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. 2020 Dec 7:13:1427-1434.
doi: 10.2147/IJGM.S286144. eCollection 2020.

Small Airways Dysfunction and Bronchial Hyper-Responsiveness in Cough Variant Asthma

Jie Gao #  1 , Hai Gui Wu #  1 , Feng Wu  1
Affiliations

Small Airways Dysfunction and Bronchial Hyper-Responsiveness in Cough Variant Asthma

Jie Gao et al. Int J Gen Med. .

Abstract

Background: Cough variant asthma (CVA) is one kind of atypical asthma. The study was to compare spirometric parameters of small airways and the degree of bronchial hyper-responsiveness (BHR) between CVA and classic asthma (CA), and examine the relationship between BHR and small airways to determine the accuracy of these markers as indicators of CVA.

Methods: A total of 825 asthmatic patients were screened for the study, and 614 were included. All patients performed spirometry and underwent a bronchial challenge with methacholine.

Results: The number of small airways dysfunctions in the CVA group was less than those of the CA group with MMEF% predicted (70% vs 80.91%, P=0.002) and FEF50% predicted (62.71% vs 73.5%, P=0.004). The degree of small airways dysfunction was less in the CVA group compared with the CA group (P<0.001). Significant positive correlations were observed between the FEV1 level below 20% of the baseline value (PD20) and MMEF% predicted (r=0.282, P<0.001), FEF50% predicted (r=0.2522, P<0.001), and FEF75% predicted (r=0.2504, P<0.001) in patients with CVA. The area under curve (AUC) of MMEF, FEF50, and FEF75 (% predicted) was 0.615, 0.621, and 0.606, respectively. In addition, 0.17 mcg of PD20 was the best diagnostic value for CVA, with an AUC of 0.582 (P=0.001).

Conclusion: Small airway dysfunction is milder in CVA. The value of BHR combined with small airways in CVA prediction, which was significant, but not enough to be clinically useful.

Keywords: bronchial hyper-responsiveness; classic asthma; cough-variant asthma; small airways.

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Conflict of interest statement

The authors report no conflicts of interest for this work.

Figures

Figure 1
Figure 1
The strategies of flow-chart with asthmatic patients. n: number of subjects.
Figure 2
Figure 2
Scatter plots of correlation between PD20 (mcg) and small airways. (A) Correlation between PD20 (mcg) and small airways (MMEF%, FEF50%, FEF75%) in CVA. (B) Correlation between PD20 (mcg) and small airways (MMEF%, FEF50%, FEF75%) in CA.
Figure 3
Figure 3
ROC curve analysis of PD20, FEV1, MMEF, FEF50, and FEF75 (%predicted) for CVA diagnosis.
Figure 4
Figure 4
Predictive value for CVA by combining PD20 and small airway resistance; combination 1: PD20+FEF50 (%predicted); combination 2: PD20+FEF75 (% predicted); combination 3: PD20+MMEF (% predicted).
See this image and copyright information in PMC

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