Abstract
BackgroundCough variant asthma (CVA) is one of the special populations of asthma. The aim of the study was to compare small airways, the degree of bronchial hyperresponsiveness (BHR) and airway inflammatory subtypes between CVA and classic asthma (CA), and investigate the relationship between these markers to determine the accuracy as indicators of CVA.MethodsA total of 825 asthmatic patients participated in the study and 614 were included. 614 patients underwent spirometry and a bronchial challenge with methacholine and 459 patients performed induction sputum cell test.ResultsThe number of CVA patients showed less small airway dysfunction than those of CA patients (p < 0.005). The degree of small airways dysfunction was higher in the CA group compared with the CVA group (p < 0.001). Small airways dysfunction was severer in the eosinophilic airway inflammatory subtype compared with other subtypes (p < 0.05).The area under curve of MMEF, FEF50 and FEF75 (% predicted) was 0.615, 0.621, 0.606, respectively. 0.17mcg of PD20 and 4.7% of sputum eosinophils was the best diagnostic value for CVA with an AUC of 0.582 and 0.575 (p = 0.001 and p = 0.005, respectively).ConclusionsThe eosinophilic airway inflammatory subtype may be increased small airway dysfunction. The value of small airways, BHR and induction sputum cells in CVA prediction, which reflected significant, but not enough to be clinically useful.
Highlights
Cough variant asthma (CVA) is one of the special populations of asthma
According to the results of spirometry, Forced expiratory volume in 1 s (FEV1)%predicted, FEV1/ forced expiratory vital capacity (FVC) (FEV1/FVC) and peak expiratory flow (PEF)%predicted were higher in CVA compared to classic asthma (CA) (p < 0.05)
This study showed that lower sputum eosinophilia, milder small airway obstruction and bronchial hyperresponsiveness (BHR) are in CVA
Summary
The aim of the study was to compare small airways, the degree of bronchial hyperresponsiveness (BHR) and airway inflammatory subtypes between CVA and classic asthma (CA), and investigate the relationship between these markers to determine the accuracy as indicators of CVA. The original definition of cough variant asthma (CVA) was described by Glauser and later by Carrao, McFadden in 1972 and 1975, 1979 [3,4,5]. Small airways were defined as the bronchial less than 2 mm in internal diameter [7] They played a role in the pathobiology of asthma and have a distinct role in specific disease phenotypes, they are involved in half of all cases of asthma [8,9,10]. This study aims to explore the validity of small airways, the degree of BHR and airway inflammatory subtypes in the diagnosis of CVA
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