Introduction: Empiric anticoagulation therapy is often used in patients with suspected deep vein thrombosis (DVT) to avoid complications if the workup is delayed. Studies have shown the safety of administering direct oral anticoagulants (DOACs) and low molecular weight heparin in patients with suspected DVT. However, the impact of empiric DOACs on D-dimer levels in patients with suspected DVT is not well established. Therefore, this study aimed to determine the effect of empiric rivaroxaban on the diagnostic performance of D-dimer.
Materials and methods: D-dimer was measured before and after the administration of one to two tablets of rivaroxaban in 418 patients 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 patients had taken rivaroxaban. All patients with negative workup were followed up at 90 days.
Results: Two hundred eighty-six (68.4 %) of the 418 included patients had lower D-dimer results after taking rivaroxaban. 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). Thirty-six patients (8.9 %) with positive D-dimer (≥ 0.5 mg/L fibrinogen-equivalent units) before taking rivaroxaban had negative D-dimer values after rivaroxaban intake. Of these, two had DVT diagnosed by compression ultrasonography. The sensitivity of D-dimer decreased from 99.0 % (95 % CI: 94.6-99.8) to 97.0 % (95 % CI: 91.6-99.0).
Conclusions: Rivaroxaban administered before measuring D-dimer may reduce the sensitivity and increase false negative results of the test. Based on these results, we recommend performing D-dimer before the administration of rivaroxaban.
Keywords: Anticoagulation; D-dimer; Deep vein thrombosis; Diagnosis; Rivaroxaban; Sensitivity.
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