Shifting to a non-vitamin K antagonist oral anticoagulation agent from vitamin K antagonist in atrial fibrillation

Aims: After non-vitamin K antagonist (VKA) oral anticoagulation agents (NOAC) have been approved for thrombo-embolic prophylaxis in non-valvular atrial fibrillation (NVAF), utilization of oral anticoagulants (OAC) in NVAF has changed. Contemporary shifting from a VKA to a NOAC (dabigatran, rivaroxaban, or apixaban) has not been quantified, and could help assess whether these drugs are used according to recommendations. Methods and results: Using Danish nationwide registries, we identified all VKA-experienced NVAF patients initiating a NOAC from 22 August 2011 to 31 December 2015 (shifters) and all VKA-experienced NVAF patients who were not switched to NOACs (non-shifters). Baseline characteristics and temporal utilization trends were examined. We included 62 065 patients with NVAF; of these, 19 386 (29.6%) shifted from a VKA to a NOAC (9973 (54.2%) shifted to dabigatran, 4775 (26.0%) to rivaroxaban, and 3638 (19.8%) to apixaban). Shifting was associated with lower age [odds ratio (OR) 0.95, 95% confidence interval (95% CI) 0.94-0.96 per 5 year increments], female gender (OR 1.33, 95% CI 1.28-1.38), and certain co-morbidities: more often stroke, bleeding, heart failure, and alcohol abuse, and less often hypertension, ischaemic heart disease, and diabetes. Shifting was common and initially dominated by shifting from VKA to dabigatran, but at the end of 2015, most shifters were shifted to rivaroxaban (45%) or apixaban (45%) whereas shifting to dabigatran decreased (to 10%). Conclusion: In a contemporary setting among VKA-experienced NVAF patients; VKA is still prevalent although about 30% by December 2015 had shifted to a NOAC.