Prophylactic Dose of Rivaroxaban Versus Warfarin for the Treatment of Isolated Calf Muscle Vein Thrombosis: A Retrospective Propensity Score-Matched Analysis

Abstract

BackgroundProphylactic dose of rivaroxaban is often used in treatment of isolated calf muscle vein thrombosis (ICMVT), nevertheless, its effect is less reported. This study aims to evaluate short-term outcomes in patients with ICMVT who received prophylactic dose of rivaroxaban or warfarin therapy. MethodsA retrospective analysis of 472 ICMVT patients who received two different treatment regimens was undertaken. Propensity score matching method was used to balance the confounding effect of baseline clinical data. Chi-squared test and logistic regression analysis were used to compare outcomes (venous thromboembolism events, bleeding events, complete clot resolution) according to the type of treatment regimens before and after propensity score matching. Univariate and multivariable analysis were used to investigate risk factors for incomplete clot resolution of ICMVT after propensity score matching. Results242 ICMVT patients received prophylactic dose of rivaroxaban (rivaroxaban group, RG), and 230 received warfarin (warfarin group, WG). After propensity score matching, 156 patients were included in each group; Venous thromboembolism (VTE) events occurred in 14 (9.0%) patients in the RG and 10 (6.4%) in the WG (P = 0.395); No major bleeding events occurred in each group, and clinically relevant non-major bleeding events occurred in 5 (3.2%) patients in the RG and 10 (6.4%) in the WG (P = 0.186); Complete clot resolution at 3 months occurred in 80 (51.3%) patients in the RG and 100 (64.1%) in the WG (P = 0.022). Logistic regression analysis showed that there were no significant differences between RG and WG in VTE events (odds ratio 1.439, 95% confidence interval 0.619 to 3.347, P = 0.397) and clinically relevant non-major bleeding events (odds ratio 0.483, 95% confidence interval 0.161 to 1.449, P = 0.194); it revealed that complete clot resolution rate at 3 months was different in the two groups (odds ratio 0.589, 95% confidence interval 0.375 to 0.928, P = 0.022). Treatment regimens (prophylactic dose of rivaroxaban), thrombosis (maximum diameter >7 mm) and risk factors for VTE (non-surgery risk factors, mainly referring to active malignancy) were risk factors for incomplete clot resolution of ICMVT (P < 0.05). ConclusionsIn this retrospective study with a short-term follow-up, ICMVT patients who received prophylactic dose of rivaroxaban had no significant differences in VTE and bleeding events compared to those who received warfarin therapy (the overall INR > 2.0 for >50% of the time); but it was not conducive to complete clot resolution.