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

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

Methods: Patients meeting criteria for SSc and IM, with planned CT chest imaging underwent LUS imaging interpreted with LUS-ILD-24 by 3 blinded readers. The sensitivity and specificity for LUS-ILD detection as noted on CT was analyzed for SSc, IM, and possible incident ILD subgroups. Inter- and intra-rater agreement was calculated. Correlations between LUS-ILD-24 severity, CT imaging severity, and pulmonary function tests (PFTs) 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 intra-reader 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 (%DLCO) and forced vital capacity.

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