Inequality in oral anticoagulation use and clinical outcomes in atrial fibrillation: a Danish nationwide perspective

Aim: To explore the potential of small-area variation analysis as a tool for identifying unwarranted variation in oral anticoagulation (OAC) use and clinical outcomes in patients with atrial fibrillation (AF) and thereby identify locations with opportunity for improvement in AF care. Methods and results: Based on Danish health care registries, we conducted a nationwide historical cohort study including first-time AF patients with a CHA2DS2-VASc (congestive heart failure, hypertension, age ≥ 75, diabetes, thromboembolism, vascular disease, age 65-74, and sex category) score ≥ 2 between 2007 and 2014 (n = 94 482). For each administrative region and municipality, we assessed OAC initiation and persistence as well as the risk of ischaemic stroke, haemorrhagic stroke, and other major bleeding, respectively. In addition, potential temporal changes were examined for all outcomes. Initiation of OAC varied among regions from 49.5% to 62.4%. In patients initiating OAC, the proportion of patients still receiving OAC after 1 year varied from 73.9% to 79.3%. Oral anticoagulation use increased in all regions during the study period, particularly after 2010, but regional variation in OAC initiation persisted. Generally, the regions and municipalities with the highest initiation of OAC also had the highest OAC persistence. The risk of ischaemic stroke and other major bleeding was lower in these regions and municipalities. We found no significant difference between regions in risk of haemorrhagic stroke. Conclusion: Substantial geographical variation in OAC use and clinical outcomes occurs in Denmark demonstrating the potential of small-area variation analysis as a tool for identifying unwarranted variation in AF care and clinical outcomes. Our findings demonstrate the need for additional initiatives to ensure uniform high-quality care for AF patients.