What is the recommended workup and treatment for a patient with a chronic cough?

Chronic Cough Workup and Treatment Algorithm

The recommended workup for chronic cough should follow a systematic protocol-based assessment that includes objective testing for bronchial hyperresponsiveness and eosinophilic bronchitis, with therapeutic trials based on the most likely causes. 1

Definition and Initial Assessment

• Chronic cough is defined as a cough persisting longer than 8 weeks in adults 1, 2
• Initial evaluation should include:
  • Chest radiography to rule out lung pathology 2
  • Pulmonary function testing/spirometry 2
  • Assessment of medications that may cause cough (e.g., ACE inhibitors) 3
  • Evaluation of environmental/occupational exposures 3

Systematic Diagnostic Approach

Step 1: Evaluate and Treat Common Causes

1. Upper Airway Cough Syndrome (UACS)

   • Trial of first-generation antihistamine-decongestant combination
   • For patients with allergic rhinitis: consider intranasal corticosteroids like fluticasone 4

2. Asthma

   • Objective testing for bronchial hyperresponsiveness 1
   • Trial of inhaled corticosteroids if positive

3. Non-asthmatic Eosinophilic Bronchitis

   • Evaluate for sputum eosinophils or exhaled nitric oxide 1
   • Trial of inhaled corticosteroids if positive

4. Gastroesophageal Reflux Disease (GERD)

   • For patients fitting the clinical profile for GERD-related cough, empiric treatment is recommended before testing 1
   • Treatment should include:
     • Dietary and lifestyle modifications (limit fat to <45g/day, avoid coffee, tea, chocolate, citrus, alcohol, smoking) 1, 5
     • Acid suppression therapy with proton pump inhibitors 1, 5
     • Addition of prokinetic therapy if no response to the above 1
     • Assess response within 1-3 months 1

Step 2: Further Investigation if Cough Persists

If cough persists despite initial management:

1. For suspected GERD that failed empiric therapy:

   • 24-hour esophageal pH monitoring (while on therapy) 1
   • Do not assume GERD is ruled out if empiric therapy fails; the therapy may not have been intensive enough 1

2. For suspected airway disorders:

   • Consider referral to pulmonologist for bronchoscopy 3
   • Consider high-resolution CT scan if red flags present (hemoptysis, weight loss, recurrent pneumonia) 2

3. For suspected upper airway pathology:

   • Consider referral to otolaryngologist for nasendoscopy 3

Management of Unexplained Chronic Cough

If cough remains unexplained after thorough investigation:

1. Speech Pathology Therapy

   • A therapeutic trial of multimodality speech pathology therapy is recommended 1, 6

2. Neuromodulator Medications

   • Consider gabapentin trial (starting at 300mg daily, gradually increasing to maximum 1,800mg/day in divided doses) 1, 6, 3
   • Alternative options include pregabalin, amitriptyline, or morphine 6
   • Discuss potential side effects and reassess risk-benefit profile at 6 months 1

3. Avoid Ineffective Treatments

   • For patients with negative tests for bronchial hyperresponsiveness and eosinophilia, inhaled corticosteroids are not recommended 1
   • For patients with unexplained chronic cough and negative workup for acid GERD, proton pump inhibitors are not recommended 1

Important Clinical Pearls

• GERD-related cough may take 2-3 months to improve with appropriate therapy 1
• Cough due to GERD may persist despite normal esophagoscopy findings 1
• Empiric treatment for GERD should be intensive and include both acid suppression and prokinetic therapy before concluding treatment failure 1
• Omeprazole 40mg twice daily has shown efficacy in treating GERD-related cough in some studies 7, 8
• The effect of omeprazole in ameliorating both cough and reflux symptoms may continue after treatment ceases 7

Treatment Pitfalls to Avoid

• Assuming GERD is ruled out when empiric therapy fails 1, 5
• Inadequate duration of treatment trials (most require at least 1-3 months) 1
• Ignoring potential side effects of long-term PPI use 5
• Failing to reassess and adjust therapy based on response 5
• Overuse of PPIs in patients without documented GERD 5