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Clinical features for indicating causes of chronic cough

Published online: July 18, 2020

Chronic cough is one of the most common complaints for patients seeking medical attention in primary care and respiratory specialist clinics, which is involved in various pulmonary and extrapulmonary diseases. The common causes of chronic cough include cough variant asthma, non-asthmatic eosinophilic bronchitis, upper airway cough syndrome and gastroesophageal reflux. Etiological diagnosis is the key to successful treatment in these patients. However, multiple investigations may be required to determine specific causes of chronic cough, such as spirometry, bronchial challenge test, induced sputum test for differential cells, and 24-hour esophageal pH value monitoring and so on. These investigations are time-consuming and are usually unavailable in the primary care setting. In addition, it is inappropriate to conduct these diagnostic tests during the outbreak of some vicious respiratory infectious disease such as COVID-19 which is transmitted via respiratory droplets and close contact. If some clinical features can be identified to indicate the etiologies of chronic cough, empiric treatments may be more targeted.

In this study Prof. Kefang Lai, Nanshan Zhong et al. in The Journal of Allergy and Clinical Immunology: In Practice investigated the usefulness of cough characteristics, concomitant symptoms, and medical history in diagnosing the causes of chronic cough in a group of 1,162 patients with confirmed causes. In this study, a fixed choice questionnaire was used to record clinical features associated with cough and the etiological diagnosis was determined based on the well-established diagnostic workflow of chronic cough. The relationships between the clinical features and the cause of cough were analyzed.

The study showed that nocturnal cough highly predicts the possibility of cough variant asthma. Cough after meals, heartburn, belching and acid regurgitation indicated gastroesophageal reflux-related cough with high specificity (85.5%-94.9%). Postnasal dripping and history of sinusitis were indicators for upper airway cough syndrome with considerable specificity (80.8% and 90.2%, respectively). Rhinitis/sinusitis-related symptoms showed moderate sensitivity (72.9%); however, they showed mild specificity (46.1%) for upper airway cough syndrome.

In summary, the causes of chronic cough can be predicated based on clinical features, including the timing of cough, concomitant symptoms associated with gastroesophageal reflux, rhinitis/sinusitis and history of sinusitis, which will be useful in guiding empiric therapy, especially in a primary care setting where etiological investigations are unavailable.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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