Abstract
Introduction
The cross-linked fibrin degradation product known as D-dimer, in combination with pretest clinical probability scores, is widely used in deep vein thrombosis（DVT） exclusion diagnosis. However, if the common normal range
for D-dimer is taken as the cutoff for all patients, regardless of medical status, the exclusion efficiency is unacceptably low. Therefore, it is necessary to establish optimal cutoffs based on patient population and reagent type.
This study retrospectively examined cases in which the LPIA Genesis D-dimer test（LG-DD） was employed.
Methods
We confirmed optimal D-dimer cutoffs for DVT exclusion diagnosis for each patient background with thrombotic tendencies. The 764 patients tested for lower extremity DVT by ultrasonography were divided into three
groups: No DVT, acute DVT, and chronic DVT. D-dimer values were compared among patients over the age of
55, patients with a malignant tumor, post-operative patients, pregnant patients, and other medical conditions.
Results
Each population, excluding pregnant patients, showed significantly higher values in the acute DVT group than in the no DVT and chronic DVT groups. The optimal D-dimer cutoff for patient characteristics was 1.9 μg/mL in the “other” category and 2.1 μg/mL in the group over 55 years old. The cutoff was as high as 3.4 μg/mL in the malignant tumor patient group and 16.6 μg/mL in the post-operative patient group. In addition, when an age-adjusted cutoff was used, the specificity and positive likelihood ratio were improved, while maintaining high sensitivity.
Conclusion
The D-dimer measurement using LG-DD is useful in DVT exclusion diagnosis. Effective and efficient DVT exclusion diagnosis can be determined by setting a D-dimer cutoff based on the characteristics of the patient.
