Diagnostic Value of Krebs Von Den Lungen (KL-6) for Interstitial Lung Disease: A European Prospective Cohort

Introduction: Krebs von den Lungen 6 (KL-6) is a mucin-1 glycoprotein produced by type II pneumocytes. High levels of KL-6 in blood may be found in patients with lung fibrosis. In Asia this biomarker is used for diagnosis and prognosis in interstitial lung diseases (ILD). There is a lack of information regarding KL-6 cut-off point for diagnosis and prognosis in European population. The aim of this study was to establish the cut-off point for serum KL-6 associated with the presence of ILD in the Spanish population. Methods: Prospective study including subjects who underwent chest HRCT, PFTs and autoimmune blood analysis. Two groups were created: non-ILD subjects and ILD patients. Serum KL-6 concentrations were measured using a Lumipulse KL-6 reagent assay and the optimal cut-off value was evaluated by a ROC analysis. Data on demographics and smoking history was also collected. Results: One hundred seventy-nine patients were included, 102 with ILD. Median serum KL-6 values overall were 762 U/mL, 1080 (+/- 787) U/mL for the ILD group vs 340 (+/- 152) U/mL for the non-ILD group (p < 0.0001). The main radiological pattern was NSIP (43%). ROC analysis showed greater specificity (86%) and sensitivity (82%) for KL-6 465 U/mL for detecting ILD patients. The multivariate logistic regression model pointed to the male sex, higher KL-6 values, lower FVC and low DLCO values as independent factors associated with ILD. Conclusion: Serum KL-6 values greater than 465 U/mL have excellent sensitivity and specificity for detecting ILD in our Spanish cohort. Multicentre studies are needed to validate our results. (c) 2024 SEPAR. Published by Elsevier Espa na,S.L.U. All rights reserved.