Key result
Apixaban was superior to rivaroxaban for bleeding risk in acute VTE, but a 9.4 percentage point difference in medication adherence (65.7% vs 75.1%) is a critical confounding variable.
Why the study?
Does apixaban reduce bleeding risk compared to rivaroxaban in patients with acute VTE?
Does apixaban reduce bleeding risk compared to rivaroxaban in patients with acute VTE?
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“For many patients with acute venous thromboembolism, the choice of anticoagulant is no longer a toss-up. Apixaban is a safer first-line option than rivaroxaban for minimizing the risk of bleeding without compromising the prevention of recurrent thrombosis.”
“As much as we were expecting to see a bleeding difference, I don't think any of us expected to see that much of a bleeding difference. COBRRA adds a ton of valuable information for acute VTE, and I think that the best information that we could have hoped for was achieved.”
“Of course, this doesn't mean we get rid of all the options because for some patients there may be a reason why one is preferred over the other. But I think for the general population in whom we're starting anticoagulation, these types of data are critical.”
Differences in medication adherence between twice-daily apixaban and rivaroxaban may confound the bleeding risk results of the COBRRA trial.
To the Editor: The Comparison of Bleeding Risk between Rivaroxaban and Apixaban (COBRRA) trial by Castellucci et al. (March 12/19 issue) 1 established the superiority of apixaban over rivaroxaban with regard to bleeding risk among patients with acute venous thromboembolism (VTE). However, a critical confounding variable — the difference in medication adherence — warrants discussion. The article mentions that “complete adherence” was reported by 65.7% of the patients in the apixaban group and by 75.1% of those in the rivaroxaban group. This gap of 9.4 percentage points is likely to be attributable to the twice-daily regimen of apixaban as compared with . . .
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A 2026 study conducted a letter in Acute venous thromboembolism (VTE). Apixaban vs. Rivaroxaban was evaluated on Bleeding risk. Apixaban was superior to rivaroxaban for bleeding risk in acute VTE, but a 9.4 percentage point difference in medication adherence (65.7% vs 75.1%) is a critical confounding variable.
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