HEAD-TO-HEAD TRIAL — In a prospective, open-label, blinded-outcome trial (COBRRA), 2760 patients with acute symptomatic pulmonary embolism or proximal deep-vein thrombosis were randomized to receive 3 months' treatment with apixaban (10 mg twice daily for 7 days, then 5 mg twice daily) or rivaroxaban (15 mg twice daily for 21 days, then 20 mg once daily). The incidence of clinically relevant bleeding (major or clinically relevant nonmajor bleeding), the primary endpoint, was significantly lower with apixaban than with rivaroxaban (3.3% vs 7.1%, RR 0.46 [95% CI 0.33-0.65]). Major bleeding occurred in 0.4% of patients taking apixaban and in 2.4% of those taking rivaroxaban (RR 0.16 [95% CI 0.06-0.40]) and clinically relevant nonmajor bleeding occurred in 2.9% of patients taking apixaban and in 4.9% of those taking rivaroxaban (RR 0.59 [95% CI 0.40-0.86]). The authors state that most bleeding events with rivaroxaban occurred during the initial higher-dose phase. Rates of recurrent symptomatic VTE were similar in the two groups (1.1% with apixaban vs 1.0% with rivaroxaban (RR 1.08 [95% CI 0.52-2.23]). Mortality rates in both groups were low (<0.5% of patients); no deaths related to bleeding or recurrent VTE were reported.3

CONCLUSION — At the FDA-approved dosages that were studied in the COBRRA trial, apixaban appears to be safer than rivaroxaban for treatment of acute VTE.