Both low-dose and full-dose rivaroxaban had superior benefit-risk profiles for extended venous thromboembolism (VTE) treatment compared with aspirin, according to results published in Thrombosis Research.
Incidences of the combined outcome of recurrent VTE and major bleeding were 2.8% and 3.4% lower for patients treated with rivaroxaban at 20 mg and 10 mg, respectively, than for those treated with aspirin, reported Paolo Prandoni, MD, of the department of cardiothoracic and vascular sciences at the University of Padua, Italy, and his coauthors.
Investigators analyzed data from the EINSTEIN-CHOICE trial, a double-blind, randomized study of 3,365 patients aged 18 years or older with deep vein thrombosis or pulmonary embolism who had previously received anticoagulant treatment for 6-12 months. Patients were given either once-daily rivaroxaban at a low dose (10 mg), once-daily rivaroxaban at full dose (20 mg), or once- daily aspirin at a dose of 100 mg.
Benefit and risk were calculated using “excess numbers of events,” or the difference in cumulative incidences in a hypothetical population of 10,000 VTE patients treated for 1 year. Excess numbers of events were defined as the number of patients in this hypothetical population who would experience a particular event when treated with rivaroxaban (at either dose), minus that in the same population treated with aspirin.
The cumulative incidences of recurrent VTE in the full-dose rivaroxaban, low-dose rivaroxaban, and aspirin groups were 1.9%, 1.6%, and 5.0%, respectively. The cumulative incidences of major bleeding in these groups were 0.7%, 0.4% and 0.5%, respectively.
In patients treated with 20 mg of rivaroxaban instead of aspirin, there would be 123 fewer episodes of pulmonary embolism (95% confidence interval, 21-226) and 198 fewer episodes of deep vein thrombosis (95% CI, 62-333).
In patients given 10 mg of rivaroxaban instead of aspirin, there would be 121 fewer episodes of pulmonary embolism (95% CI, 4-238) and 217 fewer episodes of deep vein thrombosis (95% CI, 92-342), Dr. Prandoni and his colleagues wrote.
Net clinical benefit was defined as the composite of symptomatic recurrent VTE and major bleeding events, and occurred in 23 patients in the full-dose rivaroxaban group, 17 patients in the low-dose rivaroxaban group, and 53 patients in the aspirin group.
For 10,000 patients treated for 1 year with rivaroxaban instead of aspirin, there would be 284 fewer net clinical benefit outcomes for the 20-mg dose (95% CI, 106-462) and 339 fewer (95% CI, 165-512) for the 10-mg dose. “Thus, compared with aspirin, one additional symptomatic recurrent VTE or major bleed would be avoided for every 36 or 30 patients treated with rivaroxaban 20 mg or 10 mg, respectively,” the investigators wrote.
The findings indicate that there is “no longer a place” for extended VTE treatment with aspirin, the investigators said.
“Extended anticoagulation with once daily rivaroxaban ... provides a clinically important benefit in terms of reduction in recurrent VTE,” they wrote. “Regardless of which dose is chosen ... rivaroxaban has a favourable benefit-risk profile relative to aspirin.”
Bayer AG funded the study. Dr. Prandoni reported financial relationships with Bayer, Sanofi, Daiichi Sankyo, and Pfizer.
SOURCE: Prandoni P et al. Thromb Res. 2018 Aug;168:121-9.