Study settles the apixaban vs. rivaroxaban debate for blood clots

New trial data show apixaban cuts clinically relevant bleeding by more than half compared to rivaroxaban — without any loss of clot-prevention benefit.

For years, clinicians treating venous thromboembolism (VTE) had little evidence to choose between the two most popular blood thinners. The COBRRA trial, published this month in the New England Journal of Medicine, changes that.

Among 2,760 patients treated for acute VTE, those taking apixaban experienced clinically relevant bleeding at roughly half the rate of those on rivaroxaban (3.3% vs. 7.1%). Major bleeding was even more striking — 0.4% with apixaban versus 2.4% with rivaroxaban. Crucially, rates of recurrent blood clots were identical between the two groups.

Bleeding reduction

54%

Patients enrolled

2,760

Clot recurrence difference

None

Researchers believe the difference stems largely from dosing: rivaroxaban's loading phase — twice-daily high doses for 21 days — appears to drive excess bleeding without providing additional protection against clots. Apixaban's loading phase lasts only 7 days.

An accompanying editorial concluded that for most VTE patients, the choice of anticoagulant is "no longer a toss-up." Rivaroxaban may still suit patients who prefer a once-daily regimen, but the safety edge for apixaban is now hard to ignore.

Source: Castellucci et al., NEJM, March 12/19, 2026 · COBRRA trial