STEPS - Classification of Asthma Severity

Clinical features before treatment.
 

Classification Symptoms Nighttime Symptoms Lung Function
STEP 1 
Mild Intermittent
  • Symptoms less than twice a week
  • Asymptomatic and normal PEF between exacerbations
  • Exacerbations brief (from a few hours to a few days); intensity may vary
Less than twice a month
  • FEV1 or PEF greater than 80% of predicted
  • PEF variability less than 20%
STEP 2 
Mild Persistent
  • Symptoms less than twice a week but lasting longer than a day
  • Exacerbations may affect activity
More than twice a month
  • FEV1 or PEF less than 80% of predicted
  • PEF variability 20% to 30%
STEP 3 
Moderate Persistent
  • Daily symptoms
  • Daily use of inhaled short-acting beta2-antagonist
  • Exacerbations affect activity
  • Exacerbations more often than twice a week; may last for days
More than once a week
  • FEV1 or PEF 60% to 80% of predicted
  • PEF variability greater than 30%
STEP 4 
Severe Persistent
  • Continual symptoms
  • Limited physical activity
  • Frequent exacerbations
Frequent
  • FEV1 or PEF less than 60% of predicted
  • PEF variability greater than 30%
 National Asthma Education and Prevention Program Expert Panel Report 2:  Guidelines for the Diagnosis and Management of Asthma

The presence of one of the features of severity is sufficient to place a patient in that category.  An individual should be assigned to the most severe grade in which any features occurs.  The characteristics noted in this figure are general and may overlap because asthma is highly variable.  Furthermore, an individual's classification may change over time.

Patients at any level of severity 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.