Effectiveness and Safety of Extended Oral Anticoagulant Therapy in Patients with Venous Thromboembolism: A Retrospective Cohort Study

Limited real‐world evidence exists for effectiveness and safety of extended oral anticoagulation beyond 6 months of initial treatment in prevention of recurrent venous thromboembolism (VTE) and adverse major bleeding events among patients with VTE. Using MarketScan Commercial and Medicare Supplemental databases (2013–2019), we conducted a retrospective cohort study to compare the risk of recurrent VTE and major bleeding events during extended treatment among patients with VTE who completed the 6‐month initial treatment and received extended oral anticoagulant treatment with apixaban, warfarin, or no extended treatment. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards modeling with inverse probability treatment weighting. We identified 14,818 patients with extended treatment of apixaban (n = 4,338), warfarin (n = 5,298), or no extended treatment (n = 5,182). Compared with no extended treatment, apixaban use was associated with decreased risk of recurrent VTE (HR: 0.10, 95% CI: 0.04–0.26) without increased risk of major bleeding events (HR: 1.06, 95% CI: 0.52–2.17); warfarin use was associated with decreased risk of recurrent VTE (HR: 0.23, 95% CI: 0.12–0.44) but with increased risk of major bleeding events (HR: 2.64, 95% CI: 1.51–4.59). Compared with warfarin, apixaban use was associated with decreased risk of major bleeding events (HR: 0.42, 95% CI: 0.22–0.80) but no difference in risk of recurrent VTE (HR: 0.46, 95% CI: 0.15–1.36). In a real‐world clinical setting, extended anticoagulation with apixaban or warfarin was associated with decreased risk of recurrent VTE compared with no extended treatment, and apixaban had a better safety profile with fewer major bleeding events compared with warfarin among commercially insured patients with VTE.