28 November 2022

Patients with isolated distal deep vein thrombosis (DVT) prescribed rivaroxaban for 12 weeks instead of the usual six have a reduced risk of clots developing up to two years after treatment, researchers report today.

A trial, published by The BMJ, found the additional six weeks of this anticoagulation treatment did not result in an increased risk of bleeding.

However, the researchers say that it remains unclear if all patients with distal DVT should receive anticoagulation, and for how long.

A team from Italy, led by the University of Insubria, compared two different treatment durations of rivaroxaban in 402 adults diagnosed with isolated distal DVT at 28 specialist outpatient clinics across Italy. The cohort’s average age was 65, and 58% were women.

After receiving standard dose rivaroxaban for six weeks, participants who had not developed any clotting or bleeding complications were randomly assigned to receive either 20 mg rivaroxaban or a placebo once a day for another six weeks.

The patients were assessed for new clots or serious bleeding at three weeks, six weeks, three months, and 24 months. The results found that after randomisation, 23 (11%) patients in the rivaroxaban group and 39 (19%) in the placebo group developed a further clot – representing a 41% reduction in risk for the group receiving 12 weeks of rivaroxaban.

Most of this reduction was a result of preventing recurrent DVT. In the rivaroxaban group there were 16 cases (8%) of recurrent isolated distal DVT compared to 31 (15%) in the placebo group, whereas for proximal DVT or pulmonary embolism, there were seven cases (3%) of in the rivaroxaban group and eight (4%) in the placebo group.

No major bleeding events were recorded in the two-year study period, and the researchers estimate that one blood clot was prevented for every 13 patients receiving additional rivaroxaban.

“Rivaroxaban administered for three months effectively and safely reduces the risk of recurrent venous thromboembolism compared with rivaroxaban administered for six weeks in patients with isolated distal DVT,” they write.

However, the researchers stress that their findings do not apply to patients with cancer-associated DVT and should not be extrapolated to other anticoagulant treatments.


Ageno W, Bertù L, Bucherini E, Camporese G, Dentali F, Iotti M, Lessiani G, Parisi R, Prandoni P, Sartori M, Visonà A, Bigagli E, Palareti G, on behalf of the RIDTS study group. (2022) “Rivaroxaban treatment for six weeks versus three months in patients with symptomatic isolated distal deep vein thrombosis: randomised controlled trial.” The BMJ, doi: 10.1136/bmj-2022-072623

Link: https://www.bmj.com/content/379/bmj-2022-072623 

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