What is Standard Dose of Rivaroxaban in Elderly Asian Patients with Atrial Fibrillation: 20ms versus. 15mg?

Abstract

Although there is no age criterion for rivaroxaban dose reduction, elderly patients with atrial fibrillation (AF) are often prescribed an off-label reduced dose. We aimed to evaluate whether age is a necessary criterion for rivaroxaban dose reduction in Korean patients with AF. Among 2208 patients who prescribed warfarin or rivaroxaban, 552 patients over 75 years without renal dysfunction (creatinine clearance >50 mL/min) were compared based on propensity score matching. The rivaroxaban group was further divided into a 20 mg (R20; on-label) and a 15 mg (R15; off-label). Primary net clinical benefit (NCB) was defined as the composite of stroke, systemic embolism, major bleeding, and all-cause mortality. Secondary NCB was defined as the composite of stroke, systemic embolism, and major bleeding. Patients were followed for 1 year, or until the first outcome occurrence. Both rivaroxaban groups had comparable efficacy compared with warfarin. However, both R20 (0.9% vs 7.4%, p = .014) and R15 (2.3% vs 7.4%, p = .018) had a significant reduction in major bleeding. There were no differences in efficacy or safety outcomes between R20 and R15. R20 had significantly reduced primary (hazard ratio [HR] 0.33, 95% confidence interval [CI]: 0.12-0.93) and secondary (HR 0.31, 95% CI: 0.10-0.93) NCBs compared with warfarin. However, primary and secondary NCBs were not reduced in R15. In real-world practice with elderly patients with AF, off-label rivaroxaban dose reduction to 15 mg conferred no benefits. Therefore, guideline-adherent rivaroxaban 20 mg is favorable in elderly Korean patients with AF.

Keywords: age groups; atrial fibrillation; reference standards; rivaroxaban.

Figure 1.

Patient enrollment and flowchart.

Figure 2.

Kaplan–Meier estimation for primary outcomes between patients with warfarin and rivaroxaban. (A) Cumulative incidence of thromboembolism. (B) Cumulative incidence of major bleeding.

Figure 3.

Kaplan–Meier estimation for clinical benefit between patients with warfarin and rivaroxaban. (A) Cumulative incidence of primary net clinical benefit (NCB) (stroke/systemic embolism/major bleeding/death). (B) Cumulative incidence of secondary NCB (stroke/systemic embolism/major bleeding).