D-Dimer Levels and Vitamin K Antagonist Therapy in Deep Vein Thrombosis of the Legs.

BACKGROUND: D-dimer levels are closely related to the clinical status of deep vein thrombosis (DVT). This study aimed to investigate the factors which were associated with the normalization of D-dimer level by vitamin K antagonist (VKA) therapy, the maintenance of normal D-dimer levels for 6 months during VKA therapy, and the recurrent elevations of D-dimer above normal level after VKA withdrawal, in DVT of the legs.

METHODS: The 469 consecutive patients with first-episode leg swelling were examined. All blood tests were measured from the initially sampled blood before the administration of medications.

RESULTS: Of the 469 patients, 288 (61.4%) showed positive D-dimer test. Radiologic examinations, including Doppler ultrasound and computed tomography venography, of the 288 patients revealed positive DVT of the legs in 135 (46.9%) patients and of these, 122 with total follow-up durations of >6 months were enrolled in this study. Linear regression analysis of 100 patients who experienced D-dimer normalization revealed initial D-dimer levels were positively correlated with D-dimer normalization time during VKA therapy (P = 0.010). Logistic regression analysis showed initial D-dimer level was negatively associated with the normalization of D-dimer levels by VKA therapy (P = 0.045), and being a woman (P = 0.005) and having lower protein C (P = 0.002) level had negative impacts on the maintenance of normal D-dimer levels for 6 months during VKA therapy. Finally, after VKA withdrawal, the recurrent elevations of D-dimer above normal level were more likely to occur in women than in men (P = 0.004).

CONCLUSIONS: From these observations, it is suggested that higher initial D-dimer level, lower protein C level, and female gender may be the adverse risk factors for the treatment of DVT of the legs using VKA.