How is asthma severity assessed and what are the treatment options based on severity?

Asthma Severity Assessment and Treatment

Asthma severity is assessed using two distinct domains—current impairment (symptoms, SABA use, activity limitation, and lung function) and future risk (exacerbation history)—with severity classified as intermittent, mild persistent, moderate persistent, or severe persistent based on the most severe feature in either domain. 1

When to Assess Severity vs. Control

Assess severity before initiating therapy in treatment-naïve patients to guide initial medication selection. 1 Once treatment begins, shift focus to assessing control (not severity) for all subsequent treatment adjustments—stepping up when inadequate or stepping down when stable. 1

A critical pitfall: Never classify severity during acute exacerbations, as this overestimates baseline severity and leads to overtreatment. 2 Always assess during stable periods. 3

Classification of Asthma Severity (Treatment-Naïve Patients ≥12 Years)

Severity is determined by whichever domain (impairment or risk) places the patient in the most severe category. 1, 3

Impairment Domain Components:

• Daytime symptoms: 1, 3

  • Intermittent: ≤2 days/week
  • Mild persistent: >2 days/week but not daily
  • Moderate persistent: Daily
  • Severe persistent: Throughout the day

• Nighttime awakenings: 1, 3

  • Intermittent: ≤2 times/month
  • Mild persistent: 3-4 times/month
  • Moderate persistent: >1 time/week but not nightly
  • Severe persistent: Often 7 times/week

• SABA use for symptom relief (not EIB prevention): 1, 3

  • Intermittent: ≤2 days/week
  • Mild persistent: >2 days/week but not daily
  • Moderate persistent: Daily
  • Severe persistent: Several times daily

• Activity limitation: 1, 3

  • Intermittent: None
  • Mild persistent: Minor
  • Moderate persistent: Some
  • Severe persistent: Extremely limited

• Lung function (FEV₁ % predicted and FEV₁/FVC ratio): 1, 3

  • Intermittent: FEV₁ ≥80% predicted, normal FEV₁/FVC
  • Mild persistent: FEV₁ ≥80% predicted, FEV₁/FVC reduced >5%
  • Moderate persistent: FEV₁ 60-80% predicted, FEV₁/FVC reduced >5%
  • Severe persistent: FEV₁ <60% predicted, FEV₁/FVC reduced

Age-adjusted normal FEV₁/FVC ratios are essential: 85% (ages 8-19), 80% (ages 20-39), 75% (ages 40-59), 70% (ages 60-80). 1, 3 Using fixed cutoffs misclassifies older patients. 2

Risk Domain:

Exacerbations requiring oral systemic corticosteroids: 1

• 0-1 per year suggests intermittent asthma
• ≥2 per year indicates persistent asthma regardless of impairment measures

This is crucial: A patient with normal lung function and minimal symptoms but ≥2 exacerbations/year requiring oral corticosteroids must be classified as having persistent asthma and treated accordingly. 1, 3 Ignoring exacerbation history when lung function appears normal leads to dangerous undertreatment. 2

Initial Treatment Based on Severity

Treatment follows a stepwise approach aligned with severity classification: 2

Intermittent Asthma (Step 1):

• SABA as needed only (no daily controller medication) 2

Mild Persistent Asthma (Step 2):

• Preferred: Low-dose inhaled corticosteroids (ICS) 2
• Alternatives: Leukotriene modifiers or theophylline 2

Moderate Persistent Asthma (Steps 3-4):

• Preferred: Low-to-medium dose ICS + long-acting beta-agonist (LABA) 2, 4
• Alternatives: Medium-dose ICS alone, or low-to-medium dose ICS + leukotriene modifier or theophylline 2
• For patients ≥12 years: Maximum recommended dosage is fluticasone/salmeterol 500/50 mcg twice daily 4
• For children 4-11 years not controlled on ICS: Fluticasone/salmeterol 100/50 mcg twice daily 4

Severe Persistent Asthma (Steps 5-6):

• Preferred: Medium-to-high dose ICS + LABA 2
• Consider omalizumab for allergic asthma in patients ≥12 years 2
• May require oral corticosteroids 2

Critical safety warning: LABAs should never be used as monotherapy without ICS, as this increases risk of asthma-related death, hospitalization, and intubation. 4 Patients using combination ICS/LABA should not use additional LABA for any reason. 4

Objective Measurement Requirements

Never rely on symptoms alone without spirometry. 3, 2 This leads to misclassification and undertreatment. 2 Spirometry is recommended for all patients ≥5 years at initial assessment. 1 Conventional clinical indices (symptoms, airway calibre) correlate only weakly with actual patient function and quality of life. 5

Peak flow monitoring is appropriate for ongoing monitoring in most patients, with similar benefits to symptom monitoring. 1 However, consider daily peak flow monitoring specifically for patients with moderate-to-severe persistent asthma, history of severe exacerbations, or poor symptom perception. 1

Monitoring and Adjusting Therapy

Once treatment is initiated, assess control (not severity) at every visit using validated tools: 2

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

If control is inadequate after 2 weeks of therapy, step up treatment (increase ICS/LABA strength or add additional controller). 4 If well-controlled for ≥3 months, consider stepping down. 1

Expect improvement within 30 minutes to 1 week of starting ICS/LABA therapy, with maximum benefit by 1 week or longer. 4

Additional Assessment Components

Beyond severity classification, the initial evaluation must identify: 1

• Precipitating factors (allergens, irritants at home/work/school)
• Comorbidities impeding management (sinusitis, rhinitis, GERD, OSA, obesity, stress, depression)
• Patient knowledge and self-management skills

Higher trigger burden correlates with more severe disease, frequent exacerbations, and greater need for oral corticosteroids. 3 Allergen sensitization (particularly Alternaria, cockroaches) increases risk of severe asthma and mortality. 3 Respiratory infections account for 50% of adult exacerbations and 80-85% of pediatric exacerbations. 3

Goals of Asthma Management

Treatment aims to reduce both impairment and risk: 1

Impairment reduction:

• Prevent chronic symptoms (cough, breathlessness day/night/after exertion)
• Require infrequent SABA use (<2 days/week)
• Maintain near-normal lung function
• Maintain normal activity levels including exercise, school, work
• Meet patient/family expectations

Risk reduction:

• Prevent exacerbations and minimize ED visits/hospitalizations
• Prevent lung function decline (or reduced lung growth in children)
• Provide optimal pharmacotherapy with minimal adverse effects

These domains may respond differentially to treatment—some patients achieve good symptom control but remain at high exacerbation risk and require more aggressive therapy. 1