What are the appropriate tests and treatments for a 16-year-old patient presenting with a cough?

Management of Cough in a 16-Year-Old

For a 16-year-old with cough, begin by determining the duration: if less than 3 weeks (acute), provide supportive care and reassurance; if 3-8 weeks (subacute), evaluate for post-infectious causes; if greater than 8 weeks (chronic), obtain a chest radiograph and spirometry as first-line tests, then follow a systematic algorithm based on whether the cough is wet/productive versus dry. 1, 2

Initial Assessment and Duration Classification

• Acute cough (< 3 weeks): Most commonly viral upper respiratory infection requiring only supportive care 2
• Subacute cough (3-8 weeks): Frequently post-infectious in nature, with mechanisms including persistent postnasal drip, upper airway irritation, or transient bronchial hyperresponsiveness 1
• Chronic cough (> 8 weeks): Requires systematic diagnostic workup with chest radiograph and spirometry 1, 2

Key Historical Elements to Determine

• Cough characteristics: Determine if wet/productive versus dry, as this fundamentally changes the diagnostic pathway 1, 2
• Medication history: Specifically ask about ACE inhibitor use, as this can cause cough that may take up to 26 days to resolve after discontinuation 1
• Smoking status: Current cigarette smoking commonly causes productive cough meeting criteria for chronic bronchitis, and cessation resolves cough within 4 weeks in most cases 1
• Specific cough pointers: Look for coughing with feeding, digital clubbing, hemoptysis, or weight loss that suggest serious underlying disease 1, 2

Diagnostic Testing Based on Duration

For Acute Cough (< 3 weeks)

• No routine testing needed - most cases are self-limited viral infections 2
• Consider chest radiograph only if fever >39°C, hypoxia, rales, or tachypnea/tachycardia out of proportion to fever 3

For Chronic Cough (> 8 weeks)

• Chest radiograph: Essential first-line investigation to identify structural abnormalities, pneumonia, or other pathology 1, 2
• Spirometry (pre- and post-bronchodilator): Recommended for patients aged 15 years and older to assess for airway obstruction and reversibility 1, 2
• Additional testing should be individualized based on initial findings rather than performed routinely 2

Treatment Algorithm Based on Cough Type

Wet/Productive Cough (> 4 weeks)

• Prescribe 2 weeks of antibiotics targeting common respiratory bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis) if no other specific cough pointers present 1
• If cough resolves, diagnose protracted bacterial bronchitis (PBB) 1
• If cough persists after 2 weeks, prescribe an additional 2 weeks of appropriate antibiotics 1
• If cough persists after 4 weeks total antibiotic therapy, perform further investigations including flexible bronchoscopy with quantitative cultures 1

Dry/Non-Productive Cough

• Evaluate for asthma if associated symptoms include wheeze, exercise intolerance, or nocturnal symptoms 2
• Consider post-infectious cough if following recent respiratory infection 1, 2
• Evaluate for upper airway cough syndrome (postnasal drip) 1, 2
• Do not empirically treat for asthma unless other features consistent with the condition are present 2

Treatment Recommendations

Supportive Care for Acute Cough

• Avoid over-the-counter cough and cold medications - they have not been shown to reduce cough severity or duration 2
• Avoid codeine-containing medications due to potential serious side effects including respiratory distress 2
• Address parental and patient expectations and concerns 1, 2
• Identify and eliminate environmental tobacco smoke exposure 2

Specific Therapy for Chronic Cough

• Optimize therapy for each identified diagnosis rather than using empirical approaches 1
• For asthma: inhaled corticosteroids and bronchodilators 1
• For upper airway cough syndrome: treat underlying allergic rhinitis or sinusitis 1
• For GERD: proton pump inhibitors with diet/lifestyle modifications 1
• Maintain all partially effective treatments due to possibility of multiple simultaneous causes 1

Important Pitfalls to Avoid

• Do not assume chronic cough without wheeze is asthma - chronic cough alone is not associated with airway inflammation profiles suggestive of asthma 2
• Do not use empirical treatment approaches unless specific clinical findings support a particular diagnosis 2
• If empirical trial is used, limit duration to 2-4 weeks to confirm or refute the hypothesized diagnosis 2
• Do not stop ACE inhibitor only if temporally related - stop regardless of timing, as the original cause may have resolved and persisting cough could be drug-induced 1

When to Escalate Care

• Cough persisting beyond 4 weeks of appropriate antibiotic therapy for wet cough warrants referral for bronchoscopy 1
• Presence of specific cough pointers (hemoptysis, weight loss, digital clubbing, persistent focal findings) requires specialized evaluation 2
• Recurrent episodes despite appropriate treatment suggest need for pulmonary subspecialty consultation 2