Thoracic ultrasound findings and pulmonary diagnosis in rheumatoid arthritis with respiratory symptoms

<bold>Introduction:</bold> Patients with rheumatoid arthritis (RA) associated interstitial lung disease (ILD) or emphysema have an increased mortality compared to RA patients without respiratory disease. The study aimed to determine the diagnostic accuracy of thoracic ultrasound (TUS) for detecting ILD in RA patients with respiratory symptoms. <bold>Methods:</bold> Patients with RA were systematically screened for pre-defined respiratory symptoms during routine outpatient follow-up. TUS was performed before high-resolution computed tomography (HRCT) and pulmonary function tests (PFT). TUS indicated ILD if either ≥10 B-lines or bilateral thickened and fragmented pleura were present. A blinded TUS expert evaluated the TUS clips. An ILD subspecialized radiologist assessed HRCT, and an experienced pulmonologist determined clinical diagnosis based on HRCT, PFT, journal audit, and MDT. <bold>Results:</bold> 77 participants (mean age 64.6 years (SD: 11.2 years), 52 (68%) females) received HRCT <30 days after TUS. ILD was verified in 23 (30%) and 13 (17%) had emphysema. TUS had a sensitivity of 82.6% (95% CI: 61.2 to 95.0) and a specificity of 51.9% (95% CI: 37.8 to 65.7) for detecting ILD. In patients with emphysema, 10 out of 13 (77%) had TUS findings indicating ILD. On HRCT, these emphysema patients had findings such as basal and sub-pleural bullae, bronchiolitis with peribronchiolar inflammation and/or oedema of the visceral pleura. <bold>Conclusions:</bold> TUS had a high sensitivity for detection of ILD in RA patients with respiratory symptoms. However, it had a low specificity. The clinical role of TUS in RA patients may be as a screening tool for detecting patients who should receive an HRCT.