Diagnostic Approach and Management of Asymptomatic Fibrotic ILD

Initial Diagnostic Workup

• The American Thoracic Society recommends obtaining high-resolution computed tomography (HRCT) immediately to characterize the pattern of fibrosis, followed by a detailed exposure history and pulmonary function tests, then proceeding to multidisciplinary discussion to establish a specific diagnosis before considering treatment 1, 2
• HRCT is mandatory to characterize the fibrotic pattern and determine if it meets criteria for usual interstitial pneumonia (UIP), probable UIP, indeterminate for UIP, or suggests an alternative diagnosis 1, 2
• The European Respiratory Society suggests that HRCT should be performed with thin collimation (≤2 mm slice thickness), without contrast, with both inspiratory and expiratory images 3, 4
• Look specifically for: subpleural and basal predominant reticulation, honeycombing, traction bronchiectasis, and absence of features suggesting alternative diagnoses (profuse ground-glass opacity, centrilobular micronodules, consolidation) 1, 5
• Take a comprehensive environmental exposure history to identify or exclude hypersensitivity pneumonitis, which was found in 47% of patients initially thought to have ILD of unknown cause 1, 6
• Screen for connective tissue disease (CTD) with antinuclear antibodies, rheumatoid factor, anti-CCP antibodies, myositis panel, and anti-topoisomerase antibodies, as CTD-ILD can present with minimal extrapulmonary manifestations 7, 8
• Obtain spirometry with FVC and DLCO to establish baseline lung function and assess disease severity 3, 4
• Perform 6-minute walk test with oxygen saturation monitoring, as oxygen saturation ≤88% at end of test predicts worse prognosis 3, 4

Establishing a Specific Diagnosis

• All cases should undergo multidisciplinary discussion (MDD) involving pulmonologists, radiologists, and pathologists experienced in ILD to integrate clinical, radiological, and if available, pathological features 3, 4
• If HRCT shows UIP pattern: Do NOT perform surgical lung biopsy (SLB), as the diagnosis can be made confidently with clinical and radiographic features alone 9, 8
• If HRCT shows probable UIP, indeterminate for UIP, or alternative diagnosis pattern: Consider SLB if the patient is not at high surgical risk (avoid if DLCO <25% after correction for hematocrit, severe hypoxemia at rest, or severe pulmonary hypertension) 2, 9, 8

Treatment Considerations

• Do NOT initiate triple therapy with prednisone, azathioprine, and N-acetylcysteine in patients with definite IPF 3, 4
• Do NOT use antacid medication for the purpose of improving respiratory outcomes in IPF, though it may be appropriate for GERD symptoms 5

Monitoring Strategy

• Assess prognosis using: severity of dyspnea, FVC and DLCO values, oxygen saturation at end of 6-minute walk test, extent of honeycombing on HRCT, and signs of pulmonary hypertension on echocardiography 3, 4
• Calculate GAP (gender, age, physiology) score for 1-, 2-, and 3-year survival estimates 3, 4
• Repeat PFTs every 3-6 months to detect progression, defined as ≥10% decline in FVC or ≥15% decline in DLCO over 6 months 3, 4