Chronic Cough Due to Asthma
Multiple prospective studies have shown that asthma is among the most common etiologies of chronic cough (24 to 29%) in adult nonsmokers, Usually, cough is associated with the more typical symptoms of dyspnea and wheezing, Alternatively, an isolated cough may serve as a harbinger of future asthmatic episodes, In a subgroup of asthmatic patients, however, cough is the predominant or sole symptom, This condition has been termed cough-variant asthma (CVA), The therapeutic approach to CVA is similar to that of the typical form of asthma. canadian health and care mall
In a patient with chronic cough, asthma should always be considered as a potential etiology because asthma is a common condition with which cough is commonly associated. Quality of evidence, fair; net benefit, substantial; grade of recommendation.
Recent data support the concept that patients with CVA comprise a distinct subgroup of individuals with asthma, rather than simply being asthmatic patients who cough, For example, subjects with the typical form of asthma do not differ from healthy volunteers in terms of experimentally measured cough reflex sensitivity, whereas those with CVA have a significantly more sensitive cough reflex, Interestingly, despite the presence of hypersensitive cough receptors, subjects with CVA demonstrate a lesser degree of bronchial hyperresponsiveness to inhaled metha-choline compared to those with the typical form of asthma,
Further important developments since the publication of the first American College of Chest Physicians Consensus Panel report include the demonstration that the infiltration of airway smooth muscle by mast cells is associated with the disordered airway function of asthma; that sub-epithelial layer thickening, a pathologic feature of airway remodeling, is present in CVA; and that the leukotriene receptor antagonists (LTRAs) appear to be particularly effective in treating cough due to asthma, Data for this review were obtained from a National Library of Medicine (PubMed) search, performed in April 2004, of the English language literature from 1975 to 2004, limited to human studies, using the search terms “cough” and “asthma”.