Duration of anticoagulant therapy and VTE recurrence in patients with cancer

PURPOSE: Anticoagulant therapy for at least 3-6 months is currently recommended for treatment of venous thromboembolism (VTE) in patients with cancer, but the optimal duration of treatment is unknown. This study examines the association between the duration of anticoagulation treatment and VTE recurrence in cancer patients. METHODS: The Humana claims database was used to identify newly diagnosed cancer patients who had their first VTE diagnosis between January 1, 2013, and May 31, 2015, and initiated injectable or oral anticoagulant therapy. Follow-up was calculated from the index treatment initiation to the end of eligibility or end of data (June 2015). VTE recurrence was defined as a hospitalization with a primary diagnosis of VTE. Cox proportional hazards models were used to evaluate the risk of VTE recurrence by duration of therapy in patients who discontinued therapy. RESULTS: The study included 1158 patients. Compared to patients treated for 0 to 3 months, VTE recurrences were significantly lower among patients treated for 3 to 6, or over 6 months. After adjustment for baseline characteristics, patients treated for 3 to 6 months (HR [95%CI], 0.53; 0.37-0.76) and more than 6 months (HR [95%CI], 0.48; 0.34-0.68) were still significantly less likely to have VTE recurrences compared to patients treated for 0 to 3 months (both p < 0.01). Findings were similar using a VTE event definition that included outpatient visits. CONCLUSIONS: Among newly diagnosed cancer patients with VTE, anticoagulant therapy lasting more than 3 months was associated with a lower risk of VTE recurrence.