What is the initial approach to a cough workup?

Initial Approach to Cough Workup

The initial approach to a cough workup should include a chest radiograph, detailed history focusing on cough duration, medication review (particularly ACE inhibitors), and smoking status, followed by empiric treatment of the three most common causes: upper airway cough syndrome (UACS), asthma, and gastroesophageal reflux disease (GERD). 1

Step 1: Classify Cough Duration and Obtain Chest Radiograph

• Classify cough by duration:

  • Acute: < 3 weeks
  • Subacute: 3-8 weeks
  • Chronic: > 8 weeks (> 4 weeks in children) 2, 1

• Obtain a chest radiograph for all patients with persistent cough to rule out significant pathology 1, 3

  • If abnormal findings are present (e.g., mass suggestive of lung cancer), directly investigate the specific finding 2
  • If normal, proceed with systematic evaluation of common causes

Step 2: Identify and Address Modifiable Factors

• Review medications for ACE inhibitors

  • Discontinue ACE inhibitors regardless of temporal relationship to cough onset
  • Cough resolution typically occurs within days to 2 weeks (median 26 days) 2, 1

• Assess smoking status

  • Recommend smoking cessation for current smokers
  • Majority of patients experience cough resolution within 4 weeks 2, 1

Step 3: Focused History and Physical Examination

• Key history elements:

  • Timing and pattern of cough (day vs. night)
  • Associated symptoms (postnasal drip, heartburn, wheezing)
  • Environmental/occupational exposures
  • Systemic symptoms (fever, weight loss)
  • History of cancer, tuberculosis, or immunocompromise 2, 1

• Cough characteristics to note:

  • Productive vs. non-productive
  • Triggers (exercise, position changes, eating)
  • Impact on quality of life 1

Step 4: Initial Testing

• Spirometry for persistent cough (especially if asthma is suspected) 1, 3
• Consider additional testing based on clinical suspicion:
  • Peak flow measurements for suspected asthma
  • Complete blood count if infection suspected
  • Exhaled nitric oxide (FeNO) testing for suspected asthma 1

Step 5: Empiric Treatment for Common Causes

For immunocompetent nonsmokers with normal chest radiograph findings, the three most common causes of chronic cough are UACS, asthma, and GERD 2, 1, 3, 4, 5:

1. Upper Airway Cough Syndrome (UACS):

   • Trial of first-generation antihistamine/decongestant combination for 2-4 weeks
   • Consider topical nasal corticosteroids if prominent upper airway symptoms 1, 3

2. Asthma:

   • Trial of inhaled corticosteroids and bronchodilators for 4 weeks
   • Consider short course of oral corticosteroids for severe symptoms 1

3. Gastroesophageal Reflux Disease (GERD):

   • Proton pump inhibitors with lifestyle modifications for 4-8 weeks
   • Note: Reflux-associated cough may occur without typical GI symptoms 1, 3

Step 6: Re-evaluation and Further Investigation

• Re-evaluate if cough persists beyond 4-6 weeks of appropriate treatment 1
• Consider additional testing if initial workup and empiric treatment fail:
  • High-resolution CT scan
  • Bronchoscopy
  • 24-hour esophageal pH monitoring 1, 6

Common Pitfalls to Avoid

• Failing to discontinue ACE inhibitors even when temporal relationship to cough is unclear 2, 1
• Inadequate treatment duration, especially for GERD which requires minimum 3 months 1
• Relying solely on cough characteristics for diagnosis without appropriate investigations 1
• Overlooking GERD as a cause when GI symptoms are absent 1
• Neglecting non-asthmatic eosinophilic bronchitis as a potential cause 1, 5, 6

Special Considerations

• For refractory cough: Consider neuromodulators (gabapentin, pregabalin) or speech therapy for cough suppression techniques 1, 5, 6
• For symptomatic relief: Consider dextromethorphan for non-productive cough, but avoid in patients taking MAOIs 1, 7
• In children: Most common causes are respiratory tract infections, asthma, and GERD; evaluation should include chest radiography and spirometry (in children old enough to perform) 3, 5