The Application Value Of Serum KL-6 In Connective Tissue Disease Associated Interstitial Lung Disease

Objective: To evaluate the application of the serum Krebs von den Lungen-6(KL-6)for the interstitial lung disease(ILDs)associated with connective tissue diseases(CTDs).Methods: Patients with CTDs who visited our Hospital between January,2016 and December,2017,and whose serum KL-6 level was measured were included.We analyzed 175 patients with CTDs,84 CTDs associated ILD,91 CTDs patients without ILD.Record age、gender、diagnosis、serum KL-6 levels、pulmonary function tests and performed in parallel were reviewed.Statistical analysis was performed using SPSS(version21.0)statistical package,if the data is in a normal distribution,Data were expressed as mean values ± standard deviation(SD).Group comparisons were made by using the Mann-Whitney U test.Correlation was performed using Spearman’s rank order correlation.ROC curve to determine the appropriate cut-off level resulting in optimal diagnostic accuracy.Logistic regression was used to analyze the regression analysis of classified data.Significance was defined as P< 0.05.Results:The significantly higher levels of KL-6 were determined in the CTD-ILD group than in the CTDs without pulmonary involvement group(P<0.05).By the ROC curves of serum KL-6levels in 175 patients.The optimal cutoff value of serum KL-6 for a diagnosis of CTD-ILD was409U/ml,and the sensitivity and specificity were82.1% and 86.8%,respectively.The AUC was0.905.Serum KL-6 correlated negatively with vital capacity(VC)(%predicted)、 forced vital capacity(FVC%)(%predicted)、forced expiratory volume in one second(FEV1%)(%predicted)and diffusing capacity of the lung for carbon monoxide(DLco SB)(% predicted).Serum KL-6correlated Positive correlation with Gross glass score.The optimal cutoff value of serum KL-6 for a diagnosis active of CTD-ILD was 1018U/ml,and the sensitivity and specificity were88.2% and64.0%,respectively.Conclusion:The serum KL-6 is a valuable biomarker for CTD-ILD diagnosis,and it is an important serum marker for detection of CTD-ILD activity.