Chronic Cough in Adults

Background

• Chronic cough is arbitrarily defined as a cough lasting > 8 weeks.
• Distinction should be made between chronic idiopathic cough and refractory chronic cough (for which an explanation usually exists).
• The most common causes of chronic cough in adults include upper airway cough syndrome (previously called postnasal drip syndrome), asthma (including cough-variant asthma), gastroesophageal reflux disorder (GERD), smoking, and angiotensin-converting enzyme (ACE) inhibitors.
• Postinfectious cough may occur with upper respiratory infection (URI) or bronchitis, but often resolves within 8 weeks.
• Other conditions to consider include bronchiectasis, lung cancer, and eosinophilic bronchitis.
• There is an emerging concept that chronic idiopathic cough may share similarities to some neuropathic disorders, and can be labelled “cough hypersensitivity syndrome".

Evaluation

• In all patients with chronic cough, a thorough clinical history focusing upon cough timing, characteristics, other respiratory and systemic symptoms, smoking status, inhaled exposures and other aggravating triggers and drug use plus examination is essential.
• Initial diagnostic testing should include chest x-ray (Strong recommendation) and possibly spirometry (Weak recommendation); in a young never smoker with a classic history for asthma a CXR may not always be needed.
• Chronic cough in the presence of respiratory and systemic symptoms that could indicate lung cancer merits prompt investigation.
• In the immunocompetent patient where a serious underlying cause is unlikely, diagnosis can often be made by clinical evaluation and monitoring response to empiric treatment.
• In the immunocompromised patient, infection should be considered as one of the most likely cause and a chest x-ray should be obtained.
• Other testing such as high-resolution chest computed tomography (CT), sputum analysis, bronchoscopy, or upper endoscopy may be needed depending on clinical features, presence of respiratory and/or systemic symptoms suggestive of cancer, or if unable to ascertain diagnosis through empiric therapy or abnormalities that are found on initial testing.

Management

• Provide empiric treatment systematically directed at common causes of cough (Strong recommendation).
  • If the patient smokes cigarettes, cigars, or a pipe, encourage smoking cessation (Strong recommendation).
  • If the patient is taking an ACE inhibitor, discontinue use (Strong recommendation).
  • If cough persists, consider an approach based on presumptive common causes.
    • Consider empiric treatment for upper airway cough syndrome (formerly postnasal drip syndrome) with an oral antihistamine/decongestant (Weak recommendation).
    • Assess for asthma
      • Evaluate with spirometry, but if inconclusive consider measuring fraction of exhaled nitric oxide and/or a bronchial provocation challenge.
      • Antiasthma therapy includes:
        • inhaled corticosteroid and bronchodilator
        • addition of leukotriene receptor antagonist if refractory cough
        • inhaled corticosteroids as monotherapy (or combined with a long acting beta2-agonist) are not indicated for adults with unexplained chronic cough and negative tests for bronchial hyperresponsiveness and airway eosinophilia (demonstrated by sputum eosinophils or elevated fraction of exhaled nitric oxide)
    • Assess for nonasthmatic eosinophilic bronchitis by evaluation of sputum for eosinophilia or bronchoalveolar lavage for eosinophils (Weak recommendation).
    • Provide an empiric antireflux therapy trial for patients with upper gastrointestinal symptoms for GERD, and for patients with all of the above causes ruled out (Strong recommendation).
      • In patients with GERD and chronic cough, interventions may include:
        • lifestyle modification if patient is obese or overweight
        • head of bed elevation
        • avoidance of meals ≤ 3 hours before bedtime
        • proton pump inhibitors, H2-receptor antagonists, alginate, or antacid therapy if the patient has heartburn and/or regurgitation
      • In adults with chronic cough suspected to be due to reflux who do not have heartburn or regurgitation, use of proton pump inhibitors alone is not recommended.
    • In patients with lung cancer with persistent cough, assess for coexisting causes and begin corresponding treatment.
      • Consider cough suppression exercises as an alternative to or in addition to pharmacological therapy (Weak recommendation).
      • If cough is due to localized endobronchial disease and surgery, chemotherapy, or external beam radiation are not indicated, consider endobronchial brachytherapy (Weak recommendation).
      • If a pharmacological approach is needed, consider demulcents such as butamirate linctus (syrup), simple linctus (syrup), or glycerin-based linctus (syrup), opiate-derivatives, antitussives, or local anesthetics.
    • In patients with interstitial lung disease (ILD), assess the patient for progression of ILD or complications from immunosuppressive treatment, such as a drug side effect or pulmonary infection, with further treatment trials according to guidelines for acute, subacute, and chronic cough (Weak recommendation).
    • If chronic cough is due to ILD that is not responsive to alternative treatments, and is adversely affecting quality of life, opiates may be considered for symptom control in a palliative care setting with reassessment of the benefits and risks at 1 week and then monthly (Weak recommendation).
  • Continue all partially effective treatments in case of multiple causes.
  • If there is an inadequate response to optimal treatment, consider additional diagnostic testing.
• Other medications for persistent unexplained cough may include:
  • antitussives - evidence is limited, and cough suppression may be contraindicated if cough clearance is important
  • gabapentin - a therapeutic trial may be considered for those with suspected cough hypersensitivity syndrome; adverse effects include fatigue and nausea
  • a trial of multimodal speech pathology therapy can be considered in adults with an unexplained chronic cough
• Patients should be followed for any change or worsening of cough and response to treatment.