The emerging role of ultrasound in detecting interstitial lung disease in patients with rheumatoid arthritis.

Objective: To investigate the potential role of US in the detection of ILD in a cohort of patients with RA.

Methods: Patients with diagnosis of RA were consecutively enrolled. All patients underwent pulmonary examination, laboratory data, DLCO measure, chest HRCT and radiographs, and US examination. A healthy group was included as control group. US was performed according the 14-intercostal space scanning protocol using the following semiquantitative scale [0=normal (≤5 B-lines); 1=slight (≥6 and ≤15 B-lines); 2=moderate, (≤16 and ≥30 B-lines); 3=severe (≥30 B-lines)].

Results: A total of 74 RA patients and 74 healthy controls were included. Thirty of 74 patients (40.5%) showed US signs of ILD with respect to the healthy controls (3 subjects, 4.1%) (P<0.001); whereas HRCT showed ILD in 27 (36.4%) of 74 patients. Among the 30 patients that showed US findings of ILD, 17 (56.6%) were asymptomatic from respiratory view-point. The sensitivity and specificity of US were 92% and 89% respectively. A positive correlation between US and HRCT findings were found (P<0.001) whereas no correlation was found with chest radiographs and DLCO findings. Positive association between US findings and DAS28-ESR, anti-CCP and RF (P<0.01 for each respectively) was found. Feasibility, represented by the mean time spent to perform the pulmonary US assessment was 7.8minutes (±SD 1.2, range 6 to 10minutes).

Conclusions: Our results support the potential of US in detect accurately ILD in patients with RA and provide a rationale to consider it as a friendly screening tool to be implemented in early phases of the disease.