What are the different classifications of asthma and their corresponding treatments?

Asthma Classification System

Asthma should be classified using a dual-domain system that assesses both severity (at initial diagnosis) and control (at all subsequent visits), with severity categorized as intermittent, mild persistent, moderate persistent, or severe persistent based on impairment and risk domains. 1

Classification by Severity (Initial Assessment)

Severity classification is determined before initiating treatment and guides initial therapy selection. 1, 2 The classification uses the most severe category in which any feature occurs across both domains. 1, 2

Four Severity Categories:

Intermittent Asthma: 1

• Symptoms: ≤2 days/week
• Nighttime awakenings: ≤2 times/month
• Short-acting β-agonist use: ≤2 days/week
• FEV₁: >80% predicted with normal FEV₁/FVC ratio
• Exacerbations: 0-1/year requiring oral corticosteroids

Mild Persistent Asthma: 1, 2

• Symptoms: >2 days/week but not daily
• Nighttime awakenings: 3-4 times/month
• Short-acting β-agonist use: >2 days/week but not daily
• FEV₁: >80% predicted but FEV₁/FVC reduced >5% from normal
• Exacerbations: ≥2/year requiring oral corticosteroids

Moderate Persistent Asthma: 1, 2

• Symptoms: Daily
• Nighttime awakenings: >1 time/week but not nightly
• Short-acting β-agonist use: Daily
• FEV₁: 60-80% predicted with FEV₁/FVC reduced >5%
• Some limitation in normal activity

Severe Persistent Asthma: 1, 2

• Symptoms: Throughout the day
• Nighttime awakenings: Often 7 times/week
• Short-acting β-agonist use: Several times per day
• FEV₁: <60% predicted with reduced FEV₁/FVC
• Extremely limited normal activity

Critical Severity Assessment Points:

Age-adjusted normal FEV₁/FVC ratios must be applied: 1, 2

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

Exacerbation history overrides other criteria: Patients with ≥2 exacerbations requiring oral corticosteroids in the past year should be classified as having persistent asthma, even if lung function and symptoms suggest intermittent disease. 1, 2

Classification by Control (Ongoing Management)

Once treatment is initiated, asthma management shifts from severity-based to control-based assessment at every subsequent visit. 1 This addresses the limitation that severity classification becomes unreliable once patients are on treatment. 3

Three Control Categories:

Well Controlled: 1

• Symptoms: ≤2 days/week
• Nighttime awakenings: ≤2 times/month
• Interference with activity: None
• Short-acting β-agonist use: ≤2 days/week
• FEV₁ or peak flow: >80% predicted/personal best
• Validated questionnaire scores: ATAQ 0, ACQ ≤0.75, ACT ≥20
• Exacerbations: 0-1/year requiring oral corticosteroids

Not Well Controlled: 1

• Symptoms: >2 days/week
• Nighttime awakenings: 1-3 times/week
• Interference with activity: Some limitation
• Short-acting β-agonist use: >2 days/week
• FEV₁ or peak flow: 60-80% predicted/personal best
• Validated questionnaire scores: ATAQ 1-2, ACQ 1.5-2, ACT 16-19
• Exacerbations: ≥2/year requiring oral corticosteroids

Very Poorly Controlled: 1

• Symptoms: Throughout the day
• Nighttime awakenings: ≥4 times/week
• Interference with activity: Extremely limited
• Short-acting β-agonist use: Several times per day
• FEV₁ or peak flow: <60% predicted/personal best
• Validated questionnaire scores: ATAQ 3-4, ACQ >2, ACT ≤15
• Exacerbations: ≥2/year requiring oral corticosteroids

Validated Control Assessment Tools:

Three questionnaires are validated for monitoring control: 1

• Asthma Therapy Assessment Questionnaire (ATAQ)
• Asthma Control Questionnaire (ACQ)
• Asthma Control Test (ACT)

Treatment Approach Based on Classification

Initial Treatment by Severity:

Intermittent (Step 1): 1

• Short-acting β-agonist as needed only

Mild Persistent (Step 2): 1

• Low-dose inhaled corticosteroids (preferred)
• Alternative: Leukotriene modifiers, theophylline, cromolyn, or nedocromil

Moderate Persistent (Step 3): 1

• Low-to-medium dose inhaled corticosteroids PLUS long-acting β-agonist (preferred)
• Alternative: Medium-dose inhaled corticosteroids alone, or low-to-medium dose inhaled corticosteroids plus leukotriene modifier or theophylline

Severe Persistent (Steps 4-6): 1

• Step 4: Medium-dose inhaled corticosteroids plus long-acting β-agonist
• Step 5: High-dose inhaled corticosteroids plus long-acting β-agonist, consider omalizumab for allergic asthma
• Step 6: High-dose inhaled corticosteroids plus long-acting β-agonist plus oral corticosteroids

Ongoing Management by Control:

Well controlled: Maintain current therapy for ≥3 months, then consider stepping down. 1

Not well controlled: Step up therapy after verifying adherence, environmental control, and comorbid conditions. 1

Very poorly controlled: Step up therapy immediately and consider short course of oral corticosteroids. 1

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 objective lung function testing – this frequently leads to misclassification and undertreatment. 2, 4

Do not ignore exacerbation history when lung function appears normal – patients requiring frequent oral corticosteroids need persistent asthma treatment regardless of FEV₁. 1, 2

Do not forget age-adjusted FEV₁/FVC norms – using fixed cutoffs misclassifies older patients. 2

Do not continue using severity classification once treatment begins – switch to control-based assessment for all treatment decisions. 1, 3

Inhaled corticosteroids are the most effective single long-term controller medication for improving asthma control in both children and adults across all severity levels. 1