Extending Anticoagulation with Rivaroxaban After DVT Could Further Reduce Recurrent Thrombosis Risk

Extending anticoagulation with rivaroxaban for 6 additional weeks beyond the standard 6 weeks of anticoagulation could reduce future thrombosis, according to new data from the RIDTS study.

A randomized, double-blind, placebo-controlled trial, results of the study, which compared a 6- vs 12-week course of rivaroxaban in patients with symptomatic isolated distal deep vein thrombosis (DVT), suggest adherence to a 12-week course reduced the relative risk of recurrent venous thromboembolism by 41% compared with the standard 6-week course in this patient group.

“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,” wrote investigators.

Recent advances in knowledge and therapeutics have contributed to a revolution in antithrombotic management. Soon after the advent of rivaroxaban, the factor Xa inhibitor found itself in patient algorithms and treatment guidelines. As its role in anticoagulation has become more well-defined across multiple patient groups, debate has emerged regarding the optimal treatment duration. With this in mind, a team of investigators launched the Rivaroxaban for the Treatment of Symptomatic Isolated Distal Deep Vein Thrombosis (RIDTS) study.

Recruiting individuals from 28 medical centers in Italy, RIDTS was designed as a randomized, double-blind, placebo-controlled trial with the specific intent of comparing the effects of 6 weeks vs 12 weeks of rivaroxaban on risk of recurrent thrombosis and major bleeding events over a 2-year follow-up among patients with symptomatic isolated DVT. From the 28 medical centers, investigators identified 448 people for inclusion in their trial.

Per study protocol, all participants were randomized to receive rivaroxaban 20 mg or placebo therapy once daily for 6 additional weeks following receipt of rivaroxaban for 6 weeks at the beginning of the trial. Of the 448 identified for inclusion, 46 were excluded before randomization during the first 6 weeks of treatment, yielding a total study population of 402 individuals.

Among the 402 who underwent randomization, 200 were randomized to rivaroxaban and 202 to placebo therapy. The mean age in both groups was 65 years and women represented 58% of rivaroxaban arm and 59% in the placebo arm. Investigators pointed out isolated distal DVT was unprovoked in 40% of the rivaroxaban arm and 43% of the placebo arm.

The primary efficacy outcome of interest was recurrent venous thromboembolism during the follow-up, which investigators defined as a composite of progression of isolated distal DVT, recurrent isolated distal DVT, proximal DVT, symptomatic pulmonary embolism, or fatal pulmonary embolism. The primary safety outcome of interest was major bleeding after randomization until two days from the last dose of rivaroxaban or placebo.

Upon analysis, results indicated a primary efficacy outcome event occurred among 11% of the rivaroxaban arm and 19% of the placebo arm (Relative risk [RR], 0.59 [95% CI, 0.36-0.95]; P=.03), with a number needed to treat of 12 (95% CI, 7-126). Further analysis demonstrated recurrent isolated DVT occurred among 8% in the rivaroxaban arm and 15% in the placebo arm (RR, 0.52 [95% CI, 0.29-0.92) P=.02). Additionally, proximal DVT or pulmonary embolism was observed among 3% of the patients in the rivaroxaban arm and 4% of the placebo arm (RR, 0.88 [95% CI, 0.33-2.39]; P=.80). Investigators pointed out no instances of major bleeding were observed in either study arm.

“Rivaroxaban administered for six additional weeks in patients with isolated distal DVT who had an uneventful 6-week treatment course reduces the risk of recurrent venous thromboembolism, mainly recurrent isolated distal DVT, over a 2-year follow-up without increasing the risk of haemorrhage,” investigators concluded.

This study, “Rivaroxaban treatment for six weeks versus three months in patients with symptomatic isolated distal deep vein thrombosis: randomised controlled trial,” was published in The BMJ.