Table 1.

Classification of asthma severity by clinical features [13].

Intermittent

Symptoms less than once a week

Brief exacerbations

Nocturnal symptoms not more than twice a month

FEV1 or PEF > 80% predicted

PEF or FEV1 variability < 20%

Mild Persistent

Symptoms more than once a week but less than once a day

Exacerbations may affect activity and sleep

Nocturnal symptoms more than twice a month

FEV1 or PEF > 80% predicted

PEF or FEV1 variability < 20%–30%

Moderate Persistent

Symptoms daily

Exacerbations may affect activity and sleep

Nocturnal symptoms more than once a week

FEV1 or PEF 60%–80% predicted

PEF or FEV1 variability > 30%

Severe Persistent

Symptoms daily

Frequent exacerbations

Frequent nocturnal asthma symptoms

FEV1 or PEF < 60% predicted

PEF or FEV1 variability > 30%