Abstract
BackgroundClinical features of cough variant asthma (CVA) in Chinese adults are largely uncertain.MethodsA total of 303 patients newly diagnosed as uncontrolled asthma (symptom control and future risk of adverse outcomes), including 175 CVA and 128 classic asthma (CA), were enrolled in this retrospective survey. Clinical features including basic characteristics, pulmonary function, airway hyperresponsiveness (AHR) and cell counts of induced sputum, were compared retrospectively. All patients were classified into four inflammatory subtypes based on the counts of induced sputum eosinophils and neutrophils as eosinophilic (E), neutrophilic (N), mixed granulocytic (M), and paucigranulocytic (P) subtypes. Inflammatory subtype distribution was also compared.ResultsCompared with CA patients, CVA patients were younger (P = 0.009), had a higher prevalence of female patients (P = 0.001), higher parameter values of baseline pulmonary function (P ≤ 0.01 for all), shorter duration of disease (P = 0.002), lower AHR (P = 0.001) and lower sputum eosinophil% (P = 0.009). There was a difference in the AHR distribution as the percentage of moderate and severe AHR in CVA was significantly lower than in CA (41.72% VS 64.70%, P = 0.001). The inflammatory subtype distribution was different as the proportion of E and M subtypes in CVA was lower than in CA (56.0% vs 67.19%, P = 0.049). The proportion of subtype P was the lowest and subtype M was the highest in both CVA and CA patients. There was a similar negative correlation of sputum eosinophil% with AHR in CVA and CA (r = − 0.337, P < 0.0001 and r = − 0.27, P = 0.026, respectively), and a positive correlation between sputum eosinophil% and improvement rate of FEV1 after inhalation of bronchodilator (ΔFEV1%) (r = 0.33, P = 0.01).ConclusionsCVA patients showed a better pulmonary function and lower airway inflammation in contrast to CA patients, which may participate in the pathogenesis of chronic cough in CVA.
Highlights
Clinical features of cough variant asthma (CVA) in Chinese adults are largely uncertain
CVA was diagnosed according to the following criteria: patients had a clinical history of a persistent cough and airway hyperresponsiveness (AHR), but had no wheezing or dyspnea in contrast to classic asthma (CA), bronchodilators were effective against their coughs, excluding other diseases that caused chronic cough, such as gastroesophageal reflux, upper airway cough syndrome (UACS), eosinophilic bronchitis (EB), taking angiotensin-converting enzyme inhibitors, etc
There was a difference in the AHR distribution as the percentage of moderate and severe AHR in CVA was significantly lower than in CA (41.72% VS 64.70%, P = 0.001) (Table 3)
Summary
Clinical features of cough variant asthma (CVA) in Chinese adults are largely uncertain. Many patients in clinics are suffering from a chronic cough, which is defined as cough being the sole or predominant symptom lasting for at least 8 weeks, with absence of pulmonary disease [1]. Studies have shown that CVA is one of the most common causes of chronic non-productive cough, as well as gastroesophageal. Studies of CVA are few and the sample size is small [6,7,8,9]. We conducted a retrospective study with a larger sample size to investigate: (1) the differences in clinical features between CVA and CA patients, by analyzing basic characteristics, pulmonary function, AHR, and cell counts of induced sputum; (2) the correlation between sputum eosinophil% and AHR or airway reversibility
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