Impact of Prolonged Anticoagulation with Rivaroxaban on Provoked Venous Thromboembolism Recurrence: IMPROVE-VTE

BACKGROUND: We sought to evaluate the real-world effectiveness and safety of prolonged anticoagulation with rivaroxaban following a provoked venous thromboembolism. METHODS: Using US MarketScan claims from November 2012 to March 2017, we identified adults with ≥1 primary hospitalization or emergency department diagnosis code for venous thromboembolism, a provoking (major or minor, persistent or transient) risk factor, at least 3 months of continuous rivaroxaban treatment, and ≥12 months of continuous insurance benefits prior to their qualifying venous thromboembolism. Patients were categorized as either continuing rivaroxaban or discontinuing anticoagulation (no anticoagulation or nonaspirin antiplatelet agents but may have received aspirin) after the initial 3 months of rivaroxaban treatment (index date). Differences in baseline covariates between cohorts were adjusted for using inverse probability-of-treatment weights based on propensity scores (absolute standardized differences <0.1 achieved for all covariates after adjustment). Twelve month incidences of recurrent venous thromboembolism or major bleeding were compared between cohorts using Cox regression (according to an intention-to-treat methodology) and reported as hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: Among patients experiencing a provoked venous thromboembolism and treated with rivaroxaban for the first 3 months (N=4,990), continued rivaroxaban use beyond 3 months (median [25%, 75% range duration of additional rivaroxaban use = 3 [2, 5] months) was associated with a 44% (95% CI of 9%-66%) lower hazard of recurrent venous thromboembolism without altering major bleeding risk [HR of 0.87, 95% CI of 0.51-1.49] versus anticoagulation discontinuation (with or without aspirin use). CONCLUSIONS: Our study suggests continuing rivaroxaban after the initial 3 month period was associated with a decreased risk of recurrent venous thromboembolism. The observed reduction in recurrent venous thromboembolism with prolonged rivaroxaban use was not associated with a significant change in major bleeding risk.