Value of lung ultrasonography for screening interstitial lung disease in patients with rheumatoid arthritis

Interstitial lung disease (ILD) is a common complication of RA usually diagnosed with high-resolution CT (HRCT), but emerging data suggest the interest of lung ultrasonography (LUS) for screening RA-ILD. This study aimed to determine the ability of LUS to screen ILD in RA.

This was an observational monocentre study of RA patients. All patients underwent pulmonary and rheumatology clinical evaluation, immunology screening, lung HRCT and LUS, and pulmonary function tests (PFTs). US assessment occurred the same day as HRCT, according to the 14-intercostal space scanning protocol. The total B-lines count was classified semi-quantitatively as follows: 0, normal (≤ 5 B-lines); 1, mild (6-15 B-lines); 2, moderate (16-30 B-lines) and 3, severe (≥ 30 B-lines).

We analysed data for 101 consecutive RA patients (69% women, mean age 44.7 ± 13.1 years). HRCT revealed RA-ILD in 44 patients. Using receiver operating characteristic curve analysis, we determined a threshold of > 5 B-lines for the diagnosis of RA-ILD, with sensitivity 89% and specificity 93%. B-lines count was positively correlated with mean Warrick score (r = 0.836, P < 0.001) and negatively with PFTs (r = -0.649, P < 0.001).

Our results support the potential role of LUS for screening RA-ILD. By using a short protocol, feasible in clinical routine practice, B-lines count > 5 showed good diagnostic performance and was correlated with HRCT and PFT results.