Unraveling a Common Mystery: Diagnosing and Treating Chronic Cough

By Sean Duffy, MD

Accounting for an estimated 20 to 40 percent of referrals, cough is the most common presenting complaint in the pulmonary office setting. Cough can create a severe burden for the patient and complex diagnostic dilemma for the clinician.

Physiologically, cough is a normal response to mucus or another irritant in the respiratory tract or, less commonly, in the GI tract or the pericardium. Acute cough (lasting < 3 weeks) is most commonly self-limited and related to viral upper respiratory infections. Subacute cough (lasting 3–8 weeks) can be related to pertussis or whooping cough along with a prolonged postviral cough syndrome. Chronic cough (> 8 weeks) presents a more complex diagnostic dilemma, as it may be the result of many problems. About 90 percent of chronic cough cases are related to one of three conditions: gastroesophageal reflux (GERD), asthma or upper airway cough syndrome (UACS). If asthma or another inherent lung disease is suspected, lung function testing should be performed. If GERD or UACS is suspected, establishing a firm diagnosis can be expensive and invasive. In these cases, empiric treatment should be started based on the most likely diagnosis by history and physical. For UACS, treatment can be initiated with intranasal steroids or antihistamines for at least 2 weeks. For GERD, patients may require over 2 months of proton pump inhibitor therapy before finding relief. Less common causes like malignancy, bronchiectasis, mycobacterial infection and non-asthmatic eosinophilic bronchitis may require further workup with a CT scan and sputum culture to establish a diagnosis. ■