Retrospective comparison of low molecular weight heparin vs. warfarin vs. oral Xa inhibitors for the prevention of recurrent venous thromboembolism in oncology patients: The Re-CLOT study

Background There is increasing evidence indicating oral factor Xa inhibitors can be used for secondary prevention of venous thromboembolism. Studies are needed to compare oral factor Xa inhibitors, low molecular weight heparins, and warfarin in the oncology population. The purpose of this study is to evaluate the recurrent venous thromboembolism incidence in oncology patients utilizing oral Xa inhibitors, low molecular weight heparins, or warfarin. Methods Using retrospectively collected data, we compared the recurrent venous thromboembolism incidence in oncology patients taking rivaroxaban/apixaban, enoxaparin, or warfarin with at least three months of follow-up. Patients were included if they had an active cancer, venous thromboembolism, and taking warfarin, enoxaparin, or rivaroxaban/apixaban. The primary endpoint was the first episode of recurrent venous thromboembolism at three months. Secondary endpoints included recurrent venous thromboembolism after six months, major bleeding, and mortality. Results Of 127 venous thromboembolism patients, 48 received rivaroxaban or apixaban, 23 received enoxaparin, and 56 received warfarin. The three most common cancer diagnoses were lung (21%), colorectal (14%), and breast (14%). There was no difference in venous thromboembolism recurrence at three months between the rivaroxaban/apixaban (0%), warfarin (3.6%), and the enoxaparin cohorts (4.4%) (p=0.8319). Major bleeding at three months was only seen in one patient in the enoxaparin arm (4.2%). Mortality at three months was 0%, 3.6%, and 17.4% in the rivaroxaban/apixaban, warfarin, and enoxaparin cohorts, respectively. Conclusion The results of this retrospective study suggest that oral factor Xa inhibitors are potential options for cancer patients with venous thromboembolism. However, randomized, controlled trials are needed to confirm these results.