Increased Risk of Stroke Due to Non-adherence and Non-persistence with Direct Oral Anticoagulants (DOACs): Real-World Analyses Using a Nested Case–Control Study from The Netherlands, Italy and Germany

Background: A high degree of adherence to direct oral anticoagulants is essential for reducing the risk of ischaemic stroke and systemic embolism in patients with atrial fibrillation, owing to the rapid decline in anticoagulation activity when doses are omitted (i.e. rebound effect). Objective: We aimed to assess the relationship between non-adherence and non-persistence with direct oral anticoagulants and the incidence of ischaemic stroke in patients with atrial fibrillation. Methods: A nested case–control study was conducted in the Netherlands, Italy and Germany among patients with atrial fibrillation starting direct oral anticoagulants between the drug approval date and the end of database availability. Patients with an ischaemic stroke during the follow-up were selected as cases and compared with matched controls (matched on age ± 5 years, sex, year of cohort entry date and CHA2DS2-VASc-score at cohort entry date). The cohort entry date was the first dispensing date. Study patients were those aged ≥ 45 years, with ≥ 1 year database history, ≥ 1 year follow-up and at least two direct oral anticoagulant dispensings after the cohort entry date. Adherence and persistence to direct oral anticoagulant treatment were defined as the proportion of days covered ≥ 80% or direct oral anticoagulant continuous use between the cohort entry date and the index date (i.e. date of ischaemic stroke), respectively. Results: In The Netherlands, Italy and Germany, 105 cases and 395 controls, 1580 cases and 6248 controls, and 900 cases and 3570 controls were included, respectively. Odds ratios (ORs) for stroke among current users who were non-adherent compared to adherent users were 0.43 (95% confidence interval [CI] 0.09–1.96) in The Netherlands, 1.11 (95% CI 0.98–1.26) in Italy and 1.21 (95% CI 1.01–1.45) in Germany. The risk of stroke was significantly higher among non-persistent users compared with persistent users in all three databases [OR 1.56 (95% CI 1.00–2.44), OR 1.48 (1.32–1.65) and OR 1.91 (95% CI 1.64–2.22), respectively]. In The Netherlands and Germany, the risk of stroke was higher the longer a patient had stopped using direct oral anticoagulants. Conclusions: Both non-adherence (in Germany) and non-persistence increased the risk of stroke, either using a once-daily or twice-daily regime.