Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 27-year-old man is evaluated for a 6-month history of cough, which is worse at night and after exposure to cold air. Often his cough is brought on by taking a deep breath or by laughter. He does not have postnasal drip, wheezing, or heartburn. He has a strong family history of allergies.

Physical examination, chest radiograph, and spirometry are normal. He receives no benefit from a 3-month trial of gastric acid suppression therapy, intranasal corticosteroids, and an antihistamine-decongestant combination.

Which of the following would likely provide the diagnosis of this patient’s chronic cough?

A) 24-Hour esophageal pH monitoring
B) Bronchoscopy
C) CT scan of the chest
D) CT scan of the sinuses
E) Trial of inhaled albuterol

MKSAP Answer and Critique

The correct answer is E) Trial of inhaled albuterol. This item is available to MKSAP 15 subscribers as item 93 in the Pulmonary and Critical Care Medicine section.

MKSAP 16 released Part A on July 31. More information is available online.

The patient has cough-variant asthma. A trial of inhaled albuterol could help control the patient’s symptoms and confirm the diagnosis. The most common causes of chronic cough are asthma, postnasal drip syndrome (chronic sinusitis-rhinitis), and gastroesophageal reflux disease (GERD). Bronchoscopy and chest CT play no role in diagnosing cough due to these three causes. The diagnosis of cough-variant asthma is suggested by the presence of airway hyperresponsiveness and confirmed when cough resolves with asthma therapy.

Sensitivity to cold air is a clinical marker of airway hyperresponsiveness that can be confirmed with a methacholine challenge test. The methacholine challenge test has a negative predictive value of nearly 100% in the context of cough; this test is extremely useful in ruling out asthma, but because it has a poor positive predictive value, it is not very useful in patients with high prior probability of airway hyperresponsiveness. There is little about the character and timing of chronic cough due to GERD that distinguishes it from other conditions; in addition, it often can be “silent” from a gastrointestinal standpoint. However, the patient failed to benefit from 3 months of empiric gastric acid suppression therapy for GERD; therefore it is reasonable to rule out cough-variant asthma before pursuing 24-hour esophageal pH monitoring.

The patient does not have postnasal drip, purulent nasal secretions, sinus congestion, or other symptoms to suggest chronic or recurrent sinusitis and has not responded to treatment. Therefore, CT scan of the sinuses is not necessary. If the patient does not respond to albuterol, eosinophilic bronchitis should be considered as the cause of chronic cough, and bronchoscopy should be done to confirm that diagnosis.

Key Point

• The diagnosis of cough-variant asthma is suggested by the presence of airway hyperresponsiveness and confirmed when cough resolves with a trial of inhaled albuterol.

Learn more about ACP’s MKSAP 16.

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