IMpact of Prolonged anticoagulation with Rivaroxaban On proVokEd Venous ThromboEmbolism recurrence: The IMPROVE-VTE Study.

OBJECTIVE: 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 11/2012-3/2017, we identified adults with ≥1 primary hospitalization/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 non-aspirin 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=9-66%) lower hazard of recurrent venous thromboembolism without altering major bleeding risk (HR=0.87, 95%CI=0.51-1.49) versus anticoagulation discontinuation (with/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.