The COMPASS (Cardiovascular Outcomes for People Using Anticoagulation Strategies) trial was a double-dummy, double-blind, multicentre, randomised clinical trial in patients with stable atherosclerotic vascular disease (sponsored by Bayer). Patients were randomised to one of three treatment groups: low-dose (2.5 mg twice daily) rivaroxaban plus aspirin (100 mg), higher dose (5 mg twice daily) rivaroxaban alone, or aspirin (100 mg) alone. The primary outcome, a composite of cardiovascular death, stroke, or myocardial infarction, occurred in fewer patients randomised to rivaroxaban plus aspirin, compared with aspirin alone. The study was terminated early due to the superiority of the combination therapy after a mean follow-up of 23 months. Major bleeding occurred more frequently in the combination therapy group. Twice-daily rivaroxaban 5 mg monotherapy did not significantly lower the risk of major adverse cardiovascular events versus aspirin alone (HR 0.90, p=0.12) and resulted in a significantly higher risk of major bleeding.