What investigations are recommended for assessing lung involvement in patients with rheumatoid arthritis?

For assessing lung involvement in patients with rheumatoid arthritis (RA), a combination of clinical evaluation and targeted investigations is recommended to identify interstitial lung disease (ILD) and other pulmonary complications. Initial assessment should include a detailed history and physical examination focusing on respiratory symptoms such as persistent breathlessness, cough, and chest signs including crackles or clubbing, which may suggest lung involvement (Sullivan and Ascherman, 2024). A chest X-ray is a useful first-line imaging investigation to detect gross abnormalities and to exclude other causes such as infection or malignancy, especially given the increased risk of lung cancer in RA patients (Fragoulis and Chatzidionysiou, 2020; ¹).

However, chest X-ray has limited sensitivity for early or subtle interstitial changes. Therefore, high-resolution computed tomography (HRCT) of the thorax is the gold standard imaging modality for detailed assessment of RA-associated ILD, providing superior visualization of interstitial patterns and extent of lung involvement (Sullivan and Ascherman, 2024; ⁴).

Lung function tests, including spirometry and gas transfer measurements (e.g., diffusing capacity for carbon monoxide, DLCO), are essential to quantify functional impairment and monitor disease progression (Sullivan and Ascherman, 2024; ⁴). These tests typically reveal a restrictive pattern and reduced gas transfer in RA-ILD.

Blood tests may assist in excluding alternative diagnoses and assessing systemic disease activity but are not diagnostic for lung involvement per se (Sullivan and Ascherman, 2024). In cases where infection or malignancy is suspected, sputum samples, bronchoscopy, or biopsy may be indicated to obtain microbiological or histological confirmation (¹, ²).

Multidisciplinary team (MDT) discussion involving rheumatologists, pulmonologists, radiologists, and pathologists is recommended to integrate clinical, radiological, and pathological data for accurate diagnosis and management planning (Sullivan and Ascherman, 2024; ⁴).