(A-093) Comparative Safety and Effectiveness of Apixaban and Rivaroxaban for Treatment of Cancer-Associated Venous Thromboembolism: A Retrospective Cohort Study

Background: Cancer-associated venous thromboembolism (VTE) is common, yet the comparative safety and effectiveness of direct oral anticoagulants (DOACs) among individuals with VTE and active cancer is unclear.

Objectives: To quantify recurrent VTE, major bleeding, and clinically relevant non-major bleeding among individuals with cancer-associated VTE treated with apixaban or rivaroxaban.

Methods: We conducted a retrospective cohort study using two U.S. claims databases: Medicare fee-for-service (2016-2020) and MarketScan (2016-2022). We included adults (≥65 years Medicare;18-64 years MarketScan) with active cancer, defined as a diagnosis of cancer within 6 months prior to an index VTE event, who newly initiated apixaban or rivaroxaban within 30 days of an index VTE event and who had a 365-day baseline period. Primary outcomes were hospitalization for recurrent VTE, hospitalization for major bleeding (gastrointestinal, intracranial hemorrhage, and other sites) and hospitalization or outpatient visit for non-major bleeding events. All patients were followed for outcomes over six months and the entire follow-up period. We used inverse probability treatment weighting (IPTW) to control for confounding and IPTW-adjusted Cox proportional hazards models for outcome analysis. Competing risk of death was not accounted for. We pooled estimates across the two datasets using an inverse variance-weighted fixed-effects model.

Results: The study included 6,621 patients treated with apixaban and 4,448 with rivaroxaban following the index VTE event. Over six months of follow-up, the mean follow-up duration was 110 days for apixaban and 113 days for rivaroxaban. The adjusted incidence rates for apixaban vs. rivaroxaban per 100 person years were 6.72 vs 7.93 for recurrent VTE, 7.10 vs. 7.82 for major bleeding, and 31.5 vs. 37.7 for non-major bleeding. Patients receiving apixaban had lower risks of non-major bleeding (hazard ratio [HR] 0.83, 95% confidence intervals [CI] 0.74 to 0.94) and intracranial major bleeding (HR 0.32, CI 0.13 to 0.84) compared to those on rivaroxaban. The risks of major bleeding (HR 0.90, CI 0.70 to 1.16) and recurrent VTE (HR 0.84, CI 0.65 to 1.07) were comparable between groups. Over the entire follow-up period, while the difference in intracranial bleeding became non-significant (HR 0.43, CI 0.19 to 1.01), patients receiving apixaban showed a lower risk of recurrent VTE (HR 0.76, CI 0.61 to 0.96).

Conclusions: In patients with VTE and active cancer, apixaban demonstrated a lower risk of non-major bleeding, and similar risk of major bleeding and recurrent VTE compared to rivaroxaban at six months. Similar trends were observed during the entire follow-up; however, patients receiving apixaban had a lower risk of recurrent VTE.