Discontinuation of non-Vitamin K antagonist oral anticoagulants in patients with non-valvular atrial fibrillation: a population-based cohort study using primary care data from The Health Improvement Network in the UK

Objective To determine discontinuation rates, patterns of use and predictors of discontinuation of non-vitamin K antagonist oral anticoagulants (NOACs) among patients with non-valvular atrial fibrillation (NVAF) in the first year of therapy. Design Population-based cohort study. Setting UK primary care. Population 11 481 patients with NVAF and a first prescription (index date) for apixaban, dabigatran or rivaroxaban (January 2012 to December 2016) with at least 1 year of follow-up and at least one further NOAC prescription in the year following the index date were identified. 1 year rates and patterns of discontinuation were described. Primary and secondary outcome measures Outcome measures were the percentage of patients who, in the first year from starting NOAC therapy, discontinued with their oral anticoagulant (OAC) therapy (discontinuation was defined as a gap in OAC therapy of >30 days); switched OAC within 30 days; discontinued and reinitiated OAC therapy. Predictors of discontinuation were also evaluated. Results 1 year discontinuation rates according to the index NOAC were 26.1% for apixaban, 40.0% for dabigatran and 29.6% for rivaroxaban. Reinitiation rates were 18.1% for apixaban, 21.7% for dabigatran and 17.3% for rivaroxaban, and switching rates were 2.8% for apixaban, 8.8% for dabigatran and 4.9% for rivaroxaban. More than 93% of reinitiations were with the index NOAC. Patients starting on dabigatran were more likely to switch OAC therapy than those starting on apixaban; ORs 4.28 (95% CI 3.24 to 5.65) for dabigatran and 1.89 (95% CI 1.49 to 2.39) for rivaroxaban. Severely reduced renal function was a predictor of any discontinuation, OR 1.77 (95% CI 1.28 to 2.44). Conclusion While the majority of patients with NVAF in the UK initiating NOAC treatment received continuous therapy in the first year of treatment, a substantial proportion of patients experienced gaps in treatment leaving them less protected against thromboembolism during these periods.