How are steroids prescribed for hypersensitivity pneumonitis?

Steroid Treatment for Hypersensitivity Pneumonitis

For hypersensitivity pneumonitis (HP), systemic corticosteroids are the mainstay of therapy, with oral prednisone typically prescribed at 0.5-1 mg/kg/day for 2-4 weeks followed by a gradual taper over 4-6 weeks for non-fibrotic HP, while fibrotic HP may require longer treatment courses.

Classification and Assessment

Before initiating treatment, it's essential to:

1. Classify the type of HP:

   • Non-fibrotic HP: Better response to treatment, more reversible
   • Fibrotic HP: Less responsive to treatment, poorer prognosis 1

2. Assess severity:

   • Grade 1 (mild): Asymptomatic with radiographic changes only
   • Grade 2 (moderate): Symptomatic, limiting instrumental ADLs
   • Grade 3-4 (severe): Severe symptoms, limiting self-care, may require oxygen

3. Rule out infection: Consider bronchoscopy with bronchoalveolar lavage to exclude infectious causes, especially before starting immunosuppressive therapy 1

Treatment Protocol

Non-Fibrotic HP

• Initial therapy: Prednisone 0.5-1 mg/kg/day orally (typically 40-60 mg/day) for 2-4 weeks 1
• Taper schedule: Gradually reduce over 4-6 weeks
• Monitoring: Clinical assessment every 2-3 days initially, with radiological follow-up recommended for moderate cases 1
• Expected response: Improvement in lung function typically occurs within 1 month of treatment initiation

Fibrotic HP

• Initial therapy: Same starting dose as non-fibrotic HP
• Taper schedule: More prolonged course, often over 6 weeks or more
• Response: Less predictable; may stabilize rather than improve lung function 1
• Prognosis: Poorer overall response to therapy compared to non-fibrotic HP

Severe/Refractory Cases

For patients with severe symptoms or inadequate response to oral corticosteroids:

• High-dose IV corticosteroids: Methylprednisolone 2-4 mg/kg/day 1
• Consider additional immunosuppression if no improvement after 48 hours:
  • Mycophenolate mofetil
  • Azathioprine
  • Cyclophosphamide (for severe cases) 2
  • Leflunomide (shown to improve lung function in non-fibrotic HP) 3

Monitoring and Follow-up

• Pulmonary function tests: Before treatment and at 3-6 months to assess response
• Chest imaging: Follow-up HRCT to evaluate radiological improvement
• Clinical assessment: Regular evaluation of symptoms (particularly cough and dyspnea)

Important Considerations

• Antigen avoidance: Identifying and removing the inciting antigen is crucial for treatment success and should accompany pharmacological therapy 4
• Response predictors: Positive treatment outcomes are more likely with:
  • Fever after antigen exposure
  • Higher lymphocyte count in BAL fluid (>54%)
  • Ill-defined centrilobular nodules on HRCT 5
• Negative predictors: Increased eosinophil count in BAL and fibrosis on HRCT predict poorer response 5
• Steroid failure rate: Approximately 10% of patients may develop steroid-resistant or refractory disease requiring second-line immunosuppressive therapy 2

Cautions

• Infection risk: Monitor for opportunistic infections, particularly with prolonged steroid use
• Metabolic effects: Monitor blood glucose, blood pressure, and weight
• Bone health: Consider calcium and vitamin D supplementation for prolonged courses
• GI protection: Use proton pump inhibitors for gastric protection during treatment

Treatment Efficacy

Research shows that approximately 53% of HP patients improve with immunomodulatory therapy, with 17% showing stabilization and 30% experiencing progression despite treatment. Even among patients with fibrotic HP, improvement can be seen in about 35% of cases 5, highlighting the importance of not withholding treatment based solely on the presence of fibrosis.