Evaluation of the clinical performance of the HISCL‐5000 analyzer in the detection of Krebs von den Lungen‐6 antigen and its diagnostic value in interstitial lung disease

BACKGROUND: The sputum saccharide chain antigen (Krebs von den Lungen‐6 [KL‐6]) is a serum biomarker of lung injury. We aimed to evaluate the clinical performance of the automated immunoassay analyzer HISCL‐5000 in detecting KL‐6 by comparing it with LUMIPULSE G1200 and determine the diagnostic value of KL‐6 in interstitial lung disease (ILD). METHODS: A total of 145 serum samples from patients were tested using the two automated immunoassay analyzers in parallel. RESULTS: With a cutoff level of 500 U/mL, comparing the two systems, the agreement, sensitivity, specificity, and kappa value were 99.20%, 100%, 98.63%, and 0.984 (95% CI, 0.952‐1.000), respectively. Spearman's correlation and ICC showed that there was a strong correlation between serum KL‐6 levels measured by the two systems (r (S) = .991 [95% CI, 0.981‐0.995], ICC = 0.984 [95% CI, 0.978‐0.989], P < .01). The clinical diagnosis agreement rate in both systems was >80%. The kappa value was 0.707 (95% CI, 0.582‐0.832; SYSTEM B) and 0.707 (95% CI, 0.588‐0.826; SYSTEM A). The KL‐6 level in the ILD group (1339.5, 662.5‐2363) was significantly higher than that in the non‐ILD groups (252, 158.5‐353; Mann‐Whitney U = 381.5, P < .01), and the KL‐6 level (1558, 726‐2772.5) in the ILD group detected by SYSTEM A was significantly higher than that in the lung cancer group (339, 207‐424), other respiratory disease group (249, 194‐366), and control group (198, 131.5‐297; Kruskal‐Wallis H = 63.19, P < .01). CONCLUSIONS: HISCL‐5000 showed well‐concordant results with those of HISCL‐5000 in the KL‐6 tests. In patients with ILD, KL‐6 showed a good diagnostic performance.