Selective Use of D-Dimer Test for Deep Vein Thrombosis

Some patients with high clinical pretest probability had venous ultrasonograpy without D-dimer testing and some patients presenting with symptoms had uniform testing. The study groups were all consecutive symptomatic patients with a first episode of suspected DVT from five different hospitals.

Selective testing of 860 patients, defined as d-dimer testing for outpatients with low or moderate clinical pretest probability (C-PTP), where DVT excluded at d-dimer levels of equal to or less than 1.0 µg/mL, a low C-PTP or equal to or less than 0.5 µg/mL, moderate C-PTP. The groups who had venous ultrasonography without d-dimer testing for outpatients with high C-PTP and inpatients, or the 863 uniform testing defined as d-dimer testing for all participants where DVT was excluded at d-dimer levels of less than 0.51 µg/mL.

The incidence of symptomatic venous thromboembolism at three months was 0.5% in both study groups. Selective testing reduced the proportion of patients who required d-dimer testing by 21.8% and reduced the proportion that required ultrasonography by 7.6 % overall and by 21.0% in outpatients with low C-PTP. The authors concluded that a selective d-dimer testing strategy seems as safe as and more efficient than having everyone undergo d-dimer testing when diagnosing a first episode of suspected DVT. The study was published on January 15, 2013, in the journal Annals of Internal Medicine.

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