Summary
Despite the use of a clinical score and D-dimers to exclude deep vein thrombosis (DVT),
the majority of patients still need repeated ultrasound (US).The aim of the study
was to investigate whether fibrin monomers (FMs), as markers of thrombin generation,
have additional value in the diagnosis of DVT. This is a posthoc analysis of 464 outpatients,
participants in a management study using D-dimers (Tina-Quant® ) and a clinical score
in the exclusion of DVT. Two new FM assays (Auto LIA-FM® and IATRO SF®, Japan) were performed. Overall sensitivity, negative predictive value (NPV) and
specificity of the D-dimer test were 98%, 98% and 42%.The optimal cut-off point for
the Auto LIAFM test was ≤ 3 µ g/ml with values of 88%, 88% and 59%, respectively.
The IATRO SF test had an optimal cut-off point of ≤ 2 µ g/ ml with values of 92%,
81 and 22%, respectively.The NPV of a non-high clinical score and a normal D-dimer
(n=97) was 100%. In patients with a high clinical score (n=160), the NPV of the D-dimer
was 88%. In these patients, a single US combined with a normal D-dimer or FM test
had an equal NPV as serial US (100 versus 98%, respectively) and lead to a reduction
in the need for US by 36–53%, respectively. In patients with abnormal D-dimer concentrations
(n=343), a normal US combined with a normal Auto LIA-FM test had a NPV of 97%,which
was also true for serial US.This could lead to a reduction in the need for US by 45%.
The present studied FMs are inferior to theTina-Quant D-dimer test when used as primary
screening tool to exclude DVT.Adding these FMs to patients with a normal Tina-Quant
D-dimer has no benefit. In patients with a high pretest clinical probability score,
a single US in combination with a normal D-dimer or FM test might be as safe as serial
US. In patients with abnormal D-dimer concentrations and a normal US, a normal FM
test might be able to replace the second US.
Keywords
D-dimer - fibrin monomer - diagnosis - venous thromboembolism - deep vein thrombosis
- ultrasonography