What are the treatment differences between allergic asthma and eosinophilic asthma?

Treatment Differences Between Allergic Asthma and Eosinophilic Asthma

Both allergic asthma and eosinophilic asthma require inhaled corticosteroids (ICS) as first-line therapy, but eosinophilic asthma often requires higher doses of ICS and may need targeted biologic therapies like anti-IL-5 agents (mepolizumab, benralizumab) when poorly controlled, while allergic asthma responds better to allergen avoidance and anti-IgE therapy (omalizumab).

Key Differences in Pathophysiology

• Allergic Asthma:

  • Triggered by specific allergens (pollen, dust mites, pet dander)
  • IgE-mediated immune response
  • Often presents in childhood
  • Associated with other atopic conditions (allergic rhinitis, eczema)

• Eosinophilic Asthma:

  • May not be triggered by specific allergens
  • Characterized by high levels of eosinophils in airways and blood
  • Often presents later in life (adult-onset)
  • Can be more severe and refractory to standard treatments

Diagnostic Approach

Allergic Asthma

• Positive skin prick tests or specific IgE to common allergens
• Elevated total IgE levels
• Response to allergen challenge
• Symptom correlation with allergen exposure

Eosinophilic Asthma

• Elevated blood eosinophil counts (typically >300 cells/μL)
• Elevated sputum eosinophils (>3%)
• Elevated FeNO (fractional exhaled nitric oxide) levels
• May not have positive allergy tests

Treatment Algorithm

First-Line Treatment for Both Types

• Inhaled corticosteroids (ICS) 1
• Short-acting beta-agonists (SABA) for rescue

Allergic Asthma-Specific Treatments

1. Allergen avoidance - Critical first step
2. Add-on therapy options:
   • Long-acting beta-agonists (LABA) with ICS 1, 2
   • Leukotriene receptor antagonists (LTRA)
   • Theophylline
3. For severe allergic asthma:
   • Omalizumab (anti-IgE therapy) for patients with elevated IgE and positive allergen tests 3
   • Consider allergen immunotherapy in selected cases

Eosinophilic Asthma-Specific Treatments

1. Higher doses of ICS often required 1
2. Add-on therapy options:
   • LABA with ICS (similar to allergic asthma)
   • LTRA (may be less effective than in allergic asthma)
3. For severe eosinophilic asthma:
   • Anti-IL-5 therapies:
     • Mepolizumab (100 mg SC every 4 weeks) 4
     • Benralizumab (30 mg SC every 4 weeks initially, then every 8 weeks)
   • Oral corticosteroids may be needed in refractory cases 1

Special Considerations

Allergic Asthma

• Patients may benefit from management of comorbid allergic conditions (rhinitis, sinusitis) 1
• Food allergies should be identified and avoided, especially in patients at risk for anaphylaxis 1
• Environmental control measures are crucial

Eosinophilic Asthma

• Often more steroid-resistant than allergic asthma 1
• May be associated with aspirin sensitivity and nasal polyps 5
• Can be part of systemic eosinophilic disorders (e.g., EGPA) 6, 7
• May require more aggressive therapy and closer monitoring

Treatment Response Monitoring

Allergic Asthma

• Symptom control, especially after allergen exposure
• Lung function (spirometry)
• Exacerbation frequency
• Medication requirements

Eosinophilic Asthma

• Blood eosinophil counts
• Sputum eosinophil counts (when available)
• FeNO levels
• Symptom control and exacerbation frequency

Common Pitfalls to Avoid

1. Misdiagnosis: Not all asthma with elevated eosinophils is non-allergic; overlap phenotypes exist 1
2. Undertreatment: Eosinophilic asthma often requires more aggressive therapy
3. Missing comorbidities: Both types can have significant comorbidities that affect control
4. Delayed escalation: Waiting too long to initiate biologic therapies in severe cases
5. Inadequate monitoring: Not tracking appropriate biomarkers for each phenotype

When to Consider Referral to a Specialist

• Poor response to standard therapy
• Requirement for high-dose ICS or frequent oral corticosteroids
• Uncertainty about asthma phenotype
• Consideration of biologic therapies
• Suspicion of associated systemic disorders (especially with eosinophilic asthma)

By understanding these key differences in treatment approaches, clinicians can better tailor therapy to the specific asthma phenotype, potentially improving symptom control and reducing exacerbations.