Association between fractional exhaled nitric oxide, sputum induction and peripheral blood eosinophil in uncontrolled asthma

Abstract

Background

The fractional exhaled nitric oxide (FeNO) and blood eosinophils are biomarkers of eosinophilic airway inflammation used in the diagnosis and management of asthma, although induced sputum is the gold standard test for phenotypic asthma. Nevertheless, the clinical application of the correlation between sputum eosinophils, FeNO and blood eosinophils is controversial.

Objective

To investigate the clinical application of the correlation between sputum eosinophils, FeNO and blood eosinophils with uncontrolled asthmatic patients. It also examined the relationships between these biomarkers in bronchial reversibility and bronchial hyper-responsiveness (BHR).

Methods

This study evaluated 75 uncontrolled asthmatic patients (symptom control and future risk of adverse outcomes). All patients underwent the following on the same day: FeNO, spirometry, BHR or bronchodilator reversibility, sputum induction and blood collection. Eosinophilic airway inflammation was defined as sputum eosinophils ≥ 2.5% or FeNO levels ≥ 32 parts per billion (ppb).

Results

A significant positive relationship was between percentage of sputum eosinophils and FeNO (r = 0.4556; p < 0.0001) and percentage of blood eosinophils (r = 0.3647; p = 0.0013), and a significant negative correlation was between percentage of sputum neutrophils and FeNO (r = − 0.3653; p = 0.0013). No relationship between FeNO and percentage of blood eosinophils (p = 0.5801). ROC curve analysis identified FeNO was predictive of sputum eosinophilia [area under the curve (AUC) 0.707, p = 0.004] at a cutoff point of 35.5 ppb (sensitivity = 67.3%, specificity = 73.9%). Percentage of blood eosinophils was also highly predictive with an AUC of 0.73 (p = 0.002) at a cut-off point of 1.5%, sensitivity and specificity were 61.5 and 78.3%, respectively. Although the sputum neutrophil percentage was correlated with FeNO, ROC curve of these parameters did not show useful values (AUC = 0.297, p = 0.003; AUC = 0.295, p = 0.021).

Conclusions and clinical relevance

Blood eosinophils and FeNO can accurately predict eosinophilic airway inflammation in uncontrolled asthmatic patients. FeNO is poor surrogates for sputum neutrophils and blood eosinophils. The FeNO level and blood eosinophils, which determine an optimal cutoff for sputum eosinophilia, need more studies.

Download PDF

(You must be logged in to add and reply comments)

Interasma on Twitter

Interasma Top story: WORLD ALLERGY CONGRESS | WAC2019 - WORLD ALLERGY CONGRESS https://t.co/KpUHk6kq9r, see more https://t.co/CpGiFuOOYd
5hreplyretweetfavorite
Interasma RT @worldallergy: Top story: Conjunctivitis Seen in Patients on Dupixent | Medpage Today https://t.co/WzoMs3nmNr, see more https://t.co/yY2
10hreplyretweetfavorite
Interasma RT @WAOJM: Beirut, Lebanon - 4-6 April 2019 Visit the WISC 2019 Website for details! https://t.co/Hz6qBiFuIm
10hreplyretweetfavorite
Interasma RT @AllergyEaaci: How to discontinue omalizumab in chronic spontaneous urticaria? Download Article Here: https://t.co/CnLrzLyZ4J #allergy #…
10hreplyretweetfavorite

Editor: Juan C. Ivancevich, MD

Copyright © Interasma 2003-2017  •  Terms of Use  •  Privacy Policy  •  Contact Us  •  Sitemap

Powered by FREI SA

InterAsma