Classifying Asthma Severity

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After asthma is diagnosed, the next step is to determine how severe–or intense–your asthma is.1 Asthma treatment is based on the disease severity.

Asthma may be classified as intermittent, mild persistent, moderate persistent, and severe persistent.1 The severity is judged based on:

  • how much your symptoms affect your life
  • how well your lungs work
  • the risk of having an asthma attack and death

How much do your symptoms affect your life?

Your provider will want to know about your asthma symptoms in the prior two to four weeks. Typical asthma symptoms are coughing, wheezing, shortness of breath, and chest tightness. Your provider may ask questions such as:1

  • How often do you wake up at night because of asthma symptoms?
  • How many days of work/school have you missed because of your asthma symptoms?
  • How do your asthma symptoms affect your ability to participate in normal activities?
  • If you have a rescue inhaler, how often do you use it?

How much lung function do you have?

Your provider may ask you to do a test called spirometry.1 Spirometry measures how much and how quickly you can exhale air. There are three main results from spirometry:2

  • FEV1: How much air you can forcefully exhale in one second.
  • FVC: The maximum amount of air you can forcefully exhale.
  • FEV1/FVC: Represents the percentage your total air capacity (“vital capacity”) that you can forcefully exhale in one second.

Spirometry results are given in “liters per minute.” They are also given as a percentage of the “predicted normal values.” Predicted normal values are based on expected results for someone your age, height, weight, gender, and race. Spirometry results help your health care provider figure out how severe your asthma is.1

How likely are asthma attacks?

People with asthma are always at risk of having acute asthma attacks. An acute asthma attack may also be called an “asthma flare” or “asthma exacerbation.” When this happens, asthma symptoms come on suddenly—sometimes within minutes—and quickly get worse. At other times, symptoms may develop over several days and slowly get worse. Sudden symptoms are usually treated with a rescue medication.3

Your health care provider will want to know about asthma attacks you have had in the past.1 The more severe and frequent they are, the more severe the underlying asthma usually is. However, even people with intermittent or mild asthma can have severe asthma attacks.

Your provider may want to see you more often if your risk of having an asthma attack is high.

What is intermittent asthma?

Symptoms. People with intermittent asthma usually have symptoms two days per week or less. Their symptoms do not limit normal activity. It is rare that their symptoms wake them up at night. They use rescue medications, such as short-acting beta-agonists (SABA), two days per week or less. People with intermittent asthma have normal or near-normal lung function. Signs of intermittent asthma are summarized in Table 1.1

Treatment. People with intermittent asthma may only need to use a SABA when they have symptoms. They should avoid allergens or other things that trigger asthma symptoms.

Table 1. Signs of Intermittent Asthma

Ages 0-4 years
Ages 5-11 years
Ages 12+ years, Adults
Symptoms
≤2 days/week
≤2 days/week
≤2 days/week
Nighttime awakening
0
≤2 days/month
≤2 days/month
Use of rescue medication
≤2 days/week
≤2 days/week
≤2 days/week
Interference with normal activity
None
None
None
Lung function
Spirometry not possible in this age group
  • Normal FEV1 between exacerbations
  • FEV1 80% predicted
  • FEV1/FVC >85%
  • Normal FEV1 between exacerbations
  • FEV1 >80% predicted
  • Normal FEV1/FVC

Adapted from National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma – Full Report 2007. Accessed 11/12/14 at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf; Figures 3–4 a/b/c, pgs 72-74

What is mild persistent asthma?

Symptoms. People with mild persistent asthma have asthma symptoms more than twice a week, but not every day. Daily activity is slightly limited due to asthma symptoms. People with mild asthma may wake up occasionally because of symptoms. They use rescue medications more than twice a week to control their asthma symptoms, but not daily. People with mild asthma have near-normal lung function. Signs of mild asthma are summarized in Table 2.1

Treatment. People with mild, persistent asthma usually need daily medication. If you have asthma, your airways are inflamed and swollen. The inflammation makes your airways very sensitive to triggers. People with mild asthma usually start with a low-dose inhaled corticosteroid medication.1 This medication reduces the inflammation.

