Serum Krebs von den Lungen-6 level as a diagnostic biomarker for interstitial lung disease in Chinese patients.

OBJECTIVES: The purpose of this study was to determine the diagnostic and prognostic values of serum KL-6 levels in Chinese patients with interstitial lung disease (ILDs). METHODS: A total of 1084 subjects including 373 cases of ILDs, 584 cases of non-ILD pulmonary diseases, and 127 healthy individuals were recruited from three clinical centers in China between January 2011 and December 2013. A total of 106 patients undergoing treatments for ILDs in Shanghai Pulmonary Hospital between January 2011 and December 2013 were enrolled. Baseline and posttreatment serum KL-6 levels were determined. RESULTS: Serum KL-6 levels in patients with ILDs were significantly higher than those in patients with non-ILD pulmonary diseases or in healthy individuals (1492.09 ± 2230.08 U/mL vs 258.67 ± 268.73 U/mL or 178.73 ± 71.17 U/mL, all P < 0.05). At the cut-off value of 500 U/mL, the sensitivity and specificity of serum KL-6 as a diagnostic marker for ILDs was 77.75% and 94.51%, respectively. The Kappa value was 0.743 (P < 0.001). The area below the receiver operating characteristic curve was 0.922 with a 95% Confidence interval of 0.904-0.941 (P < 0.001). The posttreatment serum KL-6 levels significantly reduced in patients with improved ILDs, whereas markedly increased in patients with exacerbated ILDs (All P < 0.05). CONCLUSIONS: Serum KL-6 levels might be a promising diagnostic biomarker for ILDs in Chinese patients. The prognostic value of serum KL-6 levels for ILDs remains to be verified by large-scaled studies.