Evaluation of patients with fibrotic interstitial lung disease: A Canadian Thoracic Society position statement

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Key Messages: High Resolution Computed Tomography • All patients being evaluated for fibrotic ILD should undergo high-resolution computed tomography (HRCT) imaging of the chest, unless contraindicated. • Expiratory and prone HRCT imaging may provide valuable diagnostic information. • Continuous images with 0.5-1.25 mm slice thickness are the standard of care for the imaging evaluation of fibrotic ILD. • Chest HRCT should be interpreted in the context of a multidisciplinary discussion in cases with diagnostic uncertainty.

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Key messages: Autoimmune Serology Testing • All patients with fibrotic ILD should undergo baseline anti-nuclear antibody testing (by indirect immunofluorescence), rheumatoid factor, and anti-cyclic citrullinated peptide antibody testing, with additional serologic testing in patients with a high pre-test probability for connective tissue disease. • Additional research is required to determine whether “interstitial pneumonia with autoimmune features“(patients with ILD who have autoimmune features that do not meet criteria for a defined connective tissue diseases) is a distinct clinical entity.

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Key Messages: Rheumatology Referral • A low-titre autoantibody may not be clinically significant and may not mandate rheumatology referral in the absence of other features of connective tissue disease. • ILD patients with suggestive clinical features, specific autoantibodies, or high titre anti-nuclear antibody (≥1:320) and/or rheumatoid factor (≥60 IU/mL) should be referred to a rheumatologist.

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Key messages: Bronchoalveolar Lavage • Bronchoalveolar lavage can be diagnostic of some pulmonary diseases in the appropriate clinical context, including infection, malignancy and some nonfibrotic ILDs. • It is unclear whether bronchoalveolar lavage adds incremental diagnostic information beyond a thorough evaluation in fibrotic ILD, and it thus cannot be routinely recommended. • The potential risks and benefits of bronchoalveolar lavage must be considered on a case-by-case basis.

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Key messages: Transbronchial Lung Biopsy • Transbronchial biopsy can be useful in the evaluation of some nonfibrotic ILD subtypes (eg, sarcoidosis) and to identify infection or malignancy. • Transbronchial biopsy is associated with an increased risk of complications, including bleeding (1%-4%) and pneumothorax (9%) in patients with fibrotic ILD. • Due to a limited diagnostic yield and increased risk of complications, transbronchial biopsy should not be used routinely in the evaluation of patients with fibrotic ILD.

Table 1. Relative contraindications to surgical lung biopsy.

• Age >75 years • Pre-operative resting hypoxemia • Mechanical ventilation • FVC <55% predicted • DLCO <35% predicted • Pulmonary hypertension • Immunocompromised state • Clinically significant co-morbidity (e.g., ischemic heart disease) • Rapidly progressive disease

Note. Abbreviations: FVC, forced vital capacity; DLCO, diffusion capacity for carbon monoxide.

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Key messages: Surgical Lung Biopsy • Surgical lung biopsy is a relatively safe procedure with a high diagnostic yield and should be considered when a definitive ILD cannot be diagnosed after a multidisciplinary discussion that incorporates all available data. • Patients with advanced/rapidly progressive lung disease, significant co-morbidities or who are mechanically ventilated or immune suppressed at the time of surgical lung biopsy are at highest risk of peri-operative complications. • The yield of surgical lung biopsy should be optimized through several means, including: 1) a biopsy depth of ≥ 2 cm and maximum diameter ≥ 4 cm (when gently inflated post-resection); 2) sampling of the more severely affected areas on HRCT; 3) avoidance of areas with severe fibrosis and honeycombing; 4) sampling of ≥ 2 lobes; 5) review by an lung pathologist with ILD experience; and 6) review in a multidisciplinary discussion.

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Key Messages: Transbronchial Lung Cryobiopsy • Transbronchial lung cryobiopsy is a potential approach for histologic sampling of the lung in patients with fibrotic ILD. • No studies have directly compared the diagnostic accuracy and safety of transbronchial lung cryobiopsy to surgical lung biopsy. • Additional data are required prior to adoption of transbronchial lung cryobiopsy into clinical practice.

Figure 1. Approach to the evaluation of fibrotic interstitial lung disease. Abbreviations: CTD, connective tissue disease; HRCT, high resolution computed tomography; ILD, interstitial lung disease; IPF, idiopathic pulmonary fibrosis; MDD, multidisciplinary discussion; UIP, usual interstitial pneumonia.

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Key Messages: Multidisciplinary Discussion • Multidisciplinary discussion is the interactive dynamic dialogue among expert respirologists, radiologists and pathologists that is currently considered the gold standard for ILD diagnosis. • A multidisciplinary discussion is an iterative process and patients should be re-reviewed if new patient information becomes available after the initial discussion (eg, new histopathological results or a change in radiological pattern). • ILD patients should be reviewed in a multidisciplinary discussion whenever possible before initiating disease-specific pharmacotherapies.