A preplanned post-hoc analysis of the AVERT trial, a randomized, placebo-controlled, double-blind clinical trial of apixaban for the prevention of venous thromboembolism (VTE), reveals that among ambulatory patients with cancer initiating chemotherapy, characteristics of both the patient and the cancer in question impact the efficacy of apixaban for VTE prophylaxis.
"Patients with active cancer have an increased risk of venous thromboembolism (VTE) complications which is associated with morbidity, mortality, and significant health care costs," write the investigators, led by Ameeta Lubina Nayak of the Ottawa Hospital Research Institute, in the abstract for their upcoming poster presentation at the International Society on Thrombosis and Haemostasis (ISTH) 2020 Virtual Congress.
Previously published results from AVERT demonstrated that a prophylactic dosage of 2.5 mg twice-daily apixaban significantly decreased the rate of VTE compared with placebo in intermediate- to high-risk patients starting chemotherapy. Seeking to investigate the efficacy of apixaban in different subgroups of patients with cancer, the researchers evaluated the risk of VTE in ambulatory patients initiating chemotherapy, with groups defined by age, gender, race, weight, prior VTE, creatinine clearance, antiplatelet therapy, cancer characteristics, bevacizumab use, and baseline Eastern Cooperative Oncology Group (ECOG) performance status.
Venous thromboembolic events occurred in 7.1% of patients, including 4.2% of patients in the apixaban group and 10.2% of patients in the placebo group. Decreased VTE risk was associated with a number of patient characteristics, including age under 75 years (hazard ratio of 0.37), male sex (hazard ratio 0.25), weight above 90 kg (hazard ratio 0.18), and no prior history of VTE (hazard ratio 0.41). Cancer characteristics linked to decreased VTE rates with apixaban usage included solid cancers (hazard ratio 0.30) and metastatic disease (hazard ratio 0.45). In addition, concurrent use of antiplatelet therapy corresponded with decreased VTE rates (hazard ratio 0.18).
"In the AVERT trial, apixaban thromboprophylaxis provided significantly decreased risk of VTE in patients with age <75, male sex, weight >90 kg, no prior VTE, solid cancer, and metastatic disease," conclude the investigators.
For More Information
Nayak AL, Zahrai A, Mallick R, et al (2020). Risk of venous thromboembolism among subgroups of cancer patients undergoing chemotherapy: post-hoc analysis of the AVERT trial. Res Pract Thromb Haemost (ISTH Congress Abstracts): 4(suppl_1). Abstract PB2105.
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