Classification of asthma

The National Asthma Education and Prevention Program has classified asthma as:

• Mild intermittent.
• Mild persistent.
• Moderate persistent.
• Severe persistent.

These classifications are based on severity, which is determined by symptoms and lung function tests. You should be assigned to the most severe category in which any feature occurs.¹

• Classification is based on symptoms before treatment.
• Classification may change over time.
• A person in any category can have severe asthma attacks.

Mild intermittent asthma

Asthma is considered mild intermittent if without treatment any of the following are true:

• Symptoms (difficulty breathing, wheezing, chest tightness, and coughing):
  • Occur no more than 2 times a week.
  • Are not present between asthma attacks.
• Attacks are brief (lasting a few hours to a few days). Attacks may vary from mild to severe.
• Nighttime symptoms occur no more than 2 times a month.
• Lung function tests (spirometry and peak expiratory flow [PEF]) are normal when the person is not having an asthma attack. The results of these tests are 80% or more of the expected value and vary little (PEF varies less than 20%) from morning to afternoon.

Mild persistent asthma

Asthma is considered mild persistent if without treatment any of the following are true:

• Symptoms occur more than 2 times a week but less than 1 time a day.
• Attacks interfere with daily activities.
• Nighttime symptoms occur more than 2 times a month.
• Lung function tests are normal when the person is not having an asthma attack. The results of these tests are 80% or more of the expected value and may vary a small amount (PEF varies 20% to 30%) from morning to afternoon.

Moderate persistent asthma

Asthma is considered moderate persistent if without treatment any of the following are true:

• Symptoms occur daily. Inhaled short-acting asthma medication is used every day.
• Attacks:
  • Interfere with daily activities.
  • Occur 2 or more times per week and may last for days.
• Nighttime symptoms occur more than 1 time a week.
• Lung function tests are abnormal (more than 60% to less than 80% of the expected value), and PEF varies more than 30% from morning to afternoon.

Severe persistent asthma

Asthma is considered severe persistent if without treatment any of the following are true:

• Symptoms:
  • Occur all the time during the day.
  • Limit daily physical activities.
• Asthma attacks occur frequently.
• Nighttime symptoms occur frequently.
• Lung function tests are abnormal (60% or less of expected value), and PEF varies more than 30% from morning to afternoon.

If you or your child has persistent asthma (mild, moderate, or severe) and is receiving appropriate therapy, the goal of treatment should be to control symptoms so that they occur only as frequently as those of mild intermittent asthma.

Citations

1. National Institutes of Health (1997). Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma. Clinical Practice Guidelines (NIH Publication No. 97-4051). Bethesda, MD: U.S. Department of Health and Human Services.