Lung Ultrasound Valid for Detecting Interstitial Lung Disease Associated With RA

Illustration of the human heart and lung.
The diagnostic utility of lung ultrasound to detect interstitial lung disease in RA patients compared with high-resolution CT was studied.

Lung ultrasound represents a valid method for detecting interstitial lung disease (ILD) associated with rheumatoid arthritis (RA) and could serve as an alternative to lung function testing (LFT) and high-resolution computed tomography (HRCT), according to findings from a study published in Clinical Rheumatology.

In this cross-sectional, observational study, researchers from Spain evaluated a cohort of patients with RA-ILD (n=35) and patients with RA but without ILD (n=36) using HRCT, LFT, and lung ultrasound. The primary variable – utility of pulmonary ultrasound scores – was based on the number of B lines. Researchers performed a receiver operator characteristic curve analysis to establish a cutoff point of the ultrasound B-lines for the detection of significant RA-ILD, while intercostal spaces were identified using logistic regression analysis.

In terms of the ultrasound score, the investigators reported a sensitivity of 62.2%, specificity of 91.3%, positive predictive value (PPV) of 88.4%, and negative predictive value (NPV) of 69.5% for the detection of 5.5 lines in a reduced score of 10 intercostal spaces. In comparison, the detection of ≥10 B lines in the 72-space score featured a sensitivity of 91.4%, specificity of 55.6%, PPV of 66.7%, and a NPV of 86.9%.

According to a multivariate analysis, the precise intercostal spaces that featured an independent association with ILD included the third right anterior axillary space (odds ratio [OR], 19.09; 95% CI, 1.34-27.58), eighth right posterior axillary space (OR, 0.04; 95% CI, 0.01-0.69), eighth right subscapular space (OR, 16.50; 95% CI, 1.8-45.57), ninth right paravertebral space (OR, 7.11; 95% CI, 1.07-37.10), and second left clavicular middle space (OR, 21.90; 95% CI, 1.26-37.83).

A limitation of this study included the investigators’ inability to distinguish whether B lines were caused by edema or fibrosis.

The investigators concluded that the simplified scoring system used in this study, which evaluates 10 intercostal spaces instead of 72, may be a helpful approach for the detection of RA-ILD as “from a technical viewpoint, examining so many intercostal spaces is very time-consuming and laborious.”

Reference

Mena-Vázquez N, Jimenez-Núñez FG, Godoy-Navarrete FJ, et al. Utility of pulmonary ultrasound to identify interstitial lung disease in patients with rheumatoid arthritis. Clin Rheumatol. 2021;40(6):2377-2385. doi:10.1007/s10067-021-05655-1