Lung Ultrasound for the Detection of Radiologic Progression of Interstitial Lung Abnormalities in Patients With Rheumatoid Arthritis

OBJECTIVE: Interstitial lung disease (ILD) is an important extra-articular manifestation of rheumatoid arthritis (RA) associated with high mortality and morbidity. Lung ultrasonography (LUS) has recently emerged as a possible screening tool. We assessed the role of LUS in monitoring radiologic progression and the development of new interstitial lung abnormalities (ILAs). METHODS: In this prospective pilot study, patients with RA underwent high-resolution computed tomography (HRCT), pulmonary function tests (PFTs), symptom assessment, and LUS at baseline and 12 to 18 months later. B-lines were quantified using a 72-zone protocol. Radiologic changes across longitudinal HRCTs were scored on a five-point Likert scale by blinded thoracic radiologists. Six multivariable logistic regression models were built to predict HRCT progression using combinations of LUS parameters, PFTs, symptoms, and clinical characteristics. RESULTS: Eighty-one patients completed the follow-up HRCT, and per-protocol LUS was performed in 95% (77/81). Radiologic progression was observed in 31% (25/81). An increase in B-lines was significantly associated with radiologic progression (P = 0.018), and a linear trend was confirmed (P = 0.026). In multivariable analysis, both baseline B-lines (P = 0.029) and the change in B-lines over time (P = 0.012) significantly predicted progression (area under the curve [AUC] 0.78, 95% confidence interval [CI] 0.64-0.92). When combining LUS and change in diffusing capacity for carbon monoxide (AUC 0.82, 95% CI 0.70-0.94), the model fit remained similar and outperformed symptom scores (AUC 0.58, 95% CI 0.40-0.75, P = 0.020) and PFTs (AUC 0.59, 95% CI 0.44-0.74, P = 0.022). CONCLUSION: LUS may be a useful, radiation-free tool to monitor and predict radiologic progression of ILAs in RA. These findings support further research into integrating LUS into longitudinal RA-ILD assessment, particularly as part of a multimodal approach.