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Cough is the most common symptom for which patients seek medical attention. Chronic cough is more common among women than among men, most commonly occurs in the fifth and sixth decades of life, and can persist for years, with substantial physical, social, and psychological effects. Professional guidelines describe systematic approaches to the evaluation and management of chronic cough; these guidelines are based largely on consensus opinion and observational data from the medical literature. The evaluation of chronic cough should address the possibilities of asthma, gastroesophageal reflux disease, and postnasal drip and may require more specialized investigations. For patients with refractory chronic cough, other treatment approaches may be necessary. A new Clinical Practice article explains.
• How is chronic cough defined?
Estimates of the prevalence of cough vary, but as much as 12% of the general population report chronic coughing, defined as a cough lasting for more than 8 weeks.
• Of the many drugs that may produce cough as a side effect, which drug class is most commonly associated with cough?
Cough is listed as a side effect of many drug treatments but is most commonly associated with the use of angiotensin-converting–enzyme (ACE) inhibitors; cough occurs in approximately 20% of patients treated with ACE inhibitors.
Morning Report Questions
Q: What tests or empiric treatment would be appropriate for a patient with a chronic cough, given the most common etiologies?
A: In the context of normal results of chest radiography and spirometry, the most common conditions associated with chronic cough are asthma, gastroesophageal reflux disease, and rhinosinusitis, although the prevalence of each of these varies substantially among cough clinics. Although most cases of asthma are associated with abnormalities on routine spirometry, methacholine challenge to assess for bronchial hyperreactivity is indicated for patients who have normal results and no other obvious cause of cough; levels of exhaled nitric oxide may also be elevated. Although data from randomized trials to guide the management of cough-variant asthma are lacking, clinical experience suggests that this condition usually responds to treatment with inhaled glucocorticoids. The relationship between cough and esophageal reflux is complex but is becoming clearer. Guidelines suggest a trial of treatment with acid-suppression therapy — for example, twice-daily treatment with proton-pump inhibitors (PPIs) for up to 3 months — in patients with chronic cough. However, many patients with cough do not have symptomatic gastroesophageal reflux disease, and most randomized, controlled trials of reflux treatment for cough have not shown a significant improvement in association with this type of treatment. Patients with chronic cough often report a sensation of postnasal drip. Guidelines recommend nasal glucocorticoids and antihistamines for patients with allergic rhinitis and chronic cough, but randomized, controlled trials to support this approach are lacking, and clinical experience indicates that the responses to this treatment are often disappointing.
Q: What is the recommended management of patients in whom asthma, rhinosinusitis, and reflux have been ruled out as a cause of cough?
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A: In patients in whom asthma, nasal disease, and reflux have been ruled out (on the basis of diagnostic investigations or trials of treatment), other conditions that may manifest with chronic coughing and could respond to treatment should be considered, and referral should be made to a specialty cough clinic, if one is available. Conditions associated with chronic cough include obstructive sleep apnea, eosinophilic bronchitis, tonsillar enlargement and recurrent tonsillitis, and external ear disease mediated through the auricular branch of the vagus nerve. In cases in which cough remains refractory, high-resolution computed tomographic (CT) scanning of the thorax is recommended to rule out parenchymal lung disease that is not visible on plain chest radiographs (e.g., pulmonary fibrosis, bronchiectasis, or sarcoidosis). Bronchoscopy may be used to identify conditions such as tracheobronchomalacia, chronic bronchitis, and tracheopathia osteochondroplastica, which may be missed on CT scanning.