What are the causes and management of cough with sputum?

Causes of Cough with Sputum

Cough with sputum production is most commonly caused by upper airway cough syndrome (40% of cases), asthma (24%), chronic bronchitis (11%), and bronchiectasis (4%), with less common causes including GERD, pneumonia, and COPD exacerbations. 1

Common Causes

Upper Airway Cough Syndrome (UACS)

• UACS is the single most frequent cause of chronic productive cough, accounting for 40% of cases in immunocompetent adults with excessive sputum production (>30 mL/day). 1
• Presents with post-nasal drip, rhinorrhea, and throat clearing. 2, 3
• Treatment requires first-generation antihistamine/decongestant combinations plus intranasal corticosteroids for 2-4 weeks. 2, 3

Asthma and Eosinophilic Bronchitis

• Asthma causes 24% of chronic productive cough cases. 1
• Cough-variant asthma may present without wheezing, with sputum production as the primary symptom. 4
• Transient bronchial hyperresponsiveness occurs in 40% of patients following viral respiratory infections, with FEV1 reversibility >15% in 17%. 1
• Non-asthmatic eosinophilic bronchitis presents with productive cough, increased sputum eosinophils, and normal spirometry. 1

Chronic Bronchitis

• Defined as cough with sputum production for ≥3 months per year during 2 consecutive years when other causes are excluded. 1
• Smoking is the major risk factor, though biomass fuels and environmental pollutants also contribute. 1
• Chronic bronchitis accounts for 11% of cases presenting with excessive sputum production. 1
• In COPD patients with chronic bronchitis, cough and sputum are associated with 2.20 exacerbations per year versus 0.97 in those without these symptoms (p<0.0001). 5

Bronchiectasis

• Causes only 4% of chronic productive cough cases but is critical to identify. 1
• Non-CF bronchiectasis affects approximately 500,000 people in the US and characteristically presents with daily cough, sputum production, and recurrent exacerbations. 6
• Associated conditions include prior pneumonia, nontuberculous mycobacterial infection, α1-antitrypsin deficiency, rheumatoid arthritis, inflammatory bowel disease, and GERD (47% of cases). 1, 6
• Diagnosis requires high-resolution CT showing dilated airways (signet ring sign), airway thickening, and mucus plugging. 1, 6
• Sputum cultures commonly grow Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa. 1

Gastroesophageal Reflux Disease (GERD)

• GERD causes 15% of chronic productive cough cases. 1
• May present without typical reflux symptoms; cough can be the sole manifestation. 1
• Requires high-dose proton pump inhibitor therapy and dietary modifications for adequate treatment trial. 3

Acute Causes

Acute Bronchitis

• Acute bronchitis is a self-limiting disease accounting for >3 million US outpatient visits annually, typically presenting with cough that may be productive or dry. 7
• Viral pathogens (influenza, parainfluenza, RSV, coronavirus, rhinovirus, adenovirus) cause the majority of cases. 1
• Bacterial causes are rare in healthy individuals: Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis account for <1% in prospective surveys. 1
• Cough duration averages 2-3 weeks; antibiotics decrease cough duration by only 0.5 days while exposing patients to adverse effects. 7
• Sputum production occurs in 69% of cases, with fever in 85% and myalgias in 49%. 1

Pneumonia

• Must be excluded in patients with productive cough, fever, and dyspnea. 1, 2
• Chest radiograph is mandatory to differentiate from acute bronchitis. 1, 7

Pertussis

• Implicated in 10% of chronic cough cases. 3
• Consider when paroxysmal cough develops; diagnosis via serology or PCR. 3

Uncommon but Important Causes

Suppurative Airway Disease

• Patients have copious purulent secretions on bronchoscopy without excessive sputum expectoration or radiographic bronchiectasis. 1

