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. 2010 Jul;35(7):377-378, 385-391, 416.

Table 2.

Classification of Asthma Severity

Components of Severity* Category
Children 5 to 11 Years of Age Adults and Youths 12 Years of Age or Older
Mild Moderate Severe Mild Moderate Severe
Impairment Symptoms More than 2 days per week but not daily Daily Throughout the day More than 2 days per week but not daily Daily Throughout the day
Nighttime awakenings 3 to 4 times per month More than 1 time/week but not nightly Often 7 times per week 3 to 4 times per month More than 1 time per week but not nightly Often 7 times per week
Short-acting beta2-agonist use for symptom control (not for prevention of exercise-induced bronchospasm) More than 2 days per week but not daily Daily Several times per day More than 2 days per week but not more than 1 time per day Daily Several times per day
Interference with normal activity Minor limitation Some limitation Extremely limited Minor limitation Some limitation Extremely limited
Lung function

  • FEV1 > 80% predicted

  • FEV1/FVC > 80%

  • FEV1 = 60%–80% predicted

  • FEV1/FVC = 75%–80%

  • FEV1 <60% predicted

  • FEV1/FVC <75%

  • FEV1 ≥80% predicted

  • FEV1/FVC normal

  • FEV1 > 60% but <80% predicted

  • FEV1/FVC reduced 5%

  • FEV1 <60% predicted

  • FEV1/FVC reduced >5%
Risk Exacerbations requiring oral systemic corticosteroids

  • More than two in one year (see note).

  • Consider severity and interval since last exacerbation. Frequency and severity may fluctuate over time for patients in any severity category.

  • Relative annual risk of exacerbations may be related to FEV1.

  • Two or more per year (see note).

  • Consider severity and interval since last exacerbation. Frequency and severity may fluctuate over time for patients in any severity category.

  • Relative annual risk of exacerbations may be related to FEV1.
Lowest level of treatment required to maintain control Step 2 Step 3 or 4 Step 5 or 6 Step 2 Step 3 or 4 Step 5 or 6

FEV1 = forced expiratory volume in one second; FVC = forced vital capacity; ICU = intensive-care unit.

*

The level of severity is determined by both impairment and risk. The impairment domain is assessed by the patient’s or caregiver’s recall of the previous two to four weeks and spirometry. Severity is assigned to the most severe category in which any feature occurs.

At present, the data are inadequate to correspond frequencies of exacerbations with different levels of asthma severity. In general, more frequent and intense exacerbations (e.g., requiring urgent, unscheduled care, hospitalization, or ICU admission) indicate greater underlying disease severity. For treatment purposes, patients who had two or fewer exacerbations requiring oral systemic corticosteroids in the past year may be considered the same as patients who have persistent asthma, even in the absence of impairment levels consistent with persistent asthma.

From the National Heart, Lung, and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma.7