Table 2. Signs of Mild Asthma

Ages 0-4 years
Ages 5-11 years
Ages 12+ years, Adults
Symptoms
>2 days/week, but not daily
>2 days/week, but not daily
>2 days/week, but not daily
Nighttime awakening
1-2 times/month
3-4 times/month
3-4 times/month
Use of rescue medication
>2 days/week, but not daily
>2 days/week, but not daily
>2 days/week, but not >1 time/day
Interference with normal activity
Minor limitation
Minor limitation
Minor limitation
Lung function
Spirometry not possible in this age group
  • FEV1 >80% predicted
  • FEV1/FVC >80%
  • FEV1 ≥80% predicted
  • Normal FEV1/FVC

Adapted from National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma – Full Report 2007. Accessed 11/12/14 at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf; Figures 3–4 a/b/c, pgs 72-74

What is moderate persistent asthma?

Symptoms. People with moderate persistent asthma have asthma symptoms every day. Daily activity is somewhat limited by asthma symptoms. Older children and adults wake up at least once a week because of asthma symptoms. They use rescue medications daily to control their asthma symptoms. People with moderate asthma have decreased lung function. Signs of moderate asthma are summarized in Table 3.

Treatment. There are many asthma medications available and different types of asthma. An asthma specialist may be helpful in finding the right treatment for people with moderate or severe asthma.1,4

Adults and older children may need to use an inhaled corticosteroid with a second medication.1 Usually, the second medication is a long-acting beta-agonist (LABA). LABA medications relax the airways, helping them to open up. Other medications are available as alternatives to LABAs. Sometimes, a moderate-dose inhaled corticosteroid is used, either alone or with a second medication.

Very young children with moderate asthma are usually treated with a moderate-dose inhaled corticosteroid. If that is not enough to control asthma symptoms, a second medication may be added.

Table 3. Signs of Moderate Asthma

Ages 0-4 years
Ages 5-11 years
Ages 12+ years, Adults
Symptoms
Daily
Daily
Daily
Nighttime awakening
3-4 times/month
>1 time/week, but not nightly
>1 time/week, but not nightly
Use of rescue medication
Daily
Daily
Daily
Interference with normal activity
Some limitation
Some limitation
Some limitation
Lung function
Spirometry not possible in this age group
  • FEV1 60%-80% predicted
  • FEV1/FVC 75%-80%
  • FEV1 >60% but <80% predicted
  • FEV1/FVC reduced 5%

Adapted from National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma – Full Report 2007. Accessed 11/12/14 at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf; Figures 3–4 a/b/c, pgs 72-74

What is severe persistent asthma?

Symptoms. People with severe persistent asthma have asthma symptoms throughout each day. As a result, daily activity is extremely limited. Older children and adults wake up most nights because of asthma symptoms. They must use rescue medications several times a day to control their asthma symptoms. People with this type of asthma have severely decreased lung function. Signs of severe asthma are summarized in Table 4.

Treatment. Most people with severe asthma are seen by an asthma specialist. People with severe asthma often take a high-dose inhaled corticosteroid with a LABA.1 In the most severe cases, an oral corticosteroid may also be used. Adults with severe allergic asthma may take a medication called omalizumab (Xolair).

Table 4. Signs of Severe Asthma

Ages 0-4 years
Ages 5-11 years
Ages 12+ years, Adults
Symptoms
Throughout the day
Throughout the day
Throughout the day
Nighttime awakening
>1 time/week
Often (7 times/week)
Often (7 times/week)
Use of rescue medication
Several times per day
Several times per day
Several times per day
Interference with normal activity
Extremely limited
Extremely limited
Extremely limited
Lung function
Spirometry not possible in this age group
  • FEV1 <60% predicted
  • FEV1/FVC <75%
  • FEV1 <60% predicted
  • FEV1/FVC reduced >5%

Adapted from National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma – Full Report 2007. Accessed 11/12/14 at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf; Figures 3–4 a/b/c, pgs 72-74

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view references
  1. National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma - Full Report 2007. Accessed 11/12/14 at: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf
  2. Johns DP, Pierce R. Spirometry: The measurement and interpretation of ventilatory function in clinical practice. National Asthma Council Australia; 2008. Accessed 1/9/14 at: http://www.nationalasthma.org.au/uploads/content/211-spirometer_handbook_naca.pdf
  3. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention 2014. Accessed 11/12/14 at: www.ginasthma.org.
  4. Corren J. Asthma phenotypes and endotypes: an evolving paradigm for classification. Discov Med. 2013;15:243-249. http://www.discoverymedicine.com/Jonathan-Corren/2013/04/26/asthma-phenotypes-and-endotypes-an-evolving-paradigm-for-classification/
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Written by: Sarah O'Brien | Last Reviewed: May 2016.
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