A 36-year-old man comes in for evaluation of 4 months of coughing. The cough is productive of white sputum and worsens at night. The patient has no hemoptysis, chest pain, dyspnea, weight loss, nasal congestion, or postnasal drip. He tried over-the-counter cough syrup that contains diphenhydramine. He says it "just makes me sleepy but doesn't help the cough." The patient's other medical problems include gastroesophageal reflux disease, for which he takes omeprazole daily. He smoked a pack of cigarettes a day for 10 years and quit 5 years ago. His BMI is 26.5 kg/m². Chest examination indicates normal breath sounds bilaterally. Cardiac examination shows a split second heart sound with inspiration and no murmurs. Chest x-ray is normal. Which of the following is the best next step in management of this patient's cough?

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This patient has a chronic cough (>8 weeks). The most common etiologies of chronic cough include upper airway cough syndrome (postnasal drip), gastroesophageal reflux disease, and asthma. Other causes include drugs (ACE inhibitors), airway disease (eg, nonasthmatic eosinophilic bronchitis, chronic bronchitis, bronchiectasis, malignancy), and pulmonary parenchymal disease (eg, lung abscess, interstitial lung disease). This patient has a chronic cough that worsens overnight and did not improve with antihistamine therapy. Such patients should be suspected of having asthma and therefore should be evaluated with pulmonary function tests (spirometry) to assess bronchodilator response. A methacholine challenge test can be performed if no bronchodilator response is seen. Nocturnal or early morning peak expiratory flow rate measurements can be used to diagnose patients with only nocturnal symptoms. An alternate approach is to treat empirically with 2-4 weeks of inhaled glucocorticoids. If the cough improves, a diagnosis of asthma can be made. (Choice A) Bronchoscopy has little role in the evaluation of chronic cough. In rare cases, it may be used if a foreign body is suspected. (Choice B) Chest CT would be useful if there is suspicion for parenchymal lung disease or malignancy. It may also be used if the etiology remains unidentified and the cough persists. (Choices C and G) Patients with normal pulmonary investigation may require further cardiac or laryngeal testing (eg, echocardiography, direct laryngoscopy) to evaluate for the less common causes of chronic cough. (Choice D) Gastroesophageal reflux disease (GERD) may cause a chronic cough, but this patient is already treated with omeprazole (proton pump inhibitor). Omeprazole does not cause cough and should not be discontinued in patients who have GERD. (Choice F) Sputum microscopy would be used to look for infectious causes of chronic cough (eg, Mycobacterium tuberculosis). Such patients usually have risk factors for infection (eg, history of exposure) and associated symptoms (eg, weight loss). Educational objective: Asthma may present with chronic cough that is predominantly nocturnal. These patients should be evaluated with spirometry to assess bronchodilator response. Other common causes of chronic cough include upper airway cough syndrome, gastroesophageal reflux disease, and ACE inhibitors. References: Evaluation of the patient with chronic cough. (http://www.ncbi.nlm.nih.gov/pubmed/22010767)

A 36-Year-Old Man Comes in for Evaluation of 4 Months