The Value of Fractional Exhaled Nitric Oxide and Impulse Oscillometric and Spirometric Parameters for Predicting Bronchial Hyperresponsiveness in Adults with Chronic Cough

Abstract

Purpose

To evaluate the contribution of fractional exhaled nitric oxide (FeNO) and impulse oscillometry (IOS) and spirometric parameters in predicting bronchial hyperresponsiveness (BHR) in adults with chronic cough.

Patients and Methods

In total, 112 patients with chronic cough were enrolled in this prospective diagnostic study. Receiver operating characteristic (ROC) curves were generated to assess the diagnostic efficiency and optimal cut-off values of FeNO and IOS and spirometric parameters in predicting BHR. Optimal combinations of FeNO and IOS and spirometric parameters for BHR prediction were investigated using univariate and multivariate logistic regression models. Bootstrapping was employed for internal validation. Model discrimination and calibration were assessed using indices and calibration plots.

Results

Rhinitis and values of FeNO, IOS parameters (resonant frequency (Fres), reactance at 5 Hz (X5), and integrated area of low-frequency X (AX)) and spirometric parameters (FEV1, PEF, MEF₇₅, MEF₅₀, MEF₂₅, MMEF) were significantly different between patients with BHR and those without BHR (P < 0.05). After adjusting for rhinitis, logistic analyses showed that FeNO combined with Fres, FeNO combined with MMEF, or the combination of FeNO, Fres and MMEF had high predictive value in diagnosing BHR; the areas under the ROC curves (AUCs) of the corresponding three models were 0.914, 0.919 and 0.927, respectively. In addition, the three models displayed good discrimination, with high C-index values and good calibration.

Conclusion

FeNO combined with Fres or MMEF or a combination of these three parameters may be conveniently used as indicators in BHR prediction.

Keywords:

• maximum mid-expiratory flow
• resonant frequency
• cough variant asthma
• ROC curve
• diagnosis

Data Sharing Statement

The datasets used and analysed during this study are available from the corresponding author on reasonable request.

Ethics and Consent Statements

This study adheres to the principles of the Declaration of Helsinki. The protocol was approved by the Ethics Committee of Zhujiang Hospital of Southern Medical University, China (Ethical Approval no.2018-HXNK-002). Each patient has been informed about the purpose of the study and gave a consent before enrolment. Patients’ privacy and personal identity information were well protected.

Acknowledgments

The study was financially supported by Guangdong Basic and Applied Basic Research Foundation (Grant no. 2020A1515010119).

Disclosure

The authors report no conflicts of interest in this work.