Comparison of a point of care device against current laboratory methodology using citrated and EDTA samples for the determination of D-dimers in the exclusion of proximal deep vein thrombosis.
D-dimer estimation is a routine part of diagnostic algorithms for the exclusion of venous thromboembolism (VTE). We evaluated a point of care device, Biosite Triage (Inverness Medical UK, Cheshire, UK) for the estimation of D-dimers in both samples taken into citrate and EDTA against our routine laboratory D-dimer (Liatest D-dimer, Diagnostica Stago, Reading, UK) performed on the STA-R Evolution. With informed consent, 102 consecutive patients presenting with possible deep vein thrombosis (DVT) were enrolled and D-dimers along with Wells scores and compression ultrasonography (CUS) were recorded. Using the manufacturers' recommended cut offs of 500 microg/l fibrinogen equivalent units and 400 microg/l for the Stago and Triage, respectively, sensitivity, specificity, positive and negative predictive values were calculated. These were 1.00, 0.42, 0.17, and 1.00 for the Triage machine using citrate samples, 1.00, 0.32, 0.14, and 1.00 using EDTA samples and 1.00, 0.29, 0.16, and 1.00 for the Stago Liatest assay, respectively. Three patients had significantly higher results for the Stago Liatest D-dimer assay compared with the Biosite Triage device although ultrasound scans were negative.


CONCLUSIONS
The Biosite Triage D-dimer assay performed on either citrate or EDTA samples is comparable with the Stago Liatest laboratory D-dimer assay when used in conjunction with clinical pretest probability scoring and CUS for the exclusion of DVT.
Oxford Haemophilia and Thrombosis Centre, Churchill Hospital, Oxford, UK. peter.baker@orh.nhs.uk
P M
PM
Baker
S J
SJ
Howgate
J
J
Atherton
D M
DM
Keeling
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019343:Citric Acid; D004492:Edetic Acid; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging
D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D019343:Citric Acid; D004492:Edetic Acid