Flowchart.

<p>All patients were followed until an event of cerebral infarction, stroke, death, emigration or end of study at 31 December 2009. Patients in warfarin/no warfarin could belong to both the exposed and non-exposed arm. ^aPatients received warfarin after 30 days or more from incident atrial fibrillation or irregular withdrawal during the study period or until occurrence of an endpoint.