What is the appropriate evaluation and treatment for a patient with a chronic cough?

Evaluation and Management of Chronic Cough

Begin with chest radiography and spirometry as mandatory first-line investigations for all patients with chronic cough (defined as lasting ≥8 weeks), then proceed with empiric treatment targeting the three most common causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD). 1, 2

Initial Mandatory Workup

Imaging

• Obtain chest X-ray in all patients as the first-line imaging test recommended by the American College of Chest Physicians (ACCP), American College of Radiology (ACR), and multiple pulmonary societies 3, 1
• Chest radiography yields abnormal findings or diagnosis in approximately 31% of cases 2
• Do not proceed to CT chest initially unless chest X-ray is abnormal or red flags are present, as wide application of CT in all chronic cough patients has low clinical yield 3, 1

Pulmonary Function Testing

• Perform spirometry with bronchodilator response testing (measure FEV1 before and after short-acting β2-agonist) in all patients to identify airflow obstruction 2
• Normal spirometry does not exclude asthma or eosinophilic bronchitis 2
• Consider exhaled nitric oxide and blood eosinophil count to support diagnosis of eosinophilic airway disease 4

Medication Review

• Immediately discontinue ACE inhibitors if the patient is taking one, as this is a common reversible cause 5
• Switch to a medication from another drug class 5

Red Flags Requiring Urgent/Advanced Evaluation

Proceed directly to CT chest and consider bronchoscopy if any of the following are present:

• Hemoptysis (even with normal chest X-ray in smokers) 6
• Smoker >45 years with new cough or change in cough pattern 1
• Prominent dyspnea, hoarseness, or systemic symptoms (fever, weight loss) 1, 7
• Trouble swallowing, vomiting, or recurrent pneumonia 1
• Finger clubbing with pleural effusion or lobar collapse 2

Empiric Treatment Algorithm for Common Causes

Treat sequentially or in combination based on clinical suspicion, as 45.5% respond to initial therapy and an additional 20.5% respond to sequential trials 8

Upper Airway Cough Syndrome (UACS)/Post-Nasal Drip

• Trial of first-generation antihistamine plus decongestant for suspected UACS 5
• UACS prevalence ranges from 6-65% in chronic cough case series 3
• Consider sinus CT only if symptoms persist despite empiric treatment, as up to 49% of patients with negative endoscopy have positive CT findings 3

Asthma/Eosinophilic Bronchitis

• For suspected cough-variant asthma with normal spirometry: trial prednisolone 30-40 mg daily for 2 weeks 2
• Alternatively, trial inhaled corticosteroids if diagnosis is being considered 2
• Confirm diagnosis based on clinical response to empiric therapy with inhaled bronchodilators or corticosteroids 5

Gastroesophageal Reflux Disease (GERD)

• Initiate intensive acid suppression with proton pump inhibitors for minimum of 2 months if GERD is suspected 2
• Empiric treatment should be initiated in lieu of testing for patients with chronic cough and reflux symptoms 5
• Add prokinetic agent (metoclopramide) and rigorous dietary measures if initial PPI therapy fails 3

When Initial Evaluation and Empiric Treatment Fail

Advanced Imaging

• Proceed to high-resolution CT (HRCT) chest only after failed empiric treatment or in selected patients with abnormal chest radiographs 3, 1
• HRCT has 90% positive predictive value when used in patients with suspected underlying pulmonary disease 3
• Most common CT findings with normal chest X-ray: bronchiectasis (28%) and bronchial wall thickening (21%) 1
• Critical pitfall: Chest radiography misses 34-42% of CT-proven bronchiectasis cases 1, 6

Geographic Considerations

• In high TB prevalence areas: obtain three separate sputum samples for acid-fast bacilli smear and culture along with chest radiography 3, 2
• If paroxysmal coughing with post-tussive vomiting or inspiratory whooping: obtain nasopharyngeal culture for Bordetella pertussis 2

Bronchoscopy Indications

• Perform bronchoscopy to evaluate for occult airway disease (endobronchial tumor, sarcoidosis, eosinophilic or lymphocytic bronchitis) if HRCT is abnormal or even if normal after complete workup fails 3
• Mandatory in smokers with hemoptysis regardless of chest X-ray findings, as 16% of central airway tumors are radiographically occult 6

Refractory Chronic Cough Management

If 4-6 weeks of empiric treatment for the five top diagnoses fails and extensive diagnostic testing is negative:

• Consider cough hypersensitivity syndrome 7, 4
• Low-dose morphine (preferred), gabapentin, or pregabalin for symptomatic management 4
• Trial of speech/cough control therapy 7

Critical Pitfalls to Avoid

• Do not rely on single peak flow measurements—they are less accurate than FEV1 for identifying airflow obstruction 2
• Do not delay CT in smokers with hemoptysis even with normal chest X-ray 6
• Do not assume consolidation equals simple pneumonia—persistent consolidation after appropriate antibiotics mandates bronchoscopy to exclude malignancy 6
• Do not perform extensive diagnostic testing before empiric treatment trials—66-74% of patients can be successfully managed clinically without advanced investigations 3, 8
• Recognize multifactorial etiology—more than one cause may be present simultaneously, requiring sequential and additive therapy 3