Zexuan Zhou, Kedi Zheng, Shaoyu Zheng, Chuzhen Chen, Guangzhou Du, Weijin Zhang, Jianqun Lin, Shijian Hu, Qisheng Lin, Jinghua Zhuang, Qingzi Chen, Barbara Ruaro, Anna-Maria Hoffmann-Vold, Marco Matucci-Cerinic, Daniel E Furst, Shaoqi Chen, Yukai Wang
LUS B-lines and serum KL-6 exhibit robust diagnostic value for SjD-ILD. The cut-offs > 22 B-lines and 329 U/mL KL-6 are recommended. Key Points • The concordance rate between LUS and HRCT was 82.86%, providing a noninvasive and reliable strategy for SjD-ILD screening, with an optimal cut-off of 22 B-lines (AUC = 0.952). • B-line score and serum KL-6 both strongly correlate with HRCT Warrick score, supporting their application as noninvasive tools to assess ILD severity in SjD.
OBJECTIVES: This study investigated the diagnostic accuracy of lung ultrasound (LUS) and serum KL-6 levels for detecting interstitial lung disease (ILD) in Sjögren's disease (SjD) patients.
METHODS: This retrospective study included 70 SjD patients evaluated at Shantou Central Hospital. All patients underwent chest high-resolution computed tomography (HRCT), LUS, and KL-6 measurement within one month. LUS was performed at 50 scanning sites. The presence and patterns of ILD were defined by HRCT findings. Serum KL-6 levels were measured using chemiluminescent enzyme immunoassay. Correlations between B-lines score, KL-6 level, and the HRCT Warrick score were analyzed. ROC curves with DeLong test and Spearman correlation analysis were performed to evaluate diagnostic efficiency and correlations with the Warrick HRCT fibrosis score.
RESULTS: The concordance rate between LUS and HRCT was 82.86% (Kappa value = 0.6572). The optimal cut-off value for detecting SjD-ILD was 22 B-lines (AUC = 0.952, sensitivity 82.86%, specificity 100%). Serum KL-6 levels were also significantly higher in patients with ILD compared to those without ILD on HRCT (430.8 [274.6-698.3] vs. 240.4 [168.5-298.8]). ROC analysis showed that a serum KL-6 concentration of 329 U/mL was the optimal cut-off value for detecting ILD in SjD patients (AUC = 0.814, sensitivity 65.71%, and specificity 88.57%). B-line score, KL-6 level, and Warrick score presented significant pairwise positive correlations.
CONCLUSIONS: LUS B-lines and serum KL-6 exhibit robust diagnostic value for SjD-ILD. The cut-offs > 22 B-lines and 329 U/mL KL-6 are recommended. Key Points • The concordance rate between LUS and HRCT was 82.86%, providing a noninvasive and reliable strategy for SjD-ILD screening, with an optimal cut-off of 22 B-lines (AUC = 0.952). • B-line score and serum KL-6 both strongly correlate with HRCT Warrick score, supporting their application as noninvasive tools to assess ILD severity in SjD.