The Optimal Cut-off Value Of Plasma D-dimer In Diagnosis Of Lung Cancer With Pulmonary Thromboembolism

Objective:To investigate the optimal cut-off value of plasma D-dimer for lung cancer with pulmonary thromboembolism.Method:The enrolled participants were 100 lung cancer patients suspected with low or intermediate probability of having a pulmonary thromboembolism(PTE)from The First Affiliated Hospital of Nanchang University between January 2011 and August2017 All of them underwent multi-slice spiral CT pulmonary angiography(CTPA)and D-dimer test.We collected and compared the clinical data,type of lung cancer,lung cancer staging,age-adjusted plasma D-dimer level between those with PE and those without.ROC curve of age-adjusted plasma D-dimer level for identifying PE in lung cancer patients was drew,and the optimal cut-off value was determined,the corresponding sensitivity,specificity,positive predictive value,negative predictive value and accuracy rate were calculated.Result:Lung cancer patients with PTE presented higher median ageadjusted D-dimer level compared with those without [5811.8(17095.7)?g/L vs 730.0(1 050.9)?g/L](P<0.001).Lung adenocarcinoma patients demonstrated higher median age-adjusted D-dimer level compared with those with other types of lung cancer [1493.7(6343.5)?g/L vs 785.2(1448.9)?g/L](Z=-2.621,P<0.05).Stage?-? lung cancer patients showed lower median age-adjusted D-dimer level compared with stage ?-? lung cancer patients [469.3(1 602.7)?g/L vs 1110.0(4750.9)?g/L](Z=-1.976,P<0.05).The AUC of age-adjusted D-dimer level for the identification of PE was 0.796[95%CI(0.696,0.896)],the optimal cut-off value was 2835 ?g/L,corresponding sensitivity,specificity,positive predictive value,negative predictive value,accuracyrate and Youden's index were 62.9%,92.3%,81.5%,82.3%,82.0%,0.552,respectively.Conclusion:The age-adjusted plasma D-dimer of 2835?g/L plays an important role in the identification of PTE in lung cancer patients.