Indefinite Anticoagulant Therapy for First Unprovoked Venous Thromboembolism A Cost-Effectiveness Study

Background: Clinical practice guidelines recommend indefinite anticoagulation for a first unprovoked venous thromboembolism (VTE). Objective: To estimate the benefit-harm tradeoffs of indefinite anticoagulation in patients with a first unprovoked VTE. Design: Markov modeling study. Data Sources: Systematic reviews and meta-analyses for the long-term risks and case-fatality rates of recurrent VTE and major bleeding. Published literature for costs, quality of life, and other clinical events. Target Population: Patients with a first unprovoked VTE who have completed 3 to 6 months of initial anticoagulant treatment. Time Horizon: Lifetime. Perspective: Canadian health care public payer. Intervention: Indefinite anticoagulation with direct oral anticoagulants. Outcome Measures: Recurrent VTE events, major bleeding events, costs in 2022 Canadian dollars (CAD), and quality-adjusted life-years (QALYs). Results of Base-Case Analysis: When compared with discontinuing anticoagulation after initial treatment in a hypothetical cohort of 1000 patients aged 55 years, indefinite anticoagulation prevented 368 recurrent VTE events, which included 14 fatal pulmonary emboli, but induced an additional 114 major bleeding events, which included 30 intracranial hemorrhages and 11 deaths from bleeding. Indefinite anticoagulation cost CAD $16 014 more per person and did not increase QALYs (similar to 0.075 per person). Results of Sensitivity Analysis: Model results were most sensitive to the case-fatality rate of major bleeding and the annual risk for major bleeding during extended anticoagulation. Limitation: The model assumed that risks for recurrent VTE and major bleeding measured in clinical trials at 1 year remained constant during extended anticoagulation. Conclusion: Clinicians should use shared decision making to incorporate individual patient preferences and values when considering treatment duration for unprovoked VTE.