LAUSR

Introduction The efficacy and safety of anticoagulant treatment is not established for patients with acute symptomatic isolated distal deep vein thrombosis (IDDVT). In real-world clinical practice, both therapeutic and prophylactic anticoagulation are used for acute IDDVT. However, therapeutic anticoagulation is associated with higher risk of bleeding than prophylactic anticoagulation. Thus, this study aims to assess the efficacy and safety in patients with first acute symptomatic IDDVT treated with therapeutic or prophylactic anticoagulation using rivaroxaban. Methods and analysis This study is a prospective, multicentre, single-blind, randomised controlled trial. Outpatients with a first, acute, symptomatic, objectively confirmed IDDVT in four centres from 1 August 2021 are recruited. Eligible patients are randomised in a 1:1 ratio to receive prophylactic anticoagulation (rivaroxaban 10 mg once a day for 3 months) or therapeutic anticoagulation (rivaroxaban 20 mg once a day for 3 months). All patients are followed for 6 months. The primary efficacy outcome is radiographically confirmed recurrent venous thromboembolism. The primary safety outcome is the incidence of major or clinically relevant non-major bleeding events. Ethics and dissemination This study has been approved by the Ethics Committee of Zhongshan Hospital Fudan University (B2021-175R). Study results will be disseminated through peer-reviewed journals. Trial registration number NCT04967573