Safety of a strategy combining D-dimer testing and whole-leg ultrasonography to rule out deep vein thrombosis.

Guidelines for the diagnostic workup of deep vein thrombosis (DVT) recommend assessing the clinical pretest probability before proceeding to D-dimer testing and/or compression ultrasonography (CUS) if the patient has high pretest probability or positive D-dimer. Referring only patients with positive D-dimer for whole-leg CUS irrespective of pretest probability may simplify the workup of DVT. In this prospective management outcome study, we assessed the safety of such a strategy. We included consecutive outpatients referred to the Emergency Department at Østfold Hospital, Norway, with suspected DVT between February 2015 and November 2018. STA-Liatest D-Di Plus D-dimer was analyzed for all patients, and only patients with levels ≥0.5 µg/mL were referred for CUS. All patients with negative D-dimer or negative CUS were followed for 3 months to assess the venous thromboembolic rate. One thousand three hundred ninety-seven patients were included. Median age was 64 years (interquartile range, 52-73 years), and 770 patients (55%) were female. D-dimer was negative in 415 patients (29.7%) and positive in 982 patients (70.3%). DVT was diagnosed in 277 patients (19.8%). Six patients in whom DVT was ruled out at baseline were diagnosed with DVT within 3 months of follow-up for a thromboembolic rate of 0.5% (95% confidence interval, 0.2-1.2). A simple diagnostic approach with initial stand-alone D-dimer followed by a single whole-leg CUS in patients with positive D-dimer safely ruled out DVT. We consider this strategy to be a valuable alternative to the conventional workup of DVT in outpatients. This trial was registered at www.clinicaltrials.gov as #NCT02486445.

Safety and feasibility of rivaroxaban in deferred workup of patients with suspected deep vein thrombosis.

Guidelines suggest using empiric low-molecular-weight heparin if the diagnostic workup of deep vein thrombosis (DVT) is expected to be delayed. The role of direct oral anticoagulants for deferred compression ultrasound imaging (CUS) in patients with suspected DVT remains unexplored. The main objective of the study was to assess the safety of deferring CUS with therapeutic doses of rivaroxaban. We prospectively included consecutive outpatients referred to the Emergency Department at Østfold Hospital, Norway, with suspected first or recurrent lower-extremity DVT between February 2015 and November 2018. Patients were discharged with rivaroxaban 15 mg twice daily while awaiting CUS within 24 hours if D-dimer level was ≥0.5 mg/L fibrinogen-equivalent units. The primary outcome was the rate of major bleeding incidents from study inclusion until DVT was confirmed and anticoagulation therapy continued, or otherwise up to 48 hours following administration of the last tablet of rivaroxaban. The secondary outcome was the rate of progressive DVT symptoms or symptoms or signs of pulmonary embolism between hospital discharge until venous thromboembolism was diagnosed. Six hundred twenty-four of 1653 patients referred with suspected DVT were included (37.7%; 95% confidence interval [CI], 35.4-40.1). DVT was diagnosed in 119 patients (19.1%; 95% CI, 16.1-22.3). There were no major bleeding incidents, yielding an observed major bleeding rate of 0% (1-sided 95% CI <0.4). No patients experienced major complications in the interval that CUS was deferred (0%; 95% CI, 0.0-0.6). Deferring CUS for up to 24 hours in patients with suspected DVT with therapeutic doses of rivaroxaban is a safe strategy. This trial was registered at www.clinicaltrials.gov as #NCT02486445.

D-dimer as a stand-alone test to rule out deep vein thrombosis.

BACKGROUND: Current guidelines recommend the use of clinical decision rules, such as Wells score, in combination with D-dimer to assess the need for objective imaging to rule out deep vein thrombosis (DVT). However, the clinical decision rule has limitations, and use of D-dimer as a stand-alone test has been suggested. OBJECTIVE: We aimed to assess the safety and efficiency of D-dimer as a stand-alone test to rule out DVT in outpatients referred with suspected DVT. METHODS: We collected data from consecutive outpatients referred to our hospital with suspected DVT in 2008-2018. D-dimer levels were analyzed using STA® Liatest® D-Di assay. D-dimer as a stand-alone test was theoretically applied in retrospect, and the number of misdiagnosed events were estimated as if such an approach had been initially used. All patients were followed for three months. RESULTS: Of 1765 included patients, 293 (16.6%) were diagnosed with DVT. A total of 491 patients (27.8%) had a negative D-dimer (<500 ng/mL). Of these, nine were diagnosed with DVT, yielding a failure rate for D-dimer as a stand-alone test of 1.8% (95% CI 0.8%-3.5%). The majority of the misdiagnosed patients had distal DVT. In analyses restricted to proximal DVTs, the failure rate was 0.6% (95% CI 0.1%-1.8%). D-dimer as a stand-alone approach reduced the proportion of required ultrasounds from 81.8% to 72.2%. CONCLUSION: D-dimer as a stand-alone test may be safe for excluding proximal DVT and reduce the proportion of required ultrasounds. Prospective management studies are needed to confirm our findings.