Diagnostic accuracy of the Triage D-dimer test for exclusion of venous thromboembolism in outpatients.
BACKGROUND
We evaluated the diagnostic performance of the Triage D-dimer test, a new fast quantitative point-of-care whole blood D-dimer assay and compared it with the Vidas D-dimer assay.


METHODS
The study population comprised 319 outpatients for whom D-dimer testing was requested in order to rule out venous thromboembolism (VTE). Routine testing consisted of a plasma ELISA D-dimer analysis (Vidas). For all included patients, an additional EDTA whole blood D-dimer test (Triage) was performed. Patients were classified by reference imaging or by follow-up of the medical record. Accuracy indices, receiver operating characteristics and the kappa coefficient for agreement were calculated using the cutoff values recommended by the manufacturer.


RESULTS
Prevalence of VTE was 14%. Sensitivity and specificity for VTE were 98% (95%CI: 88-100) and 34% (95%CI: 28-40) for Vidas and 91% (95%CI: 78-97) and 42% (95%CI: 36-48) for Triage, respectively. The differences in sensitivity and specificity between both D-dimer assays were statistically significant (McNemar, p<0.0001). ROC-curve analysis yielded an area under the curve of 0.83 (95%CI: 0.76-0.89) for the Vidas and 0.81 (95%CI: 0.74-0.88) for the Triage (p=0.396). The kappa coefficient for agreement between Vidas and Triage was 0.75 (95%CI: 0.68-0.79).


CONCLUSIONS
The Triage and Vidas D-dimer tests show comparable diagnostic accuracy. Vidas showed a significant higher sensitivity. Our findings strongly suggest lowering the cutoff for the Triage D-dimer test from 400 to 350 ng/mL. In this way specificity lowers from 42 to 38%, but, more importantly, sensitivity increases from 91 to 95%.
Ghys
Timothy
T
Department of Hematology, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, B-1090 Brussels, Belgium. tsghys@hotmail.com
Achtergael
Wim
W
Verschraegen
Inge
I
Leus
Barbara
B
Jochmans
Kristin
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019937:Diagnostic Techniques and Procedures / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D019095:Point-of-Care Systems / Q000592:standards; D011237:Predictive Value of Tests; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D054556:Venous Thromboembolism / Q000097:blood* / Q000175:diagnosis*
D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D