Rohla M, et al. - In this prospective, multicentre observational study, researchers identified factors correlated with thromboembolic and bleeding events in two contemporary cohorts of anticoagulated patients with atrial fibrillation (AF), treated with either vitamin K antagonists (VKA) or non-VKA oral anticoagulants (NOACs). For stroke prevention in AF [a major risk factor for disabling stroke], 5310 patients receiving a VKA (PREvention oF thromboembolic events - European Registry in Atrial Fibrillation (PREFER in AF), derivation cohort) and 3156 patients receiving a NOAC (PREFER in AF Prolongation, validation cohort). Some modifiable risk factors can be attributed to a substantial number of thromboembolic (ischaemic stroke, systemic embolism) and major bleeding (gastrointestinal bleeding, intracerebral haemorrhage and other life-threatening bleeding) events in anticoagulated patients with AF. An approximate 30% decrease was observed in both major bleeding and thromboembolic events for each single point decrease on an adjusted modifiable bleeding risk scale. In AF patients receiving anticoagulation, normalizing international normalised ratio (INR), avoiding exposure to antiplatelet agents or non-steroidal anti-inflammatory drugs (NSAIDs) and preventing liver disease could reduce the risk of bleeding and residual stroke. Abnormal liver function, previous stroke or transient ischaemic attack, labile INR, concomitant therapy with antiplatelet or NSAIDs, heart failure and older age (≥75 years) were independently linked to both thromboembolic and major bleeding events.