评价华法令对非瓣膜性房颤患者的治疗模式、抗凝控制水平和治疗结果：一项英国大型人群相关记录研究 Evaluation of the pattern of treatment, level of anticoagulation control, and outcome of treatment with warfarin in patients with non-valvar atrial fibrillation: a record linkage study in a large British population