What is the recommended approach for a pediatric asthma and allergy work-up?

Recommended Approach for Pediatric Asthma and Allergy Work-up

The recommended diagnostic approach for pediatric asthma should include spirometry, bronchodilator reversibility testing, and fractional exhaled nitric oxide (FeNO) measurement as first-line objective tests, while allergy testing should not be used to diagnose asthma but may be useful for management after diagnosis. 1

Diagnostic Algorithm for Asthma in Children 5-16 Years

Step 1: Clinical Assessment

• Recurrent wheeze, cough, and breathing difficulty are key symptoms of asthma, with wheeze being the most important symptom 1
• Chronic cough (>4 weeks) as the only symptom is unlikely to be asthma and requires further investigation 1
• Symptoms alone are insufficient for diagnosis; objective testing is required 1

Step 2: First-line Objective Tests

• Spirometry:

  • Strongly recommended as part of the diagnostic work-up 1
  • FEV1/FVC <80% or <LLN, or FEV1 <80% pred supports asthma diagnosis 1
  • Normal spirometry does not exclude asthma 1

• Bronchodilator Reversibility (BDR) Testing:

  • Strongly recommended in all children with abnormal spirometry 1
  • Consider BDR testing even with normal spirometry if clinical history strongly suggests asthma 1
  • An increase in FEV1 ≥12% and/or ≥200 mL after SABA inhalation is diagnostic of asthma 1
  • BDR <12% does not exclude asthma 1

• FeNO Testing:

  • Strongly recommended as part of the diagnostic work-up 1
  • FeNO value ≥25 ppb supports asthma diagnosis 1
  • FeNO <25 ppb does not exclude asthma 1
  • Should not be used alone to diagnose or manage asthma 1

Step 3: Second-line Tests (if diagnosis remains uncertain)

• Direct Bronchial Challenge Test:

  • Methacholine challenge recommended when diagnosis cannot be confirmed with first-line tests 1
  • PC20 value of ≤8 mg·mL−1 considered positive 1

• Exercise Challenge Test:

  • Recommended for children with exercise-related symptoms when diagnosis remains uncertain 1
  • Fall in FEV1 >10% from baseline is positive 1

• PEFR Variability:

  • Not recommended as primary test but can be considered in settings lacking other objective tests 1
  • Should be based on 2 weeks of measurements 1
  • Cut-off of ≥12% in PEFR variability is considered positive 1

Step 4: Trial of Treatment

• Consider a trial of preventer medication in symptomatic children with abnormal spirometry and negative BDR 1
• Repeat objective tests after 4-8 weeks 1

Allergy Testing in Asthma Management

Role of Allergy Testing

• Not recommended for asthma diagnosis:

  • Skin-prick tests to aeroallergens have low specificity (23-40%) despite high sensitivity (77-90%) 1
  • Specific IgE tests have low specificity (56-65%) 1
  • Using allergy tests for diagnosis can lead to over-diagnosis in children with other atopic diseases 1

• Useful after asthma diagnosis for:

  • Phenotyping the asthma 1
  • Planning individualized prevention measures 1
  • Identifying potential allergic triggers 1, 2

Types of Allergy Testing

• Skin-prick tests:

  • Wheal size of ≥3 mm compared to negative control is considered positive 1
  • Not practical in patients with extensive eczema, dermographism, urticaria, or those taking antihistamines 1

• Specific IgE measurements:

  • Cut-off for positive test commonly defined as <0.35 kU·L–1 1
  • Can be detected by radioallergosorbent test or ELISA 1

Important Clinical Considerations

Pitfalls to Avoid

• Relying solely on symptoms for diagnosis leads to misdiagnosis 1
• Using allergy tests alone to diagnose asthma will miss non-allergic asthma cases 1
• Clinical features alone cannot reliably distinguish allergic from non-allergic asthma in children 2
• All children with asthma should undergo allergy testing to identify potential triggers in allergic patients and avoid unnecessary environmental control measures in non-allergic patients 2

Special Populations

• In preschool children (1-5 years), diagnosis should be considered with frequent (≥8 days/month) asthma-like symptoms or recurrent (≥2) exacerbations 3
• For children 2-5 years, efficacy of treatment is extrapolated from older children, with safety demonstrated in clinical trials 4

Allergen Mitigation After Diagnosis

• For patients with symptoms related to specific indoor allergens, multicomponent allergen-specific mitigation interventions are conditionally recommended 1
• For those with sensitization to pests, integrated pest management is conditionally recommended 1
• Impermeable pillow and mattress covers should only be used as part of a multicomponent intervention, not alone 1

By following this structured approach to pediatric asthma and allergy work-up, clinicians can achieve more accurate diagnosis and develop appropriate management strategies that improve outcomes for children with asthma.