100 Also, primary ciliary dyskinesia can present with chronic cough (sinopulmonary infections) and low nNO 110,111 which can be supplemented by other testing modalities.…”