From the Guidelines
The treatment of chronic hypersensitivity pneumonitis primarily involves removing the offending antigen and using immunosuppressive therapy, with the most recent evidence suggesting that antigen avoidance is associated with decreased mortality and clinical improvement, as reported in the 2021 study by Gimenez et al 1.
Key Components of Treatment
- Identifying and completely avoiding the causative antigen is essential, whether it's bird proteins, mold, or occupational exposures.
- Corticosteroids are the mainstay of pharmacological treatment, typically starting with prednisone at 0.5-1 mg/kg/day (usually 40-60 mg daily) for 1-2 weeks, followed by a slow taper over 2-3 months, as recommended in the 2006 ACCP guidelines 1.
- For patients requiring long-term therapy or those who cannot tolerate steroids, steroid-sparing agents like mycophenolate mofetil (1000-1500 mg twice daily), azathioprine (2-3 mg/kg/day), or rituximab may be added.
- Antifibrotic medications such as nintedanib or pirfenidone can be considered in patients with progressive fibrosis despite immunosuppression.
Supportive Care
- Supplemental oxygen for hypoxemic patients
- Pulmonary rehabilitation to improve exercise capacity
- Vaccinations against influenza and pneumococcal disease
- Lung transplantation may be considered for end-stage disease
Monitoring and Follow-up
- Regular monitoring with pulmonary function tests every 3-6 months is recommended to assess treatment response, as the disease can progress despite treatment, and adjustments to the treatment plan may be necessary, as suggested by the 2021 study by Gimenez et al 1.
From the Research
Treatment Options for Chronic Hypersensitivity Pneumonitis
- Immunotherapy: The use of immunosuppressive therapy, such as azathioprine or mycophenolate mofetil, in combination with prednisone, has been shown to reduce adverse events and improve transplant-free survival in patients with chronic hypersensitivity pneumonitis (CHP) 2.
- Corticosteroids: Systemic oral corticosteroids, such as prednisone, are often used as first-line therapy for CHP, but can be associated with significant side effects 3.
- Steroid-sparing agents: Mycophenolate mofetil (MMF) and azathioprine (AZA) have been used as steroid-sparing agents in CHP, with studies showing a reduction in prednisolone dose and improvement in lung function 4.
Lung Function and Treatment Outcomes
- Forced vital capacity (FVC): Treatment with MMF or AZA has been shown to slow the decline in FVC, although the improvement may not be significant 3, 4.
- Diffusing capacity of the lung for carbon monoxide (DLCO): Treatment with MMF or AZA has been associated with a significant improvement in DLCO 3, 4.
- Carbon monoxide diffusing capacity (TLCO): Treatment with MMF or AZA for 12 months was associated with a significant improvement in TLCO 4.
Management and Monitoring
- Environmental modification: Reduction of antigenic burden, use of protective devices, and avoidance of inciting antigens are important for treatment and monitoring of CHP 5.
- Host immune response modification: Corticosteroids, lung transplantation, and smoking cessation are also important for treatment and monitoring of CHP 5.
- Serum markers: Measurement of serum Krebs von den Lungen (KL)-6 and surfactant protein (SP)-D concentrations can be used to screen for HP and detect HP activity 5.