Clinical variables and lung ultrasonography for the screening of interstitial lung disease in patients with rheumatoid arthritis.

The best screening way to detect interstitial lung disease (ILD) in patients with rheumatoid arthritis (RA) is still debated.

Objectives: To evaluate the performance of scores to identify patients with ILD in patients with RA.

Methods: Cross-sectional study, adult outpatients with RA were included and those with any disease that can affect lung ultrasonography (LUS) evaluation were excluded. Sociodemographic, clinical, and therapeutic variables were recorded. All patients underwent chest x-rays, pulmonary function tests (PFT), LUS, and high-resolution chest tomography (HRCT). Univariate and multivariate analyses and ROC curves.

Results: 107 patients with RA, median age of 62 years (IQR 36-84), 82.2% female, and median disease duration 14 years (IQR 1-42). A total of 30 patients (29.5%) had ILD by HRCT. The classic cutoff value of ≥ 5 B lines in the LUS (ILD by HRCT as the gold standard) showed an AUC of 0.86 (95% CI 0.78-0.94), Se 87.1%, and Sp 74.3% for the detection of ILD. A clinical score made up of 5 variables to identify the presence of ILD, based on the strength of association in the multivariate analysis: male sex, crackles, age ≥ 60 years, RF + , anti-CCP + . Range 0-11, cutoff value ≥ 5.5, AUC 0.80 (95% CI 0.70-0.89), Se 75%, and Sp 71%. When we added the LUS variable to this score: lines B ≥ 5, the range was 0-15, a cutoff value ≥ 7.5, AUC 0.88 (95% CI 0.81-0.94), Se improved to 84.4%, and Sp 75%. However, this last score did not exceed the performance of isolated LUS.

Conclusions: LUS is a good tool for detecting ILD in patients with RA. Key Points • Interstitial lung disease (ILD) is an extra-musculoskeletal manifestation with high morbidity and mortality in patients with rheumatoid arthritis (RA). Early detection could improve the prognosis of these patients. • High-resolution chest tomography (HRCT) is the gold standard for ILD diagnosis, but high radiation and limited access hinder its use. • Lung ultrasound (LUS) is an excellent tool for detecting ILD in RA patients and performs better than clinical scores. • LUS provides a method of screening for ILD in patients with RA in a simple, cheap, safe, and effective way.