• Faizan Khan, Doug Coyle, Kednapa Thavorn, Sasha van Katwyk, Tobias Tritschler, Brian Hutton, Grégoire Le Gal, Marc A Rodger, and Dean A Fergusson.
• O'Brien Institute for Public Health, University of Calgary, Calgary, Alberta, Canada (F.K.).
• Ann. Intern. Med. 2023 Jul 1; 176 (7): 949960949-960.

BackgroundClinical practice guidelines recommend indefinite anticoagulation for a first unprovoked venous thromboembolism (VTE).ObjectiveTo estimate the benefit-harm tradeoffs of indefinite anticoagulation in patients with a first unprovoked VTE.DesignMarkov modeling study.Data SourcesSystematic 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 PopulationPatients with a first unprovoked VTE who have completed 3 to 6 months of initial anticoagulant treatment.Time HorizonLifetime.PerspectiveCanadian health care public payer.InterventionIndefinite anticoagulation with direct oral anticoagulants.Outcome MeasuresRecurrent VTE events, major bleeding events, costs in 2022 Canadian dollars (CAD), and quality-adjusted life-years (QALYs).Results Of Base Case AnalysisWhen 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 (-0.075 per person).Results Of Sensitivity AnalysisModel results were most sensitive to the case-fatality rate of major bleeding and the annual risk for major bleeding during extended anticoagulation.LimitationThe model assumed that risks for recurrent VTE and major bleeding measured in clinical trials at 1 year remained constant during extended anticoagulation.ConclusionClinicians should use shared decision making to incorporate individual patient preferences and values when considering treatment duration for unprovoked VTE.Primary Funding SourceCanadian Institutes of Health Research.

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