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.”
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