Previous classification system for asthma severity
| Clinical features before treatment# | |||
| Symptoms¶ | Night-time symptoms | Lung function | |
| Step 4: severe persistent | Continual symptoms | Frequent | FEV1 or PEF ≤60% pred |
| Limited physical activity | PEF variability >30% | ||
| Frequent exacerbations | |||
| Step 3: moderate persistent | Daily symptoms | More than once per week | FEV1 or PEF >60 and ≤80% pred |
| Daily use of inhaled SABA | PEF variability >30% | ||
| Exacerbations affect activity | |||
| Exacerbations more than twice per week; may last days | |||
| Step 2: mild persistent | Symptoms more than twice per week but no more than once per day | More than twice per month | FEV1 or PEF ≥80% pred |
| Exacerbations may affect activity | PEF variability 20–30% | ||
| Step 1: mild intermittent | Symptoms no more than twice per week | No more than twice per month | FEV1 or PEF ≥80% pred |
| Asymptomatic and normal PEF between exacerbations | PEF variability <20% | ||
| Exacerbations are brief (from a few hours to a few days); intensity may vary | |||
From the National Asthma Education and Prevention Program Expert Panel Report 2 1. Asthma severity was classified by clinical characteristics before treatment. FEV1: forced expiratory volume in one second; PEF: peak expiratory flow; % pred: % predicted; SABA: short-acting β2-agonist. #: the presence of one of the features of severity is enough to place the patient in that category. An individual should be assigned to the most severe grade in which any feature occurs. The characteristics noted are general and may overlap because asthma is highly variable. Furthermore, an individual’s classification may change over time. ¶: Patients at any level can have mild, moderate or severe exacerbations. Some patients with intermittent asthma experience severe and life-threatening exacerbations separated by long periods of normal lung function and no symptoms.