Oral anticoagulants and outcomes in adults ≥80 years with atrial fibrillation: A global federated health network analysis

Background: The objective of this study was to determine associations between use of oral anticoagulation (OAC) and stroke and bleeding-related outcomes for older people ≥80 years with atrial fibrillation (AF), and to determine trends over time in prescribing of OAC for this population. 

Methods: A retrospective cohort study was conducted. People aged ≥80 years with AF receiving (1) no OAC; (2) warfarin; or (3) a non-vitamin-K antagonist oral anticoagulant (NOAC) between 2011 and 2019 were included. Propensity score matching was used to balance cohorts (no OAC, warfarin or a NOAC) on characteristics including age, sex, ethnicity, and co-morbidities. Cox proportional hazard models were used to derive hazard ratios (HRs) and 95% confidence intervals (CIs). 

Results: The proportion of people aged ≥80 years receiving any OAC increased from 32.4% (n = 27,647) in 2011 to 43.6% (n = 110,412) in 2019. After propensity score matching, n = 169,067 individuals were included in the cohorts receiving no OAC or a NOAC. Compared to no OAC, participants receiving a NOAC had a lower risk of incident dementia (hazHR 0.68, 95% CI 0.65–0.71), all-cause mortality (HR 0.49, 95% CI 0.48–0.50), first-time ischaemic stroke (HR 0.87, 95% CI 0.83–0.91), and a higher risk of major bleeding (HR 1.08, 95% CI 1.05–1.11). Compared to participants receiving warfarin, participants receiving a NOAC had a lower risk of dementia (HR 0.90, 95% CI: 0.86–0.93), all-cause mortality (HR 0.74, 95% CI: 0.72–0.76), ischaemic stroke (HR 0.86, 95% CI: 0.82–0.90) and major bleeding (HR 0.88, 95% CI: 0.85–0.90). Similar results were observed when only including people with additional bleeding risk factors. 

Conclusions: The proportion of people aged ≥80 years receiving OAC has increased since the introduction of NOACs, but remains low. Use of a NOAC was associated with improved outcomes compared to warfarin, and compared to no OAC, except for a small but statistically significant higher risk of major bleeding.