Remarks: It may be appropriate for the choice of anticoagulant to change in response to changes in the patient s circumstances or preferences during the long- term or extended phases of treatment. Duration of Anticoagulant Therapy Summary of the Evidence AT9 recommendations on how long VTE should be treated were based on comparisons of four durations of than 3 months but still a time-limited course of therapy (usually 6 or 12 months); or (4) extended (also termed inde nite ; no scheduled stopping date) therapy.1 These four options were assessed in four subgroups of VTE patients with different estimated risks of recurrence after stopping anticoagulant therapy: (1) VTE provoked by surgery (a major transient risk factor; 3% recurrence ; (2) VTE provoked by a nonsurgical transient risk factor (eg, estrogen therapy, pregnancy, leg injury, ight of >8 h; 15% recurrence at 5 years)51 ; (3) unprovoked (also termed idiopathic ) VTE; not meeting criteria for provoked by a transient risk factor or by cancer (30% recurrence at 5 years)52,53 ; and (4) VTE associated with cancer (also termed cancer- associated thrombosis ; 15% annualized risk of recurrence; recurrence at 5 years not estimated because of high mortality from cancer).54,55 Recurrence risk was further strati ed by estimating the risk of recurrence after: (1) an isolated distal DVT was half that after a proximal DVT or PE56,57 and (2) a second unprovoked TABLE 6 ] Factors That May In uence Which Anticoagulant Is Chosen for Initial and Long-Term Treatment of VTE Factor Preferred Anticoagulant Qualifying Remarks Cancer LMWH More so if: just diagnosed, extensive VTE, metastatic cancer, very symptomatic; vomiting; on cancer chemotherapy. Parenteral therapy to be avoided Rivaroxaban; apixaban VKA, dabigatran, and edoxaban require initial parenteral therapy. 