PB0975 - The effect of rivaroxaban on the diagnostic value of D-dimer

Background: Preemptive anticoagulation is widely used in the pre-diagnostic phase of deep vein thrombosis (DVT). In some parts of the world anticoagulation is administered prior to D-dimer testing. Direct oral anticoagulants (DOACs) have been shown to be a safe alternative empiric treatment to low-molecular weight heparin. However, the impact of DOACs on D-dimer in patients with suspected DVT is not well established.

Aims: This study aimed to determine the effect of empiric rivaroxaban on the diagnostic performance of D-dimer.

Methods: D-dimer was measured before and after the administration of one to two doses (15 mg) of rivaroxaban in 418 outpatients, referred with suspected DVT to the emergency department at Østfold hospital, Norway. To determine whether the effect of rivaroxaban significantly impacted D-dimer results, we calculated the diagnostic performance of the test before and after the administration of rivaroxaban.

Results: Median D-dimer values decreased from 1.0 mg/L (IQR, 0.7-2.2) to 0.9 mg/L (IQR, 0.6-2.0) and 286 (68.4%) of the patients had a decrease in D-dimer after administration of rivaroxaban. For the patients with decreased D-dimer, D-dimer decreased by 18.0% and 25.3% on average for the patients who took one and two tablets of rivaroxaban, respectively. Thirty-six patients (8.9%) with positive D-dimer (≥ 0.5 mg/L) before taking rivaroxaban had negative D-dimer values ( < 0.5 mg/L) after rivaroxaban intake (table 1). Of these, two had DVT diagnosed by CUS and had Wells scores of 2 and -2, respectively. The sensitivity of D-dimer decreased from 99.0% (95% CI, 94.6-99.8) to 97.0% (95% CI, 91.6-99.0) (table 1).

Conclusion(s): Rivaroxaban administered before measuring D-dimer may reduce D-dimer levels leading to false negative results and reduced sensitivity. As this study lacked a control group, caution is advised in interpretation of D-dimer results after the administration of rivaroxaban. Whether these results apply to other anticoagulant drugs should be examined in future trials.