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VOLUME 63 , ISSUE 3 ( July-September, 2021 ) > List of Articles

Original Article

Role of Fractional Exhaled Nitric Oxide in Distinguishing Asthma-COPD Overlap Among Patients with COPD: A Cross-Sectional Study

Md Monimul Islam, Md Ali Hossain, Kazi Saifuddin Bennoor, Taskina Ali

Keywords : Fractional exhaled nitric oxide, Asthma-COPD overlap, Chronic obstructive pulmonary disease

Citation Information : Islam MM, Hossain MA, Bennoor KS, Ali T. Role of Fractional Exhaled Nitric Oxide in Distinguishing Asthma-COPD Overlap Among Patients with COPD: A Cross-Sectional Study. Indian J Chest Dis Allied Sci 2021; 63 (3):137-142.

DOI: 10.5005/ijcdas-63-3-137

License: CC BY-NC 4.0

Published Online: 18-11-2022

Copyright Statement:  Copyright © 2021; The Author(s).


Objective: Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) and COPD share much of their clinical presentations, ensuring difficulties in their differentiation. As both the entities are characterised by airway inflammation, fractional exhaled nitric oxide (FeNO), as an inflammatory biomarker to distinguish between them, can be used for this purpose. The present study was done to assess the role of this local biomarker in distinguishing ACO among patients with COPD. Methods: We enrolled 63 male stable patients of COPD from March 2019 to February 2020 from two tertiary care hospitals of Dhaka, Bangladesh. Among them, 51 patients were finally selected according to inclusion and exclusion criteria and divided into two study groups, ACO (n=26) and COPD-alone (n=25), according to GINA-GOLD Joint guidelines [Global Initiative for Asthma and the Global Initiative for Chronic Obstructive Lung Disease] on syndromic approach. The levels of FeNO were measured by NOBreath FeNO Monitor® (Bedfont, England). Results: We observed that FeNO was significantly higher (P<0.01) in patients with ACO than COPD-alone. In addition, no statistically significant difference of FeNO was observed in patients with different stages of the disease severity in ACO and COPD-alone. Moreover, the correlation between FeNO levels and disease severity in both the groups was statistically insignificant. Area under the receiver operating characteristic curve of this biomarker was found as 0.724 and the optimal cut-off value was 29.5 parts per billion (ppb) to get the best diagnostic accuracy. At an optimal cut-off value, sensitivity, specificity were found to be 72.0% abd 84.6%, respectively. The positive predictive value and negative predictive value were 81.8%, 75.7%; whereas positive likelihood ratio, negative likelihood ratio and accuracy of FeNO were observed to be, 4.7%, 0.3%, 78.4%, respectively. Conclusions: Fractional exhaled nitric oxide can play a substantial role in distinguishing ACO among the stable patients of COPD with good diagnostic accuracy. However, in our study no correlation of FeNO with the disease severity was obseved.

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