From the Guidelines
The recommended serologic workup for suspected interstitial lung disease (ILD) should include antinuclear antibodies (ANA), rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP), anti-neutrophil cytoplasmic antibodies (ANCA), myositis panel (including anti-Jo-1), and specific antibodies related to systemic sclerosis (anti-Scl-70, anti-centromere) 1.
Serologic Workup
The serologic workup is crucial for identifying the underlying cause of ILD, which can be associated with various systemic autoimmune rheumatic diseases (SARDs). The following tests should be included:
- Antinuclear antibodies (ANA)
- Rheumatoid factor (RF)
- Anti-cyclic citrullinated peptide (anti-CCP)
- Anti-neutrophil cytoplasmic antibodies (ANCA)
- Myositis panel (including anti-Jo-1)
- Specific antibodies related to systemic sclerosis (anti-Scl-70, anti-centromere) Additional testing should include:
- Complete blood count
- Comprehensive metabolic panel
- Erythrocyte sedimentation rate
- C-reactive protein
- Creatine kinase
Treatment Approach
The treatment approach depends on the specific ILD diagnosis but generally involves:
- Corticosteroids as first-line therapy, typically starting with prednisone 0.5-1 mg/kg/day (maximum 60 mg daily) for 4-12 weeks, followed by a slow taper based on clinical response 1.
- For progressive or steroid-resistant disease, immunosuppressive agents like mycophenolate mofetil (1-1.5 g twice daily), azathioprine (2-3 mg/kg/day), or cyclophosphamide may be added.
- For idiopathic pulmonary fibrosis specifically, antifibrotic medications like pirfenidone (801 mg three times daily) or nintedanib (150 mg twice daily) are recommended.
- Supportive care including supplemental oxygen, pulmonary rehabilitation, vaccination against respiratory pathogens, and management of comorbidities is essential.
- Early referral to a multidisciplinary ILD clinic is crucial for accurate diagnosis through integration of clinical, radiological, and sometimes histopathological findings, which guides appropriate treatment selection and improves outcomes 1.
From the Research
Serologic Workup for Interstitial Lung Disease
The serologic workup for interstitial lung disease (ILD) is an essential component of the diagnostic evaluation, as it can help identify underlying autoimmune disorders that may be contributing to the development of ILD.
- Autoantibody testing, including anti-nuclear antibodies, rheumatoid factor, and anti-citrullinated cyclic peptide antibody testing, is recommended for patients undergoing diagnostic evaluation for ILD 2.
- Further autoantibody testing may be reserved for selected cases guided by rheumatological features 2.
- An extended panel of autoantibody testing may detect cases of connective tissue disease-associated ILD, regardless of clinical or radiological subtype, and prior to extra-pulmonary manifestations of systemic autoimmunity 2.
Treatment Approach for Interstitial Lung Disease
The treatment approach for ILD depends on the underlying cause and severity of the disease.
- Antifibrotic therapy with nintedanib or pirfenidone may slow annual forced vital capacity (FVC) decline 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 connective tissue disease-associated ILD 3.
- Structured exercise therapy and oxygen therapy may also be beneficial in reducing symptoms and improving quality of life in individuals with ILD 3.
- Lung transplant may be considered for patients with advanced ILD, as it can improve symptoms and resolve respiratory failure 3.
Autoimmune-Featured Interstitial Lung Disease
Autoimmune-featured ILD (AIF-ILD) is a distinct entity that may be identified through serologic testing and clinical evaluation.
- AIF-ILD is characterized by the presence of autoimmune features, such as positive serologic tests and signs or symptoms suggestive of a connective tissue disease, in the absence of a diagnosed connective tissue disease 4.
- Patients with AIF-ILD may have a similar survival rate to those with IPF, but worse than those with CTD-ILD 4.
- Antinuclear antibody (ANA) titers ≥ 1:1280 may be associated with improved survival in patients with AIF-ILD 4.
Rheumatoid Arthritis-Related Interstitial Lung Disease
Rheumatoid arthritis (RA)-related ILD is a complication of RA that is associated with significant morbidity and mortality.
- The usual interstitial pneumonia (UIP) subtype of RA-related ILD shares clinical and histopathologic features with idiopathic pulmonary fibrosis, suggesting common mechanistic pathways and potential therapeutic targets 5.
- Patients with RA-related ILD are at high risk of infection and drug toxicity, which complicates treatment decision-making 5.
- Further research is needed to elucidate the basic mechanisms underlying RA-related ILD and to develop more efficacious and safer treatments 5.