[Cough variant asthma among patients with chronic persistent cough and its clinical outcome]

Thirty-nine patients with chronic persistent cough continuing more than eight weeks were examined regarding to their airway responsiveness to methacholine challenge using the Astograph (TCK-6100H, Chest Corp. Japan). Of these, twenty-three individuals (59%) had airway hyperresponsiveness, leading to diagnose as having cough variant asthma (CVA). Patients with CVA had a higher percentage of eosinophils in peripheral blood and a lower forced expiratory volume in one second than those in non-CVA group. Furthermore, four patients (17%) developed the classic signs and symptoms of asthma, whereas 7 cases (30%) resolved their cough without further treatment and 12 cases (52%) continued to have CVA. These data suggested that a significant proportion of patients with chronic persistent cough had CVA and some of them may develop to classic wheezing asthma.