Tuberculosis and Nontuberculous Mycobacteria

• In endemic areas, acid-fast staining of expectorated or induced sputum is reasonable when other evaluations fail. 1
• Mycobacterium avium complex isolation suggests chronic infection but is not specific. 1

Lung Cancer

• Critical to exclude in heavy smokers (≥40 pack-years) with new persistent cough, as cough is the fourth most common presenting feature of lung cancer. 4
• Chest imaging is mandatory in this population. 4

Tracheobronchial Disorders

• Tracheopathia osteoplastica causes chronic cough in 54% and sputum production in 34% of affected patients. 1
• Tracheobronchomegaly (Mounier-Kuhn syndrome) presents with recurrent bronchitis and chronic productive cough, predominantly in men in their third-fourth decades. 1
• Tracheobronchial amyloidosis causes cough with hemoptysis; diagnosis requires bronchoscopic biopsy. 1

Diagnostic Approach

Initial Evaluation

• Medical history focusing on ACE inhibitor use, smoking status, environmental exposures, and timing of symptoms is the starting point. 1
• Physical examination may reveal rhonchi, crackles, or clubbing in bronchiectasis, though findings may be normal. 1
• Chest radiograph to exclude pneumonia, heart failure, or malignancy. 1, 2, 4

Sequential Testing When Initial Evaluation is Unrevealing

• Spirometry with bronchodilator response to assess for asthma or COPD. 3, 4
• High-resolution CT chest if routine testing fails, to evaluate for bronchiectasis, interstitial lung disease, or occult masses. 1, 2, 3
• Bronchoscopy to detect endobronchial lesions, sarcoidosis, eosinophilic bronchitis, or occult infection. 1, 2, 3
• 24-hour esophageal pH monitoring if GERD suspected despite failed empiric therapy. 2, 3

Sputum Analysis

• Routine sputum cultures are not recommended in acute bronchitis. 1, 7
• In bronchiectasis, obtain cultures for bacteria, mycobacteria, and fungi. 6
• Mucoid Pseudomonas suggests cystic fibrosis; Aspergillus suggests allergic bronchopulmonary aspergillosis. 1

Management Principles

Treatment Based on Etiology

• Sequential and additive therapy is crucial because multiple causes frequently coexist. 1
• UACS: First-generation antihistamine/decongestant plus intranasal corticosteroids for 2-4 weeks. 2, 3
• Asthma: High-dose inhaled corticosteroid/LABA combinations; add LAMA if obstruction is severe. 2
• GERD: High-dose proton pump inhibitors with dietary modifications. 3
• Bronchiectasis: Airway clearance techniques, nebulized saline, pulmonary rehabilitation; antibiotics for exacerbations; consider long-term inhaled antibiotics or oral macrolides for ≥3 exacerbations annually. 6

Chronic Bronchitis Management

• Smoking cessation is the single most important intervention, with 90% of smokers experiencing cough resolution. 4
• There is insufficient evidence to recommend routine pharmacologic treatments (antibiotics, bronchodilators, mucolytics) solely for cough relief in stable chronic bronchitis. 1

Acute Bronchitis Management

• Symptom relief and patient education regarding expected 2-3 week cough duration are recommended; antibiotics, antitussives, honey, antihistamines, and corticosteroids are not supported by evidence. 7

Critical Pitfalls to Avoid

• Do not assume bacterial infection in acute bronchitis; viral etiologies predominate and antibiotics provide minimal benefit (0.5 day reduction) with significant adverse effects. 1, 7
• Crackles on auscultation do not correlate with bronchiectasis on HRCT; imaging is required for diagnosis. 1
• Before diagnosing unexplained (idiopathic) cough, ensure adequate treatment trials (2-4 weeks minimum) for UACS, asthma, and GERD, as inadequate treatment duration is a common cause of apparent treatment failure. 1, 2
• Verify inhaler technique and adherence before escalating asthma therapy. 2
• Do not use nasal decongestant sprays >3-5 days due to rebound congestion risk. 2