Diagnostic value of fractional exhaled nitric oxide in differentiating the asthma-COPD overlap from COPD: a systematic review and meta-analysis

ABSTRACT

Background

Patients with asthma-COPD overlap (ACO) account for 15–20% of chronic obstructive pulmonary disease (COPD), and the incidence increases with age. Patients with ACO have worse outcomes without proper treatment than those with COPD alone. However, the current diagnostic criteria of ACO are mainly based on symptom features and lack of objective indicators. Recently, several studies have demonstrated that fractional exhaled nitric oxide (FeNO) was higher in ACO than in COPD alone. Thus, this study aims to determine the diagnostic value of FeNO in differentiating ACO from COPD and assisting clinical decision-making.

Methods

We conducted searches in the databases including PubMed, Web of Science, Cochrane Library, and Embase to extract original studies.

Results

In all, 10 studies involving 1335 participants were included in this meta-analysis. FeNO level was significantly higher in ACO patients than in patients with COPD alone (WMD = 11.15ppb, 95%CI = 9.01‒13.28; I² = 18.0%, p = 0.000). The sensitivity and specificity of FeNO in distinguishing ACO from COPD were both 0.71, and the area under the receiver-operating characteristic curve (AUC) was 0.76, indicating that FeNO has moderate diagnostic accuracy in differentiating ACO from COPD.

Conclusion

FeNO as an inflammatory biomarker is effective in differentiating ACO from COPD and assisting in clinical decision-making.

KEYWORDS:

• ACO
• COPD
• diagnostic value
• FeNO
• meta-analysis

Article highlight

• Patients with asthma-COPD overlap (ACO) account for 15%-20% of chronic obstructive pulmonary disease (COPD), and the incidence increasing with age.

• ACO patients without proper treatment have worse outcomes than those with COPD alone. However, current diagnostic criteria of ACO are mainly based on symptom features and lack of objective indicators.

• This systematic review and meta-analysis found that FeNO as an inflammatory biomarker was effective in differentiating ACO from COPD patients and assisting clinical decision-making.

• Moreover, there still need further studies to investigate the predictive value of FeNO in the prognosis of ACO and COPD.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

Supplemental data for this article can be accessed https://doi.org/10.1080/17476348.2022.2011221.

Author contributions

J. Liu and C. Zhang designed this systematic review. M. Zhang and Y. Wang have been involved in the search strategy. C. Zhang, M. Zhang, and Y. Wang did the collection and the analysis of the data. X. Su, T. Lei and H. Yu interpreted the data. C. Zhang wrote the systematic review and all the other authors revised the manuscript. J. Liu provided general advice on the manuscript. All the authors read and approved the final manuscript.

Additional information

Funding

This manuscript was funded by the Science and Technology Projects of Gansu Province (grant number 18JR3RA344).