Diagnostic criteria

Clinical classification of asthma (before treatment) [1]

Of note, the classification may change over time depending on the patient's health status. One factor in each category is sufficient to classify patient. Asthma is a variable disease, thus there can be overlap between categories.

Mild intermittent:

• Symptoms ≤2 times a week

• Asymptomatic and normal peak expiratory flow rate (PEFR) between attacks

• Attacks are brief with varying intensity

• Night-time symptoms ≤2 times a month

• Forced expiratory flow at 1 second (FEV1) or PEFR ≥80% of predicted

• PEFR variability <20%.

Mild persistent:

• Symptoms >2 times a week but <1 time a day

• Exacerbations may affect activity

• Night-time symptoms >2 times a month

• FEV1 ≥80% of predicted

• PEFR variability between 20% and 30%.

Moderate persistent:

• Daily symptoms

• Use of short-acting beta agonists daily

• Attacks affect activity

• Exacerbations ≥2 times a week and may last for days

• Night-time symptoms >1 time a week

• FEV1 greater than 60% to <80% of predicted

• PEFR variability >30%.

Severe persistent:

• Continual symptoms

• Limited physical activity

• Frequent exacerbations

• Frequent night-time symptoms

• FEV1 ≤60% of predicted

• PEFR variability >60%.