Trigger of bronchial hyperresponsiveness development may not always need eosinophilic airway inflammation in very early stage of asthma.

BackgroundCough variant asthma (CVA), a suggested precursor of standard bronchial asthma (SBA), is characterized by positive bronchial hyperresponsiveness (BHR) and a chronic cough response to bronchodilator that persists for >8 weeks.ObjectiveAirway inflammation, BHR, and airway obstructive damage were analyzed to assess whether CVA represents early or mild-stage SBA.MethodsPatients with newly diagnosed CVA (n = 72) and SBA (n = 84) naive to oral or inhaled corticosteroids and without exacerbated asthma were subjected to spirometry, impulse oscillometry, BHR tests, sputum induction, and fractional exhaled nitric oxide measurements.ResultsIn the patients with CVA, spirometry demonstrated higher forced expiratory volume in 1 second (FEV1) to forced vital capacity ratio, FEV1 percent predicted, flow volume at 50% of vital capacity % predicted, and flow volume at 25% of vital capacity % predicted values, and impulse oscillometry demonstrated lower R5–Z20, AX, and Fres, and higher X5 values. In addition, the ...