Clinical question: Does tailoring the duration of anticoagulation based on the persistence of residual thrombus following conventional duration therapy reduce rates of recurrent venous thromboembolism (VTE) in adults with proximal deep-venous thrombosis (DVT)?

Background: The optimal duration of oral anticoagulation therapy in adults with proximal DVT remains uncertain. This study was designed to ascertain if tailoring the duration of therapy based on ultrasonographic findings improves outcomes through a reduction in recurrent VTE.

Study design: Parallel, open-label, randomized trial with independent and blinded assessment of study outcomes.

Setting: Nine university and hospital centers in Italy.

Synopsis: Five hundred thirty-eight patients with proximal DVT who completed three months of anticoagulation were randomly assigned to fixed-duration or flexible-duration therapy. Patients in the fixed-duration group with provoked DVT received no further therapy; those with unprovoked DVT received an additional three months of anticoagulation. Patients in the flexible-duration group had no further therapy if ultrasonography demonstrated recanalized veins, and received further therapy (up to nine to 21 months for provoked and unprovoked DVT, respectively) if persistent thrombi were demonstrated. Patients were followed over three years for the primary outcomes of recurrent VTE and major bleeding events.

Significantly fewer recurrent VTE occurred in the ultrasound guided, flexible-duration treatment group (11.9% vs. 17.2%; HR 0.64; 95% CI 0.39 to 0.99). There was no significant difference in major bleeding events between the two groups.

Limitations of this study include the lack of a double-blind design and the relatively small sample size.

Bottom line: Tailoring the duration of anticoagulation in adults with proximal DVT based on ultrasonographic demonstration of residual thrombi reduces rates of recurrent VTE without increasing major bleeding events.

Citation: Prandoni P, Prins MH, Lensing AW, et al. Residual thrombosis on ultrasonography to guide the duration of anticoagulation in patients with deep venous thrombosis: a randomized trial. Ann Intern Med. 2009;150(9):577-585.

Reviewed for TH eWire by Alexander R. Carbo, MD, FHM; Suzanne Bertisch, MD, MPH; Lauren Doctoroff, MD; John Fani Srour, MD; Caleb Hale, MD; Nancy Torres-Finnerty, MD, FHM, Hospital Medicine Program, Beth Israel Deaconess Medical Center, Boston