Define each asthma classification (intermittent, mild persistent, moderate persistent, severe persistent, refractory) and give the recommended treatment for each classification.

Asthma Classification and Treatment by Severity

Classification Definitions

Asthma severity is classified into four categories based on symptoms, nighttime awakenings, SABA use, activity limitation, lung function (FEV₁ and FEV₁/FVC ratio), and exacerbation frequency, with the most severe feature determining overall classification. 1, 2

Intermittent Asthma

• Symptoms: <2 days/week 1, 2
• Nighttime awakenings: ≤2 times/month 1, 2
• SABA use: ≤2 days/week 1, 2
• Activity limitation: None 1
• Lung function: FEV₁ >80% predicted, normal FEV₁/FVC ratio 1, 3
• Exacerbations: 0-1/year requiring oral corticosteroids 1, 2

Mild Persistent Asthma

• Symptoms: >2 days/week but not daily 1, 2
• Nighttime awakenings: 3-4 times/month 1, 2
• SABA use: >2 days/week but not daily 1, 2
• Activity limitation: Minor limitation 1
• Lung function: FEV₁ >80% predicted, FEV₁/FVC reduced >5% from normal 1, 3
• Exacerbations: ≥2/year requiring oral corticosteroids 1, 2

Moderate Persistent Asthma

• Symptoms: Daily 1, 2
• Nighttime awakenings: >1 time/week but not nightly 1, 2
• SABA use: Daily 1, 2
• Activity limitation: Some limitation 1, 2
• Lung function: FEV₁ 60-80% predicted, FEV₁/FVC reduced >5% 1, 3

Severe Persistent Asthma

• Symptoms: Throughout the day 1, 2
• Nighttime awakenings: Often 7 times/week (nightly) 1, 2
• SABA use: Several times per day 1, 2
• Activity limitation: Extremely limited 1, 2
• Lung function: FEV₁ <60% predicted, FEV₁/FVC reduced >5% 1, 3

Age-Adjusted FEV₁/FVC Normal Values

• Ages 8-19 years: 85% 1, 3
• Ages 20-39 years: 80% 1, 3
• Ages 40-59 years: 75% 1, 3
• Ages 60-80 years: 70% 1, 3

Treatment by Classification

Intermittent Asthma Treatment

Short-acting β₂-agonist (SABA) as needed only—no daily controller medication required. 1, 2

• Preferred: SABA (albuterol or levalbuterol) as needed for symptom relief 1
• With viral respiratory symptoms: SABA every 4-6 hours up to 24 hours (longer with physician consultation) 1
• For exacerbations: Consider short course of oral systemic corticosteroids if severe or history of previous severe exacerbations 1
• Caution: Frequent SABA use (>2 days/week) indicates need to step up to daily long-term controller therapy 1

Mild Persistent Asthma Treatment (Step 2)

Low-dose inhaled corticosteroids are the preferred initial controller therapy, as ICS are the most consistently effective anti-inflammatory medication for persistent asthma. 1, 2

• Preferred: Low-dose inhaled corticosteroids (ICS) 1, 2
• Alternative options:
  • Leukotriene receptor antagonist (LTRA) 1, 2
  • Theophylline (requires serum concentration monitoring) 1, 2
  • Cromolyn 1
• Plus: SABA as needed for symptom relief 1
• Consider: Subcutaneous allergen immunotherapy for patients with persistent allergic asthma 1

Moderate Persistent Asthma Treatment (Step 3)

Low-to-medium dose ICS plus long-acting β₂-agonist (LABA) is the preferred combination therapy. 1, 2

• Preferred: Low-to-medium dose ICS + LABA 1, 2
• Alternative options:
  • Medium-dose ICS alone 1, 2
  • Low-to-medium dose ICS + LTRA 1, 2
  • Low-to-medium dose ICS + theophylline 1, 2
• Plus: SABA as needed 1
• Consider: Allergen immunotherapy 1

Severe Persistent Asthma Treatment (Steps 4-6)

High-dose ICS plus LABA forms the foundation, with additional controllers and biologics added as needed; consultation with asthma subspecialist is recommended at Step 4 or higher. 1, 2

Step 4:

• Preferred: Medium-dose ICS + LABA 1
• Alternative: Medium-dose ICS + LTRA, theophylline, or zileuton 1
• Plus: SABA as needed 1

Step 5:

• Preferred: High-dose ICS + LABA 1, 2
• Consider: Omalizumab (Xolair) for patients with allergic asthma 1, 2
• Plus: SABA as needed 1

Step 6:

• Preferred: High-dose ICS + LABA + oral corticosteroid 1, 2
• Consider: Omalizumab for allergic asthma 1, 2
• Alternative consideration: Before introducing oral corticosteroids, trial of high-dose ICS + LABA + LTRA, theophylline, or zileuton may be considered (though not studied in clinical trials) 1
• Plus: SABA as needed 1

Refractory Asthma (Not a Formal Classification)

While "refractory asthma" is not formally defined in the NAEPP EPR-3 classification system 1, patients requiring Step 5-6 therapy who remain poorly controlled despite maximal therapy represent this clinical phenotype. These patients require:

• Subspecialist consultation 1
• Verification of diagnosis and adherence 1
• Assessment for comorbid conditions (GERD, rhinosinusitis, vocal cord dysfunction) 1
• Environmental control measures 1
• Consideration of biologic therapies (omalizumab for allergic asthma) 1, 2

Critical Management Principles

Stepwise Approach

Treatment intensity is adjusted based on asthma control: step up when control is inadequate, step down when well-controlled for ≥3 months. 1

• Before stepping up, verify medication adherence, inhaler technique, environmental control, and comorbid conditions 1
• Step down is possible when asthma is well controlled for at least 3 months 1
• ICS are the most consistently effective anti-inflammatory therapy across all age groups and all steps of persistent asthma 1

High-Risk Patients Requiring Special Attention

Patients with ≥2 exacerbations requiring oral corticosteroids in the past year should be classified as having persistent asthma, even if impairment levels suggest intermittent asthma. 1, 2

Additional high-risk features include: 4

• History of intubation or ICU admission for asthma 4
• ≥2 hospitalizations in past year 4
• ≥3 ED visits in past year 4
• Recent hospitalization or ED visit within past month 4
• Use of >2 SABA canisters per month 4
• Difficulty perceiving symptoms or severity 4
• Lack of written asthma action plan 4

Common Pitfalls to Avoid

• Do not classify severity during acute exacerbations—this overestimates baseline severity and leads to overtreatment 2
• Do not rely on symptoms alone without spirometry—objective lung function testing is essential for accurate classification 1, 2
• Do not ignore exacerbation history when FEV₁ is normal—frequent exacerbations requiring oral corticosteroids mandate persistent asthma treatment regardless of lung function 1, 2
• Do not use fixed FEV₁/FVC cutoffs across all ages—apply age-adjusted normal values to avoid misclassification 1, 3
• Do not continue using severity classification after treatment initiation—switch to control-based assessment for ongoing management decisions 2