Table 1.

Differential Diagnosis in Adults With Suspected Asthma

Diagnosis	Symptoms	Testing
COPD	Smoking history Aged > 35 years Chronic cough	Hyperinflation and flattened diaphragms on CXR Emphysema and air-trapping on CT Fixed obstruction on spirometry
Allergic rhinitis	Rhinorrhea Nasal obstruction	Empiric therapy with: Nasal corticosteroids Antihistamines Allergy testing
GERDa	Acid reflux	pH probe Empiric therapy with PPI
Coronary artery disease Congestive heart failure	Orthopnea Paroxysmal nocturnal dyspnea Peripheral edema	Elevated pro-BNP Cardiomegaly and reduced LVEF on TTE
Vocal cord dysfunction	Inspiratory wheeze or stridor	Inspiratory symptoms Spirometry may have truncated inspiratory loop Laryngoscopy with inspiratory vocal cord closure
Allergic bronchopulmonary aspergillosis	Wheezing Fatigue Fever Brownish sputum	Elevated serum eosinophils and IgE Serum precipitins to aspergillus Obstructive spirometry Bronchiectasis Migratory infiltrates
Churg-Strauss syndrome or eosinophilic granulomatosis with polyangiitis	Long-term multiphase disease Multi-organ involvement	Elevated serum eosinophils IgE and ANCA positivity
Sarcoidosis	Dyspnea Wheezing Cough	Noncaseating granulomas
Bronchiectasis	Productive cough Wheezing	Airway enlargement Localized infiltrates Mild obstruction
Pulmonary embolism	Chest pain Sinus tachycardia Risk factors for VTE	Hypoxemia Elevated D-dimer CT chest with PE protocol
Cystic fibrosis	Productive cough Recurrent sinopulmonary infections	Abnormal sweat chloride test Hyperinflation Bronchiectasis

Abbreviations: ANCA, anti-neutrophil cytoplasmic antibody testing; COPD, chronic obstructive pulmonary disease; CT, computed tomography; CXR, chest plain film radiography; GERD, gastroesophageal reflux disease; IgE, immunoglobulin E; LVEF, left ventricular ejection fraction; PE, pulmonary embolism; PPI, proton pump inhibitor; pro-BNP, brain-natriuretic peptide; TTE, transthoracic echocardiography; VTE, venous thromboembolism.

^aTypical symptoms may be absent in some patients with GERD, and the diagnosis may require a high-index of suspicion.