Introduction 

• Prolonged (chronic) cough is a common problem in children.
• Cough arises from any causes involving upper airways (nose, throat) and/or lower airways (windpipe and lungs).
• Even though viral infections of the airways and lungs are the most common cause, the other rarer causes of prolonged cough need to be excluded.
• Chronic productive cough with purulent phlegm production always needs further evaluation to exclude potentially serious illnesses or treatable causes.
• Chronic cough in children are different with chronic cough in adults in many different ways.

Source: http://en.wikipedia.org/wiki/cough

Definition of chronic cough 

• Generally, chronic cough in children is defined as cough lasting longer than eight weeks.
• The eight week definition identifies those who need further investigations.
• This time frame is used because most viral infective causes of cough will resolve in 1- 3 weeks.
• Before investigating further.
• However, if the cough is not improving by the third week or is increasing in severity, earlier investigations are needed. 

Classification of chronic cough 

• There are many ways to classify chronic cough.
• It can be defined based on causes (specific and non-specific), duration, age of the child or cough characteristic (wet or dry, brassy etc).
• Generally, it is simpler to classify chronic cough in children into specific and non-specific cough, with an overlap.   
  • ‘Non-specific’ cough – refers to chronic dry cough without any abnormal pointers (table 1) in history and physical examination.
    • Majority is likely due to post-infectious or post-viral cough and/or cough receptor hypersensitivity.
    • Others include recurrent viral infections, pertussis-like illnesses, and psychogenic cough.
  • ‘Specific’ cough – refers to cough in the presence of pointers/red flags (table 1) which suggest underlying causes.

 Common causes of childhood specific chronic cough 

• The common causes  of chronic specific cough in children  includes:
  • Bronchial asthma (link to asthma)
  • Protracted Bacterial Bronchitis (PBB)
  • Upper Airway Cough Syndrome (postnasal drips)
  • Gastroesophageal Reflux Disease (GERD)
  • Tuberculosis (link to berculosis)
• Other less frequent causes are as follows
  • Suppurative lung diseases (eg. Bronchiectasis)
  • Bronchiolitis obliterans
  • Whooping cough (pertussis)
  • Recurrent aspiration pneumonia
  • Immunodeficiencies
  • Airway anatomical abnormalities eg.tracheobronchomalacia
  • Cystic fibrosis
  • Cardiac abnormalities 

Assessment and management of chronic cough 

• Any child with chronic cough should be seen by a doctor for a thorough evaluation.
• Appropriate relevant investigations will be performed as indicated.
• The extent of investigations should be based on clinical setting, population examined, and available expertise. 

What are the investigations for chronic cough?

• Normally your doctor will order a chest radiograph and lung function test (spirometry) in older children.
• Further investigations will depend on clues of specific pathology.

• Your doctor may check your child’s phlegm for microscopic examination and culture to many pathogens.
• If your child has contact with Tuberculosis (TB) patients, TB work-up will be carried out.
• Allergy skin testing or blood test for specific allergic testing (RAST) if atopy/asthma are likely diagnoses.
• Your doctor may take your blood for immune work-up or HIV testing if your child has recurrent chest infections or failing to thrive.
• Special tests like Chest HRCT (High-Resolution Computed Tomography), 24-hour pH study, Barium swallow, Bronchoscopy etc may be done if indicated.

How do we treat children with chronic cough? 

• The specific treatment will depend on the identifiable causes. Discuss with your doctor accordingly.
• Exposure to cigarette smoke should be removed whenever possible.

• For post-viral cough or cough reflex hypersensitivity, it is advisable to adopt wait and see approach. Parents are assured that majority will resolve spontaneously. The children should be follow-up for emergence of specific etiologic pointers.
• Cough suppressants and other cold medications are not advisable especially in young children because of potential serious side-effects.
• If cough-variant asthma is a possibility, a trial of anti-asthma therapy may be used (e.g. inhaled corticosteroids). If cough does not resolve during medication trial within expected response time (eg. minimum 4 weeks), the medications will be discontinued. Your doctor then will consider other diagnoses. 

References: 

1. Chang AB et al. Guidelines for Evaluating Chronic Cough in Pediatrics: ACCP Evidenced-based Clinical Practice Guidelines. Chest 2006;129:260S-283S.
2. Chang AB. Cough: Are children really different to adults. Cough 2005, 1:7
3. De Jongste JC et al. Chronic cough in children. Thorax 2003,58:998-1003.