Rivaroxaban Versus Warfarin and Risk of Post-Thrombotic Syndrome Among Patients with Venous Thromboembolism

The effectiveness of rivaroxaban to reduce post-thrombotic syndrome in patients with venous thromboembolism is largely unknown. We compared rates of post-thrombotic syndrome in patients given rivaroxaban versus warfarin in a cohort of patients with incident venous thromboembolism receiving routine clinical care.We linked Danish nationwide registries to identify all patients with incident venous thromboembolism who were new users of rivaroxaban or warfarin and compared rates of post-thrombotic syndrome using an inverse probability of treatment-weighting approach to account for baseline confounding.We identified 19,957 oral anticoagulation-naive patients with incident venous thromboembolism treated with warfarin or rivaroxaban (mean age, 64 years; 48% were female, 45.5% had pulmonary embolism). The propensity-weighted rate of post-thrombotic syndrome at 3 years follow-up was 0.53 incidents per 100 person-years with rivaroxaban versus 0.55 per 100 person-years with warfarin, yielding a hazard rate of 0.88 (95% confidence interval, 0.66-1.17). This association remained consistent across types of venous thromboembolism (deep venous thrombosis vs pulmonary embolism, and provoked vs unprovoked venous thromboembolism) and when censoring patients with recurrent venous thromboembolism.In this clinical practice setting, rivaroxaban was associated with lower but statistically nonsignificant rates of post-thrombotic syndrome, which did not appear to be mediated only by an effect on recurrent venous thromboembolism.