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

ABSTRACT

BACKGROUND: Prophylactic 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. METHODS: A retrospective analysis of 472 ICMVT patients who received 2 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. RESULTS: 242 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 nonmajor 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 0.619-3.347, P = 0.397) and clinically relevant nonmajor bleeding events (odds ratio 0.483, 95% confidence interval 0.161-1.449, P = 0.194); it revealed that complete clot resolution rate at 3 months was different in the 2 groups (odds ratio 0.589, 95% confidence interval 0.375-0.928, P = 0.022). Treatment regimens (prophylactic dose of rivaroxaban), thrombosis (maximum diameter >7 mm), and risk factors for VTE (nonsurgery risk factors, mainly referring to active malignancy) were risk factors for incomplete clot resolution of ICMVT (P < 0.05). CONCLUSIONS: In 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.