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Article Excerpt
ABSTRACT: The major causes of chronic cough include upper airway cough syndrome (UACS, formerly known as postnasal drip syndrome), asthma, nonasthmatic eosinophilic bronchitis, and gastroesophageal reflux disease. In fact, one or more of these is the cause of cough in the vast majority of nonsmokers who are not receiving angiotensin-converting enzyme inhibitors and who have no evidence of active disease on chest radiographs. A high index of suspicion is required, because each of these conditions may present with cough as the sole symptom. Because UACS may be the most common cause, it appears reasonable to try empiric UACS therapy in patients in whom other causes are not evident at initial evaluation. In many cases, the combination of a first-generation antihistamine and a decongestant may be most effective.
KEY WORDS: Cough, Upper respiratory tract infection, Asthma, Nonasthmatic eosinophilic bronchitis, Gastroesophageal reflux disease
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The cough reflex serves a protective function by preventing foreign material from entering the respiratory tract and by facilitating the expulsion of mucus from the airways. Cough is triggered by stimulation of sensory receptors within the respiratory tract, whose afferent impulses activate a brain stem cough center. (1) Persistent cough with no apparent benefit is a maladaptive response that typically results in significant discomfort.
Cough is the most common complaint for which outpatients seek medical attention in the United States. (2) Acute cough, which is commonly caused by a viral upper respiratory tract infection, is usually self-limited. Other causes, such as congestive heart failure, pneumonia, pulmonary embolism, and endobronchial foreign body or malignancy, may need to be considered in the appropriate clinical setting. Cough of 3 to 8 weeks' duration is termed "subacute." Chronic cough is defined as cough that persists for more than 8 weeks. (3)
In this article, we will review the evaluation and treatment of chronic cough in adults. We will focus on its most common causes: postnasal drip syndrome, which was recently renamed upper airway cough syndrome (UACS); asthma; nonasthmatic eosinophilic bronchitis; and gastroesophageal reflux disease (GERD). (4)
EVALUATION
Multiple prospective studies have demonstrated that a systematic evaluation of chronic cough leads to successful diagnosis in most cases. (3, 5-7) In the vast majority of patients who are nonsmokers, are not receiving angiotensin-converting enzyme (ACE) inhibitors, and have normal or stable chest radiographic findings, chronic cough can be explained by 4 causes, either alone or in combination: UACS, asthma, nonasthmatic eosinophilic bronchitis, and GERD. (3-7) If a specific cause is determined, treatment is usually very effective.
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In at least 25% of patients, multiple causes of chronic cough exist simultaneously, and a partial response to specific therapy may indicate that only one of the causes has been addressed. In 2006, the American College of Chest Physicians (ACCP) published updated guidelines for the management of cough, which include a diagnostic algorithm. (4) We provide a simplified algorithm for evaluating chronic cough (Figure), as well as a summary of highlights from the latest ACCP guidelines (Table 1).
It is essential to perform a meticulous history taking and physical examination. Because UACS, asthma, nonasthmatic eosinophilic bronchitis, and GERD may all present with cough as the sole symptom, a high index of suspicion is required. In the absence of associated symptoms, an empiric drug trial is often indicated in the evaluation of chronic cough. A chest radiograph should be considered in any adult who presents with chronic cough.
Upper airway cough syndrome
Multiple prospective studies have demonstrated that UACS is the most common cause of chronic cough in adults. (3, 5, 6) A clue to the presence of UACS is the sensation of mucus accumulation in the throat, leading to frequent throat clearing and cough. UACS may result from seasonal or perennial allergic rhinitis, perennial nonallergic rhinitis, vasomotor rhinitis, postinfectious (postviral) rhinitis, or chronic bacterial rhinosinusitis. Options for treatment are dictated by the specific cause (Table 2). (8)
In the minority of patients whose UACS is caused by bacterial rhinosinusitis, prolonged (3 weeks or more) therapy with antibiotics effective against Streptococcus pneumoniae, Haemophilus influenzae, and anaerobes is warranted. For all other forms of UACS, the combination of a first-generation antihistamine and a decongestant is the most effective therapy. (4)
The...
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