Anticoagulation and All-Cause Mortality in Adults Aged 80 Years and Older with Atrial Fibrillation: A Retrospective Cohort Study

BACKGROUND: The benefits and risks of anticoagulation therapy in patients aged ≥ 80 years with atrial fibrillation (AF) remain underexplored, as this population is underrepresented in randomized clinical trials. We evaluated mortality and bleeding outcomes associated with anticoagulation use in this population. DESIGN: We conducted a retrospective cohort study using MDClone, a synthetic electronic health record database from a large US health system, including 45,305 patients aged ≥ 80 years with AF after excluding those with mitral stenosis, mechanical heart valves, cirrhosis, or end-stage renal disease. Patients were categorized as continued, initiated, discontinued, or never anticoagulated. The primary outcome was all-cause mortality at 30 days, 6 months, 1 year, and 5 years; secondary outcomes were ischemic stroke, gastrointestinal bleeding (GIB), and intracranial hemorrhage (ICH). To address immortal time bias, the primary analysis used a time-varying Cox model, complemented by a 90-day landmark analysis and propensity score matching. KEY RESULTS: Patients who continued anticoagulation had lower 1-year mortality than those never anticoagulated (8.7% vs 17.7%; p < 0.001). In the time-varying Cox model, anticoagulation was associated with a 25% lower hazard of mortality (HR 0.75, 95% CI 0.71-0.79). Compared with continued anticoagulation, mortality was higher among patients who initiated (HR 1.51, 95% CI 1.38-1.66), discontinued (HR 1.64, 95% CI 1.49-1.81), or never received anticoagulation (HR 2.22, 95% CI 2.05-2.41), and persisted after propensity score matching. At 5 years, mortality converged across groups. GIB was more frequent in anticoagulated patients (continued 13.0%, initiated 11.9%), whereas ICH rates were low and comparable across groups (1.3-1.6%, p = 0.129). CONCLUSIONS: Among patients aged ≥ 80 years with AF, anticoagulation therapy was associated with lower all-cause mortality despite an increase in gastrointestinal bleeding. These findings support continued anticoagulation in appropriately selected elderly patients, rather than withholding therapy on the basis of age alone.