Validation of Lung Ultrasound Interpretation Criteria for Interstitial Lung Disease in Systemic Sclerosis and Inflammatory Myopathy

Abstract

Objective: Interstitial lung disease (ILD) has a high prevalence in patients with systemic sclerosis (SSc) and inflammatory myopathy (IM), and early identification reduces associated morbidity and mortality. We previously developed lung ultrasound (LUS) interpretation criteria for ILD detection in 2020 (LUS-ILD-20) showing excellent sensitivity and specificity in patients with SSc-ILD; herein, we sought to validate a revised LUS-ILD-24 in a large cohort with SSc and IM.

Methods: Patients meeting criteria for SSc and IM, with planned computed tomography (CT) chest imaging underwent LUS imaging interpreted with LUS-ILD-24 by three blinded readers. The sensitivity and specificity for LUS-ILD detection as noted on CT was analyzed for subgroups with SSc, IM, and possible incident ILD. Inter- and intrarater agreements were calculated. Correlations between LUS-ILD-24 severity, CT imaging severity, and pulmonary function tests were assessed.

Results: Ninety-five patients were included in the analyses. Sensitivity and specificity for ILD detection ranged from 92.4% to 95.5% and 82.8% to 86.2% across readers with similar accuracy in all subgroups. Inter- and intrareader reliability showed near perfect agreement (κ = 0.92 and κ = 0.90 to 1, respectively). LUS severity correlated with CT imaging severity and inversely correlated with diffusion capacity for carbon monoxide and forced vital capacity.

Conclusion: We validated our revised LUS-ILD-24 in cohorts with SSc and IM and found excellent sensitivity, specificity, and reliability for detection of ILD identified on CT imaging. LUS severity correlated with CT and pulmonary function test markers of ILD severity. Validation of the revised LUS-ILD-24 supports the implementation of LUS imaging in screening algorithms for ILD in patients with SSc and IM.