Heavy menstrual bleeding in women on anticoagulant treatment for venous thromboembolism: Comparison of high‐ and low‐dose rivaroxaban with aspirin

BACKGROUND: Rivaroxaban may induce heavy menstrual bleeding. It is unknown if this effect is dose related or if rivaroxaban is associated with more menstrual bleeding than aspirin. OBJECTIVES: To demonstrate and compare menstrual patterns and actions taken among women receiving aspirin and two doses of rivaroxaban. METHODS: The EINSTEIN‐CHOICE trial compared once‐daily rivaroxaban 20 mg, rivaroxaban 10 mg, and aspirin 100 mg for extended treatment of venous thromboembolism in patients who had completed 6 to 12 months of anticoagulant therapy. In 362 women with menstrual cycles, menstrual flow duration and intensity assessed at days 30, 90, 180, and 360 were compared with those before starting anticoagulant therapy. RESULTS: Menstrual flow duration increased in 12%‐18% of the 134 women given 20‐mg rivaroxaban, in 6% to 12% of 120 women given 10‐mg rivaroxaban, and in 9% to 12% of 108 women given aspirin. Corresponding increases in flow intensity were 19% to 24%, 14% to 21%, and 13% to 20%. The odds ratios (ORs) for increased menstrual flow duration were 1.36 (95% confidence interval [CI], 0.62‐2.96) for rivaroxaban 20 mg versus aspirin, 0.77 (95% CI, 0.33‐1.81) for rivaroxaban 10 mg versus aspirin, and 0.57 (95% CI, 0.26‐1.25) for rivaroxaban 10 mg versus 20 mg. The ORs for increased menstrual flow intensity were 1.41 (95% CI, 0.67‐2.99), 1.07 (95% CI, 0.49‐2.34), and 0.76 (95% CI, 0.37‐ 1.57), respectively. CONCLUSIONS: There were no statistically significant differences in menstrual hemorrhage patterns between women treated with 10 or 20 mg of rivaroxaban and aspirin. Compared with 10‐mg rivaroxaban or aspirin, 20‐mg rivaroxaban showed numerically more often increased menstrual flow duration and intensity.