When are Connective Tissue Disease (CTD) screens, Perinuclear Anti-Neutrophil Cytoplasmic Antibodies (pANA), and Centromere Anti-Neutrophil Cytoplasmic Antibodies (cANA) necessary in treating lung conditions?

From the Guidelines

Screening for connective tissue disease (CTD) with tests like CTD screen, pANA, and cANA should be considered when evaluating patients with interstitial lung disease (ILD) of unclear etiology, particularly when clinical features suggest an underlying autoimmune process, as recommended by the 2023 American College of Rheumatology (ACR)/American College of Chest Physicians (CHEST) guideline 1.

Key Considerations

• These tests are most appropriate when patients present with unexplained dyspnea, cough, or radiographic abnormalities consistent with ILD, especially if accompanied by extrapulmonary symptoms such as joint pain, Raynaud's phenomenon, skin rashes, or muscle weakness.
• The initial evaluation should include a comprehensive CTD panel with ANA testing, as a positive result may indicate conditions like systemic lupus erythematosus, systemic sclerosis, mixed connective tissue disease, polymyositis/dermatomyositis, or rheumatoid arthritis that can cause lung involvement, as highlighted in the 2023 ACR/CHEST guideline 1 and further emphasized in the practical guidance for the early recognition and follow-up of patients with CTD-related ILD 1.
• Specific antibody testing (such as anti-Jo-1, anti-Scl-70, anti-RNP) should follow positive screening results to identify the particular CTD, allowing for targeted treatment approaches.

Importance of Early Detection

• Early detection of CTD-associated lung disease is crucial as treatment approaches differ from idiopathic forms, often requiring immunosuppressive therapy rather than antifibrotic medications, as noted in the guideline for the treatment of ILD in people with systemic autoimmune rheumatic diseases 1.
• Even in patients with apparently isolated lung disease, these serologic tests may reveal an underlying systemic process before other manifestations become clinically apparent, potentially allowing earlier intervention and improved outcomes, as discussed in the practical guidance for CTD-ILD 1.

Multidisciplinary Approach

• A multidisciplinary approach, integrating both pulmonary and rheumatological perspectives, is necessary for the optimal care of patients with CTD-ILD, as emphasized in the consensus guidelines for evaluation and management of pulmonary disease in Sjögren's 1.
• This approach ensures that patients receive comprehensive care, addressing both the pulmonary and systemic aspects of their disease, and facilitating earlier recognition and management of CTD-ILD.

From the Research

Screening for Autoimmune Disease-Associated Interstitial Lung Diseases

• Patients at high risk of interstitial lung disease (ILD) should be screened using high-resolution CT (HRCT) 2
• The course of autoimmune disease-associated ILD is highly variable, and it may not mirror the activity of the underlying autoimmune disease 2
• Connective tissue disease (CTD) accounts for 25% of ILD cases, and CTD screen may be necessary in these cases 3

pANA and cANA Tests

• There is no direct mention of pANA and cANA tests in the provided studies
• However, patients with ILD may have features of connective tissue disease (CTD), and pANA and cANA tests may be relevant in diagnosing CTD 4, 5

Treatment and Management

• Management of autoimmune disease-associated ILD may involve immunosuppressant and/or antifibrotic therapy in addition to supportive care 2
• Antifibrotic therapy with nintedanib or pirfenidone slows annual FVC decline by approximately 44% to 57% in individuals with IPF, scleroderma associated ILD, and in those with progressive pulmonary fibrosis of any cause 3
• Immunomodulatory therapy, such as tocilizumab, rituximab, and mycophenolate mofetil, may slow decline or even improve FVC at 12-month follow-up in patients with CTD-associated ILD 3