Interstitial Lung Disease

Background

• Interstitial lung disease (ILD) can result from a wide variety of causes including connective tissue disease, drug reactions, occupational exposures, hypersensitivity reactions, granulomatous disorders, and idiopathic interstitial pneumonias.
• The estimated incidence of ILD is 31.5/100,000 in men and 26.1/100,000 in women.
• Idiopathic pulmonary fibrosis is the most common ILD but hypersensitivity pneumonitis, sarcoidosis, and connective tissue disease-associated interstitial lung disease are also common.

Evaluation

• Diagnosis of the type of interstitial lung disease is usually made based on a combination of clinical, radiological, and histological data.
• High-resolution computed tomography (HRCT) is usually performed in all patients.
• If the diagnosis is still not clear, bronchoalveolar lavage or transbronchial lung biopsy may be considered, but may have limited utility for diagnosis.
• If bronchoalveolar lavage or transbronchial lung biopsy is not helpful or not adequate, a surgical lung biopsy may be performed after carefully individualizing the risks and benefits.
• Pulmonary function testing (resting spirometry, lung volumes, gas transfer) are helpful in quantifying disease severity, monitoring disease progression, and identifying variables associated with mortality, and will reveal a restrictive pattern in most cases.
• Access to a multidisciplinary team with expertise in interstitial lung disease should be considered.

Management

• Specific management of interstitial lung disease depends on underlying disease type, with tailored interventions aimed at ameliorating disease and/or slowing progression while improving or maintaining quality of life.
• For patients presenting with acute respiratory failure, British Thoracic Society Interstitial Lung Disease Guideline Group suggests IV corticosteroids as typical first-line therapy, and IV cyclophosphamide as a second-line option, particularly if there is no response to parenteral corticosteroids. Cyclophosphamide use may vary by underlying disease.
• Antifibrotic therapy for nonspecific chronic progressive fibrosing interstitial lung diseases:
  • Consider Nintedanib (Ofev) as an option. Nintedanib is FDA approved for chronic progressive fibrosing ILDs in adults, including autoimmune ILD, hypersensitivity pneumonitis, and idiopathic nonspecific interstitial pneumonia.
  • Pirfenidone (Esbriet) is FDA approved for idiopathic pulmonary fibrosis (IFP), but might also improve 6-minute walk distance and lung function parameters in patients with non-IFP fibrotic interstitial lung diseases.
• In general, all patients with interstitial lung disease should receive:
  • advice on smoking cessation if actively smoking and avoidance of causative agents if identified
  • initial treatment for any specific cause of underlying chronic cough (Strong recommendation)
  • influenza and pneumococcal vaccines
  • COVID-19 vaccination (initial doses and boosters)
  • access to a multidisciplinary management team and pulmonary rehabilitation
• A corticosteroid trial (prednisolone 0.5-1 mg/kg/day for 8-12 weeks) may be considered if the patient has a suspected steroid-responsive condition such as sarcoidosis, cryptogenic organizing pneumonia, or hypersensitivity pneumonitis. Patients with disease that is primarily associated with fibrosis, including IPF, should not be treated with corticosteroids.
• Consider long-term oxygen therapy to reduce dyspnea in hypoxemic patients.
• Consider lung transplantation for patients with advanced or progressive disease.