Diagnosis and management of cough-variant asthma

Cough is a natural defence mechanism of the lungs to prevent aspiration and to keep the airway clean. Cough, wheezing and shortness of breath are common symptoms of asthma. Cough-variant asthma is one of the phenotypes of asthma with the main symptom of cough without shortness of breath and wheezing. Cough-variant asthma is largely observed in patients with bronchial hyperresponsiveness who experience cough due to innocuous stimuli, and it is associated with a family history and seasonal allergy. In the present study, in patients with cough-variant asthma, no abnormalities were found during the lung function test, particularly forced expiratory flow in the first second (FEV1) or peak expiratory flow (PEF), although these values were lower than those in normal individuals. A bronchial provocation test using methacholine is needed to assess airway hyperresponsiveness, and depending on the outcome of the test, an assessment can be made as to the probability of the patient requiring a diagnosis of cough-variant asthma. Administration of inhalation therapy with bronchodilators and corticosteroids is the mainstay of management in patients with cough-variant asthma presenting with the symptom of persistent cough. Until now, there have been no specific guidelines for drug selection, dose and duration of inhaled corticosteroid use in cough-variant asthma. If symptoms do not resolve with inhaled corticosteroid monotherapy, consideration may be given to increase the inhalation dose or to add other drugs such as long-acting B2 agonists, slow-release theophylline or leukotriene receptor antagonist (LTRA).