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430 Switching to Warfarin after 6-Month Completion of Anticoagulant Treatment for Cancer-Associated ThrombosisClinically Relevant Abstract

Antithrombotic Therapy
Program: Oral and Poster Abstracts
Type: Oral
Session: 332. Antithrombotic Therapy: Therapy in Cancer Patients
Monday, December 7, 2015: 7:45 AM
W311ABCD, Level 3 (Orange County Convention Center)

Chatree Chai-Adisaksopha, MD1, Alfonso Iorio, MD, PhD2, Mark A. Crowther, MD, MSc, FRCPC3, Javier de Miguel, MD4*, Estuardo Salgado, MD5*, Marija Zdraveska, MD6* and Manuel Monreal, MD, PhD7*

1Department of Medicine, McMaster University, Hamilton, ON, Canada
2McMaster University, Hamilton, ON, Canada
3St. Joseph's Hospital, McMaster University, Hamilton, ON, Canada
4Department of Pneumonology, Hospital General Universitario Gregorio Marañón, Madrid, Spain
5Intensive Care Unit, Hospital Clínica La Merced, Quito, Ecuador
6Department of Pneumonology and Allergy, University Clinic of Pulmonology and Allergy, Skopje, Macedonia
7Internal Medicine, Hospital Universitari Germans Trias I Pujol, Barcelona, Spain

Background: Low-molecular-weight heparin (LMWH) is considered to be an anticoagulation therapy for the treatment of cancer-associated thrombosis. The duration of treatment is recommended to maintain at least 3-6 months after the diagnosis. However, the data on continuing LMWH treatment beyond six months remains unclear.

Methods: Consecutive cancer-associated thrombosis patients who were enrolled in RIETE Registry were evaluated. We systematically selected the patients who completed treatment with LMWH for 6 months. The patients were divided into two groups whether they continued to receive LMWH or switched to warfarin. The main outcomes were recurrent venous thromboembolism (VTE), major bleeding and total bleeding. Survival curves were generated using Kaplan-Meier method and the curves were compared using the log-rank test. Hazard ratio (HR) with corresponding 95% confidence interval (CI) were calculated using Cox-proportional hazard (PH) model.

Outcomes: of the 1,502 eligible patients who completed 6-month anticoagulant therapy, 763 patients continued to received LMWH and 739 switched to warfarin. There was no significant difference in terms of recurrent VTE between two study groups (hazard ratio [HR] 0.67, 95% confidence interval [CI]; 0.44-1.02, p=0.06), Figure 1. The cumulative incidence of major bleeding was 2.6% in LMWH group and 2.7% in warfarin group (HR 1.05, 95%CI; 0.79-1.55, p=0.79), Figure 2. The cumulative incidence of total bleeding was 6.7% in LMWH group and 7.0% in warfarin group (HR 0.92, 95%CI; 0.62-1.37, p=0.70).

Conclusions: In patients with cancer-associated thrombosis who completed 6-month of anticoagulation therapy, switching to warfarin is not associated with increase in recurrent VTE, major bleeding or total bleeding when compared to continuing LMWH. Warfarin is an acceptable alternative anticoagulant in cancer-associated thrombosis patients who do not tolerate long-term treatment with LMWH.

Disclosures: Monreal: Bayer: Consultancy , Membership on an entity’s Board of Directors or advisory committees ; sanofi: Consultancy , Membership on an entity’s Board of Directors or advisory committees ; boehringer: Consultancy , Membership on an entity’s Board of Directors or advisory committees ; daichii: Consultancy , Membership on an entity’s Board of Directors or advisory committees .

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