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Table 1 Diagnosis of asthma based on medical history, physical examination and objective measurements [5, 15, 16]

From: Asthma

Medical history
• Assess for classic symptoms of asthma:
     − Wheezing
     − Breathlessness
     − Chest tightness
     − Cough (with our without sputum)
 • Assess for symptom patterns suggestive of asthma:
     − Recurrent/episodic
     − Occur/worsen at night or early in the morning
     − Occur/worsen upon exposure to allergens (e.g., animal dander, pollen, dust mites) or irritants (e.g., exercise, cold air, tobacco smoke, infections)
     − Respond to appropriate asthma therapy
 • Assess for family or personal history of atopic disease (particularly allergic rhinitis)
Physical examination
 • Examine for wheezing on auscultation
 • Examine upper respiratory tract and skin for signs of other atopic conditions
 Objective measures for confirming variable expiratory airflow limitation (spirometry preferred)
 • Documented airflow limitation:
    ▪ Diagnostic criteria: at least once during diagnostic process when FEV1 is low, confirm that FEV1/FVC is reduced (normally > 0.75–0.80 in adults, > 0.90 in children)
 • Documented excessive variability in lung function using one or more of the tests below (the greater the variations, or the more occasions excess variation is seen, the more confident the diagnosis):
  Diagnostic criteria
   ▪ Positive bronchodilator (BD) reversibility testa (more likely to be positive if BD is withheld before test: SABA ≥ 4 h, LABA ≥ 15 h) → Adults increase in FEV1 of > 12% and > 200 mL from baseline, 10–15 min after 200–400 μg albuterol or equivalent (greater confidence if increase is > 15% and > 400 mL)
→ Children increase in FEV1 of > 12% predicted
   ▪ Excessive variability in twice-daily PEF over 2 weeksa → Adults average daily diurnal PEF variability > 10%b
→ Children average daily diurnal PEF variability > 13%b
   ▪ Significant increase in lung function after 4 weeks of anti-inflammatory treatment → Adults increase in FEV1 by > 12% and > 200 mL (or PEFc by > 20%) from baseline after 4 weeks of treatment, outside respiratory infections
   ▪ Positive exercise challenge testa → Adults fall in FEV1 of > 10% and > 200 mL from baseline
→ Children fall in FEV1 of > 12% predicted, or PEF > 15%
   ▪ Positive bronchial challenge test (usually only performed in adults) Fall in FEV1 from baseline of ≥ 20% with standard doses of methacholine or histamine, or ≥ 15% with standardized hyperventilation, hypertonic saline or mannitol challenge
   ▪ Excessive variation in lung function between visits (less reliable)a → Adults variation in FEV1 of > 12% and > 200 mL between visits, outside of respiratory infections
→ Children variation in FEV1 of > 12% or > 15% in PEFc between visits (may include respiratory infections)
Allergy testing
 • Perform skin tests to assess allergic status and identify possible triggers
  1. FVC forced vital capacity, FEV1 forced expiratory volume in 1 s, PEF peak expiratory flow (highest of three readings), BD bronchodilator (short-acting SABA or rapid-acting LABA), LABA long-acting beta2-agonist, SABA short-acting beta2-agonist
  2. aThese tests can be repeated during symptoms or in the early morning
  3. bDaily diurnal PEF variability is calculated from twice daily PEF as ([day’s highest minus day’s lowest]/mean of day’s highest and lowest), and averaged over 1 week
  4. cFor PEF, use the same meter each time, as PEF may vary by up to 20% between different meters. BD reversibility may be lost during severe exacerbations or viral infections. If bronchodilator reversibility is not present at initial presentation, the next step depends on the availability of other tests and the urgency of the need for treatment. In a situation of clinical urgency, asthma treatment may be commenced and diagnostic testing arranged within the next few weeks, but other conditions that can mimic asthma should be considered, and the diagnosis of asthma confirmed as soon as possible