What is the recommended initial evaluation and work‑up for a child with suspected asthma?

Pediatric Asthma Work-Up

Initial Evaluation for Children Aged 5-16 Years

The European Respiratory Society strongly recommends performing spirometry, bronchodilator reversibility (BDR) testing, and fractional exhaled nitric oxide (FeNO) measurement as first-line diagnostic tests, with at least two abnormal objective test results required to confirm asthma diagnosis. 1

Clinical History Assessment

Focus your history on these specific high-yield elements:

• Wheeze characteristics: Document frequency (>3 attacks per year has 44% sensitivity and 90% specificity), timing, and whether the child awakens due to wheeze 2
• Specific triggers: Ask specifically about pollen exposure (46% sensitivity, 83% specificity) and pet exposure (29% sensitivity, 99% specificity) 2
• Avoid relying on nonspecific symptoms: Cough alone or breathing difficulty without wheeze are poor predictors and should prompt investigation for alternative diagnoses 3, 4

First-Line Objective Testing (Ages 5-16)

Perform these tests in sequence:

1. FeNO measurement (perform before spirometry): Use cut-off ≥25 ppb; elevated levels suggest eosinophilic airway inflammation (AUC 0.80) 1, 2

2. Spirometry: Measure FEV₁ and FEV₁/FVC ratio; abnormal is defined as <lower limit of normal (LLN) or <80% predicted 1

   • Critical caveat: Normal spirometry does NOT exclude asthma, as it is frequently normal during stable disease 1, 3

3. Bronchodilator reversibility testing: Perform even if spirometry is normal when clinical suspicion is high (AUC 0.81 for methacholine challenge) 1, 2

Diagnostic Decision Algorithm

• Confirm asthma: When ≥2 objective tests are abnormal (e.g., abnormal spirometry + positive BDR, or elevated FeNO + positive BDR) 1, 4
• If initial tests normal but symptomatic: Repeat testing when the child presents with active symptoms, particularly when wheezing is present 3, 4
• If tests normal and relatively asymptomatic: Consider "watchful waiting" with scheduled follow-up 3, 4

Additional Testing When Diagnosis Remains Unclear

• Peak flow variability: Only consider in settings lacking other objective tests; requires 2 weeks of twice-daily measurements with ≥12% variability as positive cut-off 4, 5
• Exercise or methacholine challenge: These have higher diagnostic accuracy (AUC 0.74-0.81) than baseline spirometry 2

Evaluation for Children Under 5 Years

In children aged 2-4 years who cannot reliably perform spirometry or peak flow measurements, use a therapeutic trial approach rather than attempting objective testing. 3, 5

Clinical Assessment for Young Children

• Document recurrent wheeze: This is the most important symptom suggesting asthma in this age group 3
• Assess symptom patterns: Note triggers (viral infections, exercise, allergens) and response to any previous treatments 3
• Avoid vague labels: Do not use terms like "bronchitis" or "reactive airway disease" as these delay proper diagnosis 3

Therapeutic Trial Protocol

When objective testing is not feasible:

• Initiate inhaled corticosteroid (ICS) trial in symptomatic children 1
• Do NOT diagnose based on symptom improvement alone 1, 3
• Reassess after 4-8 weeks with repeat attempt at objective testing if age-appropriate 1
• Consider supervised stepping down of preventer medication to confirm or refute active asthma 1

Critical Pitfalls to Avoid

• Never diagnose asthma on symptoms alone in children ≥5 years without objective testing 1, 4
• Do not use allergy testing (skin prick or IgE) to diagnose asthma: These have low specificity and should only identify triggers after diagnosis is established 3, 4
• Do not rely on single abnormal test: At least two objective abnormalities are required 1, 4
• Do not assume normal spirometry excludes asthma: Repeat when symptomatic 1, 3
• Avoid diagnosing based solely on treatment response: Symptom improvement after ICS trial must be accompanied by objective improvement in lung function 1, 3

When to Refer

If spirometry is unavailable or unsuccessful in your setting, refer for specialist opinion rather than making diagnosis based on symptoms alone 3