What is the management approach for interstitial lung disease (ILD) and how does it differ from chronic obstructive pulmonary disease (COPD) management?

Management of Interstitial Lung Disease and Differentiation from COPD

The management of interstitial lung disease (ILD) requires a targeted approach based on the specific ILD subtype, with first-line therapy typically including antifibrotic agents for idiopathic pulmonary fibrosis (IPF) and immunomodulatory drugs for connective tissue disease-associated ILD (CTD-ILD), which fundamentally differs from COPD management that focuses on bronchodilators and anti-inflammatory agents.

ILD Classification and Diagnosis

Key Diagnostic Features

• High-Resolution CT (HRCT) is the gold standard for ILD diagnosis with ~91% sensitivity and 71% specificity 1
• Pulmonary Function Tests (PFTs) show a restrictive pattern (reduced FVC, normal FEV1/FVC ratio) and reduced DLCO 2
• A 5% decline in FVC over 12 months is associated with doubled mortality 2, 1

ILD Subtypes

• Idiopathic pulmonary fibrosis (IPF): ~33% of ILD cases
• Hypersensitivity pneumonitis (HP): ~15% of ILD cases
• Connective tissue disease-associated ILD (CTD-ILD): ~25% of ILD cases 1

Management of ILD by Subtype

Idiopathic Pulmonary Fibrosis (IPF)

• First-line therapy: Antifibrotic agents (nintedanib or pirfenidone)
  • These slow annual FVC decline by 44-57% 1
• Supportive care:
  • Oxygen therapy for patients who desaturate below 88% on 6-minute walk test
  • Pulmonary rehabilitation to improve symptoms and exercise capacity

Connective Tissue Disease-Associated ILD (CTD-ILD)

First-Line Therapy Options

• Mycophenolate mofetil is the preferred first-line agent for most CTD-ILDs 3, 2
• Short-term corticosteroids (except in systemic sclerosis where they are strongly discouraged) 3
• Disease-specific recommendations:
  • Systemic sclerosis: Mycophenolate (preferred), tocilizumab (alternative) 3
  • Myositis: Mycophenolate (preferred), azathioprine, JAK inhibitors 3
  • Rheumatoid arthritis: Mycophenolate (preferred) 3

For Progressive Disease Despite First-Line Treatment

• Rituximab, cyclophosphamide, or nintedanib are recommended options 3
• For RA-ILD specifically: Consider adding pirfenidone 3
• For SSc-ILD, MCTD-ILD, or RA-ILD: Consider tocilizumab 3
• For IIM-ILD: Consider calcineurin inhibitors or JAK inhibitors 3

For Rapidly Progressive ILD

• Pulse intravenous methylprednisolone as first-line treatment 3
• Consider upfront combination therapy (especially for MDA-5 positive patients) 3
• Early referral for lung transplantation is recommended 3

Hypersensitivity Pneumonitis (HP)

• First action: Antigen identification and avoidance 4
• If no improvement: Consider anti-inflammatory drugs like prednisolone 4

Monitoring and Follow-up

• Regular PFTs every 3-6 months to assess disease progression 2
• HRCT when clinically indicated to evaluate disease extent 2
• During initial evaluation, short-term PFTs (within 3 months) and HRCT (within 6 months) to determine progression rate 3
• For mild ILD (FVC ≥70% and <20% fibrosis on HRCT), PFTs every 6 months for 1-2 years 3
• For moderate-to-severe ILD, more frequent PFTs (every 3-6 months) 3

Supportive Care for ILD

• Oxygen therapy for patients with desaturation
• Structured exercise therapy/pulmonary rehabilitation
• Vaccination (influenza, pneumococcus, COVID-19) 2
• Pneumocystis jirovecii pneumonia prophylaxis for patients on high-dose immunosuppression 2
• Calcium and vitamin D supplementation for patients on corticosteroids 2

Lung Transplantation

• Consider for end-stage ILD
• Improves median survival to 5.2-6.7 years compared to <2 years without transplant 1
• Early referral recommended for patients with progressive disease 2

Differences Between ILD and COPD Management

Pathophysiology

• ILD: Primarily restrictive lung disease with inflammation and/or fibrosis of lung parenchyma
• COPD: Primarily obstructive lung disease with airflow limitation due to airway inflammation and parenchymal destruction

Diagnostic Approach

• ILD: HRCT showing interstitial abnormalities, restrictive pattern on PFTs
• COPD: Obstructive pattern on PFTs (reduced FEV1/FVC ratio)

Treatment Differences

• ILD: Antifibrotic agents (IPF) or immunomodulatory drugs (CTD-ILD)
• COPD: Bronchodilators (LABA, LAMA), inhaled corticosteroids, smoking cessation

Combined Pulmonary Fibrosis and Emphysema (CPFE)

• Patients with both emphysema and diffuse ILD have higher mortality than COPD alone 5
• May require management strategies addressing both conditions
• Associated with increased risk of pulmonary hypertension and lung cancer 5

Special Considerations

• Multidisciplinary discussion is essential for accurate diagnosis and management 3
• Progressive fibrosing ILD (PF-ILD) is a phenotype that can occur across various ILD subtypes and may benefit from antifibrotic therapy 6
• Regular assessment for pulmonary hypertension is important, as it occurs in up to 85% of patients with end-stage fibrotic ILD 1