Decision Aid for Anticoagulation Duration After Unprovoked Venous Thromboembolism

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is a common condition that is typically treated with blood thinners (anticoagulants). After completing at least 3 months of treatment for a first unprovoked or weakly provoked VTE, patients and clinicians must decide whether to stop anticoagulation or continue treatment for a longer period. Continuing anticoagulation reduces the risk of another blood clot but increases the risk of bleeding. Because both options involve important benefits and risks, this decision should reflect the patient's values and preferences. The DECIDE-VTE study will evaluate whether a patient decision aid can improve decision-making for patients facing this choice. The decision aid provides evidence-based information about the risks and benefits of continuing versus stopping anticoagulation and includes a values clarification exercise to help patients identify what matters most to them. This multicentre batched stepped-wedge cluster randomized trial will be conducted in 12 thrombosis clinics across Canada. Clinics will transition from usual care to implementation of the patient decision aid according to a randomized schedule. The primary outcome is decisional conflict immediately following the anticoagulation decision visit, measured using the Decisional Conflict Scale. Secondary outcomes include patient knowledge, treatment decisions, decisional regret, concordance with the chosen treatment strategy, recurrent venous thromboembolism, major bleeding, all-cause mortality, and implementation outcomes.

Inclusion Criteria: * Age 18 years or older * First episode of objectively confirmed unprovoked or weakly provoked venous thromboembolism (VTE) * Objectively confirmed proximal deep vein thrombosis and/or segmental or greater pulmonary embolism * Completed at least 3 months of therapeutic anticoagulation and currently receiving anticoagulation * Enrollment within 12 months of diagnosis of the index/qualifying VTE event * Able to provide written informed consent * Able to participate in shared decision-making in English or French Exclusion Criteria: * Recurrent unprovoked or weakly provoked VTE I(i.e. multiple unprovoked/weakly provoked VTE) * Index/qualifying VTE is a strongly provoked VTE (e.g., associated with major surgery, major trauma, plaster cast immobilization, or prolonged bed rest) * Index/qualifying VTE associated with a persistent strong provoking risk factor (e.g., active cancer or ongoing immobility) * Women at very low recurrence risk (HERDOO2 score 0-1) * High bleeding risk such that anticoagulation should be discontinued * Requirement for long-term anticoagulation for another indication (e.g., atrial fibrillation) * Prior dedicated long-term anticoagulation Decision Visit regarding anticoagulation duration