Journal Article

Serum KL-6 levels reflect the severity of interstitial lung disease associated with connective tissue disease

Kang, Eun Ha, Song, Yeong Wook, Ha, You-Jung, Lee, Eun Young, Lee, Jeong Seok, Lee, Yun Jong

2019

Overview

Background Biomarkers have been actively investigated to supplement functional and imaging modalities to predict the severity, therapeutic responsiveness, and progression of connective tissue disease-associated interstitial lung disease (CTD-ILD). This study aimed to evaluate Krebs von den Lungen 6 (KL-6) as a potential biomarker reflecting the severity of CTD-ILD as assessed through computed tomography (CT) and pulmonary function test (PFT) parameters. Methods This retrospective study included 549 Korean patients with rheumatoid arthritis, systemic sclerosis, inflammatory myositis, and other CTDs with or without concurrent ILD. Serum KL-6 concentration (U/mL) was measured using the latex-enhanced immunoturbidimetric assay method. CT and PFT results were collected within 1 year of serum collection. A semiquantitative grade of ILD extent was evaluated through CT scan (grade 1, 0–25%; grade 2, 26–50%; grade 3, 51–75%; grade 4, 76–100%). Results CTD-ILD patients ( n  = 165) had elevated serum KL-6 levels compared to CTD patients without ILD ( n  = 384) ( p  < 0.001), and those findings were preserved after adjusting for age, sex, and CTD type. The semiquantitative grade of ILD on CT scan was significantly proportional to the KL-6 level, and the optimal cut-off KL-6 value effectively differentiated each ILD grade. The percent diffusing capacity of the lung for carbon monoxide (DLCO) ( p  < 0.001) and forced vital capacity (FVC) ( p  < 0.001) parameters had a moderate, negative correlation with the KL-6 level. Conclusion Serum KL-6 levels were increased in CTD-ILD patients and had a positive correlation with CT grade and a negative correlation with FVC and DLCO. Serum KL-6 levels may reflect CTD-ILD severity.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adult / Aged / Arthritis / Autoimmune diseases / Biomarkers / Biomarkers - blood / Cancer / Carbon monoxide / CAT scans / Connective tissue disease / Connective Tissue Diseases - blood / Connective Tissue Diseases - complications / Connective Tissue Diseases - pathology / Development and progression / Diagnosis / Diagnostic imaging / Disease Progression / Female / Glycoproteins / Humans / Interstitial lung disease / Interstitial lung diseases / KL-6 / Lung diseases / Lung Diseases, Interstitial - blood / Lung Diseases, Interstitial - complications / Lung Diseases, Interstitial - pathology / Lung volume measurement / Male / Medical imaging / Medical prognosis / Medical research / Medical tests / Medicine / Medicine & Public Health / Middle Aged / Mucin-1 - blood / Myositis / Orthopedics / Pneumonia / Pulmonary function test / Pulmonary function tests / Research Article / Respiratory Function Tests / Respiratory tract diseases / Retrospective Studies / Rheumatoid arthritis / Rheumatoid factor / Rheumatology / Scleroderma (Disease) / Severity of Illness Index / Tomography / Tomography, X-Ray Computed