Diagnostic value of serum KL-6 in Interstitial Lung Disease: preliminary results from an European cohort.

Abstract

Introduction: Krebs von den Lungen 6 (KL-6) is a mucin-like glycoprotein. KL-6 over-expression in regenerating type II epithelial cells lead to increased concentration in serum and is related to the presence of fibrotic lung lesions. KL-6 has been widely studied and used as a diagnostic and prognostic biomarker for Interstitial Lung Disease (ILD) in Asia. Data generated within European populations to evaluate its value is scarce. Objective: To investigate the diagnostic value of serum KL-6 levels to detect ILD in a Spanish cohort. Methods: New ILD cases and controls were prospectively included. At time of diagnosis, without especific treatment, both groups underwent blood tests. KL-6 levels were determined using a chemiluminescence assay “Lumipulse® G KL-6” (Fujirebio Europe NV). Sensitivity and specificity to discriminate between ILD and control subject was studied. ROC analysis was performed to determine optimal cut-off value of serum KL-6. Results: A total of 101 subjects were included, 58 with ILD. Median age (years±SD) was 69±13 in ILD and 59 ±11 in control group. In ILD group the median FVC and DLCO (%predicted ±SD) was 80±17 and 63±18 respectively. In ILD group the most frequent diagnosis was autoimmune systemic diseases and idiopathic pulmonary fibrosis. The main radiological pattern was NSIP (43%) followed by UIP (32%). ROC analysis using area under curve (Table 1) demonstrated higher specificity (88%) and sensibility (88%) with serum KL-6 level > 425 U/ml. Conclusions: Our data show that a value of serum KL-6 greater than 425 U/mL has excellent sensitivity and specificity to detect ILDs. Therefore, KL-6 could be a useful biomarker for ILDs diagnosis in European population.