Utility of pulmonary ultrasound to identify interstitial lung disease in patients with rheumatoid arthritis

Abstract

Objectives To analyze the diagnostic utility of lung ultrasound (US) to detect interstitial lung disease (ILD) in rheumatoid arthritis (RA) patients comparing with high-resolution computed tomography (HRCT) Patients and methods We performed a cross-sectional, observational study in patients with RA-ILD (cases) controlled with a group of RA patients without ILD (controls) paired by sex, age, and time of disease evolution. Patients were assessed using HRCT, PFT, and US. The main variables were B-line number, evaluation of the lung-US score already described, pleural irregularities, and A pattern US lost. ROC curve analysis was performed to establish the cut-off point of the US B-lines number for detecting the presence of significant RA–ILD in relation to HRCT, and logistic regression analysis was performed to identify the intercostal spaces. Results Seventy-one patients were included, 35 (49.2%) with ILD-RA and 36 (50.8%) RA controls. Regarding US score, we found that the detection of 5.5 lines in a reduced score of 8 intercostal spaces had a sensitivity = 62.2%, specificity = 91.3%, PPV = 88.4%, and NPV = 69.5%. In multivariate analysis, the intercostal spaces which showed independent association with ILD were 3rd right anterior axillary space (OR [IC 95%] 19.0 [1.3–27.5]), 8th right posterior axillary space (OR [IC 95%] 0.04 [0.0–0.6]), 8th right subscapular space (OR [IC 95%] 16.5 [1.8–45.5]), 9th right paravertebral space (OR [IC 95%] 7.11 [1.0–37.1]), and 2nd left clavicular middle space (OR [IC 95%] 21.9 [1.26–37.8]). Conclusions Lung ultrasound could be a useful tool for ILD diagnosis associated with rheumatoid arthritis. A 8-space reduced score showed a similar total predictive capacity than 72-space score. Key Points • Lung ultrasound could be a useful tool for ILD diagnosis associated with rheumatoid arthritis. • The 72-space evaluation is highly sensitive, whereas a simplified score enables a more specific and faster diagnosis. • The number of B lines is correlated with DLCO, ACPA, inflammatory activity, and physical function.