The use of D-dimer in exclusion of diagnosis of suspected Deep Vein Thrombosis

Abstract

Background: Deep venous thrombosis is a common disorder associated with significantmorbidity, chronic venous insufficiency as well as fatal pulmonary embolism. venography hasbeen the gold standard of diagnosis, however it has been replaced in most areas by duplexultrasound which is generally very good method .An interesting new approach to the diagnosis ofDVT is D-dimer testing, D-dimer levels reflect the amount of lysed, crossed-linked fibrin andmay be useful diagnostic marker in the clinically suspected DVT .D-dimer can be measuredeither quantitatively by ELISA or qualitatively by latex agglutination.Objectives: The aim of the study was to evaluate the use of D-dimer in exclusion of the diagnosisof DVT.Patient and methods: A total of 50 patients presented to vascular outpatient department withclinical suspicion of DVT have been studied ,patients with old DVT ,patients on anticoagulant,and patient with severe infection or inflammation were excluded .Venous duplex ultrasonographyof the affected limb or limbs was done and citrated blood sample was analyzed for D-dimer by aVIDAS method for all patients blindly to the results of venous duplex .Sensitivity ,specificity,negative and positive predictive values were calculated .ROC curve then was generated fromsensitivity and 1 _ specificity values at a continuum of D-dimer level to determine the optimalcut-off level of VIDAS D-dimer for exclusion of DVT.Results: The mean age of DVT group was 43 year. DVT was confirmed in 37 patients (74%),and excluded in 13 patients (26%) by venous duplex .The mean D-dimer level in the DVT groupwas 5498.021ng/dl while in non DVT group was 1906.384ng/dl this difference was statisticallysignificant (P=0.0003). The sensitivity , specificity , negative and positive predictive values ofVIDAS method at cut-off points(500 and 900) ng/dl were ( 100% , 33% , 100% , 82% )respectively ,and at 3000ng/dl ( 71% ,75%, 47%,90% ) respectively Conclusions: VIDAS D-dimer method is a sensitive method that can be used in the initialmanagement of deep vein thrombosis if a level of 900ng/dl is used as a cut-off point for exclusionof deep vein thrombosis. VIDAS D-dimer method is not a specific test so it cannot be used for thediagnosis of deep vein thrombosis.

Keywords

D-Dimer, Diagnosis, DVT