Effectiveness and Safety of Rivaroxaban Versus Warfarin in Frail Patients with Venous Thromboembolism

PURPOSE: Frailty predicts poorer outcomes in patients receiving anticoagulation. We assessed the effectiveness and safety of rivaroxaban vs warfarin in frail patients experiencing venous thromboembolism. METHODS: Using US MarketScan claims data from January 2012-December 2016, we identified frail patients (using the Johns Hopkins Claims-Based Frailty Indicator score) who had ≥1 primary hospitalization/emergency department visit diagnosis codes for venous thromboembolism, received rivaroxaban or warfarin as their first outpatient oral anticoagulant within 30 days of the index event, and had ≥12 months of insurance prior to the index venous thromboembolism. Differences in baseline covariates between cohorts were adjusted using inverse probability of treatment weights based on propensity scores. The primary endpoint was the composite of recurrent venous thromboembolism or major bleeding. Patient claims were tracked for up to 12 months after the index venous thromboembolism or until endpoint occurrence oral anticoagulant discontinuation/switch, insurance disenrollment, or end of follow-up. Cox regression was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: Of 58,089 incident venous thromboembolism patients identified, 6869 (1365 rivaroxaban and 5504 warfarin users) were classified as frail. Rivaroxaban reduced patients' hazard of the composite of recurrent venous thromboembolism or major bleeding (HR 0.75; 95% CI, 0.57-0.98) and recurrent venous thromboembolism alone (HR 0.65; 95% CI, 0.44-0.97) compared with warfarin. No significant difference in major bleeding was observed between cohorts (HR 0.88; 95% CI, 0.61-1.27). CONCLUSIONS: Frail patients experiencing a venous thromboembolism and given rivaroxaban experience less recurrent venous thromboembolism, with at least as good bleeding outcomes, as patients prescribed warfarin.