Safety and Efficacy of Rivaroxaban 10 Mg in Advanced Aged Patients with Non-Valvular Atrial Fibrillation and Preserved Renal Function

Background: The J-ROCKET AF Study demonstrated the safety and efficacy of rivaroxaban 15 mg for the prevention of stroke and systemic embolism in Japanese patients with non-valvular atrial fibrillation (AF) and preserved renal function. However, the safety and efficacy of rivaroxaban 10 mg, which is given to advanced aged patients (75 years old or older) with preserved renal function, is unknown. To investigate the plasma concentration of rivaroxaban, a follow-up survey was performed with regard to the activated partial thromboplastin time (APTT) and the prothrombin time (PT). APTT and PT have been known to correlate closely with plasma levels of rivaroxaban.

Method: The study group consisted of 50 patients (mean age 84 ± 5 years, 23 men) who had received 10 mg once-daily rivaroxaban, regardless of their renal function. The control group consisted of 30 patients with preserved renal function (mean age 68 ± 7 years, 16 men) who had received 15 mg once-daily rivaroxaban.

Results: There was no correlation among renal function (eGFR), APTT, and the PT-international normalized ratio (PT-INR) in the study group. Therefore, using multiple regression analysis we examined factors that affected APTT and PT-INR in the study group. The multiple regression models: APTT = -17.072 + 0.676*(age) + 3.169*(sex) – 0.051*(body weight) R² = 0.342 P < 0.001, PT-INR = -0.103 + 0.017*(age) + 0.081*(sex) – 0.002*(body weight) R² = 0.292 P < 0.01. The ages in APTT and PT-INR models were the most significantly affected factors (standardized partial regression coefficient, β : 0.407, P < 0.01 and 0.366, P < 0.05). APTT and PT-INR in the study group were 39.5 ± 6.5 seconds and 1.33 ± 0.16, while those in the control group were 39.6 ± 7.1 seconds and 1.34 ± 0.19, respectively. There was no significant difference between the two groups regarding APTT and PT-INR.

Conclusions: The safety and efficacy of rivaroxaban 15 mg were consistent with advanced aged patients with preserved renal function who had received rivaroxaban 10 mg once-daily.