Comparison of rivaroxaban and low molecular weight heparin in the treatment of cancer-associated venous thromboembolism: a Swedish national population-based register study

Background: Treating cancer-associated venous thromboembolism (CAT) with anticoagulation prevents recurrent venous thromboembolism (rVTE), but increases bleeding risk. Objectives: To compare incidence of rVTE, major bleeding, and all-cause mortality for rivaroxaban versus low molecular weight heparin (LMWH) in patients with CAT. Methods: We developed a cohort study using Swedish national registers 2013–2019. Patients with CAT (venous thromboembolism within 6 months of cancer diagnosis) were included. Those with other indications or with high bleeding risk cancers were excluded (according to guidelines). Follow-up was from index-CAT until outcome, death, emigration, or end of study. Incidence rates (IR) per 1000 person-years with 95% confidence interval (CI) and propensity score overlap-weighted hazard ratios (HRs) for rivaroxaban versus LMWH were estimated. Results: We included 283 patients on rivaroxaban and 5181 on LMWH. The IR for rVTE was 68.7 (95% CI 40.0–109.9) for rivaroxaban, compared with 91.6 (95% CI 81.9–102.0) for LMWH, with adjusted HR 0.77 (95% CI 0.43–1.35). The IR for major bleeding was 23.5 (95% CI 8.6–51.1) for rivaroxaban versus 49.2 (95% CI 42.3–56.9) for LMWH, with adjusted HR 0.62 (95% CI 0.26–1.49). The IR for all-cause mortality was 146.8 (95% CI 103.9–201.5) for rivaroxaban and 565.6 (95% CI 541.8–590.2) for LMWH with adjusted HR 0.48 (95% CI 0.34–0.67). Conclusions: Rivaroxaban performed similarly to LMWH for patients with CAT for rVTE and major bleeding. An all-cause mortality benefit was observed for rivaroxaban which potentially may be attributed to residual confounding. Trial registration number: NCT05150938 (Registered 9 December 2021).