The Bottom Line
The COBRRA trial provides the first head-to-head randomized comparison of apixaban versus rivaroxaban in acute VTE, demonstrating that apixaban is associated with significantly lower bleeding risk (3.3% vs. 7.1%; RR 0.46, P0.001) with no apparent difference in recurrent VTE.
Study Design
This international PROBE (prospective, randomized, open-label, blinded endpoint) trial enrolled 2,760 patients across 32 centers in Canada, Australia, and Ireland from December 2017 to January 2025. Patients were randomized 1:1 to:
– Apixaban: 10 mg BID × 7 days → 5 mg BID
– Rivaroxaban: 15 mg BID × 21 days → 20 mg daily
Treatment duration was 3 months.
Who Was Included
Adults ≥18 years with acute symptomatic proximal DVT or segmental/more proximal PE. Mean age was 58 years, 44% female, and 77% had unprovoked VTE.
Who Was Excluded (Important for Oncology)
– Active cancer
– Weight >120 kg
– CrCl 30 mL/min
– Severe liver disease (Child-Pugh B/C)
– Active bleeding
Key Results
| Outcome | Apixaban | Rivaroxaban | Relative Risk (95% CI) |
|---|---|---|---|
| Clinically relevant bleeding | 3.3% | 7.1% | 0.46 (0.33–0.65) |
| Major bleeding | 0.4% | 2.4% | 0.16 (0.06–0.40) |
| Recurrent VTE | 1.1% | 1.0% | 1.08 (0.52–2.23) |
| Death (any cause) | 0.1% | 0.3% | 0.25 (0.03–2.26) |
Most bleeding events occurred in the first 3 weeks—when rivaroxaban dosing is 50% higher than maintenance.
Limitations to Consider
– Open-label design
– Cancer patients excluded (LMWH was standard of care at trial initiation)
– Limited racial/ethnic diversity (~90% White)
– Not powered for VTE recurrence
– 3-month data only
Clinical Implications
For non-cancer VTE patients, this trial suggests apixaban may be the preferred DOAC when bleeding risk is a concern. However, these findings should not be extrapolated to cancer-associated thrombosis, extended VTE prophylaxis, or atrial fibrillation populations.