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

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)

AND

 • 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 test^a (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 weeks^a

→ 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 PEF^c by > 20%) from baseline after 4 weeks of treatment, outside respiratory infections

   ▪ Positive exercise challenge test^a

→ 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 PEF^c between visits (may include respiratory infections)

Allergy testing

 • Perform skin tests to assess allergic status and identify possible triggers