Abstract
OBJECTIVE: Isolated distal deep vein thrombosis (IDDVT) is defined as thrombosis involving the infrapopliteal veins. The optimal anticoagulant therapy of IDDVT remains controversial. This study aimed to assess whether reduced dose of rivaroxaban was suitable in patients with IDDVT. METHODS: Consecutive patients with acute IDDVT were identified by reviewing the venous thromboembolism (VTE) registry databases. Outcomes including VTE recurrence, major bleeding, clinically relevant non-major (CRNM) bleeding, and death. Patients were followed until the first occurrence of any outcomes or the study end date (December 31, 2018). Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed. RESULTS: A total of 1246 patients were divided into low-dose (10 or 15 mg/day; n = 716) and standard-dose (20 mg/day; n = 530) groups. The incidences of VTE recurrence, major bleeding, CRNM bleeding, and death between the two groups were 9.64% vs 5.66%, 1.68% vs 3.02%, 4.61% vs 8.68%, and 13.83% vs 10.75%, respectively. After the inverse probability of treatment weighting, HRs for standard-dose vs low-dose of VTE recurrence, major bleeding, CRNM bleeding, and death were 0.54 (95% CI, 0.35-0.84), 1.71 (95% CI, 0.80-3.67), 2.28 (95% CI, 1.40-3.74), and 1.30 (95% CI, 0.91-1.86), respectively. For the subgroup analysis, the interaction with anticoagulation duration and treatment was evident for VTE recurrence (P for interaction = .002), but not for major bleeding. Patients with residual vein thrombosis were associated with an increased risk of VTE recurrence (HR, 1.95; 95% CI, 1.29-2.95). The interaction between risk factors and residual vein thrombosis was evident for VTE recurrence (P for interaction = .085). CONCLUSIONS: Standard-dose rivaroxaban reduced the risk of VTE recurrence without increasing the risk of major bleeding in patients with IDDVT. Anticoagulant therapy for >1.5 months should be preferred over shorter durations. Residual vein thrombosis should be assessed as a predictor of recurrence in patients with IDDVT, especially for patients with non-transient factors.